JP4843949B2 - Lighting device and projector - Google Patents

Description

  The present invention relates to a lighting device and a projector.

  In a projector, in an optical system including a light source and a spatial light modulation device, a spatial spread in which a light beam that can be effectively handled exists can be expressed as a product of an area and a solid angle (Etendue, Geometric Extent). The product of the area and the solid angle is stored in the optical system. There is a limit to the angle at which light can be effectively modulated by the spatial light modulator. For this reason, when the spatial spread of the light source increases, it becomes difficult to effectively use the light flux from the light source.

For example, a PBS (Polarized Beam Splitter) array is provided as a member for performing polarization conversion in a projector illumination device including a liquid crystal spatial light modulator. The PBS array separates one light beam into two polarized light beams whose vibration directions are substantially orthogonal, and converts one of them with a phase plate. For this reason, when the PBS array is used, the luminous flux is approximately doubled. In particular, when light-emitting diode elements (hereinafter referred to as “LEDs”), which are solid-state light-emitting elements, are provided in an array, the light-emitting area of the light source increases. From this, it is considered that when the arrayed LED and the PBS array are used in combination, the luminous flux, that is, the etendue is increased and the illumination efficiency is lowered. Therefore, in the configuration in which the LEDs are arranged in an array, it is required to supply polarized light having a specific vibration direction without increasing the etendue. Techniques for supplying polarized light in a specific vibration direction without increasing etendue have been proposed (see, for example, Patent Documents 1 and 2).
JP 2000-212499 A JP 2003-57445 A

  However, since the technique proposed in Patent Document 1 is provided with a polarization conversion element inside the LED, it becomes difficult to manufacture the LED, and the reflective polarizing film is altered by the heat from the LED, and the polarization conversion is performed. It may be difficult to perform. In the technique proposed in Patent Document 2, a reflecting surface is provided on the incident end face of the rod integrator, and a polarization conversion element is provided on the exit side of the rod integrator. Since an opening for allowing light from the light source to enter is provided on the incident end surface of the rod integrator, the light reflected by the reflective polarizing element is emitted from the opening, and the light recycling efficiency by the rod integrator may decrease. . In addition, in order to make the light from the arrayed LED efficiently enter the rod integrator, the rod integrator should be made large corresponding to the region where the LED is arranged, and a plurality of openings corresponding to the LED are made into the rod integrator. It is necessary to take measures such as installing in

  Further, the technique proposed in Patent Document 2 has difficulty in using a plurality of light sources because the opening of the rod that guides the light emitted from the light emitting means to the quarter-wave plate is small. Furthermore, light that is obliquely incident on the quarter-wave plate becomes elliptically polarized light instead of circularly polarized light due to the angle dependency of the quarter-wave plate, and the recycling efficiency is lowered.

  The reflective polarizing element can efficiently separate light incident from a direction substantially perpendicular to the reflective polarizing element. On the other hand, in any of the configurations proposed in Patent Documents 1 and 2, a part of the light is incident on the reflective polarizing element at an angle. For this reason, it becomes difficult to efficiently separate light. Thus, according to the conventional technique, there is a problem because it may be difficult to efficiently supply polarized light having a specific vibration direction.

  SUMMARY An advantage of some aspects of the invention is that it provides an illumination device and a projector that can improve light use efficiency without reducing the extinction ratio of illumination light.

In order to achieve the above object, the present invention provides the following means.
The illumination device of the present invention includes a light source that emits light, a light guide element that equalizes an illuminance distribution of the light emitted from the light source, and polarized light in a specific vibration direction among the light emitted from the light guide element. A reflective polarizing element that transmits light and reflects polarized light in another vibration direction different from the specific vibration direction; and provided in the light source, reflected by the reflective polarizing element and travels in the direction of the light source A reflective portion that reflects light in the direction of the light guide element, wherein the reflective polarizing element is disposed on the emission end face of the light guide element, and at least a part of the light guide element is provided in the reflective polarizing element. The diameter of the light guide element is gradually increased, and a phase plate is provided between an output end face of the light guide element and an incident end face of the reflective polarizing element. A plurality of elements are provided corresponding to the plurality of light sources, The light guide element is provided with a plurality of incident end faces corresponding to the plurality of light sources, arranged on the exit end faces of the plurality of light guide elements, and the light emitted from the plurality of light guide elements is reflected by the reflection type An optical element that is incident on the polarizing element; a condensing optical system that condenses the polarized light that has passed through the reflective polarizing element; and the condensing optical system is a fly-eye optical system that includes a pair of fly-eye lenses And one of the pair of fly-eye lenses is arranged on an output end face of the reflective polarizing element .

