JP4505554B2 - Display device - Google Patents

Description

  The present invention relates to an illuminating device used for illumination of a display device that displays an image by adjusting the amount of transmitted light, and a display device using the illuminating device. In particular, even when the screen is enlarged, it is thin, lightweight, high brightness, and The present invention relates to an illumination device that can emit illumination light with high in-plane luminance uniformity, and a display device including the illumination device.

  Display devices are media that visually convey information to humans, and in today's modern information society, they are important for humans and society.

  Display devices are broadly classified into light-emitting display devices such as CRT (Cathode Ray Tube) and PDP (Plasma Display Panel), and non-light-emitting display devices such as liquid crystal display devices, ECD (Electrochromic Display), and EPID (Electrophoretic Image Display). And can be classified.

  Non-light-emitting display devices display images by adjusting the amount of light transmitted (or reflected), and among them, liquid crystal display devices have improved significantly in recent years, and are used as display devices for personal computers and the like. Increasingly adopted.

  Generally, a liquid crystal display device can be classified into a transmissive type and a reflective type. In a transmissive liquid crystal display device, an illuminating device is provided on the back of the liquid crystal panel, and the light emitted from the illuminating device increases the visibility of the display screen. Yes.

  Liquid crystal panels can be broadly classified into two types: active matrix driving liquid crystal panels using switching elements such as TFTs (Thin Film Transistors), and multiplex driving liquid crystal panels. Examples of liquid crystal panels driven by active matrix include TN (Twisted Nematic) liquid crystal panels and IPS (In Plan Switching) liquid crystal panels that realize a wide viewing angle. As a multiplex drive liquid crystal panel, there is an STN (Super Twisted Nematic) liquid crystal panel. In either case, a liquid crystal layer is held by a glass substrate, polarizing plates are arranged on both sides thereof, and display is performed by modulating the polarization state of linearly polarized light incident on the liquid crystal layer.

  Such a liquid crystal panel has a non-display portion (non-opening portion) such as an electrode, a switching element, or a pixel, which causes a reduction in display brightness.

  In addition, all the liquid crystal display devices have a problem that when a moving image is displayed, the image is blurred and deteriorated. This is said to occur because the liquid crystal display device is a so-called hold type display system that continuously displays the same image within one frame (Non-Patent Document 1). Here, one frame means one period of the video signal. The mechanism of the moving image deterioration due to the hold type display will be described as follows. That is, in a real image, for example, a moving object continues to move from moment to moment and does not stay in the same position. On the other hand, in the hold-type display, even if a moving object continues to be displayed at the same position for one frame, an image at the correct position is displayed at one moment of one frame, but at another moment. Images different from actual ones will continue to be displayed. The human eye averages and recognizes them, so the image is blurred.

  In order to solve this problem, it has been reported that an image is displayed only at the moment when the lighting device is blinked, and the blurring of the image due to the averaging as described above is eliminated and the image quality of the moving image is improved (Non-Patent Document). 2).

  On the other hand, as an illumination device, there are an edge light method (light guide method), a direct method (reflecting plate method), and a planar light source method (Non-patent Documents 3 and 4).

  Among these, the edge-light type and the direct type are mainly used for medium-sized and larger liquid crystal display devices.

  In the edge light system, a light guide made of a transparent material such as acrylic whose back surface is processed, a linear light source made of a fluorescent lamp, for example, disposed on the end surface of the light guide, and a surface of the light guide (light emitting surface) It consists of a diffuser plate. Light emitted from the fluorescent lamp (light source) enters the light guide and propagates through the light guide. The light propagating through the light guide changes its direction of travel due to the process applied to the back of the light guide, exits from the surface of the light guide, and after the angle distribution of the illumination light is made uniform by the diffuser, the liquid crystal panel display Irradiated to an illumination surface such as a part.

  In the direct type, the light source is placed directly under the illumination surface of the liquid crystal panel display, etc., and the transmittance is adjusted according to the distance from the light source in order to improve the uniformity of brightness at the lower part of the light source and the reflector above the light source. It has a configuration in which a changed light screen or diffuser plate is arranged. The light emitted from the light source is reflected directly or after being reflected by a reflector disposed below the light source, and then enters a light screen or a diffuser plate. The light quantity distribution and the angular distribution of illumination light are made uniform, and the liquid crystal panel display unit, etc. The illumination surface is irradiated.

  Further, in Patent Document 1, the surface on which the diffusion plate is disposed is a flat surface, the back surface forms an inclined surface, and a plurality of transparent light guides having a light shielding / reflecting portion are arranged on the inclined surface. An illuminating device having a configuration in which a light source is disposed at a position that is one end of a thick portion and is a light shielding and reflecting portion lower surface of an adjacent light guide is described. In the case of this configuration, of the light emitted from the light source, the light directly incident on the light guide is reflected by the light shielding / reflecting portion of the light guide and is emitted as illumination light through the diffusion plate. In addition, a part of the light emitted from the light source that is not directly incident on the light guide is reflected by the light shielding / reflecting portion disposed on the back surface of the adjacent light guide and then incident on the light guide to block the light. After being reflected by the cum reflecting portion, it is emitted as illumination light through the diffusion plate.

  In a liquid crystal display device provided with such an illumination device, most of the power consumption is the power consumption of the light source of the illumination device. Therefore, in order to reduce the power consumption or increase the brightness of the liquid crystal display device, the light source is used. It is necessary to increase the utilization efficiency of the emitted light. However, since the light emitted from the conventional illumination device is non-polarized light and 50% or more is absorbed by the polarizing plate of the liquid crystal panel, high light utilization efficiency cannot be expected.

  On the other hand, the polarizer described in Patent Document 2 uses a cholesteric liquid crystal layer having a Grand Jean structure and a mirror that reverses the rotational direction of circularly polarized light to specify light emitted from a non-polarized light source. A technique for efficiently converting to polarized light is disclosed. This polarizer is composed of a light source, a specular reflection mirror, a cholesteric liquid crystal layer, and a retardation plate (¼ wavelength plate) arranged in a laminated manner on the polarizer.

  The cholesteric liquid crystal layer exhibits unique optical properties based on a helical molecular arrangement. Light incident in parallel to the helical axis is circularly polarized in a rotational direction corresponding to the rotational direction of the spiral at a wavelength corresponding to the pitch of the cholesteric spiral. Indicates selective reflection in which the other is reflected and the other is transmitted.

  Therefore, for example, when the cholesteric liquid crystal layer transmits clockwise circularly polarized light (hereinafter, right circularly polarized light) and reflects counterclockwise circularly polarized light (hereinafter, left circularly polarized light), the light emitted from the non-polarized light source Of these, the right circularly polarized light component is transmitted through the cholesteric liquid crystal layer and the left polarized light component is reflected. The light transmitted through the cholesteric liquid crystal layer is converted into desired linearly polarized light by the action of the retardation plate. On the other hand, the left circularly polarized light reflected by the cholesteric liquid crystal layer is reflected by the specular reflection mirror and travels again to the cholesteric liquid crystal layer. Therefore, this time, the light passes through the cholesteric liquid crystal layer and is converted into the desired linearly polarized light by the action of the retardation plate. That is, all the light emitted from the light source ideally becomes right circularly polarized light, passes through the cholesteric liquid crystal layer, and can be converted into desired linearly polarized light by the action of the retardation plate. It is possible to effectively use the light that has been absorbed and wasted.

Ishiguro et al, IEICE Technical Report, EID96-4, pp. 19-26 (1996) K. Sueoka et al, IDRC '97 pp 203-206 (1998) Liquid crystal display technology p252-256 Sangyo Tosho Co., Ltd. Issued November 8, 1996 Full color liquid crystal display technology p201-202 Trikeps Co., Ltd. Issued February 26, 1990 Japanese Utility Model Publication No. 63-21906 Japanese Patent No. 2,509,372

  The edge light type illumination device has high brightness uniformity, can be reduced in thickness to the diameter of a light source (fluorescent lamp), and has a feature that heat is not easily transmitted to the liquid crystal. For this reason, this method is employed in notebook personal computers that are particularly required to be thin. However, the utilization efficiency of the light source light is lower than that of the direct system, which is disadvantageous for increasing the brightness. Further, in order to make the edge light type illumination device correspond to a large screen exceeding 20 inches diagonally, it is necessary to increase the number of light sources and to increase the thickness of the light guide. In this case, by arranging a plurality of light sources on one end face of the light guide, the incident efficiency of the light source light to the light guide is reduced, the use efficiency of the light source light is further reduced, and the thickness of the light guide Due to the increase, there is a problem that the volume increases and the weight increases.

  On the other hand, direct-type lighting devices can be realized by an easy method such as increasing the number of light sources to cope with an increase in screen size, and by using an appropriate optical design, high brightness can be obtained and the light source light utilization efficiency is also improved. Higher than the light guide system. However, the thickness of the illuminating device needs to be several times the size of the light source (for example, the fluorescent lamp diameter) and cannot be thinned, and there is a problem that the in-plane uniformity of luminance is not as good as the edge light method.

  Further, in the illumination device described in Japanese Utility Model Publication No. 63-21906, the light guide is divided into a plurality of required sizes, and a light source is disposed in each of the light guides. Even when the illumination area is large, it is possible to obtain uniform illumination light than the direct type, and even if the area of the illumination surface is increased, the overall thickness is reduced by increasing the number of divided light guides. It can be made.

  However, in the illumination device of the above publication, there is no description about the coupling portion of the plurality of light guides. However, when the plurality of light guides are simply arranged, the emission angle distribution of the illumination light and the luminance at the joint of the light guides There is a problem in that the distribution is different and it is actually difficult to obtain uniform illumination light over the entire light exit surface of the illumination device. Further, in the above configuration, a part of the light emitted from the light source directly enters the light guide, and the other part is also reflected by the light shielding / reflecting portion disposed on the back surface of the adjacent light guide and enters the light guide. However, since there is no way for other light to enter the light guide, there is a problem in that the light source light cannot be used effectively and the use efficiency of the light source light is low.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a lighting device that is thin and lightweight even when applied to a large-screen liquid crystal panel, has high luminance, and high in-plane uniformity of luminance. is there.

  Further, as described above, the liquid crystal panel has non-opening portions that do not contribute to display such as electrodes, switching elements, or pixels, and these non-opening portions contribute to a decrease in brightness of the liquid crystal panel. In the case of an active matrix driven liquid crystal panel, in particular, most of the non-opening is a metal electrode, so that light incident on the non-opening is reflected and returned to the lighting device. For example, in the case of a direct illumination device, the light returned to the illumination device is reflected by a diffusion plate, an optical screen, or a reflection plate, and is irradiated again to the liquid crystal panel. However, the light re-irradiated to the liquid crystal panel is depolarized or the polarization state is changed by a diffusion plate or the like, so that more than 50% of the light is absorbed again by the polarizing plate disposed on the light incident side of the liquid crystal panel. Therefore, it hardly contributed to the brightness.

  Therefore, another object of the present invention is to irradiate the liquid crystal panel with the reflected light from the non-opening portion of the liquid crystal panel again while maintaining the polarization, even if the liquid crystal panel has a low aperture ratio at the same time as achieving the above object. It is an object of the present invention to provide an illumination device that effectively uses light and a liquid crystal display device using the same.

  It is another object of the present invention to provide a liquid crystal display device that is brighter and consumes less power by converting light emitted from the light source of the illumination device into desired polarized light and reducing light absorption in the liquid crystal panel.

  By the way, as described above, there is a method of blinking the illumination device as a method of suppressing the deterioration of the moving image of the liquid crystal display device which is a hold type display method. However, in this method, it is necessary to significantly increase the scanning time and the response time of the liquid crystal in order to turn on the illumination device after the entire surface of the liquid crystal panel is scanned and the liquid crystal on the entire surface of the liquid crystal panel responds. Further, since the lighting time of the lighting device is short, it is necessary to increase the emission intensity in order to achieve the same luminance as the conventional one.

  The present invention has been made in view of the actual situation, and an object of the present invention is to provide a high-brightness liquid crystal display device that can display a moving image without a sense of incongruity by providing an illumination device that can divide and illuminate the display surface independently. It is in.

  Other objects of the present invention will become clear from the following description of the embodiments.

  The gist of the present invention for solving the above problems is as follows.

  The display device of the present invention illuminates a plurality of illumination regions in which the display surface of the liquid crystal panel is divided by individually controlling the liquid crystal panel, the illumination device having the plurality of unit illumination devices, and the plurality of unit illumination devices. A unit lighting device having at least a pair of opposed end portions with a light guide made of a plate-like transparent body, and a pair of end portions with different thicknesses of the light guide, The light guide is composed of a light source arranged close to the end with the larger thickness, and the light guide is on the irradiation target side of the light guide at the end with the larger thickness among the pair of ends with different thicknesses. The protrusion has a protrusion whose width on the back surface side is larger than the width on the front surface side, and the protrusion has a structure in which light of the light source incident from the end surface propagates while repeating total reflection, and a plurality of light guides The body has a pair of ends with different thicknesses, one with the smaller thickness and the other with the larger thickness. The end portions are aligned and arranged so that the protruding portions are arranged on the back surface side of the adjacent light guide, and the light source is located near the end surface of the protruding portion, and the back surface of the adjacent light guide body Further, the optical member is arranged at a position on the side, and further includes an optical member that guides light emitted from the light source to the end face of the light guide in the vicinity of the light source or the light source.

  As described above, according to the present invention, it is possible to realize an illuminating device that emits illumination light that is thin and lightweight, has high luminance, and has a uniform in-plane luminance distribution even when the size is increased (large screen).

  Therefore, in the display device using the lighting device of the present invention, the luminance of the lighting device does not decrease and the thickness does not increase even when the screen size increases. A display device capable of obtaining a uniform high-quality display can be realized.

  Further, when a liquid crystal panel is used as a display panel, there is a display device that can obtain a brighter display by efficiently reusing reflected light from the non-opening portion of the liquid crystal panel even when the aperture ratio of the liquid crystal panel is low. realizable.

  Furthermore, the illumination device of the present invention can efficiently irradiate the liquid crystal panel after converting the non-polarized light emitted from the light source into the desired linearly polarized light, so that the light utilization efficiency is increased, and a bright display can be obtained with low power consumption. A display device can be realized.

  Further, by controlling the blinking of a plurality of light sources constituting the illumination device and independently illuminating the liquid crystal panel, the moving image can be displayed without a sense of incongruity, and a bright liquid crystal display device can be realized.

  Hereinafter, embodiments of the present invention will be described based on some examples with reference to the drawings.

Example 1
FIG. 1 is a partial schematic cross-sectional view showing an example of a lighting device of the present invention and a display device using the same. This display device includes a liquid crystal panel 200 that displays an image by adjusting the amount of transmitted light and a lighting device 100 disposed on the back surface of the liquid crystal panel 200.

  As the liquid crystal panel 200, a display panel that displays an image by adjusting the amount of transmitted light that is incident can be used, and in particular, a liquid crystal panel that can display a matrix with a long lifetime can be used.

  Display modes of the liquid crystal panel 200 include a GH (Guest Host) mode, a PC (Phase Change) mode, a TN (Twisted Nematic) mode, an STN (Super Twisted Nematic) mode, an ECB (Electrically Controlled Birefringence) mode, and a PDLC (Polymer Dispersed Liquid). Crystal) mode can be used, but as a display mode in which a high contrast ratio can be obtained with a low driving voltage, a polarizing plate is used, and a mode in which display is performed by modulating the polarization state of light incident on the liquid crystal layer is used. Is desirable for realizing a display device with good image quality.

  The liquid crystal panel 200 is roughly divided into two types, an active matrix driving liquid crystal panel using a switching element such as a TFT (Thin Film Transistor) and a multiplex driving liquid crystal panel, and polarization of light incident on the liquid crystal layer. Active matrixes such as TN (Twisted Nematic) liquid crystal panels, IPS (In Plane Switching) liquid crystal panels that realize a wide viewing angle, and MVA (Multi-domain Vertical Aligned) liquid crystal panels A liquid crystal panel by driving or a multiplex driving liquid crystal panel such as an STN (Super Twisted Nematic) liquid crystal panel can be used.

  Here, the case of a TN liquid crystal panel will be described below, but the present invention is not limited to this.

  The liquid crystal panel 200 includes a first transparent glass substrate 204 on which a color filter, a transparent electrode, and a light distribution film (not shown) are stacked, a light distribution film (not shown), a transparent electrode that forms a pixel, and an electrode connected thereto. And a second transparent glass substrate 202 having a switching element such as a thin film transistor and a nematic having a positive dielectric anisotropy sealed between the two transparent glass substrates 204 and 202 via a frame-shaped sealant 203 And a liquid crystal layer 208 made of liquid crystal. The direction of the major axis of the liquid crystal molecules of the liquid crystal layer 208 is determined by performing an alignment treatment such as rubbing on the alignment film formed on the two transparent glass substrates 204 and 202, and is continuous between the transparent glass substrates. 90 degrees twisted. A polarizing plate 201 and a polarizing plate 205 are arranged on the illumination light incident surface of the transparent glass substrate 202 and the light output surface of the transparent glass substrate 204 so as to transmit linearly polarized light orthogonal to each other. The alignment direction of the major axis of the liquid crystal molecules on the substrate 204 is configured to be both parallel or orthogonal to the transmission axes of the linearly polarized light of the polarizing plate 201 and the polarizing plate 205.

