TW201305627A - Light guide plate, surface light source device, transmission-type image display device - Google Patents

Abstract

A light guide plate is a light guide plate disposed on the back surface side of a prim plate having a plurality of prism units each extending in one direction arranged in a row on one surface and comprises a body having first and second surfaces opposing each other and an entrance surface intersecting the first and second surfaces and a plurality of lens units formed on the second surface. Each lens unit has such an outer form that a value obtained by multiplying a ratio of a luminous flux of light emitted from a point on the first surface into a predetermined direction to a luminous flux of light emitted from the point to all the directions by a light emission efficiency which is a ratio of the quantity of light emitted from the first surface to the quantity of light incident on the entrance surface is greater than 1.055%. The predetermined direction is a direction forming an angle of about 30 DEG with a normal to the first surface within a plane substantially orthogonal to the extending direction of the prism units.

Description

Light guide plate, surface light source device, transmissive image display device

The present invention relates to a light guide plate, a surface light source, and a transmissive image display device.

In general, a transmissive image display device such as a liquid crystal display device has a surface light source device which is disposed on a back surface side of a transmissive image display unit such as a liquid crystal display panel for transmitting a transmissive image The display unit supplies backlight. An edge-light type surface light source device is known as the surface light source device (see, for example, Japanese Patent Application Laid-Open No. 2005-38768).

The edge-emitting surface light source device includes a light guide plate that transmits light and a light source that is disposed beside the light guide plate for supplying light to a side surface of the light guide plate. A white point (reflection point) for reflecting light is disposed on the back surface side of the light guide plate. In this configuration, light emitted from the light source enters the light guide plate opposite to the light source from the side of the light guide plate, and propagates through the light guide plate while being totally reflected in the light guide plate. A plurality of white dots are formed on the back surface side of the light guide plate (for example, see Japanese Patent Application Laid-Open No. 2005-38768), whereby the emission surface of the light guide plate on the side of the transmissive image display unit is reflected by white spots Light.

In order to converge the light emitted from the exit surface of the light guide plate toward the front direction so that the light efficiently enters the transmissive image display unit, the seesaw is conventionally disposed between the light guide plate and the transmissive image display unit. An example of the seesaw is a table of a plurality of unit cells on the side of the transmissive image display unit The fascia is arranged in a row on the surface.

However, when the seesaw formed by the unit is disposed on a surface opposed to the light guide plate having the white point as described above, there is a case where the brightness in the forward direction cannot be sufficiently improved.

Accordingly, it is an object of the present invention to provide a light guide plate capable of improving the brightness in the forward direction, and a surface light source device including the light guide plate and a transmissive image display device.

A light guide plate according to the present invention is a light guide plate disposed on a back surface side of a gusset plate opposite to a surface of the dam plate, the dam plate having each of the surfaces formed on the surface in one direction An extended plurality of unit cells, the plurality of unit units being arranged in a row in a direction substantially perpendicular to an extending direction of the unitary unit. The light guide plate includes: a planar body having a first surface on the side of the seesaw, a second surface on the opposite side of the first surface, and a surface intersecting the first surface and the second surface An incident surface for receiving light; and a plurality of lens units formed on the second surface, the plurality of lens units protruding toward a side opposite the first surface. Each of the plurality of lens units has an outer shape such that a ratio of a second luminous flux of light emerging from the first surface to a first luminous flux is multiplied by a ratio of a first luminous flux incident on the incident surface A value obtained from a light emission efficiency of light emitted from the first surface is greater than 1.055%. The first luminous flux is the total luminous flux of light emitted from all of the points on the first surface in all directions. The second luminous flux is a luminous flux per unit solid angle of light emitted from the point in a predetermined direction. The predetermined direction is A direction substantially perpendicular to the direction of extension of the unit of the crucible and a normal to the first surface at an angle of about 30[deg.]. The emission efficiency is the ratio of the amount of light emitted from the first surface to the amount of light incident on the incident surface.

A surface light source device according to the present invention is a light source device for supplying light to a back surface of a seesaw opposite to a surface of the seesaw, each of which has a surface formed on the surface a plurality of germanium cells extending in a direction, the plurality of germanium cells being arranged in a row in a direction substantially perpendicular to the extending direction of the germanium cells. The surface light source device includes: a light guide plate, the light guide plate includes: a planar body having a first surface on the side of the seesaw, a second surface on the opposite side of the first surface, and the first surface An incident surface for receiving light intersecting the surface and the second surface, and a plurality of lens units formed on the second surface protruding toward a side opposite to the first surface; and a light source unit It is disposed beside the incident surface of the light guide plate for supplying light to the incident surface. Each of the plurality of lens units has an outer shape such that a ratio of a second luminous flux of light emerging from the first surface to a first luminous flux is multiplied by a ratio of a first luminous flux incident on the incident surface A value obtained from a light emission efficiency of light emitted from the first surface is greater than 1.055%. The first luminous flux is the total luminous flux of light emitted from all of the points on the first surface in all directions. The second luminous flux is a luminous flux per unit solid angle of light emitted from the point in a predetermined direction. The predetermined direction is a direction that is at an angle of about 30 to a normal to the first surface in a plane substantially perpendicular to the direction of extension of the unit. The emission efficiency is a ratio of the amount of light emitted from the first surface to the amount of light incident on the incident surface rate.

A transmissive image display apparatus according to the present invention includes: a cymbal plate having a plurality of cymbal units extending in one direction formed on each of the surfaces, the plurality of cymbal units being substantially vertical Disposed in a row in a direction in which the unit is extended; a light guide plate disposed on a back surface side of the seesaw opposite the surface, the light guide plate comprising: a planar body having a first surface on the side of the seesaw, a second surface on the opposite side of the first surface, and an incident surface for receiving light intersecting the first surface and the second surface, and formed on a plurality of lens units on the second surface protruding toward a side opposite the first surface; a light source unit disposed beside the incident surface of the light guide plate for supplying light to the incident surface And a transmissive image display unit disposed on the surface side of the seesaw for displaying an image when illuminated by light emitted from the seesaw. Each of the plurality of lens units has an outer shape such that a ratio of a second luminous flux of a light emerging from the first surface incident to the incident surface to a first luminous flux is multiplied by A value obtained by a light emission efficiency of the light emitted from the first surface is greater than 1.055%. The first luminous flux is the total luminous flux of light emitted from all of the points on the first surface in all directions. The second luminous flux is a luminous flux per unit solid angle of light emitted from the point in a predetermined direction. The predetermined direction is a direction that is at an angle of about 30 to a normal to the first surface in a plane substantially perpendicular to the direction of extension of the unit. The emission efficiency is a ratio of the amount of light emitted from the first surface to the amount of light incident on the incident surface.