In the illumination device according to the present invention, the light emitted from the light source travels through the light guide element and is guided to the reflective polarizing element. Of the light incident on the reflective polarizing element, polarized light in a specific vibration direction is transmitted. In contrast, light in a vibration direction other than the specific vibration direction is reflected by the reflective polarizing element and travels toward the light source. The light directed from the reflective polarizing element to the light source is reflected by the reflecting portion provided in the light source, and travels again in the light guide element toward the reflective polarizing element. As a result, the light that has passed through the reflective polarizing element and the light that has passed through the reflective polarizing element after being reflected by the reflecting portion are aligned with light that vibrates in a specific direction, so that the polarized light rotates in the subsequent illumination system. (The polarization direction does not change), it is possible to obtain illumination light with high light utilization efficiency without reducing the extinction ratio. In addition, since the light guide element is formed in a tapered shape, the light that has undergone polarization conversion by the reflective polarizing element has a high degree of parallelism and becomes uniform light, which increases recycling efficiency.

In the illuminating device of the present invention, it is preferable that at least a portion of the light guide element that is close to the light source is formed in a tapered shape that is gradually expanded in diameter toward the reflective polarizing element.
In the illuminating device according to the present invention, at least a portion of the light guide element that is close to the light source is formed in a tapered shape, so that the light emitted from the light source can travel in the light guide element after being collimated as much as possible. it can. Therefore, it is possible to reduce reflection loss due to an unnecessary increase in the number of reflections in the light guide element, and it is possible to obtain illumination light with high light utilization efficiency.

It is preferable that the illuminating device of this invention is distribute | arranged so that the output end surface of the said light source may contact the incident end surface of the said light guide element directly.
In the illuminating device according to the present invention, the light emitted from the light source can be incident on the light guide element without wasting it by disposing the light emission end face of the light source on the incident end face of the light guide element. Therefore, since the light use efficiency can be increased, illumination light with a high extinction ratio can be obtained.

The illuminating device of the present invention preferably includes a phase plate between the exit end face of the light guide element and the entrance end face of the reflective polarizing element.
In the illumination device according to the present invention, for example, linearly polarized light reflected by the reflective polarizing element is converted into circularly polarized light by the phase plate. The circularly polarized light that has traveled in the direction of the light source is reflected in the direction of the light guide element by a reflecting portion provided in the light source, and then is transmitted through the phase plate again to be converted into linearly polarized light. For example, if a λ / 4 phase plate is used, the phase of the linearly polarized light reflected by the reflective polarizing element is changed by λ / 2 by passing through the phase plate twice. For this reason, a part of the linearly polarized light reflected by the reflective polarizing element is converted into linearly polarized light in a specific vibration direction before being incident on the reflective polarizing element again. Therefore, the light converted into linearly polarized light in a specific vibration direction can pass through the reflective polarizing element. On the other hand, the linearly polarized light converted to another vibration direction different from the specific vibration direction by transmitting again through the phase plate is reflected by the reflective polarizing element, and the above-described recirculation is repeated. Thus, by providing the phase plate, conversion between linearly polarized light and circularly polarized light can be performed efficiently, so that a desired linearly polarized light component can be easily extracted.

In the illumination device of the present invention, it is preferable that a plurality of the light sources are provided, and a plurality of the light guide elements are provided corresponding to the plurality of light sources.
In the illuminating device according to the present invention, by providing a plurality of light guide elements corresponding to a plurality of light sources, light emitted from the plurality of light sources can be efficiently supplied to the light guide elements. As a result, a large volume of light can be emitted from the emission end face of the light guide element.