  As the polarizing plates 201 and 205, for example, those obtained by absorbing iodine in stretched polyvinyl alcohol and imparting a polarizing function to both surfaces of the film can be used. The transparent glass substrate 204 is bonded so as to be optically bonded with an acrylic adhesive.

  With the above configuration, linearly polarized light transmitted through the polarizing plate 201 out of light incident from the back surface of the liquid crystal panel 200 passes through the liquid crystal layer 208 and enters the polarizing plate 205. At this time, the light transmitted through the liquid crystal layer 208 is transmitted. The polarization state can be changed by a voltage applied to the liquid crystal layer 208. Therefore, a voltage corresponding to the image information is applied to the transparent electrodes on the transparent glass substrates 202 and 204, and an electric field is applied to the liquid crystal layer 208, thereby changing the polarization state of the light passing through the liquid crystal layer 208 and polarizing plate 205. An optical image can be formed by controlling the amount of light transmitted through the light.

  Next, the illumination device 100 will be described. The lighting device 100 is arranged on each of a plurality of light guides 103 (103a, 103b, 103c in the figure) arranged in alignment and one side surface (end surface) of the plurality of light guides 103, and the length of the side surface (end surface). A plurality of light sources 101 (101a, 101b, 101c in the figure) having a light emission length corresponding to the above and a plurality of lamp covers 102 arranged so as to cover portions of the plurality of light sources 101 excluding the direction of the light guide 103 (FIG. 102 a, 102 b, 102 c) and a plurality of reflectors 104 (104 a, 104 b, 104 c in the figure) respectively disposed on the back surfaces (surfaces opposite to the liquid crystal panel 200) of the light guides 103 via air layers. 104c) and a diffusion plate 105 disposed on the surface (surface on the liquid crystal panel 200 side) side of the plurality of light guides 103 (103a to 103c) so as to cover the entire surface thereof. It is.

  That is, the lighting device 100 includes a light guide 103, a light source 101 disposed on one side surface (end surface) of the light guide 103, a lamp cover 102, and a reflector 104 disposed on the back surface of the light guide 103. A plurality of unit illumination devices 1000 (1000a, 1000b, and 1000c in the figure) are arranged and arranged, and the diffusion plate 105 is arranged on the surface side so as to cover the entire surface.

  Here, in order to increase the uniformity of the in-plane luminance distribution of the illumination light from the illumination device 100, the unit illumination device has a high uniformity of the in-plane luminance distribution of the illumination light of each unit illumination device. It is important that the in-plane luminance distribution of illumination light obtained when a plurality of unit lighting devices are arranged in a line is also highly uniform.

  In order to realize this, the lighting device according to the present invention has substantial steps and seams on the surface side (liquid crystal panel 200 side) of the plurality of light guides constituting the unit lighting device when a plurality of unit lighting devices are arranged and arranged. It was configured to be eliminated.

  That is, when the light guide constituting the unit lighting device is composed of a pair of plate-like transparent bodies having different thicknesses of facing end faces, when arranging a plurality of light guides in an aligned manner, the end face having a large thickness and the thickness are arranged. Join the end face with a small diameter. In addition, the light source is disposed at a position close to the end face having the larger thickness among a pair of facing end faces having different thicknesses of the light guide and serving as the back face of the adjacent light guide. In this way, the light source does not become an obstacle when aligning and arranging a plurality of light guides, so that the plurality of light guides can be aligned and arranged without a step or gap on the surface side.

  Further, the joints between the light guides are connected so as to be optically coupled. Here, the optical coupling means that the refractive index difference at the interface is substantially eliminated by filling the interface between the light guides with a transparent body having substantially the same refractive index as the transparent body constituting the light guide. For example, it can be realized by adhering the light guides with an acrylic adhesive.

  According to this configuration, there is no step on the surface side (liquid crystal panel 200 side) between the light guides constituting the unit lighting device, and the seam is optically eliminated, so that a lighting device with a more uniform in-plane luminance distribution can be realized. .

  Next, the unit lighting device constituting the lighting device 100 will be described more specifically. FIG. 2 is a perspective view showing an outline of the unit lighting device 1000 constituting the lighting device 100.

  The unit illumination device 1000 is disposed on the light guide 103, one side surface (end surface) 1031 of the light guide 103, and has a light source 101 having a light emission length corresponding to the length of the side surface (end surface), and the light guide body of the light source 101. The lamp cover 102 is disposed so as to cover a portion excluding the end surface direction 103, and the reflector 104 is disposed on the back surface of the light guide 103 (the surface opposite to the liquid crystal panel 200) via an air layer. As described above, the light guide body 103 is composed of a plate-like transparent body having a rectangular cross-sectional shape with different thicknesses at the pair of opposed end faces 1031 and 1032. The light source 101 is located near the end face 1301 having the larger thickness among a pair of opposite end faces with different thicknesses of the light guide 103. It is arranged at a position where it does not become, that is, a lower region of the end surface 1031 (region opposite to the liquid crystal panel 200).

  As the light source 101, a light source that satisfies the conditions such as small size, high luminous efficiency, and low heat generation may be used. For example, a fluorescent lamp such as a cold cathode tube or a hot cathode tube, or a plurality of LEDs (Light Emitting Diodes) arranged in an array is used. can do. Here, the case where a cold cathode fluorescent lamp having a tube diameter of 2.6 mm is used will be described. As the cold cathode fluorescent lamp used here, a so-called three-wavelength tube having an emission peak wavelength corresponding to the transmission spectrum of the color filter of the liquid crystal panel 200 may be used. For example, the emission peak wavelengths are 453 nm, 544 nm, and 611 nm. The cold cathode fluorescent lamp which has can be used.

  Here, as described above, the light source 101 is disposed in the lower region of the end face 1031 of the light guide 103. This is because when a plurality of unit lighting devices 1000 are arranged and arranged, the unit lighting devices adjacent to each other in order to eliminate joints between the plurality of light guides and steps on the light guide surface side (liquid crystal panel 200 side). It is for enabling it to arrange | position to the back surface side of the light guide which comprises this.

Therefore, when the size of the light source (here, the diameter of the cold cathode fluorescent lamp) is d and the thicknesses of the end face 1031 and the end face 1032 of the light guide 103 are t ₁ and t ₂ , respectively, the following relationship is satisfied. desirable.

t ₁ > d + t ₂ (Expression 1)
Further, in order to increase the incident efficiency of the light emitted from the light source 101 to the light guide body 103, it is desirable that the size of the light source light emitting portion is smaller than the cross-sectional area of the end surface 1301 on the light source side of the light guide body.

FIG. 3 shows the effective thickness t (= t ₁ -t ₂ ) of the light source side end face of the light guide when illumination tube having a tube diameter of 2.6 mm is used as the light source and the illumination light emitted from the light guide It is a figure which shows an example of the relationship with a brightness | luminance. As is clear from FIG. 3, the brighter illumination light is obtained as the effective thickness of the end face of the light guide is larger than the tube diameter of the light source. However, when the light guide is thickened, there is a problem that the thickness and weight of the lighting device increase. Therefore, considering that the effective thickness of the end face of the light guide is about 1.2 to 1.5 times the diameter of the light source tube and the increase in luminance of the illumination light is saturated, the size of the light source (here, the cold cathode fluorescent lamp) It is more desirable that the diameter d), the thickness t ₁ of the end face 1031 of the light guide, and the thickness t ₂ of the end face 1032 satisfy the following relationship.

1.5 * d> t ₁ −t ₂ > 1.2 * d (Equation 2)
Here, t ₁ = 4.5 mm, t ₂ = 1 mm, and the center position of the light source 101 is arranged at a height of 1.75 mm from the back surface of the light guide.

  The lamp cover 102 is used for efficiently allowing the light emitted from the light source 101 to enter the light guide 103. The lamp cover 102 covers the light source 101 around the light source 101 except for the end surface portion of the light guide 103. A reflective plate or a reflective film having a shape having an opening in a part of a cylindrical shape or an elliptical cylindrical shape arranged with a gap can be used.

  Specifically, the lamp cover 102 is formed by depositing a metal thin film layer such as silver or aluminum on the surface of a polymer film by vapor deposition or sputtering, and laminating it on a support plate such as a polymer film sheet or aluminum plate. Can be used. Here, a PET (polyethylene terephthalate) sputtered with silver was bonded to an aluminum plate having a thickness of 0.2 mm and molded.

  The reflecting plate 104 is disposed so as to cover the entire back surface of the light guide 103 and has a function of reflecting light from the back of the light guide 103 toward the light guide 103. As the reflection plate 104, a reflection surface having a high reflectance formed on a support substrate such as a glass plate, a metal plate, a resin plate, or a polymer film can be used. The reflective surface is formed by depositing a metal thin film with high reflectivity such as aluminum or silver on the support substrate by vapor deposition or sputtering, or a dielectric multilayer film so as to be an increased reflection film on the support substrate. Or a support substrate coated with a white pigment can be used. Moreover, you may use what was made to function as a reflecting plate by laminating | stacking multiple layers of transparent media from which a refractive index differs.

  Here, in order to reduce the size and weight of the apparatus, a PET (polyethylene terephthalate) film was used as the support base and a silver metal thin film was used as the reflecting surface.

  As described above, the light guide body 103 is composed of a plate-like transparent acrylic resin having different thicknesses at the end face 1031 and the end face 1032 facing each other, and confines the light incident from the end face 1031 inside by total reflection; A structure having a structure in which the reflection angle of light propagating through the inside is changed and light is emitted to the liquid crystal panel 200 side is used.

  Here, a structure having a structure in which the reflection angle of light propagating inside the light guide is changed and light is emitted has a large number of fine inclined surfaces formed on the back surface side (opposite side of the liquid crystal panel 200) of the light guide. A surface that is realized by a concavo-convex surface or a minute inclined reflecting surface constituted by steps is used.

  FIG. 4 is a partial cross-sectional view showing an example of the light guide 103. The light guide 103 illustrated in FIG. 4 has a surface 103C that is a flat surface, a back surface that is a substantially flat main surface 103B, and a flat minute inclined reflective surface 103A formed on one side of a plurality of triangular grooves. Consists of. The main surface 103B on the back surface of the light guide body 103 is configured to be emitted from the light source 101, propagate the light 300 incident on the light guide body with the surface 103C of the light guide body by total reflection, and confine it inside. Further, the minute inclined reflecting surface 103A on the back surface of the light guide 103 has a function of emitting a part of the light propagating in the light guide 103 from the surface 103C of the light guide 103 by changing the reflection angle. The minute inclined reflecting surface 103A may be configured as a mirror reflecting surface by a metal thin film such as aluminum or silver, or a dielectric multilayer film. However, even if a reflecting surface is not formed by adding a special reflecting member, The function can be sufficiently achieved by reflection due to the difference in refractive index from the acrylic resin.

  Here, an acrylic resin having a refractive index of 1.49 is used as the light guide 103, and the minute inclined reflective surface 103A on the back surface of the light guide is formed so that its long axis direction is parallel to the long axis direction of the light source 101, The average pitch P of the minute inclined reflecting surface 103A is 200 μm, the average height h is 10 μm, and the average inclination angle θ with respect to the surface 103C of the light guide 103 is 40 °.

  Further, by inclining the main surface 103B on the back surface of the light guide body 103 with respect to the surface 103C of the light guide body 103, the thickness of the end surface 1031 on the light source 101 side of the light guide body 103 is increased. It comprised so that thickness might become thin.

  The height h of the inclined reflecting surface 103A is continuously changed so as to be low near the light source 101 and high in a place far from the light source 101, or the pitch P or the inclination angle θ of the inclined reflecting surface 101A is changed. Or the thickness of the light guide 103, that is, the distance between the front surface 103C of the light guide and the main surface 103B of the back surface is reduced nonlinearly according to the distance from the light source. It is preferable to improve the uniformity of the light emitted from the light guide 103 by configuring it. At this time, when a plurality of light guides are joined, light propagating from the adjacent light guides is also taken into consideration so that the in-plane uniformity of luminance is increased.

  Further, in order to effectively use the light incident on the light guide body 103, the front and back surfaces of the light guide body 103, the end face 1031 on the light source side, and the side face (end face) excluding the end face 1032 facing this, It is preferable to form a reflection surface (not shown) so that the light incident on the light guide does not leak.

  According to this configuration, the outgoing light 300 from the light source 101 incident on the light guide 103 propagates between the surface 103C of the light guide 103 and the main surface 103B on the back of the light guide while repeating total reflection. Of the light propagating through the light guide, the light reaching the inclined reflection surface 103A changes its reflection angle and exits from the total reflection condition on the light guide surface 103C. The light emitted from the light guide 103 becomes light having a spread in the longitudinal direction (ridge line) of the inclined portion of the triangular groove forming the inclined reflecting surface 103A, but the direction perpendicular to the longitudinal direction of the inclined reflecting surface 103A. Substantially parallel light having a half-value angle of about ± 10 ° is obtained.

  The shape of the light guide 103 is not limited to this shape as long as the above functions are satisfied. As illustrated in FIG. 5 or FIG. 6, the back surface of the light guide 103 enters the light guide between the front surface 103C. The main surface 103B that has a structure for propagating and confining light by total reflection and a plurality of minute inclined reflecting surfaces 103A may have a fine continuous waveform or a stepped structure.

  The diffusion plate 105 is disposed so as to cover the entire surface of the light guides 103 (103a to 103c) of the plurality of unit lighting devices 1000 (1000a to 1000c) (surface on the liquid crystal panel 200 side).

  The diffusion plate 105 changes the angular distribution of the light emitted from the light guide 103 (103a to 103c) and the luminance distribution to change the angular distribution of the illumination light irradiated on the liquid crystal panel 200 and the uniformity of the in-plane luminance distribution. It has a function to enhance.

  As the diffusion plate 105, a surface of a transparent polymer film such as PET or PC (polycarbonate) formed with irregularities, or fine particles having a refractive index different from that of the transparent body are mixed on the surface of the polymer film. A film in which a diffusion layer is formed, a film in which air bubbles are mixed into the film to impart diffusibility, or a milky white member in which a white pigment is dispersed in a transparent member such as acrylic can be used.

  Note that the change in the in-plane luminance distribution of the illumination light at the joint where the unit illumination devices are joined becomes less visible as the distance between the diffusion plate 105 and the light guide surface increases. Specifically, although depending on the diffusibility of the diffusion plate 105, the distance between the diffusion plate 105 and the surface of the light guide 103 is 0.1 mm to 15 mm as long as the diffusion plate has a realistic transmittance that does not reduce the efficiency. If it is about, the change of the in-plane luminance distribution of the illumination light at the joint where the unit lighting devices are joined cannot be visually recognized, and the illumination light with higher uniformity of the in-plane luminance distribution can be obtained.

  Even if the diffuser plate 105 is not provided, it is not always necessary to dispose the diffuser plate 105 if the angular distribution of illumination light and the uniformity of the in-plane luminance distribution are high, but it is usually necessary.

  Next, the operation of this display device will be described. The light emitted from the light source 101 (101a to 101c) enters the light guide 103 (103a to 103c) directly or after being reflected by the lamp cover 102 (102a to 102c). The light that has entered the light guide 103 (103a to 103c) propagates while repeating total reflection in the light guide. Of the light that propagates in the light guide, the light that reaches the inclined reflection surface on the back of the light guide is The reflection angle changes, and the light guide body emits light out of the total reflection condition. The light emitted from the light guide 103 (103a to 103c) is irradiated on the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105.

  The amount of light applied to the liquid crystal panel 200 is controlled according to image information, and an image is displayed.

  Here, in the illumination device of the present invention, the width of the light guide, that is, the distance between the light source side end surface of the light guide and the end surface facing the light guide can be set to be short regardless of the size of the liquid crystal panel display unit. it can. In general, when the width of the light guide is shortened, it becomes easier to increase the uniformity of the in-plane luminance distribution of the illumination light, and the brightness of the illumination light emitted from one light guide can be increased. .

  That is, if the luminance of the illumination light per unit illumination device is increased by reducing the width of the light guide, an illumination device that emits light with higher luminance and high uniformity of in-plane luminance distribution can be realized.

  Further, in a state in which the plurality of unit lighting apparatuses 1000 are arranged, that is, as the lighting apparatus 100, there is no step on the surface side of the plurality of light guides constituting the unit lighting apparatus 1000 (1000a to 1000c), and the joint is optical. Therefore, it is possible to obtain illumination light with high luminance in-plane uniformity.

  Further, since the screen size can be increased by increasing the number of unit lighting devices, the thickness of the lighting device does not increase.

  Accordingly, the lighting device of the present invention is thin and light even when a large size (large screen) is achieved by arranging and arranging a plurality of unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector. Illumination light with high brightness and uniform in-plane brightness distribution can be emitted. Further, by using this lighting device, a display device can be realized that is thin and light, has a high luminance, and has a uniform in-plane luminance distribution.

  In addition, when using the illuminating device which concerns on a present Example, it is desirable to set it as the structure shown in FIG. 7 for the following reasons. FIG. 7 is a schematic perspective view showing the illumination device of the present embodiment and a display device using the same. When the light guide according to the present embodiment does not form a special reflective surface such as a metal thin film on the minute inclined reflective surface, the direction in which the luminance of the illumination light emitted from the light guide is highest is the surface normal direction of the light guide The direction is tilted several degrees from. That is, as shown in FIG. 7, the positional relationship between the light guide and the light source constituting the unit illumination device is such that the light source is positioned below the display surface with respect to the light guide to which the light emitted from the light source is to enter. When arranged, the direction in which the display luminance is highest is a direction inclined 5 to 10 ° upward with respect to the display surface normal line 200A. In general display devices, especially computer monitors, there is almost no observation from below, and there is a need for improved visibility from above. It is very effective in distributing. That is, in the present embodiment, limited light can be effectively distributed and used efficiently.