Hereinafter, the surface of the seesaw opposite to the light guide plate (i.e., the surface on the opposite side of the one surface) will also be referred to as a rear surface.

In the light guide plate, the surface light source device, and the transmissive image display device thus constructed, light incident on the light guide plate from the incident surface of the light guide plate propagates through the light guide plate while being totally reflected in the light guide plate. The light propagating through the light guide plate is reflected by the lens unit under conditions different from the total reflection condition when incident on the lens unit disposed on the second surface. Therefore, light reflected by the lens unit is emitted from the first surface of the body. Since each of the plurality of lens units formed on the second surface is shaped into a shape satisfying the above condition, it is directed from the first surface to a predetermined direction at a large ratio (substantially perpendicular to the unit of the 稜鏡 unit) Light is emitted in a plane extending in a direction that is at an angle of about 30[deg.] to a normal to the first surface. Since the light guide plate is disposed on the back surface side of the seesaw, light emitted from the light guide plate is incident on the seesaw from the rear surface of the seesaw. The angle of incidence of the light to the raft is substantially equal to the angle of exit of the light from the light guide. Therefore, light emitted from the first surface is likely to be incident on the raft at an incident angle of about 30°. The incident light at this incident angle is emitted from the 稜鏡 unit toward the front direction at a large ratio. Therefore, the brightness in the forward direction is improved. In the transmissive image display device according to the present invention, the transmissive image display unit is disposed on the seesaw, and thus is illuminated by light having a higher brightness in the forward direction. Therefore, the brightness of the image displayed by the transmissive image display unit can be improved.

The present invention can provide a light guide plate capable of improving the brightness in the forward direction, and a surface light source device and a transmissive image display device including the light guide plate.

Embodiments of the present invention will be explained below with reference to the drawings. In the explanation of the drawings, the same components will be referred to by the same symbols, and the repeated description thereof will be omitted. The size ratio in the drawing does not always coincide with the interpreted size ratio. Terms in the explanation such as "upper" and "lower" are terms that are used for convenience according to the state illustrated in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing the outline structure of a transmissive image display apparatus using an embodiment of a light guide plate according to the present invention. Fig. 1 illustrates a cross-sectional structure of the transmissive image display device 10 in an exploded state. Figure 1 schematically illustrates light as a light beam. The transmissive image display device 10 can be advantageously used as a display device or a television set for mobile phones and various electronic devices.

The transmissive image display device 10 includes a transmissive image display unit 20, a surface light source unit 30 for outputting surface light to be supplied to the transmissive image display unit 20, and a transmissive image display unit 20 and a surface light source. A seesaw 40 between the units 30. Hereinafter, for convenience of explanation, the direction in which the seesaw 40 and the transmissive image display unit 20 are arranged in a row with respect to the surface light source 30 is referred to as a Z-axis direction or a forward direction as illustrated in FIG. 1 . The two directions perpendicular to the Z-axis direction are referred to as the X-axis direction and the Y-axis direction, respectively. The X-axis direction and the Y-axis direction are perpendicular to each other.

The transmissive image display unit 20 displays an image when illuminated by surface light emitted from the light guide plate 50. An example of the transmissive image display unit 20 includes a liquid crystal display panel as a polarizing plate laminate in which linear polarizing plates 22, 23 are disposed on both sides of the liquid crystal cell 21. In this case, the transmissive image display device 10 is a liquid crystal display device (or liquid crystal TV). Transmissive pattern A liquid crystal cell and a polarizing plate used in a display device such as a liquid crystal display device are used as the liquid crystal cell 21 and the polarizing plates 22 and 23. Examples of the liquid crystal cell 21 include a TFT type and an STN type liquid crystal cell.

The seesaw 40 is for condensing light emitted from the light guide plate 50 toward the front direction. The seesaw 40 is an optical sheet, and a plurality of turns 41 are disposed on the front surface 40a thereof, and the front surface 40a is a surface on the side of the transmissive image display unit 20. Examples of the shape of the seesaw 40 regarded as a plane include a substantially rectangular shape and a substantially square shape.

The unit 41 extends in one direction (the Y-axis direction in Fig. 1). The plurality of turns unit 41 are arranged in a row in the extending direction of the weir unit 41. Each of the unit cells 41 has a triangular 稜鏡 shape, and the cross section of the 稜鏡 unit 41 perpendicular to the extending direction of the 稜鏡 unit 41 is a right-angled triangle whose apex angle α is substantially a right angle. The apex angle α can be at least 80° but less than or equal to 100°. The apex angle α is preferably at least 80° but less than or equal to 90°, more preferably 90°. Preferably, the weir unit 41 has an isosceles right triangle cross section. The apex 41a of the 稜鏡 unit 41 can be bent to such an extent as to be caused by manufacturing errors and the like.

The seesaw 40 is made of a light transmissive material (or a transparent material). For example, the light transmissive material has a refractive index of 1.46 to 1.62, preferably 1.49 to 1.59. Examples of the light transmissive material include a light transmissive resin material and a light transmissive glass material. Examples of the light-transmitting resin material include polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin; refractive index: 1.56 to 1.59), and polystyrene resin (refractive index: 1.59) ), AS resin (acrylonitrile-styrene copolymer resin; refractive index: 1.56 to 1.59), acrylic-based UV curable resin (refractive index: 1.46 to 1.58) and polymethyl methacrylate (PMMA; refractive index: 1.49). The seesaw 40 may comprise a diffuser and the like as long as the gist of the invention is not lost. The seesaw 40 has a rear surface 40b that is generally a smooth surface. However, the back surface 40b may be a roughened surface as long as the gist of the present invention is not lost. For example, when the optical member is disposed between the seesaw 40 and the light guide plate 50, roughening the rear surface 40b as mentioned above can prevent the optical member and the seesaw 40 from adhering to each other.

The thickness of the seesaw 40 may be the distance between the vertex 41a of the crucible unit 41 and the substantially flat rear surface 40b (the surface on the opposite side of the front surface 40a). An example of the thickness of the seesaw 40 is at least 0.1 mm but less than or equal to 5 mm.

The surface light source device 30 is an edge light-emitting type backlight unit for supplying a backlight to the transmissive image display unit 20. The surface light source device 30 includes a light guide plate 50 and light source units 60, 60 which are disposed beside the side faces 50a, 50b of the light guide plate 50 opposed to each other.