The illuminating device of the present invention preferably includes an optical element that is disposed on the emission end face of the plurality of light guide elements and that causes the light emitted from the plurality of light guide elements to enter the reflective polarizing element.
In the illumination device according to the present invention, by providing the optical element, the light emitted from the plurality of light guide elements is collectively guided to the reflective polarizing element, and the light between the plurality of light guide elements is made uniform. Can do.

The illuminating device of the present invention preferably includes a condensing optical system that condenses the polarized light that has passed through the reflective polarizing element.
In the illuminating device according to the present invention, the polarized light can be efficiently advanced to a specific region by condensing the polarized light using the condensing optical system. Therefore, for example, even when a plurality of light sources are provided in an array, light can efficiently travel to a specific region.

In the illumination device of the present invention, it is preferable that the condensing optical system is a telecentric optical system.
In the illuminating device according to the present invention, the light transmitted through the reflective polarizing element becomes uniform and stable illumination light by the telecentric optical system.

In the illumination device of the present invention, it is preferable that the condensing optical system is a fly-eye optical system.
In the illumination device according to the present invention, the light transmitted through the reflective polarizing element is subjected to extremely uniform wavefront division and image formation with low loss by the fly-eye optical system. In other words, it is possible to suppress illumination unevenness and obtain illumination light with a high extinction ratio.
For example, by using an illuminating device including the above-described condensing optical system for a projector, it is possible to provide a projector having good image display quality because the image contrast in each region of the screen is substantially the same.

  A projector of the present invention is modulated by an illumination device that supplies polarized light in a specific vibration direction, a spatial light modulation device that modulates light emitted from the illumination device in accordance with an image signal, and the spatial light modulation device. A projection lens that projects the light, and the illumination device is the illumination device described above.

  In the projector according to the present invention, the light emitted from the illumination device enters the spatial light modulation device. Then, the image modulated by the spatial light modulator is projected by the projection lens. At this time, since the light emitted from the illumination device is aligned with the light that vibrates in a specific direction as described above, the amount of light is not reduced when passing through the spatial light modulation device. The ratio can be maintained and an image with uniform brightness can be projected.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size.

Next, a first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the projector 1 according to the present embodiment spatially modulates different color lights of R (red), G (green), and B (blue) emitted from a light source by a spatial light modulator, This is a three-plate type color projector that displays a color image by combining with a dichroic prism 30.

FIG. 1 is a diagram showing an outline of a projector 1 according to this embodiment.
As shown in FIG. 1, the projector 1 includes illumination devices 10 r, 10 g, and 10 b that emit different color lights of R, G, and B, and R, G, and B emitted from the illumination devices 10 r, 10 g, and 10 b, respectively. Transmissive liquid crystal light valves (spatial light modulators) 20r, 20g, and 20b that modulate the luminance of the light in accordance with the image signal, a dichroic prism 30 that combines the modulated color lights into a color image, and a dichroic prism 30 And a projection lens 40 that projects the emitted color image onto a screen 50.

  As shown in FIG. 2, the illumination devices 10r, 10g, and 10b emit light from a red LED (light source) 11r, a green LED (light source) 11g, and a blue LED (light source) 11b that supply light, and the LEDs 11r, 11g, and 11b. Is transmitted through the tapered rod 12 and the λ / 4 plate 13, the λ / 4 plate 13 arranged on the output end surface 12 b of the tapered rod 12, and the tapered rod 12 and the λ / 4 plate 13. A reflective polarizing element 14 that transmits polarized light having a specific vibration direction among reflected light and reflects polarized light having another vibration direction different from the specific vibration direction is provided. The LEDs 11r, 11g, and 11b are arranged in parallel for two of each color. The λ / 4 plate 13 generates a quarter-wave phase difference with respect to the wavelength of each light emitted from each of the LEDs 11r, 11g, and 11b.

The LEDs 11r, 11g, and 11b are provided with a reflecting portion 15 that reflects the light reflected by the reflective polarizing element 14 and traveling in the direction of the LEDs 11r, 11g, and 11b in the direction of the tapered rod 12.
The reflector 15 is made of a member having a high light reflectance, for example, a metal member such as aluminum or silver. When the reflecting portion 15 is made of a metal member, the reflecting portion 15 has a configuration excellent in heat resistance. Note that an electrode for driving the LED may function as the reflecting portion 15.