  In the present embodiment, the case where the number of unit lighting devices is three is shown. However, the present invention is not limited to this, and the number of unit lighting devices can be arbitrarily increased to cope with a wide range of screen sizes. Needless to say.

  Further, in the above embodiment, the case where a minute inclined reflecting surface is formed as the structure of the back surface of the light guide has been described. However, the back surface of the light guide may be formed by patterning a diffuse reflecting surface with white pigment ink or the like. good. At this time, the area ratio of the diffuse reflection surface is preferably changed in accordance with the distance from the light source 101 in order to make the amount of light irradiated to the liquid crystal panel uniform.

  In this case, the same effect as in the above embodiment can be obtained.

  In other words, by arranging multiple unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector, they are thin and have a uniform in-plane luminance distribution even when the size is increased (large screen). Thus, a lighting device that emits light with high luminance can be realized, and a display device that can display a high-quality display with higher brightness and in-plane uniformity of luminance can be realized.

(Example 2)
FIG. 8 is a partial schematic sectional view showing another embodiment of the illumination device and display device of the present invention. This embodiment is obtained by modifying a part of the above-described embodiment. The same reference numerals are given to portions having the same functions as those in the above-described embodiment, and detailed description of the same portions is omitted.

  In the above embodiment, the plurality of light guides constituting the unit lighting device are optically coupled. However, in this embodiment, the light guide body that forms the unit lighting device from the beginning is integrally formed. A light body is used.

  FIG. 9 is a perspective view of the light guide of this embodiment. As shown in FIG. 9, if the light guide body 103 in which a plurality of light guide bodies are integrally formed from the beginning is used, the steps on the surface side of the plurality of light guide bodies and the joints that should realize the unit lighting device are completely formed. Therefore, illumination light with a more uniform in-plane luminance distribution can be obtained. Furthermore, since the number of parts is reduced, it is possible to expect an effect that productivity is increased and costs are reduced.

(Example 3)
Next, another embodiment of the illumination device and the display device according to the present invention will be described with reference to the drawings.

  10 is a partial schematic cross-sectional view showing another embodiment of the illumination device and display device of the present invention, FIG. 11 is a partial schematic cross-sectional view of the illumination device 100 of this embodiment, and FIG. 12 is this embodiment. It is a schematic perspective view of the light guide which comprises the unit illuminating device 1000 of this.

  In the present embodiment, a part of the lighting device 100 described in the first embodiment is modified, parts having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and detailed description of the same parts is omitted. To do.

  As shown in FIG. 10 and FIG. 11, the present embodiment is a lighting device described in the first embodiment (FIG. 1), and a plurality of light guides 103 (103 a to 103 c) constituting the unit lighting device 1000 (1000 a to 1000 c). ) Where the light source light is incident protrudes from the light guide joint portion, and the protrusion 103L and the light source 101 (101b, 101c) are arranged on the back surface of the adjacent light guide.

  Therefore, as shown in FIG. 12, the light guide 103 constituting the unit illumination device 1000 has a width Lr on the back side (the side opposite to the liquid crystal panel 200) longer than a width Ls on the front side (the liquid crystal panel side). Thus, a step is formed between the end surface 10311 on which the light source light of the light guide 103 is incident and the joint end surface 10312 between the adjacent light guides.

  The protrusion 103L of the light guide 103 has a substantially flat surface both on the front surface and the back surface, and has a structure in which light source light incident from the end surface 10311 propagates while repeating total reflection. Further, the portion excluding the protruding portion 103L is a flat surface as in the light guide described in the first embodiment (FIGS. 4 to 6), and a plurality of minute inclined reflective surfaces are formed on the back surface. Is done.

  Here, in general, the amount of illumination light emitted from the light guide increases in the portion close to the light source, which may be an obstacle to achieving uniform in-plane distribution of luminance. In this embodiment, the light source adjacent to the light source that causes this uneven luminance distribution is projected and disposed on the back surface of the adjacent light guide so that the actual illumination has high in-plane luminance uniformity. By using only the portion, illumination light with higher uniformity of in-plane luminance distribution is obtained.

  As described above, the light source 101 and the protrusion 103L of the light guide 103 are disposed on the back surface of the adjacent light guide. This is because when a plurality of unit lighting devices 1000 are arranged and arranged, the seams of the plurality of light guides and the step on the light guide surface side (the liquid crystal panel 200 side) are eliminated, and the light source is actually illuminated by the light guides. This is because a more uniform illumination light can be obtained by separating from the portion that contributes to.

Here, even if the light guide body 103 has the light source 101 disposed on the back surface of the adjacent light guide body, in order to prevent a step on the light guide body surface side (the liquid crystal panel 200 side), light source light is incident. The thickness of the end face 1032 facing this is made thinner than the thickness on the side. That is, the main surface of the back surface of the light guide 103 is inclined with respect to the surface of the light guide 103. When the inclination angle in the vicinity of the end surface 10312 is β, when the thickness of the end surface 10312 and the end surface 1032 is t ₁₃ and t ₂ , and the protrusion length of the protrusion 103L is L ₁ , the light guide surface side (liquid crystal In order to prevent a step from occurring at the joint between the light guides on the panel 200 side), it is desirable to satisfy the following relationship.

t ₁₃ > L ₁ * tan β + t ₂ (Equation 3)
Further, in order to increase the incident efficiency of the light emitted from the light source 101 to the light guide 103, the brighter illumination light is obtained as the thickness of the end face 10311 is larger than the tube diameter of the light source. However, when the light guide is thickened, there is a problem that the thickness and weight of the lighting device increase. In view of the fact that the effective thickness of the end face of the light guide is about 1.2 to 1.5 times the diameter of the light source tube and the increase in luminance of the illumination light is saturated, the size of the light source (here, the cold More preferably, the diameter (d) of the cathode fluorescent lamp (d) and the thickness t ₁₂ of the end face 10311 of the light guide satisfy the following relationship.

1.5 * d> t ₁₂ > 1.2 * d (Equation 4)
Here, a fluorescent lamp having a tube diameter d = 2.6 mm is used as the light source 101, t ₁₂ = 3.5 mm, t ₁₃ = 1.5 mm, t ₂ = 1 mm, and the center position of the light source 101 is the back surface of the light guide. It arrange | positioned so that it might be located in height 1.75mm from.

Although the increased uniformity of the in-plane luminance distribution of the illumination light emitted from the projection length L ₁ is longer light guide protrusions 103L, equal protruding length L ₁ is the illuminating device is thickened longer This causes a problem that the apparatus becomes large. For this reason, in this embodiment, in view of the fact that the in-plane luminance uniformity is almost saturated if L ₁ = 8 mm or more, L ₁ = 8 mm is set here.

  According to this configuration, the light emitted from the light source 101 entering the light guide 103 passes through the protrusion 103L of the light guide 103 while repeating total reflection, and further propagates through the light guide. Of the light propagating through the light guide, the light reaching the minute inclined reflective surface on the back surface of the light guide changes its reflection angle and is emitted from the surface of the light guide.

  At this time, the illumination light that is emitted from the light guide and actually contributes to the illumination of the liquid crystal panel has a high luminance near the light source and does not include a portion with a nonuniform luminance distribution. Illumination light is obtained.

  The light emitted from the light guide is irradiated to the liquid crystal panel 200 after the angle distribution of the illumination light and the in-plane luminance distribution are made uniform by the diffusion plate 105.

  The amount of light applied to the liquid crystal panel 200 is controlled according to image information, and an image is displayed.

  Even in the present embodiment, similarly to the first embodiment, even when a plurality of unit lighting devices including a light source, a light guide, a lamp cover, and a reflector are arranged and arranged, a large screen (large screen) can be achieved. A thin and light illuminating device that emits high-luminance light with a uniform in-plane luminance distribution can be realized. In addition, by using such an illuminating device, it is possible to realize display devices having various screen sizes that are brighter and can display a high-quality display with high luminance in-plane uniformity.

  Further, in this embodiment, since the portion near the light source where the luminance of the light guide is particularly high is separated from the portion that emits the illumination light that actually contributes to the display of the liquid crystal panel, the unit illumination device is separated. The illumination light becomes more uniform in the in-plane luminance distribution.

  Therefore, the change in the in-plane luminance distribution of the illumination light at the joint where the unit lighting devices are joined is not visible even if the distance between the diffusion plate 105 and the surface of the light guide 103 is shorter than in the first embodiment. A thin lighting device and a display device can be realized.

  In the above description, it is described that it is desirable to satisfy the relationship of (Equation 3) in order to prevent a step from occurring at the joint between the light guides on the light guide surface side (liquid crystal panel 200 side).

  However, as shown in FIG. 13, if the following relationship is satisfied so that the surface 10313 from the end surface 10311 of the light guide 130 to the end surface 10312 is substantially equal to the inclined shape of the back surface of the adjacent light guide 130, the light guide The step of the joint seam can be eliminated, and this condition may be satisfied.

t _l3 > t _r + t ₂ ( _Expression 5)
Here, _tr is the thickness of the reflector 104.

  By the way, as the light guide of the lighting device shown in FIG. 13, a light guide integrally formed from the beginning as described with reference to FIG. 9 may be used.

  In this case, since there is no step on the surface side of the plurality of light guides that should realize the unit lighting device, and there is no seam, illumination light with a more uniform in-plane luminance can be obtained. Furthermore, since the number of parts is reduced, the effect of lowering costs can be expected.

  However, in the case of the shape of the light guide shown in FIG. 13, there is a problem that it is difficult to integrally form the protruding portion and the gap by injection molding, and the productivity is deteriorated.

  Here, another embodiment of the lighting device shown in FIG. 13 will be described with reference to FIG.

  The lighting device shown in FIG. 32 includes a flat light guide 3231 having a single light guide and a plurality of wedge-shaped light guides 3232 with protrusions 3233. The plurality of wedge-shaped light guides 3232 are aligned so that the protrusions 3233 are arranged on the back surfaces of the adjacent wedge-shaped light guides, and are optically coupled to the plate-like light guide 3231 with, for example, an acrylic transparent adhesive. The external appearance is the same as that of the lighting device described with reference to FIG.

  Reference numeral 3234 denotes a joint surface between the flat light guide 3231 and the wedge-shaped light guide 3232 with protrusions.

  In this embodiment, since the surface side of the light guide is composed of a single flat light guide 3231, there is no step on the surface side of the plurality of light guides that realize the unit lighting device, and there is no seam. Therefore, there is an effect that illumination light with a more uniform in-plane luminance can be obtained.

  In addition, since the flat light guide 3231 and the wedge light guide 3232 can be easily formed if they are separately formed, productivity does not decrease as in the case of integral molding.

Example 4
Next, another embodiment of the illumination device and the display device according to the present invention will be described with reference to the drawings.

  This embodiment obtains a new effect by further limiting the functions of some of the components of the illumination device and display device described in (Embodiment 1), and has the same function as the above embodiment. Are denoted by the same reference numerals, and detailed description of the same parts is omitted.

  FIG. 14 is a partial schematic cross-sectional view showing another embodiment of the illumination device and display device of the present invention. This display device includes a display panel 200 that displays an image by adjusting the amount of transmitted light, and an illumination device 100 disposed on the rear surface thereof.

  As the display panel, a liquid crystal panel similar to that in Embodiment 1 may be used. Here, the liquid crystal panel 200 has electrodes, switching elements, or pixels (gaps between pixels), and these portions become non-display portions (non-openings 206) and do not contribute to the brightness of the image. . That is, in such a liquid crystal panel, the non-opening portion 206 that causes light loss necessarily exists.

  These non-opening portions 206 do not contribute to the brightness of the image, but most of them are metal electrodes and reflect light. In general, Cr is often used as the metal electrode, but in the liquid crystal panel of this example, the reflectance of light at the non-opening portion 206 is increased by using an Al (aluminum) alloy in addition to the Cr (chromium) alloy. . Specifically, in the liquid crystal panel 200 according to the present embodiment, the area ratio when viewed from the back side of the Cr and Al liquid crystal panel 200 was set to Cr: Al = 1: 1.4. By doing so, the reflectivity of 54% when only Cr was used as the metal electrode could be increased to a reflectivity of 74%.

  The illumination device 100 has a plurality of light guides 103 (103a to 103c in the drawing) arranged in alignment and one side surface (end surface) of the plurality of light guides 103 in the same manner as the illumination device described in the first embodiment. A plurality of light sources 101 (101a to 101c in the drawing) that are respectively disposed and have a light emission length corresponding to the length of the side surface (end surface) and a portion of the plurality of light sources 101 other than the end face direction of the light guide body 103 are covered. A plurality of lamp covers 102 (102a to 102c in the figure) respectively arranged, and a plurality of reflectors 104 respectively arranged on the back surfaces (surfaces opposite to the liquid crystal panel 200) of the light guides 103 via an air layer. (104a to 104c in the figure) and a diffusion plate 105 arranged on the surface (surface on the liquid crystal panel 200 side) side of the plurality of light guides 103 (103a to 103c) so as to cover the entire surface thereof. It is.

  That is, the lighting device 100 includes a light guide 103, a light source 101 disposed on one side surface (end surface) of the light guide 103, a lamp cover 102, and a reflector 104 disposed on the back surface of the light guide 103. A plurality of unit lighting devices 1000 (1000a to 1000c in the figure) are arranged and arranged, and the diffusion plate 105 is arranged on the surface side so as to cover the entire surface.

  Next, the specific parts of the present embodiment will be described in detail.

  Similar to the first embodiment, the reflective plate 104 of this embodiment is disposed so as to cover the entire back surface of the light guide 103 and has a function of reflecting light from the back of the light guide 103 toward the light guide 103. In this embodiment, a reflector having a reflecting surface that maintains the polarization state of the reflected light is used. The reflecting surface that maintains the polarization state described here is a reflecting surface that reflects linearly polarized light as linearly polarized light at least for vertically incident light, and reflects circularly polarized light as circularly polarized light whose rotation direction is opposite. .

  As such a reflection plate 104, a glass plate, a metal plate, a resin plate, or a support substrate such as a polymer film formed with a reflection surface capable of maintaining polarized light can be used. The reflective surface is formed by depositing a metal thin film with high reflectivity such as aluminum or silver on the support substrate by vapor deposition or sputtering, or a dielectric multilayer film so as to be an increased reflection film on the support substrate. Or formed by laminating a plurality of transparent media having different refractive indexes so as to function as a reflecting plate can be used.

  Here, in order to reduce the size and weight of the apparatus, a PET (polyethylene terephthalate) film was used as the support base and a silver metal thin film was used as the reflecting surface.

  As the light guide 103, the light guide described in the first embodiment with reference to FIGS. 4 to 6 can be used. That is, a pair of opposed end surfaces 1031 and 1032 are plate-like transparent bodies having different thicknesses, and the configuration in which light incident from the end surface 1031 is confined inside by total reflection, and the direction of light propagating through the inside are determined. A structure in which the light is output to the liquid crystal panel 200 side by being changed by a large number of concave and convex surfaces having fine inclined surfaces formed on the back surface (opposite side of the liquid crystal panel 200) or a minute inclined reflecting surface formed by steps. Can be used.

  At this time, it is important that the transparent body constituting the light guide body 103 is optically isotropic for the reason described later. As the optically isotropic transparent body, glass or an acrylic resin formed by injection molding can be used. Here, glass generally has a specific gravity greater than that of acrylic resin, so if it has the same volume, it becomes heavier, and further, processing and molding are not as easy as acrylic resin. Therefore, acrylic resin may be used as the light guide.

  Here, the light guide 103 is made of an acrylic resin having a refractive index of 1.49 formed by injection molding, and the minor inclined reflecting surface 103A on the back surface of the light guide is parallel to the long axis direction of the light source 101. The average pitch P of the minute inclined reflecting surface 103A is 200 μm, the average height h is 10 μm, and the average inclination angle θ with respect to the surface 103C of the light guide 103 is 40 °.

  Further, by inclining the main surface 103B on the back surface of the light guide body 103 with respect to the surface 103C of the light guide body 103, the thickness of the end surface 1031 on the light source 101 side of the light guide body 103 is increased. It comprised so that thickness might become thin.

  In addition, the height h of the minute inclined reflecting surface 103A is continuously changed so as to be lower near the light source 101 and higher at a place far from the light source 101, or the pitch P or the inclination angle θ of the minute inclined reflecting surface 101A is changed. It is continuously changed according to the distance from the light source 101, or the thickness of the light guide 103, that is, the distance between the front surface 103C of the light guide and the main surface 103B of the back surface is reduced nonlinearly according to the distance from the light source. It is preferable that the uniformity of the light emitted from the light guide body 103 is improved by configuring so as to be. At this time, when a plurality of light guides are joined, light propagating from the adjacent light guides is also taken into consideration so that the in-plane uniformity of luminance is increased.

  The diffusion plate 105 is disposed so as to cover the entire surface of the light guides 103 (103a to 103c) of the plurality of unit lighting devices 1000 (1000a to 1000c) (surface on the liquid crystal panel 200 side).

  The diffusion plate 105 changes the angular distribution of the light emitted from the light guide 103 (103a to 103c) and the luminance distribution to change the angular distribution of the illumination light irradiated on the liquid crystal panel 200 and the uniformity of the in-plane luminance distribution. It has a function to enhance.