Each of the light source units 60, 60 has a plurality of point-like light sources 61 similar to the line configuration (configured in the Y-axis direction in Fig. 1). An example of a point-like light source 61 is a light emitting diode. In order to efficiently inject light onto the light guide plate 50, the light source unit 60 may be provided with a reflector as a reflecting member disposed on the opposite side of the light guide plate 50 for reflecting light. Although the light source unit 60 having a plurality of point-like light sources 61 is exemplified herein, the light source unit 60 may also be a linear light source such as a fluorescent tube.

The surface light source device 30 may be provided with a reflection unit 70 on the side of the light guide plate 50 opposite to the transmissive image display unit 20. The reflecting unit 70 is used to make self The light emitted from the light guide plate 50 to the reflection unit 70 is incident on the light guide plate 50 again. The reflecting unit 70 may have a sheet shape as illustrated in FIG. The reflecting unit 70 may be a mirror-polished bottom surface of the outer casing of the surface light source device 30 that houses the light guide plate 50.

The light guide plate 50 will now be explained with reference to FIGS. 1 and 2. Fig. 2 is a plan view of the light guide plate 50 illustrated in Fig. 1 as seen from the side of the back surface. Examples of the shape of the light guide plate 50 regarded as a plane include a substantially rectangular shape and a substantially square shape.

The light guide plate 50 has a planar body 51 and a plurality of lens units 52 formed on the body 51. The body 51 is composed of a light transmissive material (or a transparent material). For example, the light transmissive material has a refractive index of 1.46 to 1.62. Examples of the light transmissive material include a light transmissive resin material and a light transmissive glass material. Examples of the light-transmitting resin material include polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin; refractive index: 1.56 to 1.59), and polystyrene resin (refractive index: 1.59) ), AS resin (acrylonitrile-styrene copolymer resin; refractive index: 1.56 to 1.59), acrylic-based UV curable resin (refractive index: 1.46 to 1.58), and polymethyl methacrylate (PMMA; refractive index: 1.49) ). From the viewpoint of transparency, PMMA is more preferable as a light-transmitting resin material.

As illustrated in Fig. 1, the body 51 has an exit surface (first surface) 51a and a back surface (second surface) 51b which are opposed to each other in the thickness direction. The exit surface 51a and the back surface 51b are substantially flat. The body 51 has four side faces 51c, 51d, 51e, 51f that intersect the exit surface 51a and the back surface 51b. Fig. 1 illustrates two side faces 51c, 51d which are opposed to each other in the X-axis direction. side The faces 51c, 51d also serve as side faces 50a, 50b opposite the light source unit 60. In this case, the side faces 51c and 51d are incident surfaces on which light from the light source unit 60 is incident. Among the four side faces 51c, 51d, 51e, 51f of the body 51, the remaining two side faces 51e, 51f (see Fig. 3) oppose each other in the Y-axis direction. As an example of the positional relationship between the side faces 51c, 51d and the exit surface 51a and the back surface 51b, FIG. 1 illustrates a state in which the side faces 51c, 51d are substantially perpendicular to the exit surface 51a and the back surface 51b. In this embodiment, it is also assumed that the other side faces 51e, 51f are perpendicular to the exit surface 51a and the back surface 51b.

As illustrated in FIGS. 1 and 2, a plurality of lens units 52 are formed on the back surface 51b. The transparent lens unit 52 is for emitting light propagating through the light guide plate 50 from the exit surface 51a side. Each lens unit 52 has a dome-like outer shape.

The shape of each lens unit 52 will now be explained. To simplify the explanation, it is assumed that a plurality of lens units 52 have the same size.

The lens unit 52 has an outer shape such that when light is emitted from a given point (one point) p on the exit surface 51a, the ratio of the second light flux of the light emitted from the point p at which the position is made to the first light flux is proportional The value obtained by multiplying the emission efficiency is greater than 1.055%. The point p may be a point (a point) in the central portion of the exit surface (first surface) 51a, that is, the center of the exit surface 51a.

The first luminous flux is the total luminous flux of light emitted from all directions (all azimuths) of the outside of the light guide plate 50 from the point p. The second luminous flux is the luminous flux per unit solid angle of light emitted from the point p in a predetermined direction. In this embodiment, the unit solid angle is 1/4π. The predetermined direction is a plane perpendicular to the Y-axis direction The inner and outer directions of the exit surface 51a are in the direction of an angle of about 30°. The emission efficiency is a ratio of the total amount of light emitted from the exit surface 51a to the amount of light incident on the side faces 51c, 51d serving as the incident surface (i.e., light incident on the light guide plate 50).

A more specific explanation will be provided with reference to FIG. FIG. 3 is a set of diagrams for explaining the shape of the lens unit 52. Fig. 3(a) is a view for explaining a state in which a partial coordinate system on the exit surface 51a is set. Fig. 3(b) is a view for explaining a method of defining an angle formed with the z-axis and the x-axis in the coordinate system illustrated in Fig. 3(a).

As illustrated in Fig. 3(a), a local xyz coordinate system with a given point p on the exit surface 51a as the origin is set so as to assume a unit sphere with respect to the origin. In the xyz coordinate system, the z-axis is perpendicular to the exit surface 51a. That is, the z-axis corresponds to the normal to the exit surface 51a. The x-axis is substantially parallel to the X-axis direction. That is, the x-axis is a direction substantially perpendicular to the side faces 51c, 51d serving as the incident surface. In this case, the y-axis substantially coincides with the Y-axis direction. In FIG. 3(b), the x-axis, the y-axis, and the z-axis also correspond to the X-axis, the Y-axis, and the Z-axis direction, respectively.

As illustrated in FIG. 3(b), it is assumed that θ is the angle (deflection angle) between the direction of the light emitted from the point p and the z-axis, and φ is the angle between the direction of the emitted light and the x-axis ( Deflection angle). In this setting, the predetermined direction is a direction of θ=30° in the xz plane. In other words, the predetermined direction is a direction defined by θ=30° and φ=0°. The predetermined direction may be a direction in which θ and φ satisfy a range of θ=30°±5° and φ=0°±5°, respectively. It is assumed that Φ ₁ is the total luminous flux of light emitted from all points p in all directions, and Φ ₂ is the luminous flux per unit solid angle of light emitted in a predetermined direction. The ratio of the luminous flux Φ ₂ to the total luminous flux Φ _{1 is} the ratio of light emission in a predetermined direction. Hereinafter, the light emission ratio in the predetermined direction is also simply referred to as "light emission ratio". Let R be the light emission ratio, R = Φ ₂ / Φ ₁ . It is assumed that Q ₁ is the amount of light incident on the light guide plate 50, and Q ₂ is the total amount of light emitted from the exit surface 51a. Let E be the light emission efficiency, E = Q ₂ / Q ₁ .