The taper rod 12 is disposed between the LEDs 11r, 11g, and 11b and the reflective polarizing element 14, and is provided corresponding to the number of LEDs 11r, 11g, and 11b. Further, as shown in FIG. 3, the taper rod 12 is formed in a taper shape having a cross-sectional area that gradually increases from the incident end surface 12a toward the output end surface 12b, and includes a tapered portion 12c and a parallel rod portion 12d. . That is, the portions close to the LEDs 11r, 11g, and 11b are formed in a tapered shape. With this configuration, the light emitted from the LEDs 11r, 11g, and 11b is substantially parallelized and uniformed by the tapered portion 12c, and then the illuminance distribution of the light from each tapered portion is uniformized by the parallel rod portion 12d. .
Further, as shown in FIG. 3, the incident end face 12a of the taper rod 12 is in direct contact with the emission end face 16 of the LEDs 11r, 11g, and 11b, and the emission end face 12b is in direct contact with the incident end face 13a of the λ / 4 plate 13. .
In addition, the taper rod 12 is comprised from the material which has light transmittances, such as glass and resin, for example.

  As shown in FIG. 2, the reflective polarizing element 14 is in direct contact with the incident end face 13 b of the λ / 4 plate 13. Thus, by arranging the taper rod 12, the λ / 4 plate 13 and the reflective polarizing element 14 so as to be in direct contact with each other in order, it is possible to prevent light from leaking between them, so that the light utilization efficiency can be improved. It is possible to prevent the decrease.

  The reflective polarizing element 14 transmits polarized light having a specific vibration direction, for example, p-polarized light, and reflects polarized light having another vibration direction different from the specific vibration direction, for example, s-polarized light. The s-polarized light reflected by the reflective polarizing element 14 is converted into circularly polarized light by passing through the λ / 4 plate 13. And the light which permeate | transmitted (lambda) / 4 board 13 permeate | transmits the taper rod 12, and returns to LED11r, 11g, 11b. And the light which returned to LED11r, 11g, 11b is reflected by the reflection part 15, and advances to the direction of the taper rod 12 again. Of the light passing through the taper rod 12 and entering the λ / 4 plate 13 again, circularly polarized light is converted into, for example, p-polarized light that is linearly polarized light. The p-polarized light, which is polarized light in a specific vibration direction, can be transmitted through the reflective polarizing element 14. On the other hand, the linearly polarized light converted to another vibration direction different from the specific vibration direction by transmitting again through the λ / 4 plate 13 is reflected by the reflective polarizing element 14 and repeats the above circulation. It is like that.

Further, a wire grid type polarizing filter is adopted as the reflective polarizing element 14. This wire grid type polarizing filter is a kind of structural birefringent polarizing plate and has a structure in which fine ribs (not shown) extending in a predetermined direction are formed on a metal thin film formed on a transparent substrate. Yes. This metal thin film can be formed by vapor deposition or sputtering using aluminum, tungsten, or the like. Fine ribs can be formed by combining etching with a two-beam interference exposure method, an electron beam drawing method, an X-ray lithography method, or the like. The pitch of the fine ribs is shorter than the wavelength of light to be reflected. Thereby, the linearly polarized light in the direction parallel to the fine ribs can be reflected and the linearly polarized light in the vertical direction can be transmitted. Since this wire grid type polarizing filter has a simple structure, it can be easily manufactured. Further, since it is composed of an inorganic material, it is extremely excellent in heat resistance and hardly absorbs light.
The reflective polarizing element 14 is not limited to the wire grid polarizing filter described above, and a multilayer laminated polarizing plate in which a plurality of thin films having birefringence and thin films not having birefringence are laminated may be used. .

  As shown in FIG. 1, the dichroic prism 30 has a structure in which four right-angle prisms are bonded to each other, and a dielectric multilayer film (blue light reflecting dichroic film 31) that reflects blue light and red light are contained therein. A reflecting dielectric multilayer film (red light reflecting dichroic film 32) is formed in an X-shaped cross section. Then, the green light from the transmissive liquid crystal light valve 20g is transmitted, and the red light from the transmissive liquid crystal light valve 20r and the blue light from the transmissive liquid crystal light valve 20b are bent to synthesize these three colors of light. Forming a color image.