  In this embodiment, in particular, a light having a function of diffusing incident light in a state where the polarization state is substantially maintained is used. As such a diffusion plate, on a transparent substrate that is optically isotropic, for example, a plurality of spherical transparent beads are densely arranged in a plane, and a diffusion layer is formed by fixing with a transparent resin, or optical A hologram diffusion plate formed on a transparent isotropic substrate or LCG (light control glass) described in SPIE Vol. 1536 Optical Materials Technology for Energy Efficiency and Solar Energy Conversion X (1991) pp 138-148 can do.

  15 and 16 show an example of the diffusion plate 105 having a polarization maintaining function. FIG. 15 is a partial perspective view of the diffusion plate 105, and FIG. 16 is a partial cross-sectional view of the diffusion plate 105.

  The diffusion plate 105 is made of glass, a polycarbonate film formed by a casting method (solution casting method), a polymer film such as a triacetyl cellulose film, or an alicyclic acrylic resin formed by injection molding (trade name: Optretz: An optically isotropic transparent base material 1501 made of Hitachi Chemical Co., Ltd.) is arranged on the surface of an optically isotropic spherical transparent bead 1502 made of glass or resin, and is arranged in a single layer in a single layer. Alternatively, it is fixed with a transparent adhesive resin 1503 such as polyester.

  Transparent beads 1502 having a diameter of several μm to several hundreds of μm can be used, but it is desirable to use particles having a uniform particle size as much as possible in order to control diffusion performance and achieve in-plane uniformity. .

  As shown in FIG. 16, the polarization maintaining diffusion plate 105 functions as a diffusion plate by converging and diverging light 1504 incident on the transparent bead 1502 by refraction at the interface of the transparent bead 1502, and its diffusibility is transparent. It is possible to design arbitrarily by changing the refractive index of the beads 1502.

  Further, unlike the illustrated case, a transparent bead 1502 entirely covered with a transparent adhesive resin 1503 may be used. In this case, it is necessary that the refractive index of the transparent bead 1502 and the transparent resin 1503 be different from each other, but the transparent bead 1502 having a refractive index of 1.5 to 2.0 is relatively easily available. Since 1503 having a refractive index of 1.4 to 1.6 can be obtained relatively easily, a polarization maintaining diffusion plate capable of obtaining a desired diffusibility can be configured by appropriately combining them.

  Furthermore, as shown in FIG. 17, a polarization maintaining diffusion plate 105 that obtains a desired diffusibility by stacking a plurality of layers of transparent beads 1502 can also be used.

  Unlike the conventional diffuser plate with multiple scattering, the polarization maintaining diffusion plate utilizes a refraction function and has a scattering property at a small interface, so that there is little loss of light and less influence on the polarization state. It functions as a diffusion plate that substantially maintains the state.

  On the other hand, when a hologram diffusion plate is used as the polarization maintaining diffusion plate 105, an optically isotropic transparent substrate such as glass or a polycarbonate film formed by a casting method (solution casting method) or a triacetyl cellulose film is used. It is possible to use a material in which a photopolymer is coated on a material and recorded so as to have a desired scattering characteristic by two-beam interference, which is a known technique. Further, a CGH (Computer Generated Hologram) may be used in which a desired hologram pattern is calculated by a computer and drawn and produced by an electron beam or the like.

  As the hologram material, it is desirable to use an acrylic photopolymer from the viewpoint of durability and the like, and it is desirable to use a volume phase type hologram in view of obtaining high diffraction efficiency.

  In order to cope with white light, the center diffraction wavelength of the hologram should correspond to the bright line spectrum corresponding to the three primary colors of the light emitted from the light source 101. For example, as an exposure light source for red, a He-Ne laser, green A hologram produced using an Ar + Dye laser for blue and an Ar laser for blue may be used. At this time, a plurality of holograms individually exposed at each wavelength may be stacked and used, but a single sheet subjected to multiple exposure at a plurality of wavelengths may be used.

  In addition, a hologram type diffusion plate having a polarization maintaining function with high mass productivity has been realized by a release-type hologram created by a method of forming a hologram pattern with a transparent UV curable resin on an optically isotropic transparent substrate. May be.

  Note that the change in the in-plane luminance distribution of the illumination light at the joint where the unit illumination devices are joined becomes less visible as the distance between the diffusion plate 105 and the light guide surface increases. Specifically, depending on the diffusibility of the diffusion plate 105, if it is a realistic diffusion plate, the unit illumination device can be obtained by setting the distance between the diffusion plate 105 and the surface of the light guide 103 to about 0.1 mm to 15 mm. The change in the in-plane luminance distribution of the illumination light at the joint where the two are joined cannot be visually recognized, and the illumination light with high uniformity of the in-plane luminance distribution can be obtained.

  Even if the diffuser plate 105 is not provided, it is not always necessary to dispose the diffuser plate 105 if the angular distribution of illumination light and the uniformity of the in-plane luminance distribution are high, but it is usually necessary.

  Next, the operation of this display device will be described with reference to FIG. The light emitted from the light source 101 (101a to 101c) enters the light guide 103 (103a to 103c) directly or after being reflected by the lamp cover 102 (102a to 102c). The light that has entered the light guide 103 (103a to 103c) propagates while repeating total reflection in the light guide, and among the light that propagates in the light guide, the light that reaches the minute inclined reflective surface on the back of the light guide is The reflection angle changes, and the light guide body emits light out of the total reflection condition. The light emitted from the light guide 103 (103a to 103c) is irradiated on the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105.

  The amount of light applied to the liquid crystal panel 200 is controlled according to image information, and an image is displayed.

  Also in this embodiment, the same effect as the above embodiment can be obtained. In other words, by arranging a plurality of unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector, it is thin and lightweight and has an in-plane luminance distribution even when the size is increased (large screen). An illuminating device that emits uniform and high-luminance light can be realized, and a display device that can display a high-quality display with higher brightness and in-plane uniformity of luminance can be realized.

  Further, as described above, the liquid crystal panel 200 has electrodes, switching elements, or non-display portions (non-opening portions) 206 such as between pixels. These non-opening portions 206 do not contribute to the brightness of the image, but most of them are metal electrodes and reflect light.

  Accordingly, among the light irradiated to the liquid crystal panel 200, the light 301 incident on the opening 207 is used as it is for display, but the light 302 incident on the non-opening 206 of the liquid crystal panel 200 does not contribute to the display. And return to the lighting device 100 after reflection.

  The light 302 that has returned to the illumination device 100 passes through the diffusion plate 105 and the light guide 103 and travels toward the reflection plate 104. The light directed toward the reflection plate 104 is reflected and irradiated to the liquid crystal panel 200 again through the light guide 103 and the diffusion plate 105. At this time, in this embodiment, the polarization state of the light does not change greatly by the transmission through the diffusion plate 105 and the light guide 103 and the reflection by the reflection plate 104. For this reason, the light 302 re-irradiated to the liquid crystal panel 200 maintains almost the polarization state when initially reflected by the non-opening portion 206 of the liquid crystal panel 200, and thus is hardly absorbed by the polarizing plate 201. It can contribute to the display. That is, in the display device of this embodiment, since the light that has been shielded by the non-opening portion 206 of the liquid crystal panel 200 and has not been able to contribute to the display can be reused without a large loss, the liquid crystal with a low aperture ratio can be used. Even if it is a panel, there exists an effect that a bright display is obtained.

  Specifically, when the liquid crystal panel 200 having an aperture ratio of 70% is used, the luminance is improved by about 2% as compared with the case where the reflection plate 104 and the diffusion plate 105 do not have a polarization maintaining function. Further, when the liquid crystal panel 200 having an aperture ratio of 40% was used, the luminance was improved by about 15%. That is, in the illumination device of this embodiment and the display device using the same, the effect appears more remarkably when a liquid crystal panel having a low aperture ratio is used.

  In this embodiment, Cr alloy and Al alloy are used together as the metal electrode, but the present invention is not limited to this. That is, ideally, a metal having high reflectivity such as Al or Ag is used on at least the back side of the liquid crystal panel 200 of the electrode, or a reflective surface such as a dielectric multilayer film is formed on the back side of the liquid crystal panel of the non-opening 206. Thus, it is desirable to minimize light loss due to light absorption in the non-opening portion 206 by reflecting light incident on the non-opening portion 206 to the lighting device side with a high reflectance.

(Example 5)
Next, another embodiment of the illumination device and the display device according to the present invention will be described with reference to the drawings.

  FIG. 18 is a partial schematic sectional view showing another embodiment of the illumination device of the present invention and a display device using the same.

  In this embodiment, in the illuminating device and the display device described in (Embodiment 4), between the liquid crystal panel 200 and the light guide body 103 (103a to 103c) constituting the illuminating device 100, the polarization separating means is used. A cholesteric liquid crystal layer 106 and a retardation plate (¼ wavelength plate) 107 are arranged in this order from the liquid crystal panel 200 in the order of the retardation plate 107 and the cholesteric liquid crystal layer 106. The same parts as in the above embodiment are the same. Reference numerals are assigned and detailed description is omitted.

  The cholesteric liquid crystal layer 106 is a liquid crystal cell containing a low molecular cholesteric liquid crystal between two aligned glass substrates, or a polymer cholesteric liquid crystal layer on an optically isotropic and transparent substrate such as glass or a transparent resin. Use what was formed. The cholesteric liquid crystal layer 106 exhibits unique optical characteristics based on a helical molecular arrangement. Light incident in parallel to the helical axis reflects circularly polarized light in one rotational direction according to the rotational direction of the cholesteric spiral, and the other is This indicates selective reflection of transmission. Therefore, in order to make the main light beam incident on the cholesteric liquid crystal layer 106 parallel to the helical axis, the helical axis of the cholesteric liquid crystal layer 106 is configured to be perpendicular to the display surface of the liquid crystal panel 200. Further, since the wavelength range of selective reflection is determined by the pitch of the molecular arrangement, selective reflection occurs in the entire visible wavelength range in order to cope with white, or selective reflection occurs in the emission line spectral wavelengths corresponding to the three primary colors of the light source 101. Therefore, it is necessary to use a plurality of cholesteric liquid crystal layers having different pitches in a stacked manner. In order to obtain selective reflection in the entire visible wavelength range, a cholesteric liquid crystal layer with a continuously changing pitch as described in Asia Display 95 Digest p735 is used instead of stacking a plurality of cholesteric liquid crystal layers having different pitches. May be.

  The phase difference plate 107 transmits circularly polarized light transmitted through the cholesteric liquid crystal layer 106 to linearly polarized light transmitted through the polarizing plate 201 on the back side (illumination light incident side) of the liquid crystal panel 200, that is, oscillation of the transmission axis of the polarizing plate 206 and the electric vector. A material that converts linearly polarized light having the same direction and that functions as a quarter-wave plate in the visible wavelength region is used. As the retardation plate 107, a stretched polymer film having high transmittance in the visible wavelength region, such as polyvinyl alcohol, polycarbonate, polysulfone, polystyrene, polyarylate, or the like can be used. In addition, a mica, a crystal, or a liquid crystal layer in which molecular axes are aligned in one direction can be used.

  In general, due to the wavelength dependence (wavelength dispersion) of the refractive index of the material constituting the retardation plate, a retardation plate that functions as a quarter-wave plate with respect to the entire visible wavelength range is formed with one type of retardation plate. Although it is difficult, a phase difference plate that functions as a quarter wavelength plate in a wide wavelength range is configured by bonding at least two types of phase difference plates having different wavelength dispersions so that their optical axes are orthogonal to each other. It should be used.

  Next, the operation of the illumination device of this embodiment and a display device using the same will be described.

  The light emitted from the light source 101 (101a to 101c) enters the light guide 103 (103a to 103c) directly or after being reflected by the lamp cover 102 (102a to 102c). The light that has entered the light guide 103 (103a to 103c) propagates while repeating total reflection in the light guide, and among the light that propagates in the light guide, the light that reaches the minute inclined reflective surface on the back of the light guide is The reflection angle changes, and the light guide body emits light out of the total reflection condition. The light emitted from the light guide 103 (103a to 103c) is incident on the cholesteric liquid crystal layer 106 after the light distribution and the angular distribution of the illumination light are uniformized by the diffusion plate 105.

  As described above, the cholesteric liquid crystal layer 106 exhibits selective reflection in which the circularly polarized light in one rotational direction is reflected and the other is transmitted in accordance with the rotational direction of the cholesteric spiral. A case will be described in which right-handed circularly polarized light is transmitted and left-handed circularly polarized light (hereinafter, left-handed circularly polarized light) is reflected.

  The light emitted from the light source 101 (101a to 101c) and incident on the cholesteric liquid crystal layer 106 through the light guide 103 (103a to 103c) is non-polarized light. Among these, the right circularly polarized component is the cholesteric liquid crystal layer. 106 is transmitted, and the left circularly polarized component is reflected. The light 301 </ b> A that has passed through the cholesteric liquid crystal layer 106 is converted into linearly polarized light whose vibration direction of the electric vector coincides with the linearly polarized light transmission axis of the polarizing plate 201 by the action of the retardation plate 107, and then enters the liquid crystal panel 200. . On the other hand, the light 301 </ b> B reflected by the cholesteric liquid crystal layer 106 passes through the diffusion plate 105 and the light guide 103 (103 a to 103 c), is reflected by the reflection plate 104, and travels toward the cholesteric liquid crystal layer 106 again. At this time, the light passing through the diffusion plate 105 and the light guide 103 (103a to 103c) is not greatly affected by the polarization state, and the light reflected by the reflection plate 104 has a reverse rotation direction of the circular polarization. Becomes circularly polarized light. For this reason, the light 301B first reflected by the cholesteric liquid crystal layer 106 becomes right circularly polarized light when reflected by the reflector 104, and this time is transmitted through the cholesteric liquid crystal layer 301B. After being converted into linearly polarized light whose linear polarization transmission axis 201 matches the vibration direction of the electric vector, it enters the liquid crystal panel 200.

  Therefore, the non-polarized outgoing light from the light source 101 is efficiently converted into the desired linearly polarized light and then irradiated onto the liquid crystal panel 200. Here, the desired linearly polarized light refers to linearly polarized light that passes through the polarizing plate 201 on the illumination light incident side of the liquid crystal panel 200.

  In the liquid crystal panel 200, the amount of transmitted illumination light is controlled according to image information, and an image is displayed. At this time, the lights 301A and 301B incident on the liquid crystal panel 200 are hardly absorbed by the polarizing plate 201 and contribute to display. That is, conventionally, light that has been absorbed by the polarizing plate 201 of the liquid crystal panel 200 and wasted can be used effectively, so that a bright and low power consumption display device can be realized. Actually, the luminance of the display surface was improved by about 45% with the same power consumption as compared with the case of using an illumination device without the cholesteric liquid crystal layer 106 and the retardation plate 107.

  Needless to say, the same effects as in the above embodiment can be obtained in this embodiment. In other words, by arranging a plurality of unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector, it is thin and lightweight and has an in-plane luminance distribution even when the size is increased (large screen). An illuminating device that emits uniform and high-luminance light can be realized, and a display device that can display a high-quality display with higher brightness and in-plane uniformity of luminance can be realized.

  By the way, among the light irradiated on the liquid crystal panel 200, the light 302 </ b> A incident on the non-opening 206 of the liquid crystal panel 200 does not contribute to the display at first and is reflected toward the illumination device 100. When the light traveling toward the illuminating device 106 passes through the phase difference plate 107, it receives the action and becomes right circularly polarized light, and passes through the cholesteric liquid crystal layer 106. The light transmitted through the cholesteric liquid crystal layer 106 passes through the diffusion plate 105 and the light guide 103 (103a to 103c), is reflected by the reflection plate 104 (104a to 104c), and becomes left circularly polarized light. The left circularly polarized light 302A is reflected by the cholesteric liquid crystal layer 106, passes through the diffusion plate 105 and the light guide 103 (103a to 103c) again, is reflected by the reflection plate 104 (104a to 104c), and is reflected to the right circle. Become polarized. The right circularly polarized light 302A is then transmitted through the cholesteric liquid crystal layer 106, and is converted into linearly polarized light whose electric polarization direction coincides with the linearly polarized light transmission axis of the polarizing plate 201 by the action of the phase difference plate 107. After that, the light reenters the liquid crystal panel 200. The light 302 </ b> A that re-enters the liquid crystal panel 200 is hardly absorbed by the polarizing plate 201 and contributes to display. Therefore, since the light that was initially reflected by the non-opening portion 206 of the liquid crystal panel 200 and could not contribute to the display can be reused, there is an effect that a bright display can be obtained even with a liquid crystal panel having a low aperture ratio.

  In the above description, the diffusion plate 105 is disposed on the back surface of the cholesteric liquid crystal layer 106. However, the diffusion plate 105 may be located anywhere between the liquid crystal panel 200 and the light guide 103 (103a to 103c). The present invention is not limited to the examples.

(Example 6)
Next, another embodiment of the illumination device according to the present invention and a display device using the same will be described with reference to the drawings. FIG. 19 is a partial schematic cross-sectional view showing an example of the illumination device of the present invention and a liquid crystal display device using the same. In this embodiment, in the illumination device described in (Embodiment 5) and a display device using the same, a retardation plate 108 and a linearly polarized light separating element 109 are used instead of the cholesteric liquid crystal layer 106 and the retardation plate 107. The linearly polarized light separating element 109 and the retardation plate 108 are arranged in this order from the liquid crystal panel 200 side. The same reference numerals are given to the same parts as those in the above embodiment, and detailed description is omitted.