In this case, the outer shape of the lens unit 52 satisfies 1.055 (%) < R × E × 100 (= R _E ). In the following explanation, R _{E is} also referred to as an effective light emission ratio.

4 is a diagram for explaining an example of the outer shape of the lens unit 52, that is, a schematic view of a cross-sectional structure of the light guide plate 50 including the central axis C of the lens unit 52.

In the lens unit 52, the apex of the lens unit 52 on the opposite side of the back surface 51b is referred to as the front end portion 52a of the lens unit 52, and the side of the back surface 51b of the lens unit 52 is referred to as the bottom portion 52b. In this embodiment, it is assumed that the lens unit 5 has a shape obtained by rotating the cross-sectional shape illustrated in Fig. 4 around a central axis C serving as an axis of rotation. Therefore, the lens unit 52 is bidirectionally symmetrical in a given cross section including the central axis C. The lens unit 52 also has an outer shape such that an angle formed between the back surface 51b and the cut surface of the contact lens unit 52 monotonously decreases from the side of the bottom portion 52b in the lens unit 52 toward the side of the front end portion 52a.

Various examples of the outer shape of the lens unit 52 will be explained with reference to FIG. In FIG. 4, it is assumed that w _a (μm) and h _a (μm) are the width (diameter) and the maximum height of the lens unit 52, respectively.

It is assumed that (I) h _a /w _a is an aspect ratio which is _a ratio of _a maximum height h _a to a width w _a , and (II) r / w _a is a radius of curvature r (μm) and a width w of the front end portion 52a of the lens unit 52. the ratio _a, and (III) γ (°) is a bottom 52b of the lens unit 52 with respect to the back surface 51b of the angle (hereinafter referred to as a corner), the effective light emission ratio R _E (%) falls within the above range Lens unit 52 may have an outer shape defined by h _a /w _a , r/w _a , and γ as defined by any combination within the graph of FIG. 5. Preferably, lens unit 52 has an outer shape defined by any combination of h _a /w _a , r/w _a , and γ by the combination within the graph of FIG. 6.

The shape condition to be satisfied by the lens unit 52 will now be specifically exemplified in accordance with the classification of the aspect ratio [h _a /w _a ] explained based on the graphs of FIGS. 5 and 6.

(1)0.17 In the case of h _a /w _a <0.19, the lens unit 52 has a shape in which r/w _a and γ satisfy any of the following conditions: (1a) 0.66 r/w _a 0.94 and 34.48 γ 48.00(1b)1.22 r/w _a 1.28 and 70.93 γ 78.28 Preferably, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 0.66 r/w _a 0.80 and 34.48 γ 40.32

(2)0.15 In the case of h _a /w _a <0.17, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 0.74 r/w _a 1.21 and 31.41 γ 55.00 Preferably, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 0.82 r/w _a 1.05 and 34.02 γ 44.64

(3) 0.13 In the case of h _a /w _a <0.15, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 0.94 r/w _a 1.47 and 30.57 γ 58.14 Preferably, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 1.03 r/w _a 1.29 and 33.44 γ 45.63

(4)0.11 In the case of h _a /w _a <0.13, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 1.30 r/w _a 1.72 and 32.70 γ 54.09 Preferably, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 1.41 r/w _a 1.51 and 36.55 γ 41.25

(5)0.09 In the case of h _a /w _a <0.11, the lens unit 52 has a shape in which r/w _a and γ satisfy the following conditions: 1.81 r/w _a 2.06 and 36.17 γ 49.07

The radius of curvature r of the distal end portion 52a indicates a curved state of the distal end portion 52a which is the vertex of the lens unit 52. For example, as illustrated in FIG. 4, the radius of curvature of the front end portion 52a is a radius of a circle (indicated by a broken line in FIG. 4) assumed to be in contact with the front end portion 52a. The base angle γ is an angle formed in a cross section passing through the center axis C between the cut surface P of the lens unit 52 and the back surface 51b at the intersection of the contour of the lens 52 and the back surface 51b. When the lens unit 52 is assumed to be a droplet, the bottom angle γ corresponds to the contact angle. The bottom portion also functions as a skirt of the lens unit 52 with respect to the front end portion 52a. Therefore, the base angle γ is also the skirt angle.

For example, the width w _a is at least 5 μm but less than or equal to 1 mm, preferably at least 10 μm but less than or equal to 500 mm. The lens unit 52 having this size is a so-called microlens.

Since FIG. 4 illustrates the structure including the cross section of the central axis C of the lens unit 52, the width w _a corresponds to the maximum width of the lens unit 52. On the other hand, h _a is the thickness of the lens unit 52 at the position of the front end portion 52a. The aspect ratio [h _a /w _a ] corresponds to the ratio of the thickness (or height) of the lens unit 52 at the position of the front end portion 52a to the maximum width of the lens unit 52, that is, [thickness at the position of the front end portion] / [Maximum Width of Lens Unit]. In general, the lens unit 52 has a maximum thickness at the position of the front end portion 52a such that the thickness of the lens unit 52 at the position of the front end portion 52a is also the maximum thickness of the lens unit 52. The ratio explained in the above (II) corresponds to the ratio of the radius of curvature r to the maximum width of the lens unit 52, that is, [curvature radius] / [maximum width of the lens unit].

The lens unit 52 may be made of the same material as that of the body 51. The lens unit 52 may also be made of a material different from that of the body 51 as long as the material is a light transmissive material.

The body 51 of the light guide plate 50 thus constructed may be a single-layer planar body composed of a single light-transmitting material or a multilayer planar body stacked with a plurality of layers made of light-transmitting materials different from each other. When the lens unit 52 is made of the same material as that of the body 51, the light guide plate 50 is a planar body made of a single light transmissive material.

When the light transmissive resin material is used as the light transmissive material constituting the body 51 and the lens unit 52, the light transmissive resin material may further contain an additive such as a UV absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, And lubricants. These additives may be used singly or in combination of two or more kinds. It is preferable to include the UV absorber in the light guide plate 50 because the UV absorber can prevent the light guide plate 50 from being deteriorated by the UV rays when the light emitted from the light source unit 60 includes a large amount of UV rays and the like.

Examples of the UV absorber include UV absorbers based on benzotriazole, benzophenone, cyanoacrylate, malonate, oxalic acid, and triazine, based on benzotriazole and triazine The UV absorber is preferred.

A light-transmitting resin material containing no light-diffusing agent as an additive is generally used, but the light-transmitting resin material may contain a small amount of a light-diffusing agent as long as the gist of the present invention is not lost.