Next, a method of projecting an image on the screen 50 using the projector 1 of the present embodiment having the above configuration will be described.
In addition, since the effect | action about each color light inject | emitted from LED11r, 11g, 11b is the same, the effect | action about the red light inject | emitted from LED11r is demonstrated, and description about the effect | action about other green light and blue light is abbreviate | omitted. To do.

First, when current is supplied to the LED 11r, red light is emitted from the LED 11r toward the tapered rod 12, as shown in FIG.
As shown in FIG. 4, the red light incident on the inside from the incident end face 12a of the taper rod 12 repeats total reflection within the taper rod 12, thereby making the illuminance distribution uniform and propagating toward the emission end face 12b. Further, each time the red light propagates toward the emission end face 12 b and is totally reflected within the tapered rod 12, it is collimated (parallelized). Thereafter, the red light is incident on the λ / 4 plate 13 from the emission end face 12b.

  The red light transmitted through the λ / 4 plate 13 and incident on the reflective polarizing element 14 is incident from the incident end face of the reflective polarizing element 14 as shown in FIG. The red light incident on the reflective polarizing element 14 reflects s-polarized light that vibrates in a direction parallel to the extending direction of the rib (not shown), and the direction perpendicular to the extending direction of the rib (not shown) (the rib is not shown). The p-polarized light oscillating in the arrangement direction) is transmitted.

The red s-polarized light reflected by the reflective polarizing element 14 propagates in the tapered rod 12 toward the LED 11r and enters the LED 11r. The red light incident on the LED 11r is reflected again toward the incident end face 12a of the taper rod 12 by the reflecting portion 15.
As described above, the s-polarized light that does not pass through the reflective polarizing element 14 travels within the tapered rod 12 between the reflective polarizing element 14 and the reflecting portion 15, but passes through the λ / 4 plate 13 twice. The phase changes by λ / 2. For this reason, a part of the linearly polarized light reflected by the reflective polarizing element 14 is rotated by 90 degrees until it is incident on the reflective polarizing element 14 again to be converted to p-polarized light. . The light thus converted into p-polarized light is transmitted through the reflective polarizing element 14.

As described above, the p-polarized light of the red light transmitted through the reflective polarizing element 14 is incident on the transmissive liquid crystal light valve 20r, modulated based on the video signal input to the projector 1, and directed toward the dichroic prism 30. And injected.
Similarly, green light p-polarized light and blue light p-polarized light modulated based on the video signal are also incident on the dichroic prism 30. These color lights are combined by a blue light reflecting dichroic film 31 that reflects blue light and an R light reflecting dichroic film 32 that reflects red light, thereby forming light representing a color image and emitted toward the projection lens 40. The The projection lens 40 enlarges and projects light representing a color image toward the screen 50 to display a color image.

According to the projector 1 and the illuminating devices 10r, 10g, and 10b according to the present embodiment, since the reflective polarizing element 14 is disposed on the emission end face 12b of the tapered rod 12, the light reflected by the reflective polarizing element 14 is efficiently used. It can return to LED11r, 11g, 11b well. Thereby, in the process in which the polarized light circulates (recycles) in the optical path between the reflective polarizing element 14 and the reflecting portion 15, the reflective polarizing element 14 can sequentially extract polarized light in a specific vibration direction. As a result, polarized light having a specific vibration direction can be obtained with high light utilization efficiency. Thereby, polarized light having a specific vibration direction can be efficiently supplied, and the illumination devices 10r, 10g, and 10b suitable for the projector 1 using the transmissive liquid crystal light valves 20r, 20g, and 20b can be obtained. Further, by using the lighting devices 10r, 10g, and 10b, it is possible to increase the light use efficiency without reducing the extinction ratio of the illumination light, and it is possible to obtain the projector 1 with a bright image.
Further, since the portions adjacent to the LEDs 11r, 11g, and 11b are formed in a tapered shape, the light emitted from the LEDs 11r, 11g, and 11b can be made parallel as much as possible before proceeding through the tapered rod 12, and therefore the tapered rod 12 It is possible to reduce reflection loss due to an unnecessarily increase in the number of reflections, and to obtain illumination light with high light utilization efficiency.
In addition, by using the λ / 4 plate 13, there is an effect that a desired linearly polarized light component circulating in the taper rod 12 can be extracted more efficiently. In the present embodiment, two LEDs 11r, 11g, and 11b are arranged in parallel. However, LEDs 11r, 11g, and 11b are arranged one by one, and the taper rod 12 corresponds to each LED. It may be provided as follows. Moreover, although the taper rod 12 showed the example which consists of the taper part 12c and the parallel rod part 12d in order from the incident end surface 12a, it should just have the taper part 12c in at least one part of the taper rod 12. FIG. Furthermore, the taper rod 12 may consist only of the taper portion 12c.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described with reference to FIG. In each embodiment described below, portions having the same configuration as those of the projector 1 according to the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The projector 60 according to this embodiment is different from the first embodiment in that the second embodiment includes a condensing optical system 61 that condenses the polarized light transmitted through the reflective polarizing element 14. .