  The linearly polarized light separating element 109 has a function of transmitting a specific linearly polarized light component of light incident on the linearly polarized light separating element 109 and reflecting a different polarized light component, and various configurations are conceivable.

  For example, a birefringence reflective polarizing film obtained by alternately laminating a plurality of different birefringent polymer films described in International Publication Number: WO95 / 27919, or an apex angle of approximately 90 degrees described in SID92 Digest p427 Two prism arrays can be stacked, and a polarization separation surface formed of a dielectric multilayer film can be formed on the overlapping portion.

  The linearly polarized light transmission axis of the linearly polarized light separating element 109 is arranged so as to coincide with the linearly polarized light transmission axis of the polarizing plate 201 on the back side of the liquid crystal panel 200.

  The retardation plate 108 has a function of converting linearly polarized light reflected or transmitted by the linearly polarized light separating element 109 into circularly polarized light, and functions as a quarter wavelength plate in the visible wavelength range. As the retardation plate 108, a stretched polymer film that is transparent in the visible wavelength region and has high transmittance, such as polyvinyl alcohol, polycarbonate, polysulfone, polystyrene, polyarylate, or the like can be used. In addition, a mica, a crystal, or a liquid crystal layer in which molecular axes are aligned in one direction can be used.

  In general, due to the wavelength dependence (wavelength dispersion) of the refractive index of the material constituting the retardation plate, a retardation plate that functions as a quarter-wave plate with respect to the entire visible wavelength region is configured with one type of retardation plate. Although it is difficult, a phase difference plate that functions as a quarter wavelength plate in a wide wavelength range is formed by bonding at least two types of phase difference plates having different wavelength dispersions so that their optical axes are orthogonal to each other. Can do.

  Next, the operation of the illumination device of this embodiment and a display device using the same will be described.

  The light emitted from the light source 101 (101a to 101c) enters the light guide 103 (103a to 103c) directly or after being reflected by the lamp cover 102 (102a to 102c). The light incident on the light guide 103 (103a to 103c) propagates while repeating total reflection in the light guide, and among the light propagated in the light guide, the light reaching the inclined reflection surface on the back surface of the light guide is reflected. The angle changes and the light guide surface exits the total reflection condition. The light emitted from the light guide 103 (103a to 103c) is made uniform by the diffusion plate 105 in the light quantity distribution and the angle distribution of the illumination light, and then transmitted through the phase difference plate 108 to the linearly polarized light separating element 109. Incident. As described above, the linearly polarized light separating element 109 transmits a linearly polarized light component in which the linearly polarized light transmission axis of the polarizing plate 201 on the back side of the liquid crystal panel 200 coincides with the vibration direction of the electric vector, and reflects a polarized light component different from this. To do.

  Therefore, out of the light that is emitted from the light guide 103 (103a to 103c), passes through the diffusion plate 105 and the retardation plate 108, and enters the linearly polarized light separating element 109, the linearly polarized light transmission axis of the polarizing plate 201, The linearly polarized light component having the same vibration direction of the electric vector is transmitted through the linearly polarized light separating element 109, and the linearly polarized light component orthogonal thereto is reflected. The light 301C that has passed through the linearly polarized light separating element 109 is irradiated to the liquid crystal panel 200 as it is. On the other hand, the light 301D reflected by the linearly polarized light separating element 109 becomes circularly polarized light (hereinbelow, a case where it becomes left circularly polarized light) by the action of the phase difference plate 108, and the diffusion plate 105 and the light guide 103 (103a). -103c), is reflected by the reflector 104, and travels toward the retardation plate 108 again. At this time, the light passing through the diffusion plate 105 and the light guide 103 is not greatly affected by the polarization state, and the light reflected by the reflection plate 104 becomes circularly polarized light whose rotational direction of circularly polarized light is reversed.

  Therefore, the light 301D (left circularly polarized light) reflected by the linearly polarized light separating element 109 and transmitted through the retardation plate 108 becomes right circularly polarized light when reflected by the reflective plate 104, and is transmitted through the retardation plate 108 again. At this time, the action causes the linearly polarized light to pass through the linearly polarized light separating element 109, so that the liquid crystal panel 200 is irradiated through the linearly polarized light separating element 109 this time.

  Therefore, the non-polarized outgoing light from the light source 101 is efficiently converted into the desired linearly polarized light and then irradiated onto the liquid crystal panel 200. Here, the desired linearly polarized light refers to linearly polarized light that passes through the polarizing plate 201 on the illumination light incident side of the liquid crystal panel 200.

  In the liquid crystal panel 200, the amount of transmitted illumination light is controlled according to image information, and an image is displayed. At this time, the light 301C and 301D incident on the liquid crystal panel 200 is hardly absorbed by the polarizing plate 201 and contributes to display. That is, conventionally, light that has been absorbed by the polarizing plate 201 of the liquid crystal panel 200 and wasted can be used effectively, so that a bright and low power consumption display device can be realized. Actually, the luminance of the display surface was improved by about 49% with the same power consumption as compared with the case of using an illuminating device that does not have the retardation plate 108 and the linearly polarized light separating means 109.

  Needless to say, the same effects as in the above embodiment can be obtained in this embodiment. In other words, by arranging a plurality of unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector, it is thin and lightweight and has an in-plane luminance distribution even when the size is increased (large screen). An illuminating device that emits uniform and high-luminance light can be realized, and a display device that can display a high-quality display with higher brightness and in-plane uniformity of luminance can be realized.

  By the way, among the light irradiated to the liquid crystal panel 200, the light 302B incident on the non-opening portion 206 of the liquid crystal panel 200 does not contribute to the display at first and is reflected toward the illumination device 100. The light traveling toward the illumination device 100 passes through the linearly polarized light separating element 109, and when it passes through the phase difference plate 108, it receives the action and becomes right circularly polarized light. The light transmitted through the phase difference plate 108 is transmitted through the diffusion plate 105 and the light guide 103 (103a to 103c), reflected by the reflection plate 104 (104a to 104c), and becomes left circularly polarized light. When the light 302B that has become left circularly polarized light passes through the phase difference plate 108, the light 302B becomes linearly polarized light that is reflected by the linearly polarized light separating element 109 and reflected by the linearly polarized light separating element 109. When the light 302B reflected by the linearly polarized light separating element 109 passes through the phase difference plate 108, the light 302B receives the action and becomes left circularly polarized light, and is again transmitted through the diffusion plate 105 and the light guide 103 (103a to 103c). When the light is reflected by the reflector 104, it becomes right circularly polarized light. The light 302 </ b> B that has become right circularly polarized light again passes through the light guide 103 (103 a to 103 c) and the diffusion plate 105, and passes through the phase difference plate 108. Since the linearly polarized light is transmitted, the liquid crystal panel 200 is irradiated through the linearly polarized light separating element 109. The light 302 </ b> B re-entering the liquid crystal panel 200 is linearly polarized light in which the linearly polarized light transmission axis of the polarizing plate 201 and the vibration direction of the electric vector coincide with each other, and thus contributes to display without being almost absorbed by the polarizing plate 201. In other words, since light that has been reflected by the non-opening portion 206 of the liquid crystal panel 200 and has not contributed to display can be reused without a large loss, a bright display can be obtained even with a liquid crystal panel having a low aperture ratio. There is also.

  In the above description, the diffusion plate 105 is disposed on the back surface of the retardation plate 108, but the position of the partial diffusion plate 105 may be anywhere between the liquid crystal panel 200 and the light guide 103 (103a to 103c). The present invention is not limited to the above embodiment.

(Example 7)
Next, another embodiment of the illumination device according to the present invention and a display device using the same will be described with reference to the drawings. FIG. 20 is a partial schematic cross-sectional view showing an example of the illumination device of the present invention and a display device using the same. In this embodiment, a linearly polarized light separating element 701 is arranged between the light source 101 constituting the unit illumination device 1000 described in (Embodiment 4) and the end face of the light guide 103 on which the light source 101 is arranged adjacently. The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Similarly to the illumination device described in (Example 4), the illumination device 100 is arranged on each of the aligned light guides 103 and one side surface (end surface) of the plurality of light guides 103, and the side surface (end surface). ) A plurality of light sources 101 having light emission lengths corresponding to the lengths, a plurality of lamp covers 102 arranged so as to cover portions of the plurality of light sources 101 excluding the direction of the light guide 103, and a plurality of light guides 103 The plurality of reflectors 104 respectively disposed on the back surface (the surface opposite to the liquid crystal panel 200) via an air layer and the entire surface of the plurality of light guides 103 on the front surface (surface on the liquid crystal panel 200 side) are covered. And a diffuser plate 105 disposed on the surface. In this embodiment, a linearly polarized light separating element 701 is further disposed between the light source 101 and the end surface of the light guide body 103 adjacent to the light source 101.

  That is, the illumination device 100 includes a light guide 103, a light source 101 disposed on one side surface (end surface) of the light guide 103, a lamp cover 102, a reflector 104 disposed on the back surface of the light guide 103, and a straight line. A plurality of unit illumination devices 1000 each including a polarization separation element 701 are arranged and arranged, and the diffusion plate 105 is arranged on the surface side so as to cover the entire surface.

  In the unit lighting device 1000, the light guide constituting this is composed of a pair of plate-like transparent bodies having opposite end face thicknesses, and when arranging a plurality of light guide bodies, The end face having a small thickness is joined so as to have no step on the surface side and optically seamless. The light source is disposed at a position close to the end face having the larger thickness among a pair of facing end faces with different thicknesses of the light guide and at the position to be the back face of the adjacent light guide. Further, the end surface portion of the light guide 103 on which the light source light is incident, that is, the end surface having the larger thickness among the pair of facing end surfaces having different thicknesses, and the joint portion between the light guides A linearly polarized light separating element 701 is disposed in a portion excluding.

  The reflection plate 104 of this embodiment is disposed through an air layer so as to cover the entire back surface of the light guide 103 and has a function of reflecting light coming from the direction of the light guide 103 toward the light guide 103. Further, a reflecting plate having a reflecting surface that maintains the polarization state of the reflected light is used.

  The reflecting surface that maintains the polarization state described here is a reflecting surface that reflects linearly polarized light as linearly polarized light at least for vertically incident light, and reflects circularly polarized light as circularly polarized light whose rotation direction is opposite. .

  As the reflection plate 104, the reflection plate 104 described in (Example 4) can be used, and for example, a film obtained by forming a silver thin film on a support base made of a PET film by a sputtering method can be used.

  The light guide 103 can be the same as (Embodiment 4) and the light guide described with reference to FIGS. That is, a pair of opposing end face thicknesses are plate-like transparent bodies, in which light incident from the thick end face is confined inside by total reflection, and the direction of light propagating inside is a light guide body A structure in which the light is emitted to the liquid crystal panel 200 side by changing with a large number of uneven surfaces having fine inclined surfaces formed on the back surface (the opposite side of the liquid crystal panel 200) or a minute inclined reflecting surface constituted by steps. Can be used.

  At this time, the transparent body constituting the light guide body 103 needs to be optically isotropic for the reason described later. As the optically isotropic transparent body, glass or an acrylic resin formed by injection molding can be used. Here, glass generally has a higher specific gravity than an acrylic resin, so if it has the same volume, it becomes heavier, and further, processing and molding are not as easy as an acrylic resin, so an acrylic resin may be used as the light guide.

  Here, as the light guide 103, an alicyclic acrylic resin (trade name Optretz: manufactured by Hitachi Chemical Co., Ltd.), which is a low birefringent material, is used by injection molding. The minute inclined reflecting surface 103A on the back surface of the light guide is formed so that the major axis direction thereof is parallel to the major axis direction of the light source 101, and the average pitch P of the minute inclined reflecting surface 103A is 200 μm, the average height h is 10 μm, The average inclination angle θ with respect to the surface 103C of the light guide 103 was set to 40 °.

  Further, the light guide 103 is configured such that the thickness of the end surface 1032 facing the light source 101 side is continuously thinner than the thickness of the end surface 1031 on the light source 101 side.

  In addition, the height h of the minute inclined reflecting surface 103A is continuously changed so as to be lower near the light source 101 and higher at a place far from the light source 101, or the pitch P or the inclination angle θ of the minute inclined reflecting surface 101A is changed. It is continuously changed according to the distance from the light source 101, or the thickness of the light guide 103, that is, the distance between the front surface 103C of the light guide and the main surface 103B of the back surface is reduced nonlinearly according to the distance from the light source. It is preferable that the uniformity of the light emitted from the light guide body 103 is improved by configuring so as to be.

  The diffusing plate 105 is arranged on the surface (surface on the liquid crystal panel 200 side) side of the plurality of light guides 103 constituting the plurality of unit lighting devices 1000 so as to cover the entire surface.

  The diffusion plate 105 has a function of improving the uniformity of the angular distribution of the illumination light irradiated to the liquid crystal panel 200 and the in-plane luminance distribution by changing the angular distribution of the light emitted from the light guide 103 and the luminance distribution. It is.

  In this embodiment, in particular, a light having a function of diffusing incident light in a state where the polarization state is substantially maintained is used. As such a diffusion plate, the diffusion plate described in (Example 4) may be used. For example, it is possible to use an optically isotropic spherical transparent bead made of glass or resin on a triacetylcellulose film and fixed by an acrylic transparent adhesive resin.

  The change in the in-plane luminance distribution of the illumination light at the joint portion of the unit illumination device becomes less visible as the distance between the diffuser plate 105 and the light guide surface is increased. Specifically, depending on the diffusibility of the diffusion plate 105, if it is a realistic diffusion plate, the unit illumination device can be obtained by setting the distance between the diffusion plate 105 and the surface of the light guide 103 to about 0.1 mm to 15 mm. The change in the in-plane luminance distribution of the illumination light at the joint where the two are joined cannot be visually recognized, and the illumination light with high uniformity of the in-plane luminance distribution can be obtained. Even if the diffuser plate 105 is not provided, it is not always necessary to dispose the diffuser plate 105 if the angular distribution of illumination light or the uniformity of the in-plane luminance distribution is high, but it is usually necessary.

  The linearly polarized light separating element 701 has a function of transmitting a specific linearly polarized light component of light incident thereon and reflecting a different polarized light component. Various configurations can be considered. For example, a birefringence reflective polarizing film in which a plurality of different birefringent polymer films described in International Publication No. WO95 / 27919 described in International Application are alternately laminated, and SID92 Digest p427 are described. It is possible to use a plate-like one in which two prism arrays having apex angles of approximately 90 degrees are overlapped and a polarization separation surface is formed by a dielectric multilayer film on the overlap portion.

  In addition, a layer in which a cholesteric liquid crystal layer and a retardation plate are stacked can be used as the linearly polarized light separating element 701. In this case, a cholesteric liquid crystal layer and a retardation plate are laminated in this order from the light source 101 side toward the end face of the light guide 103.

  As described above, the cholesteric liquid crystal layer exhibits selective reflection in which the circularly polarized light in one rotational direction is reflected and the other is transmitted. A plurality of cholesteric liquid crystal layers having different pitches are laminated so that selective reflection occurs in the entire visible wavelength range in order to correspond to white, or selective reflection occurs in the wavelength of the emission line spectrum corresponding to the three primary colors of the light source 101. Use. Alternatively, a cholesteric liquid crystal layer in which the pitch is continuously changed as described in Asia Display 95 Digest p735 may be used.

  The retardation plate converts circularly polarized light transmitted through the cholesteric liquid crystal layer into linearly polarized light, and uses a plate that functions as a quarter wavelength plate in the visible wavelength range. As the retardation plate, a stretched polymer film having high transmittance in the visible wavelength region, for example, polyvinyl alcohol, polycarbonate, polysulfone, polystyrene, polyarylate, or the like can be used. In addition, a mica, a crystal, or a liquid crystal layer in which molecular axes are aligned in one direction can be used.

  The transmission axis of the linearly polarized light of the linearly polarized light separating element 701 is arranged so that the linearly polarized light that has passed therethrough is an s-polarized component with respect to the minute inclined reflecting surface formed on the back surface of the light guide 103. That is, in FIG. 20, if the longitudinal direction of the triangular groove forming the minute inclined reflection surface on the back surface of the light guide 103 is the perpendicular direction to the paper surface, the transmission axis of the linearly polarized light of the linearly polarized light separating element 701 is also the perpendicular direction to the paper surface. To place.

  Next, the operation of the illumination device of the present embodiment will be described with reference to FIG. 20 while focusing on the single unit illumination device 100 constituting the illumination device.

  The light 3000 emitted from the light source 101 enters the linearly polarized light separating element 701 directly or after being reflected by the lamp cover 102. At this time, since the outgoing light 3000 from the light source 101 is non-polarized light, a specific linearly polarized component corresponding to about half of the light incident on the linearly polarized light separating element 701 is transmitted and a polarized component different from this is reflected. To do.

  The light 3002 reflected by the linearly polarized light separating element 701 is reflected by the light source 101 or the lamp cover 102 and enters the linearly polarized light separating element 701 again. When the light re-entered the linearly polarized light separating element 701 is reflected by the light source 101 or the lamp cover 102, the polarization state is changed or the polarized light is depolarized. Is transmitted, and a polarized component different from this is reflected again. While this operation is repeated, about 65% of the light emitted from the light source 101 becomes specific linearly polarized light and passes through the linearly polarized light separating element 701.

  Light 3001 transmitted through the linearly polarized light separating element 701 enters the light guide 103. The light 3001 incident on the light guide body 103 propagates through the light guide body 103 while repeating total reflection, and reaches the minute inclined reflection surface 103A on the back surface of the light guide body 103 out of the light propagating through the light guide body 103. The light changes its reflection angle and exits the light guide surface 103C outside the total reflection condition.