As the light diffusing agent, a powder having a refractive index different from that of the transparent material, which is mainly dispersed in the above-mentioned transparent material constituting the light guiding plate 50 (which specifically includes the body 51 and the lens unit 52), is used. Examples of the light diffusing agent include organic particles such as styrene resin particles and methacrylic resin particles, and inorganic particles such as potassium carbonate particles and vermiculite particles, and the particle diameter thereof is usually from 0.8 to 50 μm.

Preferably, the exit surface 51a is flat. However, in order to reduce the Murray fringes, the exit surface 51a may exhibit slight diffusibility on its surface layer.

The light guide plate 50 equipped with the lens unit 52 can be manufactured by inkjet printing (inkjet technology), photopolymerization, extrusion molding, injection molding, or the like.

When the light guide plate 50 is manufactured by inkjet printing (inkjet technology) or photopolymerization, a UV curable resin can be used as the material of the lens unit 52. Examples of the UV curable resin include an acrylic based UV curable resin.

An example of a method for manufacturing the light guide plate 50 by inkjet printing while using an acrylic-based UV curable resin as a material of the lens unit 52 will now be explained. In this case, the body 51 as a planar body is formed by extrusion molding, injection molding, or the like. Subsequently, while the ink jet head is being operated, the UV curable resin is dropped (printed) on the surface of the body 51 to become the back surface 51b. Next, the UV curable resin is cured by irradiation with UV rays to form the lens unit 52.

When the lens unit 52 is formed using inkjet printing, an original or the like which is indispensable in screen printing as another printing technique is unnecessary. The plurality of lens units 52 are usually arranged in a predetermined dot pattern by appropriately repeating the design and test steps, so that the brightness of the light emitted from the exit surface 51a becomes high. In original inkjet printing can reduce the time required to determine a predetermined dot pattern. Therefore, the light guide plate 50 can be manufactured more efficiently.

Although the manufacturing method based on inkjet printing is exemplified here, the light guide plate 50 in which the lens unit 52 is directly formed by extrusion molding, injection molding, or the like can be manufactured as described above. In this case, the lens unit 52 is made of the same material as that of the body 51.

The operation and effect of the light guide plate 50 will now be explained in the case where the light guide plate 50 is used in the transmissive image display device 10 as a part of the surface light source device 30 illustrated as an example in Fig. 1. Fig. 7 is a partially enlarged view of the transmissive image display device 10 illustrated in Fig. 1. Figure 7 is an enlarged view of the side of the side 50a (side 51c) of Figure 1.

When the point-like light source 61 in the light source unit 60 is turned on, light from the point light source 61 enters the light guide plate 50 from the side surface 50a of the light guide plate 50 opposite to the point light source 61. Light that has entered the light guide plate 50 propagates through the light guide plate 50 while being totally reflected in the light guide plate 50. When incident on the lens unit 52, light propagating through the light guide plate 50 is reflected in the lens unit 52 under conditions different from total reflection conditions. Therefore, the reflected light is emitted from the exit surface 51a.

Since the lens unit 52 has a shape such that the effective light emission ratio R _E (%) is more than 1.055%, the ratio of light emitted from the exit surface 51a at the exit angle θ _{o of} about 30° becomes higher. Therefore, the brightness of light incident on the transmissive image display unit 20 through the seesaw 40 is improved.

As an example, this point will now be explained with reference to the light guide plate 80 formed with the white dot 81 instead of the lens unit 52 formed on the back surface 51b. FIG. 8 is a schematic view showing an example of the structure of the light guide plate 80 on which the plurality of white dots 81 are formed on the back surface 51b. For purposes of explanation, FIG. 8 also illustrates a point-like light source 61 and a seesaw 40. The light guide plate 80 has the same structure as the light guide plate 50 except that the white dot 81 is formed on the back surface 51b instead of the lens unit 52. In the light guide plate 80, constituents similar to those in the light guide plate 50 will be referred to with the same symbols.

Light entering the light guide plate 80 after the self-point source 91 is emitted also propagates through the light guide plate 80 while being totally reflected in the light guide plate 80. When incident on the white point 81, the light propagating through the light guide plate 80 is reflected at the position of the white point 81 under conditions different from the total reflection condition. Therefore, the light reflected by the white point 81 is emitted from the exit surface 51a. Here, as illustrated in FIG. 9, the exit angle θ _o tends to become close to 60°. Fig. 9 is a graph showing the measurement results of the intensity distribution of emitted light with respect to the exit angle θ _o of the emitted light. In Fig. 9, the abscissa is the exit angle θ _o of the light emitted from the exit surface 51a, and the ordinate is the illuminance (cd). Light emitted from the light guide plate 80 is incident on the raft 40 at substantially the same angle as the exit angle θ _o . Therefore, light emitted from the light guide plate 80 at an exit angle θ _o of about 60° is incident on the dam plate 40 at an incident angle θ _{i of} about 60°.

However, as illustrated in FIG. 8, light incident on the raft 40 at an incident angle θ _{i of} approximately 60° may be emitted from the Z unit 41 when it is emitted from the 稜鏡 unit 41. Therefore, the light incident on the transmissive image display unit 20 tends to decrease.

On the other hand, in the light guide plate 50, the ratio of light emitted at an exit angle θ _o falling within a range of 30° ± 5° (that is, at least 25° but less than or equal to 35°) is high. In this case, a relatively large amount of light is incident on the raft 40 at an incident angle θ _{i of} 30° ± 5°. As illustrated in Fig. 7, when the incident angle θ _i on the seesaw 40 is close to 30°, the light emitted from the crucible unit 41 may be emitted toward the thickness direction (Z-axis direction). In other words, the light emitted from the light guide plate 50 may converge toward the forward direction as the thickness direction. Therefore, light is emitted to the transmissive image display unit 20 at a large ratio. This case improves the brightness in the forward direction, thereby allowing the transmissive image display unit 20 to display a brighter image.

It will now be explained based on the results of the simulation that the amount of outgoing light whose exit angle θ _{o is} close to 30° becomes larger when the lens unit 52 satisfies the condition illustrated in FIG. 5 .

Figure 10 is a schematic diagram illustrating a simulation model. For convenience of explanation, as in the light guide plate 50 _M , the suffix M will be added to the constituent components corresponding to the constituent components illustrated in FIG. 1 . The simulation is performed by using ray tracing in the model as illustrated in Fig. 10, in which the point-like light sources 61 _M , 61 _M are respectively disposed beside the side faces 50 _M a, 50 _M b of the light guide plate 50 _M , The reflective sheet is disposed as a reflection unit 70 _M under the light guide plate 50 _M. The point-like light sources 61 _M , 61 _{M are} arranged beside the side faces 50 _M a, 50 _M b . On the other hand, the point light sources 61 _M , 61 _{M are} located at the central portion in the shorter side direction of the light guide plate 50 _M .