As the condensing optical system 61, a telecentric optical system is used.
FIG. 5 is a side view showing the configuration of the condensing optical system 61 of the present embodiment. The condensing optical system 61 forms an image on the pixel surfaces of the transmissive liquid crystal light valves 20r, 20g, and 20b for color modulation, and includes a front lens group 63 and a rear lens disposed to face the aperture stop 62. This is an imaging lens composed of a group 64. The front lens group 63 and the rear lens group 64 are configured to include a plurality of convex lenses and concave lenses, and have bilateral telecentricity. However, the lens shape, size, arrangement interval and number, telecentricity, magnification, and other lens characteristics can be appropriately changed according to required characteristics, and are not limited to the example of FIG.
According to the projector 60 according to the present embodiment, since the condensing optical system 61 is composed of a large number of lenses, aberration correction is good, and the transmissive liquid crystal light valves 20r, 20g, and 20b for color modulation are uniform. Stable illumination light can be transmitted.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIG.
The projector 70 according to this embodiment is different from the first embodiment in that the second embodiment includes a condensing optical system 71 that condenses the polarized light that has passed through the reflective polarizing element 14. .

As the condensing optical system 71, a fly-eye optical system is used.
FIG. 6 is a side view showing the configuration of the condensing optical system 71 of the present embodiment. The condensing optical system 71 includes a first fly-eye lens 72 disposed on the output end face 14 b of the reflective polarizing element 14, and a second fly-eye lens disposed separately from the first fly-eye lens 72. 73.
Illumination light emitted from the illuminating devices 10r, 10g, and 10b passes through the first fly-eye lens 72 and the second fly-eye lens 73 so that the illuminance distribution is uniformed, and the transmissive liquid crystal light valve 20r, Images are formed on 20g and 20b.

According to the projector 70 according to this embodiment, the illumination light emitted from the illumination devices 10r, 10g, and 10b is subjected to extremely uniform wavefront division and image formation with low loss by the fly-eye optical system. In other words, it is possible to suppress illumination unevenness and obtain illumination light with a high extinction ratio.
Further, by using the condensing optical systems 61 and 71 of the second and third embodiments, the emission direction is regulated so that the emitted light emitted from the emission end face 14b of the reflective polarizing element 14 is not diffused. Therefore, the projectors 60 and 70 having good image display quality can be provided because the image contrast in each region of the screen is substantially the same.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, even if the λ / 4 plate 13 is not used, by repeating the process of circulating (recycling) the polarized light through the optical path between the reflective polarizing element 14 and the reflecting portion 15, polarized light having a specific vibration direction can be obtained. It can be taken out.

Moreover, as the taper rod 12, it is good also as a hollow structure which makes an inner surface a reflective surface.
Further, although two LEDs 11r, 11g, and 11b of each color have been described, the number of LEDs 11r, 11g, and 11b may be one, or three or more. In the case of the lighting device 80 having a plurality of LEDs 11r, 11g, 11b in parallel or in a matrix, a taper rod 81 is provided corresponding to the plurality of LEDs 11r, 11g, 11b. As shown in FIG. 7, light guide rods (optical elements) 82 are arranged on the emission end faces 81 b of the plurality of taper rods 81, and the illuminance distribution of the light emitted from the plurality of taper rods 81 is made uniform. Thus, the light is incident on the reflective polarizing element 14.