  At this time, the light incident on the light guide 103 is light that has passed through the linearly polarized light separating element 701, so that most of the light has a larger amount of s-polarized light or s-polarized light component than the minute inclined reflective surface 103 </ b> A on the back surface of the light guide 103. Since light is light and the light guide 103 is optically substantially isotropic, the light propagating in the light guide 103 is maintained in the polarization state. It is light with many s-polarized components.

  Here, in general, light incident obliquely with respect to a reflecting surface made of a dielectric or conductor is reflected light as incident light if the light is s-polarized light or p-polarized linearly polarized light with respect to the reflecting surface. The same linearly polarized light.

  Therefore, among the light that propagates through the light guide 103 and reaches the minute inclined reflection surface 103A, the light that is s-polarized with respect to the minute inclined reflection surface changes the traveling direction of the light as it is s-polarized, and the light guide 103.

  That is, the light emitted from the light guide 103 has a larger amount of s-polarized light than the inclined reflective surface 103A on the back surface of the light guide 103, that is, the vibration direction of the electric vector is a minute inclined surface 103A on the back surface of the light guide 103. Illuminating light of substantially linearly polarized light parallel to the longitudinal direction is obtained.

  Here, the following effects can be obtained by changing the light propagating through the light guide into linearly polarized light that is s-polarized light with respect to the minute inclined reflecting surface 103A.

  FIG. 21 is a diagram showing the relationship between the light incident angle and the reflectance with respect to p-polarized light and s-polarized light when no special reflective surface is formed on the minute inclined reflective surface 103A. That is, the case where the reflection at the minute inclined reflecting surface 103A is caused by the difference in refractive index between the light guide and air is shown.

  As apparent from FIG. 21, the reflectance of s-polarized light is higher than that of p-polarized light. For example, the reflectance of s-polarized light is 10% with respect to the reflectance of p-polarized light at an incident angle of 30 °, and is 30 at an incident angle of 40 °. % Higher. That is, the illumination light reflected from the minute inclined reflecting surface 103A and emitted from the light guide has a high reflectance of s-polarized light. Therefore, the light incident on the light guide from the beginning is changed to s-polarized light so that it can be specified more efficiently. Linearly polarized light is obtained.

  The light emitted from the light guide 103 is irradiated on the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105. At this time, since the diffusion plate 105 maintains the polarization state, the liquid crystal panel 200 is irradiated with predetermined linearly polarized light.

  In the illumination device of the present embodiment, the width of the light guide, that is, the distance between the light source side end surface of the light guide and the end surface facing the light guide can be set short regardless of the size of the liquid crystal panel display unit. it can. If the width of the light guide is shortened, the propagation distance of light propagating through the light guide is shortened. For this reason, even when a transparent body having a small amount of refractive index anisotropy such as an acrylic resin is used as the light guide, the light propagation distance can be shortened with the illumination device of the present invention, so that the polarization state changes. Therefore, it is possible to realize an illumination device that efficiently emits illumination light having a large amount of predetermined linearly polarized light components.

  Next, the liquid crystal panel 200 will be described. As described above, in the illumination device according to the present embodiment, the linearly polarized light having the vibration direction of the electric vector parallel to the longitudinal direction of the minute inclined reflection surface 103 </ b> A (the triangular groove constituting the light guide 103) on the back surface of the light guide 103. Illumination light with many components can be obtained. Therefore, when configuring the illumination device, the longitudinal direction of the light source 101 is arranged in a direction parallel to the left-right direction of the display surface of the liquid crystal panel 200, and the longitudinal direction of the triangular grooves that constitute the minute inclined reflecting surface 103A on the back surface of the light guide 103 If it is configured to be parallel to this, the illumination light from the illumination device becomes linearly polarized light having a vibration direction in a direction parallel to the horizontal direction of the display surface.

  As the liquid crystal panel 200, a TN liquid crystal panel can be used as in the above embodiment. However, in general, in the TN liquid crystal panel, in order to obtain left-right symmetry of the viewing angle, the linearly polarized light transmission axes of the polarizing plate 201 and the polarizing plate 205 are inclined by 45 ° (or 135 °) with respect to the horizontal direction of the display surface. To do. For this reason, illumination light cannot be used efficiently even when the illumination device 100 that emits linearly polarized light having a specific angle of curvature, that is, linearly polarized light having a vibration direction in a direction parallel to the horizontal direction of the display surface.

  Therefore, in this embodiment, it is necessary to use a display mode in which the polarizing plate 201 does not adversely affect the viewing angle even if the transmission axis of linearly polarized light coincides with the horizontal direction of the display surface.

  As a liquid crystal panel using such a display mode, an IPS (In Plane Switching) liquid crystal panel that realizes alignment division with a cross-shaped electrode, or an MVA (Multi-domain Vertical Aligned) liquid crystal panel can be used.

  In the present embodiment, the case where an IPS liquid crystal panel is used as the liquid crystal panel 200 will be described below with reference to FIGS. 20 and 22, but the present invention is not limited to this.

  FIG. 22 is a front view showing a configuration of one pixel of the liquid crystal panel 200 of the present embodiment. One pixel of the liquid crystal panel 200 has a common electrode 2003 and an scanning signal electrode 2004 made of an Al alloy coated on an alumina film formed on a transparent glass substrate 202, and a gate insulating film made of SiN not shown in the upper layer thereof. TFT as a switching element formed by the formed video signal electrode 2001 and pixel electrode 2002 made of Al / Cr and these electrodes and an amorphous Si (a-Si) film, n-type a-Si film, etc. (not shown). (Thin Film Transistor) 2006.

  Further, a protective layer made of SiN is formed on these upper layers, and a liquid crystal layer 208 is formed thereon via an alignment film.

  The pixel electrode 2002 partially overlaps with the common electrode 2003 to form a storage capacitor.

  The common electrode 2003 and the pixel electrode 2002 divide one pixel into four regions, and are formed in a shape in which the U-shapes are connected while maintaining a substantially constant gap, that is, a zigzag shape. The inclination angles α of the cross-sections of the common electrode 2003 and the pixel electrode 2002 with respect to the vertical direction of the display portion of the liquid crystal panel 200 are + 10 ° and −10 °.

  Here, a liquid crystal having a positive dielectric anisotropy is used as the liquid crystal constituting the liquid crystal layer 208, and the alignment film formed on the two transparent glass substrates 202 and 204 is subjected to an alignment treatment to obtain a liquid crystal molecular length. The direction of the axis was defined. The liquid crystal alignment direction of the liquid crystal layer 208 is a so-called homogeneous alignment that is not twisted between the two transparent glass substrates 202 and 204, and is aligned so that the direction of the major axis of the liquid crystal molecule is perpendicular to the horizontal direction of the display portion of the liquid crystal panel 200. did.

  FIG. 23 is a diagram showing the conditions of each member when the horizontal direction of the display part of the liquid crystal panel 200 is used as a reference, the transmission axis of linearly polarized light of the polarizing plate 205 and the polarizing plate 201 of this embodiment, and the liquid crystal molecules of the liquid crystal layer 208. The orientation direction of the long axis and the longitudinal direction of the minute inclined reflecting surface 103 </ b> A (the triangular groove forming the same) on the back surface of the light guide 103 are shown.

  As shown in the figure, in the display device of this example, the transmission axis of the linearly polarized light of the polarizing plate 205 on the viewer side of the liquid crystal panel 200 forms 90 ° with the horizontal direction of the display surface, and the liquid crystal molecule long axis of the liquid crystal layer 208 Is also arranged to form 90 ° with the horizontal direction of the display surface. The transmission axis of linearly polarized light of the polarizing plate 201 on the illumination light incident side of the liquid crystal panel 200 is parallel to the horizontal direction of the display surface, and the longitudinal direction of the minute inclined reflective surface 103A on the back surface of the light guide 103 constituting the illumination device is also the display surface. It comprised so that it might become parallel with the left-right direction.

  With this configuration, the liquid crystal panel 200 of this embodiment has a so-called normally closed display characteristic in which a dark display is obtained when no voltage is applied to the liquid crystal layer 208 and a bright display is obtained when the applied voltage to the liquid crystal layer 208 is increased. can get.

  Here, the liquid crystal panel 200 includes electrodes, switching elements, and the like, and these portions serve as non-display portions (non-openings 206) and do not contribute to the brightness of the image. These non-opening portions 206 do not contribute to the brightness of the image, but most of them are metal electrodes and reflect light. In the liquid crystal panel of this example, the reflectance of light at the non-opening portion 206 was increased by using an Al (aluminum) alloy in addition to the Cr (chromium) alloy. Specifically, in the liquid crystal panel 200 according to the present embodiment, the area ratio when viewed from the back side of the Cr and Al liquid crystal panel 200 was set to Cr: Al = 1: 1.4. By doing so, the reflectivity of 54% when only Cr was used as the metal electrode could be increased to a reflectivity of 74%.

  Next, the operation of the present display device will be described with reference to FIG.

  In the illumination device 100 of this embodiment, as described above, about 65% of the light emitted from the non-polarized light source 101 becomes specific linearly polarized light, passes through the linearly polarized light separating element 701, and enters the light guide 103. To do. The light incident on the light guide 103 propagates through the light guide while repeating total reflection, and the light reaching the inclined reflection surface 103A on the back surface of the light guide 103 changes its reflection angle and is totally reflected on the light guide surface 103C. Exits and exits. The light emitted from the light guide 103 has a larger amount of s-polarized light than the minute inclined reflecting surface 103A on the back surface of the light guide 103, that is, the vibration direction of the electric vector is that of the minute inclined surface 103A on the back surface of the light guide 103. Illumination light with many linearly polarized light components parallel to the longitudinal direction can be obtained.

  The light emitted from the light guide 103 is applied to the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105. At this time, since the diffusion plate 105 maintains the polarization state, the diffusion plate 105 reaches the liquid crystal panel 200 while maintaining the polarization state of the light emitted from the light guide 103. The amount of light transmitted to the liquid crystal panel 200 is controlled according to image information, and an image is displayed to the observer.

  At this time, the transmission axis of the linearly polarized light of the polarizing plate 201 on the illumination light incident side of the liquid crystal panel 200 is configured to be parallel to the longitudinal direction of the minute inclined reflection surface 103A on the back surface of the light guide 103 constituting the illumination device. Most of the illumination light contributes to the display while being hardly absorbed by the polarizing plate 201 on the illumination device side of the liquid crystal panel 200.

  In other words, the non-polarized light emitted from the light source 101 is efficiently converted into the desired linearly polarized light, and then irradiated to the liquid crystal panel 200 and contributes to display with almost no absorption by the polarizing plate 201. Therefore, conventionally, light that has been absorbed by the polarizing plate 201 of the liquid crystal panel 200 and wasted can be used effectively, so that a bright and low power consumption display device can be realized.

  As described above, the liquid crystal panel 200 has the non-opening 206 such as electrodes and switching elements. These non-opening portions 206 do not contribute to the brightness of the image, but most of them are metal electrodes and reflect light.

  Therefore, among the light irradiated to the liquid crystal panel 200, the light 30001A incident on the opening 207 is used for display as it is, but the light 3001B incident on the non-opening 206 of the liquid crystal panel 200 does not contribute to the display. And return to the lighting device 100 after reflection.

  The light 3001B returned to the illumination device 100 is transmitted through the diffusion plate 105 and the light guide 103, reflected by the reflection plate 104, and again transmitted through the light guide 103 and the diffusion plate 105 to be irradiated on the liquid crystal panel 200. The At this time, in this embodiment, the polarization state of the light is maintained and does not change greatly by the transmission through the diffusion plate 105 and the light guide 103 and the reflection by the reflection plate 104. For this reason, the light 3001 </ b> B irradiated again to the liquid crystal panel 200 maintains almost the polarization state when it is first reflected by the non-opening portion 206 of the liquid crystal panel 200, and thus is hardly absorbed by the polarizing plate 201. It can contribute to the display. That is, in the display device of this embodiment, since the light that has been shielded by the non-opening portion 206 of the liquid crystal panel 200 and has not been able to contribute to the display can be reused without a large loss, the liquid crystal with a low aperture ratio can be used. Even if it is a panel, there exists an effect that a bright display is obtained.

  Here, the illumination device described in (Embodiment 5) and (Embodiment 6) has a function of converting non-polarized light source light into desired linearly polarized light as in the present embodiment. The return light from the non-opening portion 206 is reflected twice on the reflection plate 104 on the back surface of the light guide 103 and transmitted twice through the light guide 103 and the diffusion plate 105, and then irradiated to the liquid crystal panel.

  On the other hand, in this embodiment, the light source light that is non-polarized light has a function of converting the light source light into desired linearly polarized light, and return light from the non-opening portion 206 of the liquid crystal panel 200 is reflected by the reflector 104 on the back surface of the light guide 103. After being reflected once, the liquid crystal panel 200 is irradiated again with only one round-trip transmission through the light guide 103 and the diffusion plate 105.

  For this reason, the loss of the return light from the non-opening portion 206 in the reflection plate 104, the light guide 103 and the diffusion plate 105, and the disturbance of the polarization state are reduced, and the return light from the non-opening portion 206 is more efficiently used. Can be reused.

  That is, in the illumination device of this embodiment and the display device using the same, the effect is more prominent when a liquid crystal panel having a low aperture ratio is used. Therefore, a relatively open aperture such as an IPS liquid crystal panel is used as the liquid crystal panel. A combination with a liquid crystal panel having a low rate or a liquid crystal panel having a low aperture ratio due to high definition is preferable.

  In this embodiment, Cr alloy and Al alloy are used together as the metal electrode, but the present invention is not limited to this. That is, ideally, a metal having high reflectivity such as Al or Ag is used on at least the back side of the liquid crystal panel 200 of the electrode, or a reflective surface such as a dielectric multilayer film is formed on the back side of the liquid crystal panel of the non-opening 206. Thus, it is desirable to minimize light loss due to light absorption in the non-opening portion 206 by reflecting light incident on the non-opening portion 206 to the lighting device side with a high reflectance.

  By the way, in (Example 6), a linearly polarized light separating element having an area equal to or larger than that of the liquid crystal panel display unit was required. On the other hand, the linearly polarized light separating element used in the present embodiment only needs to cover the specific end face of the light guide. Decreases to 1/5 to 1/20. Since the linearly polarized light separating element is generally expensive, there is an effect that the cost of the apparatus can be reduced by reducing the amount of the linearly polarized light separating element used.

  Needless to say, the same effects as in the above embodiment can be obtained in this embodiment. In other words, by arranging multiple unit lighting devices consisting of a light source, a light guide, a lamp cover, and a reflector, they are thin and have a uniform in-plane luminance distribution even when the size is increased (large screen). Thus, a lighting device that emits light with high luminance can be realized, and a display device that can display a high-quality display with higher brightness and in-plane uniformity of luminance can be realized.

(Example 8)
Next, another embodiment of the illumination device according to the present invention and a display device using the same will be described with reference to the drawings. FIG. 24 is a partial schematic cross-sectional view showing an example of the illumination device of the present invention and a display device using the same.

  In this embodiment, the light converging unit 103M is disposed between the light source 101 and the linearly polarized light separating element 701 disposed on the end face of the light guide body 103 adjacent to the light source 101 in the illumination device described in the seventh embodiment. The same reference numerals are given to the same parts as those in the above embodiment, and the detailed description is omitted.

  The light converging unit 103M has a function of converging the divergent light from the light source 101, and is a means for making the light source light enter a linearly polarized light separating element 701 in a state closer to parallel light.

  The light converging unit 103M is disposed between the light source 101 and the linearly polarized light separating element 701 at a position that is the back surface of the adjacent light guide. The light converging portion 103M is made of a transparent material such as acrylic resin or glass, and has a tapered shape whose cross-sectional area increases from the light source 101 side toward the light guide body 103 side.

  In addition, a reflecting plate 1041 is disposed on the surface other than the end surface on the light source side of the light converging unit 103M and the end surface on the linearly polarized light separating element 701 side through an air layer.

  Although the details of the design of the light converging unit 103M are already well known and will not be described in detail, the end surface on the light source side of the light converging unit 103M is 1.2 of the tube diameter of the light source 101 in order to increase the incident efficiency of the light source light. It should be about 1.5 times thicker.

  Next, the operation of the lighting apparatus of the present embodiment will be described with reference to FIG. 24 while focusing on the single unit lighting apparatus 100 constituting the lighting apparatus.

  The light 3000 emitted from the light source 101 enters the light converging unit 103M directly or after being reflected by the lamp cover 102. The light incident on the light converging unit 103M is converged by reflection on the front surface, the back surface, and the side surface of the light converging unit 103M, and enters the linearly polarized light separating element 701.

  Here, the linearly polarized light separating element 701 has a function of transmitting a specific linearly polarized light component of light incident thereon and reflecting a different polarized light component. As described above, as the linearly polarized light separating element 701, a birefringence reflective polarizing film in which a plurality of different birefringent polymer films described in International Publication No. WO95 / 27919 described in International Application are alternately laminated, and SID92 Digest p427 are used. Two prism arrays with an apex angle of approximately 90 degrees are overlapped, and a polarization separation surface formed of a dielectric multilayer film is formed on the overlapped portion, or a cholesteric liquid crystal layer and a retardation plate are stacked. be able to.

  Each of these functions efficiently with respect to light incident at an angle close to or perpendicular to the angle, but the function is deteriorated with respect to light incident at an angle.