The simulation conditions are as follows:

Material composition of the light guide plate 50 _M : It is assumed that each of the body 51 _M and the lens unit 52 _M is made of PMMA (refractive index: 1.49)

●The shape of the light guide plate 50 _M (in the thickness direction): a rectangle

●The longer side length of the light guide plate 50 _M is W1: 500 mm

●The shorter side length of the light guide plate 50 _M is W2: 20 mm

●The thickness of the body 51 _M t: 4 mm

Distance between the front end portion 52 _M a of the lens unit 52 _M of the light guide plate 50 _M and the reflection unit 70 _M : 0.1 mm

Reflective unit 70 _M : assumed to be specular (with 100% reflectivity)

● Class point source 61 _M : is assumed to be a point source with isotropic emission

● Wavelength of light emitted by a self-point source 61 _M : assumed to be 550 nm

●Distance between point-like light source 61 _M and light guide plate 50 _M : 0.1 mm

Periodic boundary conditions are assumed on the sides 51 _M e, 51 _M f of the body 51 _M . That is, it is assumed that the side faces 51 _M e, 51 _M f reflect all the light back into the light guide plate 50.

In the simulation, the outline of the lens unit 52 _M is represented by a conical section in the cross-sectional structure of the lens unit 52 _M including its central axis C as illustrated in FIG. Specifically, as illustrated in FIG. 11, the uv coordinate system is set, and the cross-sectional shape of the lens unit 52 _M is defined by the conic section v(u) expressed by the following formula (1). The v-axis in the uv coordinate system corresponds to the central axis C of the lens unit 52 in FIG. The u axis corresponds to the X-axis direction illustrated in FIG.

In the statement (1), k _a is a parameter indicating the sharpness of the conic section indicated by the statement (1), and the sharpness of the front end portion 52 _M a of the lens unit 52 _M is explained. For example, when k _a is 0, 1, and -1, the outer shape of the lens unit 52 _M becomes a parabola, a prism-like prism, and a semi-elliptical shape, respectively.

In the simulation model, a plurality of lens units 52 _M are disposed on the rear surface 51 _M b of the body 51 _M at regular intervals. Specifically, a square formed by arranging a plurality of squares is set for the rear surface 51 _M b , and a lens unit 52 _{M is} disposed for each square which is a constituent unit of the square. The ratio of the constituent units of the lens unit 52 _M occupying the square (the ratio of the lens unit 52 _M covering the constituent units) is 78.5%. The length of each side of the square used as a constituent unit of the square is 500 μm.

First, in the simulation, a lens unit 52 _M having an outer shape defined by the statement (1) is designed. It is assumed that the light from the point light source 61 _{M is} incident on the light guide plate 50 _M having the lens unit 52 _M thus designed, assuming that the point p serving as the light emission position is at the central portion of the exit surface 51 _M a of the light guide plate 50 _M .

Subsequently, the local xyz coordinate system illustrated in Fig. 3(a) (or Fig. 3(b)) is set, and the total radiant flux from point p and the direction from point p to θ = 30° and φ = 0° are estimated. The radiant flux per unit solid angle of light emitted (hereinafter referred to as a predetermined direction). Specifically, in order to compare with a comparative experiment to be explained later, in the simulation, it is calculated at 0° at each of a plurality of points on the surface of the hemisphere. θ 90° and 0° Φ a range of 360° (corresponding to z in the spherical surface of the unit sphere illustrated in Fig. 3(b) The amount of radiation of light emitted within the hemispherical surface in the region of 0. Thereafter, the total radiant flux of the entire hemispherical surface and the radiant flux per unit solid angle in a predetermined direction are estimated from the thus calculated amount of radiation.

A plurality of points for estimating the amount of radiation are set in increments of 5° and 10° in the θ and φ directions, respectively, so as to include points in a predetermined direction. The total radiant flux and the radiant flux are estimated as follows based on the amount of radiation.

First, the amount of radiation at each estimated point is converted to a radiant flux per unit solid angle. Set 1/4π as the unit solid angle. Each radiant flux is then converted to a radiant flux per surface element on a unit spherical surface. Thereafter, the radiant flux per surface element on the unit spherical surface is numerically integrated on the hemispherical surface to estimate the total radiant flux. For the radiant flux per unit solid angle toward the predetermined direction, the converted value at the estimated point in the predetermined direction is used. Although the radiant flux is estimated as a physical quantity in the simulation, the radiant flux corresponds to the luminous flux (the amount of light per unit time) as a so-called psychophysical quantity. Therefore, the ratio of the radiant flux per unit solid angle in the predetermined direction to the estimated total radiant flux, that is, [radiation flux per unit solid angle] / [total radiant flux] corresponds to the ratio of light emission ( The ratio of the light emitted in the predetermined direction)R.

The ratio of the total amount of light emitted from the exit surface 51 _M a to the amount of light incident on the light guide plate 50 _M is estimated, thereby obtaining the light emission efficiency E.

The above simulation is performed for each of the shapes of the plurality of lens units 52 _M set by changing k _a and h _a /w _a to estimate the light emission ratio R and the light emission efficiency E, thereby for each simulation As a result, an effective light emission ratio R _{E is obtained} .

For comparison, the effective light emission ratio R _E based on the actual measured value is obtained by using the light guide plate 80 equipped with the white point 81. In the experiment for comparison (hereinafter referred to as "comparative experiment"), a backlight unit used in UN46B8000 manufactured by Samsung Electronics Co., Ltd. was used, and the guide of the backlight unit was used. The light plate serves as the light guide plate 80. A structure similar to that of FIG. 10 is obtained by using the light guide plate 80 and the light source of the backlight unit and providing a silver-deposited reflective film on the back surface side of the light guide plate 80. The light guide plate 80 used for the comparative experiment is equipped with a white point 81. In the comparative experiment, as in the simulation model illustrated in Fig. 10, white light is supplied from the side of the light guide plate 80 to the light guide plate 80, and is measured at a predetermined position of the exit surface 51a (center position of the light guide plate 80). Brightness. The measurement was performed by using a lightness meter (Brightness Colorimeter BM-5AS manufactured by Topcon Corporation). Specifically, z in the spherical surface illustrated in Figure 3(b) The brightness is measured at each of a plurality of measurement points in the hemispherical surface of 0. A plurality of measurement points are set to correspond to the estimated points of the amount of radiation in the simulation.