In the case of this configuration, by providing the plurality of taper rods 81 corresponding to the plurality of LEDs 11r, 11g, 11b, the light emitted from the plurality of LEDs 11r, 11g, 11b can be efficiently supplied to the taper rod 81. Further, by providing the light guide rod 82, the illuminance distribution of the light emitted from the plurality of taper rods 81 can be uniformly guided to the reflective polarizing element 14.
Further, the light emitting end face 16 of the LEDs 11r, 11g, and 11b is arranged so as to be in direct contact with the light incident end face 12a of the tapered rod 12, but may be separated from each other. In this configuration, the light emitting end face 16 of the LEDs 11r, 11g, and 11b What is necessary is just to fill in the silicon resin etc. which have the refractive index equivalent to the taper rod 12 between the entrance end surfaces 12a of the taper rod 12. FIG.

1 is a schematic diagram showing a projector according to a first embodiment of the invention. It is a perspective view which shows the light guide element of FIG. It is principal part sectional drawing which shows the illuminating device which concerns on 1st Embodiment of this invention. It is a figure explaining the effect | action of the light guide element of FIG. It is a side view which shows the condensing optical system of the projector which concerns on 2nd Embodiment of this invention. It is a side view which shows the condensing optical system of the projector which concerns on 3rd Embodiment of this invention. It is a side view which shows the modification of the projector which concerns on each embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,60,70 ... Projector, 10r, 10g, 10b ... Illuminating device, 11r ... Red LED (light source), 11g ... Green LED (light source), 11b ... Blue LED (light source), 12 ... Tapered rod (light guide element), DESCRIPTION OF SYMBOLS 13 ... (lambda) / 4 board (phase plate), 14 ... Reflection type polarization element, 15 ... Reflection part, 20r, 20g, 20b ... Transmission type liquid crystal light valve (spatial light modulation device), 40 ... Projection lens, 61 ... Condensing Optical system (telecentric optical system), 71 ... Condensing optical system (fly eye optical system), 82 ... Light guide rod (optical element)

Claims (4)

A light source that emits light;
A light guide element that equalizes the illuminance distribution of the light emitted from the light source;
A reflective polarizing element that transmits polarized light in a specific vibration direction out of the light emitted from the light guide element and reflects polarized light in another vibration direction different from the specific vibration direction;
A reflection unit provided in the light source, and reflecting light that is reflected by the reflective polarizing element and travels in the direction of the light source, in the direction of the light guide element;
The reflective polarizing element is disposed on the output end face of the light guide element, and at least a part of the light guide element is formed in a tapered shape having a diameter gradually increased toward the reflective polarizing element;
A phase plate is provided between the exit end face of the light guide element and the entrance end face of the reflective polarizing element ,
A plurality of the light sources are provided,
A plurality of the light guide elements are provided corresponding to the plurality of light sources, and the light guide element is provided with a plurality of incident end faces corresponding to the plurality of light sources,
An optical element that is disposed on the emission end face of the plurality of light guide elements and that makes the light emitted from the plurality of light guide elements enter the reflective polarizing element;
A condensing optical system for condensing the polarized light transmitted through the reflective polarizing element;
The condensing optical system is a fly eye optical system composed of a pair of fly eye lenses,
Of the pair of fly-eye lenses, one fly-eye lens is disposed on the exit end face of the reflective polarizing element .   2. The illumination device according to claim 1, wherein at least a portion of the light guide element that is close to the light source is formed in a tapered shape having a diameter gradually increased toward the reflective polarizing element.   The lighting device according to claim 1, wherein the light-emitting element is arranged so that an emission end face of the light source is in direct contact with an incident end face of the light guide element. The lighting device according to any one of claims 1 to 3 ,
A spatial light modulation device that modulates light emitted from the illumination device in accordance with an image signal;
A projector comprising: a projection lens that projects light modulated by the spatial light modulation device.

Images