  In the present embodiment, the light exiting from the light source is converged by the light converging unit 103M, thereby increasing the proportion of light that is perpendicularly incident on the linearly polarized light separating element 701 and increasing the proportion of light that the linearly polarized light separating element 701 functions effectively. It is an enhanced one.

  The outgoing light 3000 from the non-polarized light source 101 is converged by the light converging unit 103M and then enters the linearly polarized light separating element 701. Since the light incident on the linearly polarized light separating element 701 has a large proportion of light that is perpendicularly incident on the linearly polarized light separating element 701, it is efficiently transmitted as a specific linearly polarized light component, and a different polarized light component is reflected.

  The light 3004 reflected by the linearly polarized light separating element 701 is reflected by the reflecting plate 1041 arranged outside the light converging unit 103M or the light source 101 or the lamp cover 102 and again travels toward the linearly polarized light separating element 701.

  The light that re-enters the linearly polarized light separating element 701 is reflected by the reflector 1041, the light source 101, or the lamp cover 102, and its polarization state has changed or has been depolarized. The linearly polarized light component is transmitted, and a different polarized light component is reflected again. While this operation is repeated, about 70% of the non-polarized light emitted from the light source 101 becomes specific linearly polarized light and passes through the linearly polarized light separating element 701.

  The light 3003 transmitted through the linearly polarized light separating element 701 enters the light guide 103. The light 3003 incident on the light guide 103 propagates while repeating total reflection in the light guide 103, and reaches the minute inclined reflection surface 103A on the back surface of the light guide 103 out of the light propagating in the light guide 103. The light changes its reflection angle and exits the light guide surface 103C outside the total reflection condition.

  At this time, the light propagating through the light guide 103 is light that has passed through the linearly polarized light separating element 701, so that most of the light has more s-polarized light or s-polarized components than the inclined reflective surface 103 </ b> A on the back surface of the light guide 103. The light emitted from the light guide 103 is also light having a large amount of s-polarized component with respect to the inclined reflection surface 103A on the back surface of the light guide 103, that is, the vibration direction of the electric vector is slightly inclined on the back surface of the light guide 103. The light has a large amount of linearly polarized light components parallel to the longitudinal direction of the surface 103A.

  Next, the operation of the present display device will be described with reference to FIG.

  In the illumination device 100 of the present embodiment, as described above, about 70% of the light emitted from the non-polarized light source 101 becomes specific linearly polarized light, passes through the linearly polarized light separating element 701, and enters the light guide 103. To do. The light incident on the light guide 103 propagates through the light guide while repeating total reflection, and the light reaching the inclined reflection surface 103A on the back surface of the light guide 103 changes its reflection angle and is totally reflected on the light guide surface 103C. Exits and exits. Since the light emitted from the light guide 103 has a larger amount of s-polarized light component than the minute inclined reflecting surface 103A on the back surface of the light guide 103, the vibration direction of the electric vector is the longitudinal direction of the minute inclined surface 103A on the back surface of the light guide 103. Illumination light having a large amount of linearly polarized light parallel to the direction can be obtained.

  The light emitted from the light guide 103 is applied to the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105. At this time, since the diffusion plate 105 maintains the polarization state, the diffusion plate 105 reaches the liquid crystal panel 200 while maintaining the polarization state of the light emitted from the light guide 103. The amount of light transmitted to the liquid crystal panel 200 is controlled according to image information, and an image is displayed to the observer.

  At this time, since the transmission axis of the linearly polarized light of the polarizing plate 201 on the lighting device side of the liquid crystal panel 200 is configured to be parallel to the longitudinal direction of the minute inclined reflection surface 103A on the back surface of the light guide 103 constituting the lighting device, Most of the illumination light is absorbed by the polarizing plate 201 on the illumination device side of the liquid crystal panel 200 and contributes to display.

  In other words, the non-polarized light emitted from the light source 101 is efficiently converted into the desired linearly polarized light, and then irradiated to the liquid crystal panel 200 and contributes to display with almost no absorption by the polarizing plate 201. Therefore, conventionally, light that has been absorbed by the polarizing plate 201 of the liquid crystal panel 200 and wasted can be used effectively, so that a bright and low power consumption display device can be realized.

  Of the light irradiated to the liquid crystal panel 200, the light 3003A incident on the opening 207 is used for display as it is, but the light 3003B incident on the non-opening 206 of the liquid crystal panel 200 does not contribute to the display. And return to the lighting device 100 after reflection.

  The light 3003B returning to the illumination device 100 is transmitted through the diffusion plate 105 and the light guide 103, reflected by the reflection plate 104, and again transmitted through the light guide 103 and the diffusion plate 105 to be irradiated on the liquid crystal panel 200. The At this time, in this embodiment, the polarization state of the light is maintained and does not change greatly by the transmission through the diffusion plate 105 and the light guide 103 and the reflection by the reflection plate 104. For this reason, the light 3003B irradiated again on the liquid crystal panel 200 maintains almost the polarization state when it is first reflected by the non-opening portion 206 of the liquid crystal panel 200, and therefore is hardly absorbed by the polarizing plate 201. It can contribute to the display. That is, in the display device of this embodiment, since the light that has been shielded by the non-opening portion 206 of the liquid crystal panel 200 and has not been able to contribute to the display can be reused without a large loss, the liquid crystal with a low aperture ratio can be used. Even if it is a panel, there exists an effect that a bright display is obtained.

  Also in this embodiment, the light source light that is non-polarized light has a function of converting it into desired linearly polarized light, and the return light from the non-opening portion 206 of the liquid crystal panel 200 is once reflected by the reflector 104 on the back surface of the light guide 103. After the reflection, the liquid crystal panel 200 is irradiated again with only one round-trip transmission through the light guide 103 and the diffusion plate 105. For this reason, the return light from the non-opening portion 206 is less absorbed by the reflector 104, the light guide 103 and the diffusion plate 105, and the polarization state is less disturbed. Can be used.

  Therefore, in the illumination device of this embodiment and the display device using the same, the effect is more prominent when a liquid crystal panel having a low aperture ratio is used. Therefore, a relatively open aperture such as an IPS liquid crystal panel is used as the liquid crystal panel. A combination with a liquid crystal panel having a low rate or a liquid crystal panel having a low aperture ratio due to high definition is preferable.

  In the present embodiment, since the light converging portion is provided between the light source and the light guide, the following effects can be obtained. That is, since the portion near the light source where the luminance is high and the portion that emits the illumination light that contributes to the display of the liquid crystal panel are separated by the light convergence portion, the in-plane luminance distribution of the illumination light from the unit illumination device is uniform. Sex is higher.

  Furthermore, since the function of the linearly polarized light separating element is enhanced by converging the light emitted from the light source by the light converging unit and incident on the linearly polarized light separating element, an illuminating device that emits predetermined linearly polarized light more efficiently Therefore, a brighter and lower power consumption display device can be realized.

Example 9
Next, another embodiment of the illumination device according to the present invention and a display device using the same will be described with reference to the drawings. FIG. 25 is a partial schematic cross-sectional view showing an example of the illumination device of the present invention and a display device using the same.

  In this embodiment, in the illumination device described in (Example 7), a light source disposed in the vicinity of the light guide 103, a lamp cover disposed so as to cover the light source, and linearly polarized light disposed on the end face of the light guide 103 Instead of the separation element 701, a plurality of aligned LEDs (Light Emitting Diodes) 501, a lens 502 that converges and collimates the light emitted from the LED 501, and converts the light emitted from the LED 501 into predetermined linearly polarized light. The polarization converting means 510 is arranged, and the same parts as those in the above embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

  The illuminating device 100 includes a plurality of light guides 103 arranged in an aligned manner, a plurality of reflectors 104 disposed on the back surfaces (surfaces opposite to the liquid crystal panel 200) of the light guides 103 via an air layer, A diffusion plate 105 disposed so as to cover the entire surface of the light guide body 103 (surface on the liquid crystal panel 200 side), and a plurality of aligned LEDs 501 on one end surface of the light guide body 103; A lens 502 that collimates the light emitted from the LED 501 and a polarization conversion means 510 that converts the light emitted from the LED 501 into predetermined linearly polarized light are arranged.

  FIG. 26 shows a plurality of aligned LEDs 501 when the illumination device is viewed from the liquid crystal panel side, a lens 502 that collimates the light emitted from the LED 501, and polarized light that converts the light emitted from the LED 501 into predetermined linearly polarized light. FIG. 6 is a partial cross-sectional view showing a schematic configuration of conversion means 510.

  In the illumination device of the present embodiment, a white light emitting LED is used as a light source.

  As a white light emitting LED, a YAG (yttrium, aluminum, garnet) phosphor is applied to the surface of a GaN blue light emitting LED chip, and blue light emission and fluorescence generated by blue light are mixed to become white light, Alternatively, a blue light emitting LED in which ZnxCd1-xS is an active layer is formed on a ZnSe substrate, and blue light emission and yellow fluorescence generated in the ZnSe substrate by blue light are mixed to form white light can be used.

  Or what implement | achieved white light by the mixture of the luminescent color of three single color light emitting LED elements which light-emit in red, green, and blue can be used.

  The lens 502 has a function of converging and collimating the diffused light emitted from the LED 501, and is arranged in a one-to-one correspondence with the plurality of LEDs 501.

  Some LED lamps equipped with a commercially available transparent lens have a strong directivity, that is, a light beam with high parallelism can be obtained. This is used as an integrated LED 501 and lens 502. Also good.

  Specifically, the product name NSPW500BS (manufactured by Nichia Corporation) or the like can be used. In this case, emitted light with high directivity having a half-value angle of about ± 10 ° is obtained.

  The polarization conversion unit 510 includes a polarization separation prism array 509 and a phase difference plate 504 that aligns the polarization state of light emitted from the polarization separation prism array 509.

  A polarization separation prism array 509 separates light emitted from the LED 501 into two types of linearly polarized light whose reflection directions and transmission directions are orthogonal to each other, and polarization separation of the light reflected by the polarization separation surface 503. A plurality of reflective surfaces 505 that reflect in the same direction as the light transmitted through the surface 503 are alternately arranged via columnar translucent members 506 having a parallelogram cross section.

  The translucent member 506 is made of a material that is transparent to the emission spectrum of the light source and does not have birefringence, for example, a glass material such as BK-7, or an acrylic resin. The translucent member 506 is a columnar transparent body whose cross-sectional shape is a parallelogram with an inner angle of 45 °, and forms a plate-like appearance by sequentially joining the translucent member 506. Joining of the translucent member 506 Polarization separation surfaces 503 and reflection surfaces 505 are alternately formed on the interface.

  The polarization splitting surface 503 is formed by alternately laminating a plurality of different birefringent polymer films as described in the dielectric multilayer film formed on the translucent member 506 or the international publication number WO95 / 27919. What is necessary is just to implement | achieve by inserting | pinching the birefringent reflection type polarizing film in the joining interface of the translucent member 506. The polarization splitting surface 503 of this embodiment is configured to transmit linearly polarized light that becomes p-polarized light and reflect linearly polarized light that becomes s-polarized light with respect to the polarization separating surface 503.

  The reflection surface 505 reflects the light reflected by the polarization separation surface 503 in the same direction as the light transmitted through the polarization separation surface 503, and is the same dielectric multilayer film as the polarization separation surface 503 or a metal thin film such as Al or Ag. What is necessary is just to implement | achieve by the mirror surface of this.

  The retardation plate 504 has a function of aligning light emitted from the polarization separation prism array 509 with linearly polarized light that is s-polarized light with respect to the minute inclined reflective surface 103A on the back surface of the light guide 103. In this embodiment, the light transmitted through the polarization separation surface 503 of the polarization separation prism array 509 is s-polarized light with respect to the minute inclined reflection surface 103A on the back surface of the light guide 103, reflected by the polarization separation surface 503, and further reflected by the reflection surface. The light reflected at 504 is p-polarized with respect to the minute inclined reflecting surface 103A on the back surface of the light guide 103.

  For this reason, as the phase difference plate 504, a retardation plate 504 having a function of converting linearly polarized light that is p-polarized light to s-polarized light with respect to the minute inclined reflective surface 103A on the back surface of the light guide 103 is used. It arrange | positions in the part through which the light reflected by the polarization separation surface 503 and the reflective surface 505 passes among surfaces.

  That is, as the retardation plate 504, one that functions as a half-wave plate with respect to the emission spectrum of the light source is used. As the half-wave retardation plate, a stretched polymer film having a high transmittance with respect to the emission spectrum of the light source, such as polyvinyl alcohol, polycarbonate, polysulfone, polystyrene, polyarylate, or the like can be used. In addition, a mica, a crystal, or a liquid crystal layer in which molecular axes are aligned in one direction can be used.

  In general, a transparent body constituting a retardation plate has a wavelength dependency of refractive index (wavelength dispersion), and a single retardation plate has sufficient performance for light with a wide wavelength band such as white light. Cannot be obtained. Therefore, it is preferable to realize a half-wave plate corresponding to a wide wavelength band by laminating two types of retardation plates having different wavelength dispersions while shifting their optical axes.

  As shown in the figure, the LED 501 and the collimating lens 502 are the center positions of the light incident surfaces of the plurality of translucent members 506 constituting the polarization separation prism array 509 and are bonded interfaces corresponding to the traveling direction of the light emitted from the LED 501. Is disposed at a position where the polarization separation surface 503 is formed. That is, the plurality of LEDs 501 and the collimating lens 502 are arranged in a row with an interval corresponding to one width of the light incident surface of the translucent member 506. The phase difference plate 504 transmits light to the light exit surface of the translucent member 506 through which the light reflected from the polarization separation surface 503 of the light exit surface of the polarization separation prism 501 and further reflected by the reflection surface 505 passes. It arrange | positions, keeping the space | interval of the width | variety for one light-projection surface of the property member 506. FIG.

  The polarization conversion means 510 is connected to the end face of the light guide 103 so as to be optically coupled. That is, the polarization conversion unit 510 and the light guide 103 are coupled by a transparent adhesive having a refractive index close to that of the light transmitting member 506 constituting the light guide 103 and the polarization separation prism 501.

  The liquid crystal panel 200 is arranged such that the linearly polarized light transmission axis of the polarizing plate 201 on the illumination light incident side is parallel to the longitudinal direction of the minute inclined reflective surface 103A (which constitutes the triangular groove) on the back surface of the light guide 103. Should be used. In the present embodiment, the IPS (In Plane Switching) liquid crystal panel divided in alignment described in the seventh embodiment is used.

  Next, the operation of the display device will be described with reference to the drawings.

  The divergent light 3005 emitted from the LED 501 converges by the action of the lens 502, is collimated, and then enters the polarization separation prism array 509. The light incident on the polarizing prism array 509 is separated on the polarization separation surface 503 as two kinds of linearly polarized light whose electric vector vibration directions are orthogonal to each other as reflected light and transmitted light.

  The light transmitted through the polarization separation surface 503 is s-polarized light with respect to the minute inclined reflection surface 103A on the back surface of the light guide 103, and the light reflected by the polarization separation surface 503 is directed to the minute inclination reflection surface 103A on the back surface of the light guide 103. P-polarized light.

  The light 3005A transmitted through the polarization separation surface 503 is incident on the light guide 103 as s-polarized light with respect to the minute inclined reflection surface 103A on the back surface of the light guide 103.

  On the other hand, the light reflected by the polarization separation surface 503 is further reflected by the reflection surface 505, the traveling direction thereof is the same direction as the light transmitted through the polarization separation surface 501, and enters the phase difference plate 504. When the light 3005B incident on the phase difference plate 504 is transmitted through the phase difference plate 504, it receives the action of the phase difference plate 504, so that the polarization direction of the electric vector is rotated by 90 °, that is, a minute amount on the back surface of the light guide 103. The s-polarized light enters the light guide 103 with respect to the inclined reflecting surface 103A.

  That is, the non-polarized light emitted from the LED 501 that is the light source is converted into specific linearly polarized light (s-polarized light with respect to the minute inclined reflecting surface 103A on the back surface of the light guide 103) and then enters the light guide 103.

  Lights 3005A and 3005B incident on the light guide body 103 propagate while repeating total reflection in the light guide body 103, and out of the light propagating in the light guide body 103, on the minute inclined reflection surface 103A on the back surface of the light guide body 103. The incident light changes its reflection angle and exits from the total light reflection condition on the light guide surface 103C.

  At this time, the light propagating through the light guide 103 is light that has a large amount of s-polarized light or s-polarized light with respect to the minute inclined reflective surface 103A on the back surface of the light guide 103, and s-polarized light with respect to the minute inclined reflective surface 103A. , The traveling direction of the light changes as it is s-polarized light and is emitted from the light guide 103.

  That is, the light emitted from the light guide 103 is light having a larger amount of s-polarized light than the inclined reflective surface 103A on the back surface of the light guide 103. Therefore, the direction of vibration of the electric vector from the illumination device 100 is the light guide 103. Illumination light having a large amount of linearly polarized light components parallel to the longitudinal direction of the minute inclined surface 103A on the back surface is obtained.

  The light emitted from the light guide 103 is applied to the liquid crystal panel 200 after the light distribution and the angular distribution of the illumination light are made uniform by the diffusion plate 105. At this time, since the diffusion plate 105 maintains the polarization state, the diffusion plate 105 reaches the liquid crystal panel 200 while maintaining the polarization state of the light emitted from the light guide 103. The amount of light transmitted to the liquid crystal panel 200 is controlled according to image information, and an image is displayed to the observer.