The thus measured brightness is converted into luminous intensity, that is, luminous flux per unit solid angle. The 1/4 π set by the above light meter is used as the unit solid angle. Subsequently, the luminous flux (emission intensity) per unit solid angle is converted into the luminous flux per surface element on the unit spherical surface. Thereafter, the luminous flux per surface element on the unit spherical surface is numerically integrated over the entire hemispherical surface to estimate the total luminous flux. The converted value at the estimated point in the predetermined direction is used as the luminous flux per unit solid angle toward the predetermined direction. The luminous flux Φ ₁ per unit solid angle in a predetermined direction is divided by the total luminous flux Φ ₂ to estimate the light emission ratio (light emission ratio in a predetermined direction).

It is known that the light guide plate 80 having the white dots 81 formed by screen printing has an emission efficiency of 80%. Therefore, in the comparative experiment, the emission efficiency of the light guide plate 80 was assumed to be 80%. The estimated light emission ratio R to the predetermined direction is multiplied by 80% as the assumed light emission efficiency E to calculate the effective light emission ratio R _E in the comparative experiment. The effective light emission ratio R _{E obtained} was 1.055%.

The results of the simulation are illustrated in the graphs of Figures 12-21. 12 and 13 are graphs illustrating the relationship between the lens shape defined by k _a and the aspect ratio [h _a /w _a ] in the formula (1) and the light emission efficiency E. Figure 12 illustrates a range in which k _a is at least 0.1 but less than or equal to 0.9. Figure 13 illustrates a range in which k _a is at least -0.9 but less than or equal to zero. In Figs. 12 and 13, the light emission efficiency E is expressed by a percentage (%). 14 and 15 are graphs for explaining the relationship between the lens shape defined by k _a and the aspect ratio [h _a /w _a ] in the statement (1) and the light emission ratio R in a predetermined direction. Figure 14 illustrates a range in which k _a is at least 0.1 but less than or equal to 0.9. Figure 15 illustrates a range in which k _a is at least -0.9 but less than or equal to zero. As in FIGS. 12 and 13, the light emission ratio R is expressed as a percentage in FIGS. 14 and 15.

16 and 17 are graphs illustrating the relationship between the lens shape defined by k _a and the aspect ratio [h _a /w _a ] in the statement (1) and the effective light emission ratio R _E . Figure 16 illustrates a range in which k _a is at least 0.1 but less than or equal to 0.9. Figure 17 illustrates a range in which k _a is at least -0.9 but less than or equal to 0. The values of the data grids in the graph of FIG. 16 are based on the values of the corresponding data grids in the graphs of FIGS. 12 and 14. Similarly, the values of the data grids in the graph of FIG. 17 are based on the values of the corresponding data grids in the graphs of FIGS. 13 and 15.

18 and 19 are graphs for explaining the base angle γ of the lens shape determined by k _a and the aspect ratio [h _a /w _a ] shown in Figs. 16 and 17 , respectively. 20 and FIG. 21 are ratios of the curvature radius r and the width w _a of the front end portion 52 _M a of the lens shape determined by k _a and the aspect ratio [h _a /w _a ] as shown in FIGS. 16 and 17 , respectively. [r/w _a ] chart.

In the graphs of FIGS. 16 and 17, the value of the effective light emission ratio R _E larger than the value (1.055%) of the effective light emission ratio R _E estimated for the white point 81 is bottomed. This situation indicates that a large amount of light is emitted near the exit angle of 30° because the effective light emission ratio R _{E is} high. That is, when combined with the seesaw 40 _M , since the effective light emission ratio R _{E is} high, the brightness can be more improved. Therefore, when combined with the seesaw 40 _M , compared with the light guide plate 80 of the comparative experiment, a guide of a lens unit having a shape corresponding to the bottom line position (data grid) in the graphs of FIGS. 16 and 17 is provided. The light panel 50 _M can improve the brightness more.

In the data grid in the region surrounded by the thick frame in Figs. 16 to 21, h _a /w _a and k _a satisfy the following conditions (1) and (2): condition (1): h _a /w _a <0.19

Condition (2): k _a 0

In FIGS. 18 to 21 (special map 19 and FIG. 21), values in the data grid corresponding to the data grid including the bottom line values in FIGS. 16 and 17 in the region surrounded by the thick frame are underlined.

In the data grid in the area surrounded by the thick frame in Figs. 17, 19, and 21, the data grid having the bottom line value will now be studied. The aspect ratio [h _a /w _a ] of the lens unit 52 corresponding to these data frames, the ratio [r/w _a ] of the radius of curvature to the width w _a , and the base angle γ fall within the range of the graph of Fig. 5 . Therefore, the light guide plate of the lens unit 52 defined by the combination of the aspect ratio [h _a /w _a ], the ratio of the radius of curvature to the width w _a [r/w _a ], and the base angle γ illustrated in FIG. 5 is provided. In 50, the ratio of light emitted near the exit angle of 30° is large. Therefore, in the transmissive image display device 10 equipped with the seesaw 40, the transmissive image display unit 20 can be illuminated with higher brightness using the light guide plate 50 in this embodiment. This case can improve the brightness of the image displayed by the transmissive image display unit 20.

As h _a /w _a becomes smaller, the lens unit becomes flatter, and as k _a becomes larger, the apex of the lens unit 52 becomes rounder. When h _a /w _a and k _a satisfy the condition (1) and the condition (2), respectively, the apex (front end portion 52a) of the lens unit 52 tends to have a rounded and flat shape, thereby being easier to use by Printing is performed to form the lens portion 52. Therefore, the lens unit 52 defined by the combination of the aspect ratio [h _a /w _a ], the ratio of the radius of curvature to the width w _a [r/w _a ], and the base angle γ illustrated in FIG. 5 is easier to print by. To make the shape. When the lens unit 52 is formed by inkjet printing, since the lens unit 52 is relatively flat, the liquid repellent treatment required for the back surface 51b becomes weak (or unnecessary), and the adhesion of the lens unit 52 to the body 51 is further improved. Thus, each of the lens units 52 illustrated in Figure 5 is another preferred shape when using an inkjet printing scheme.

Although the emission efficiency E has been assumed to be 80% in the comparative experiment so far, when the light emission efficiency E is assumed to be 100%, the effective light emission ratio R _E in the comparative experiment is 1.5075%.

In the data frame in the thick frame in Fig. 17, the data grid with the effective light emission ratio R _E greater than 1.5075% is shaded. In Figs. 19 and 21, the data grid corresponding to the shaded data frame in Fig. 16 is also shaded. The aspect ratio [h _a /w _a ], the ratio of the radius of curvature to the width w _a [r/w _a ] of the shape of the lens unit 52 _M of the shaded data frame in FIGS. 17 , 19 and 21 is defined, And the base angle γ falls within the range of the graph of FIG.