  As described above, the transmission axis of the linearly polarized light of the polarizing plate 201 on the lighting device side of the liquid crystal panel 200 is configured to be parallel to the longitudinal direction of the minute inclined reflection surface 103A on the back surface of the light guide 103 constituting the lighting device. Most of the illumination light contributes to the display while being hardly absorbed by the polarizing plate 201 on the illumination device side of the liquid crystal panel 200.

  That is, the outgoing light which is non-polarized light from the light source 501 is efficiently converted into desired linearly polarized light, and then irradiated to the liquid crystal panel 200 and contributes to display with almost no absorption by the polarizing plate 201. Therefore, conventionally, light that has been absorbed by the polarizing plate 201 of the liquid crystal panel 200 and wasted can be used effectively, so that a bright and low power consumption display device can be realized.

  Of the light irradiated to the liquid crystal panel 200, the light 3005C incident on the opening 207 is used for display as it is, but the light 3005D incident on the non-opening 206 of the liquid crystal panel 200 does not contribute to the display. And return to the lighting device 100 after reflection.

  The light 3005D that has returned to the lighting device 100 is transmitted through the diffusion plate 105 and the light guide 103, is reflected by the reflection plate 104, is transmitted through the light guide 103 and the diffusion plate 105 again, and is applied to the liquid crystal panel 200. The At this time, in this embodiment, the polarization state of the light is maintained and does not change greatly by the transmission through the diffusion plate 105 and the light guide 103 and the reflection by the reflection plate 104. For this reason, the light 3005D irradiated again on the liquid crystal panel 200 substantially maintains the polarization state when initially reflected by the non-opening portion 206 of the liquid crystal panel 200, and thus is hardly absorbed by the polarizing plate 201. It can contribute to the display. That is, in the display device of this embodiment, since the light that has been shielded by the non-opening portion 206 of the liquid crystal panel 200 and has not been able to contribute to the display can be reused without a large loss, the liquid crystal with a low aperture ratio can be used. Even if it is a panel, there exists an effect that a bright display is obtained.

  Also in this embodiment, the light source light that is non-polarized light has a function of converting the light into desired linearly polarized light. After the reflection, the liquid crystal panel 200 is irradiated again with only one round-trip transmission through the light guide 103 and the diffusion plate 105. For this reason, the return light from the non-opening portion 206 is less absorbed by the reflector 104, the light guide 103 and the diffusion plate 105, and the polarization state is less disturbed. Can be used.

  Therefore, in the illumination device of this embodiment and the display device using the same, the effect is more prominent when a liquid crystal panel having a low aperture ratio is used. Therefore, a relatively open aperture such as an IPS liquid crystal panel is used as the liquid crystal panel. A combination with a liquid crystal panel having a low rate or a liquid crystal panel having a low aperture ratio due to high definition is preferable.

  In the lighting device of the present invention, the width of the light guide, that is, the distance between the light source side end surface of the light guide and the end surface facing the light guide can be set short regardless of the size of the liquid crystal panel display unit. . If the width of the light guide is shortened, the propagation distance of light propagating through the light guide is shortened. For this reason, even when a transparent body having a small amount of refractive index anisotropy such as an acrylic resin is used as the light guide, the light propagation distance can be shortened with the illumination device of the present invention, so that the polarization state changes. Therefore, it is possible to realize an illumination device that efficiently emits illumination light with a large amount of predetermined linearly polarized light components.

  In the present embodiment, the following effects can be obtained by using an LED as the light source. That is, since the size of the light emitting portion of the LED is extremely smaller than that of the fluorescent lamp, it is easy to increase the directivity of light with an optical member such as a lens. Here, in general, the efficiency of converting non-polarized light into a predetermined polarization state is higher for light with high directivity. In other words, by using an LED as the light source, non-polarized light emitted from the light source can be efficiently converted into desired polarized light (linearly polarized light that is not absorbed by the polarizing plate on the liquid crystal panel light incident side), thereby further increasing the light source light utilization efficiency. Can do.

  Further, the LED does not require an inverter required for a fluorescent lamp, which is advantageous for downsizing the device body. Furthermore, since LED hardly uses mercury, it has the feature that it is environmentally friendly.

(Example 10)
Next, another embodiment of the illumination device according to the present invention and a display device using the same will be described with reference to the drawings. FIG. 27 is a partial perspective view showing a schematic configuration of the illumination device of the present invention and a display device using the same, and FIG. 28 shows the overall configuration of the display device of this example.

  This embodiment includes a liquid crystal panel 200 and an illumination device 100 that can divide and illuminate the display surface of the liquid crystal panel 200 independently. That is, the areas a to c obtained by dividing the display surface of the liquid crystal panel 200 into three equal parts in the vertical direction are individually illuminated by the three unit illumination devices 1000 a to 1000 c constituting the illumination device 100. Corresponding to the display operation, lighting and extinguishing of the three unit lighting devices 1000a to 1000c constituting the lighting device 100 are individually controlled.

  As the illumination device 100 of this embodiment, the one described in the above embodiment may be basically used. Hereinafter, the case where a cold cathode fluorescent lamp is used as the light source will be described, but the present invention is not limited to this. Further, detailed description of portions common to the above embodiment is omitted.

  A scanning driver (scanning electrode driving circuit) 3 and a video driver (pixel electrode driving circuit) 4 are connected to the liquid crystal panel 200, and a power supply circuit 5 and an illumination driver (illumination control circuit) 6 are connected to the lighting device 100. The The liquid crystal controller 1 is connected to the scanning driver (scanning electrode driving circuit) 3, the video driver (pixel electrode driving circuit) 4, and the illumination driver (illumination control circuit) 6.

  In this configuration, in response to the display operation of the liquid crystal panel 200, the lighting driver 6 individually controls the plurality of unit lighting devices 1000a to 1000c constituting the lighting device 100 for the purpose of preventing blurring of moving images. The display surface of 200 is divided and illuminated.

  As the liquid crystal panel 200, a liquid crystal panel having a fast response speed of 9 ms or less is used. A liquid crystal panel having a quick response time includes a liquid crystal panel using a ferroelectric liquid crystal or a panel using an OCB (Optically Compensated Bend) mode. Further, even a TN liquid crystal panel or an IPS liquid crystal panel can satisfy the above requirements by using a low-viscosity liquid crystal material and narrowing the liquid crystal layer.

  In this embodiment, a case where an IPS liquid crystal panel having a normally closed characteristic and a liquid crystal layer gap of about 2 μm, a halftone response time of 9 ms is used will be described. However, the present invention is limited to this. It is not a thing.

  The liquid crystal controller 1 takes in a signal from the outside, and outputs data to be displayed on the liquid crystal panel 200, a horizontal synchronization signal HSYNC, and a vertical synchronization signal VSYNC. The configuration of the liquid crystal controller 1 differs depending on the input signal. First, a case where an analog signal is input to the liquid crystal controller 1 will be described. In this case, the analog signal includes a signal to be displayed on the liquid crystal panel 200 and a video start signal indicating the start of the video signal for each pixel. The liquid crystal controller 1 includes an A / D converter, extracts a video signal from the superimposed analog signal, converts it to a digital signal by the A / D converter, and outputs it as data. In addition, an analog video start signal is output as a vertical synchronization signal VSYNC, and a sampling clock in the A / D converter is output as a horizontal synchronization signal HSYNC.

  When the signal input to the liquid crystal controller 1 is a digital signal, data generated by an external processing unit is input to this signal. In this case, since the external arithmetic processing unit performs an operation based on the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC, the liquid crystal controller 1 receives the data, the horizontal synchronization signal HSYNC, and the vertical synchronization signal VSYNC. The data, horizontal synchronization signal HSYNC, and vertical synchronization signal VSYNC are output as they are.

  The vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC output from the liquid crystal controller 1 are input to the scanning driver 3. In the scan driver 3, the shift register 8 generates a signal for each scan electrode of the liquid crystal panel 200, the level shift circuit 9 determines the level of the signal for each scan electrode, and outputs the scan electrode signal.

  The video driver 4 receives the data output from the liquid crystal controller 1, the horizontal synchronization signal HSYNC, and the vertical synchronization signal VSYNC. Data is input to the shift register 10 and input to the line scale 11 as data for one line. Next, the level is determined by the level shift circuit 12 and converted into an analog signal by the D / A converter 13. The converted analog signal is output as a signal to each pixel electrode of the liquid crystal panel 200.

  Next, the illumination driver 6 that individually controls the unit illumination devices 1000a to 1000c constituting the illumination device 100 will be described.

  The illumination driver 6 is connected to the power supply circuit 5 and the light sources 101a to 101c of the unit illumination devices 1000a to 1000c, and the unit illumination devices 1000a to 1000c constituting the illumination device 100 in order to prevent blurring that occurs when displaying moving images. Is controlled individually.

  FIG. 29 shows the configuration of the illumination driver 6. The illumination driver 6 includes counters 61, 62, 63, pulse generators 64, 65, 66, switches 67, 68, 69, and inverters 70, 71, 72. Each of the counters 61 to 63 receives the horizontal synchronization signal HSYNC and counts the number of pulses of the horizontal synchronization signal HSYNC. Further, the counter 61 inputs the vertical synchronization signal VSYNC, the counter 62 inputs the output signal of the counter 61, and the counter 63 inputs the output signal of the counter 62 as signals for starting the respective counts. When the pulse generators 64 to 66 respectively receive the outputs of the counters 61 to 63, the pulse generators 64 to 66 output Hi level signals for a predetermined time. The switches 67 to 69 are turned on when the signals from the pulse generators 64 to 66 are at the Hi level, whereby electric power from the power supply circuit is input to the inverters 70 to 72, and the light sources 101a to 101c are individually turned on.

  FIG. 30 shows the outputs of the vertical synchronization signal VSYNC, the horizontal synchronization signal HSYNC, and the inverters 70-72.

  Here, a case where the period of the vertical synchronization signal VSYNC is 16.6 ms, the period of the horizontal synchronization signal HSYNC is 15 μs, and it takes 9 ms to scan the entire display surface of the 800 × 600 pixel liquid crystal panel 200 will be described.

  In this embodiment, the illumination device 100 is composed of three unit illumination devices that illuminate the display surface of the liquid crystal panel 200 by dividing the display surface into three illumination regions, and the unit illumination device in charge of each illumination region corresponds to the corresponding liquid crystal. After scanning of the display surface of the panel 200 is started, control is performed so that illumination light is irradiated after the scanning of the region is completed and the liquid crystal responds. Therefore, in the area c of the liquid crystal panel 200, illumination light is irradiated for 4.6 ms after 12 ms from the start of scanning. In the area b, illumination light is irradiated for 4.6 ms after 15 ms, and in area a, illumination light is irradiated for 4.6 ms after 18 ms.

  In order to realize this, the counter 61 outputs an output signal when it counts 800 horizontal synchronizing signals. Similarly, the counter 62 outputs an output signal when the counter 61 counts 200 horizontal synchronizing signals after the output of the counter 61, and the counter 63 outputs 200 horizontal synchronizing signals after the counter 62 outputs the output signal. Outputs an output signal when counted. Each of the pulse generators 64 to 66 receives the output signal of each counter and outputs a Hi level signal for 4.6 ms.

  FIG. 31 shows the relationship between the transmittance of the display surface of the liquid crystal panel 200 and the luminance of the lighting device 100 in this case. The transmittance of the liquid crystal panel represents the average value of each region. As described above, the unit lighting devices 1000a to 1000c constituting the lighting device 100 are turned on after the liquid crystal in the region to be irradiated with the illumination light of the liquid crystal panel responds and has a desired transmittance, and after illumination for a certain period of time, It is controlled to turn off.

  Even if a moving image in which a still image is moved at a viewing angle speed of 10 ° / s is displayed under such conditions, no blurring of the image can be felt at all. That is, a liquid crystal display device that can display a moving image without a sense of incongruity can be easily provided.

  In this embodiment, it is not particularly necessary to wait for the lighting device to turn on until the entire display surface of the liquid crystal panel responds. That is, since the lighting device is turned on in a shorter standby time in which a smaller display area responds, illumination light can be irradiated for a longer time, and a brighter image can be obtained.

It is a partial schematic sectional drawing which shows one Example of the illuminating device of this invention. It is a partial perspective view which shows schematic structure of the unit illuminating device which comprises the illuminating device of this invention. It is a figure which shows an example of the relationship between the effective thickness of the light-incidence part end surface of a light guide, and the brightness | luminance of an illuminating device. It is a fragmentary sectional view showing an example of a light guide concerning the present invention. It is a fragmentary sectional view showing an example of a light guide concerning the present invention. It is a fragmentary sectional view showing an example of a light guide concerning the present invention. It is a schematic perspective view which shows one Example of the illuminating device of this invention and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a schematic perspective view which shows one Example of the light guide which concerns on this invention. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a schematic perspective view which shows one Example of the light guide which concerns on this invention. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a partial perspective view which shows an example of the polarization maintaining diffuser plate which concerns on this invention. It is a partial sectional view showing an example of a polarization maintaining diffusion plate according to the present invention. It is a partial sectional view showing an example of a polarization maintaining diffusion plate according to the present invention. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a figure which shows the relationship between the light-incidence angle of a minute inclination reflective surface formed in the back surface of the light guide which concerns on this invention, and a reflectance. It is a front view which shows an example of one pixel of the liquid crystal panel which concerns on this invention. It is explanatory drawing of the structure of the liquid crystal panel which concerns on this invention. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention, and a display apparatus using the same. It is a partial cross section figure which shows an example of the polarization conversion means which concerns on this invention. It is a schematic perspective view which shows one Example of the illuminating device of this invention and a display apparatus using the same. It is a schematic block diagram of the display apparatus of this invention. It is a schematic block diagram of the illumination driver concerning this invention. It is operation | movement explanatory drawing of the illumination driver concerning this invention. It is explanatory drawing which shows an example of the relationship between the liquid crystal panel transmittance | permeability of the display apparatus of this invention, and the brightness | luminance of an illuminating device. It is a fragmentary sectional view which shows one Example of the illuminating device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal controller, 3 ... Scan driver, 4 ... Video driver, 5 ... Power supply circuit, 6 ... Illumination driver, 8, 10 ... Shift register, 9, 12 ... Level shift circuit, 11 ... Line memory, 13 ... D / A Converter, 61, 62, 63 ... counter, 64, 65, 66 ... pulse generator, 67, 68, 69 ... switch, 70, 71, 72 ... inverter, 100 ... lighting device, 101, 101a, 101b, 101c ... Light source, 102, 102a, 102b, 102c ... lamp cover, 103, 103a, 103b, 103c ... light guide, 103A ... minute inclined reflective surface on the back of the light guide, 103B ... main surface on the back of the light guide, 103C ... guide Light body surface, 103L ... Projection part of light guide, 103M ... Light converging part, 104, 104a, 104b, 104c ... Reflector plate, 105 ... Diffuser plate, 106 ... Lesteric liquid crystal layer, 107, 108, 504 ... retardation plate, 109 ... linearly polarized light separating element, 200 ... liquid crystal panel, 200A ... vertical surface of liquid crystal panel, 201, 205 ... polarizing plate, 202, 204 ... transparent glass substrate, DESCRIPTION OF SYMBOLS 203 ... Seal agent, 206 ... Non-opening part, 207 ... Opening part, 208 ... Liquid crystal layer, 501 ... LED, 502 ... Lens, 503 ... Polarization separation surface, 505 ... Reflection surface, 506 ... Translucent member, 509 ... Polarization Separation prism array, 510 ... polarization conversion means, 701 ... linearly polarized light separation element, 1000, 1000a, 1000b, 1000c ... unit illumination device, 1031, 1032 ... end face of light guide, 1501 ... transparent substrate, 1502 ... transparent beads, 1503 ... Transparent adhesive resin, 2001 ... Video signal electrode, 2002 ... Pixel electrode, 2003 ... Common electrode, 2004 ... Scanning No. electrode, 3231 ... flat light guide, 3232 ... wedge-shaped light guide with protrusion, 3233 ... protrusion, 3234 ... joint surface, 10311 ... end face of light guide on which light source light enters, 10312 ... adjacent light guide Joint end face with the body.

Claims (2)

LCD panel,
A lighting device having a plurality of unit lighting devices;
A driver for individually controlling the plurality of unit lighting devices to illuminate a plurality of illumination areas in which a display surface of the liquid crystal panel is divided;
The unit lighting device has a larger thickness among at least a pair of opposite ends having a light guide made of a plate-like transparent body and a pair of ends having different thicknesses of the light guide. A light source disposed in proximity to an end of the light guide, and the light guide has a surface side that is the irradiation target side of the light guide at the end having the larger thickness among a pair of ends having different thicknesses A plurality of light guides having a protrusion whose width on the back surface side is larger than the width of the light source, and the protrusion has a structure in which light of the light source incident from an end surface propagates while repeating total reflection. Of the pair of end portions having different thicknesses, the end portion having the smaller thickness and the end portion having the larger thickness are aligned so that the protruding portion is disposed on the back side of the adjacent light guide The light source is positioned near the end surface of the protruding portion and the back side of the adjacent light guide Disposed made position, further, the light source, or a display device provided with an optical member for guiding the light emitted from the light source to the light guide end face in the vicinity of the light source. The display device according to claim 1,
The driver, after the scanning of the illumination area of the liquid crystal panel corresponding to the unit illumination device in charge of each of the plurality of illumination areas is started, the scanning of the illumination area is completed, and the liquid crystal panel A display device that controls to emit illumination light after the liquid crystal responds.

Images