Therefore, compared with the case where the light emission efficiency E is assumed to be 100% in the comparative experiment, the aspect ratio [h _a /w _a ], the radius of curvature and the width w which fall within the range of the graph of Fig. 6 are provided. _a ratio of [r / w _a], and the base angle γ defined by the lens unit 50 of the light guide plate 52 in the direction of a higher rate of about 30 ° to emit light. Therefore, the lens unit 52 defined by the aspect ratio [h _a /w _a ], the ratio of the radius of curvature to the width w _a [r/w _a ], and the base angle γ defined by the range falling within the graph of FIG. 6 is provided. When the light guide plate 50 is combined with the crucible unit 40, the transmissive image display unit 20 can be illuminated with higher brightness. This case can improve the brightness of the image displayed by the transmissive image display unit 20.

While the embodiments of the present invention have been explained, the present invention may be modified in various ways without being limited to the above embodiments without departing from the gist of the present invention.

In the above embodiment, it is assumed that the plurality of lens units 52 formed on the back surface 51b have a shape in which the effective light emission ratio R _{E is} more than 1.055%. However, it suffices if at least half of the plurality of lens units formed on the back surface 51b are the lens unit 52 explained in the above embodiment. In other words, the plurality of lens units formed on the back surface 51b may be composed of two halves composed of the first lens unit serving as the lens unit 52, and the second lens unit which does not satisfy the conditions explained in the above embodiment. The other half of the composition. The ratio between the number of first lens units used as the lens unit 52 and the number of second lens units may also be 6:4.

Preferably, as illustrated in FIG. 4, the lens unit 52 has a shape in which the angle formed between the cut surface of the lens unit 52 and the back surface 51b monotonously decreases from the bottom side to the front end side of the lens unit 52. However, as long as the lens unit 52 has a shape such that the effective light emission ratio R _{E is} greater than 1.055% (for example, a shape defined by a combination of h _a /w _a , r/w _a , and γ illustrated in FIG. 5), The angle formed between the cut surface of the lens unit 52 and the back surface 51b is required to monotonically decrease toward the front end portion 52a.

The number of light source units 60 is not limited to two. For example, the number of light source units 60 may be 3 or greater. In this case, for example, at least one of the side faces 51e and 51f of the body 51 may further include the light source unit 60. A light source unit 60 may be provided separately. In this case, the light source unit 60 is disposed at one of the side faces 51c, 51d illustrated in FIG.

In the transmissive image display device 10, other optical members can be disposed between the light guide plate 50 and the seesaw 40 and between the seesaw 40 and the transmissive image display unit 20 without losing the gist of the present invention. Examples of the optical member disposed between the light guide plate 50 and the seesaw 40 may include a light diffusing sheet and a microlens sheet having light diffusing characteristics as long as the gist of the present invention is not lost. Examples of the optical member disposed between the seesaw 40 and the transmissive image display unit 20 include a reflective polarizing separation sheet, a light diffusion sheet, and a microlens sheet.

10‧‧‧Transmissive image display device

20‧‧‧Transmissive image display unit

21‧‧‧ liquid crystal cell

22‧‧‧Linear polarizer

23‧‧‧Linear polarizer

30‧‧‧Spot light source unit/surface light source device

40‧‧‧稜鏡板

40a‧‧‧ front surface

40b‧‧‧Substantially flat rear surface

41‧‧‧稜鏡 unit

41a‧‧‧ apex

50‧‧‧Light guide plate

50a‧‧‧ side

50b‧‧‧ side

50 _M ‧‧‧Light guide

50 _M a‧‧‧ side

50 _M b‧‧‧ side

51‧‧‧ planar body

51a‧‧‧Outlet surface/first surface

51b‧‧‧Back surface

51c‧‧‧ side

51d‧‧‧ side

51e‧‧‧ side

51f‧‧‧ side

51 _M ‧‧‧ Ontology

51 _M b‧‧‧Back surface

51 _M e‧‧‧ side

51 _M f‧‧‧ side

52‧‧‧ lens unit

52a‧‧‧ front end

52b‧‧‧ bottom

52 _M ‧‧‧Lens unit

60‧‧‧Light source unit

61‧‧‧ class point light source

61 _M ‧‧‧ point light source

70‧‧‧reflection unit

70 _M ‧‧‧reflection unit

80‧‧‧Light guide plate

81‧‧‧White spots

C‧‧‧ center axis

h _a ‧‧‧Maximum height of the lens unit

P‧‧‧ facet of the lens unit

P‧‧‧ given point

R‧‧‧ radius of curvature of the front end of the lens unit

T‧‧‧ body thickness

The longer side length of the W1‧‧‧ light guide

Short side length of W2‧‧‧ light guide plate

w _a ‧‧‧Lens unit width/diameter

‧‧‧‧顶角

1 is a schematic view showing a outline structure of a transmissive image display apparatus using an embodiment of a light guide plate according to the present invention; FIG. 2 is a plan view of the light guide plate of FIG. 1 as seen from the back surface side; FIG. 3 is for A set of diagrams explaining the shape of the lens unit, wherein (a) is a diagram illustrating a state of setting a local coordinate system on the exit surface, and (b) is for explaining a definition and a coordinate system explained in (a) FIG. 4 is a diagram for explaining an example of an outer shape of a lens unit; FIG. 5 is a diagram illustrating conditions defining an outer shape of a lens unit; FIG. 6 is an illustration FIG. 7 is a partially enlarged view of the transmissive image display device illustrated in FIG. 1; FIG. 8 is a structural example of a light guide plate in which a plurality of white dots are formed on the back. FIG. 9 is a graph illustrating the measurement results of the intensity distribution of the emitted light with respect to the exit angle θ _o of the emitted light; FIG. 10 is a schematic diagram illustrating the simulation model; FIG. 11 is a view illustrating the exterior of the lens unit for simulation Shaped figure; Figure 1 2 is a graph illustrating the relationship between the lens shape for simulation and the light emission efficiency; FIG. 13 is a graph illustrating the relationship between the lens shape for simulation and the light emission efficiency; and FIG. 14 is a view illustrating the lens for simulation. A graph of the relationship between the shape and the ratio of light emitted in a predetermined direction; FIG. 15 is a graph illustrating a relationship between a lens shape for simulation and a ratio of light emitted in a predetermined direction; FIG. A graph of the relationship between the simulated lens shape and the effective light emission ratio; FIG. 17 is a graph illustrating the relationship between the lens shape for simulation and the effective light emission ratio; FIG. 18 is a view illustrating the relationship shown by FIG. A graph of the base angle of the lens shape determined by the value of k _a and the aspect ratio [h _a /w _a ]; FIG. 19 is a diagram for explaining the value of k _a and the aspect ratio [h _a /w _a ] shown in FIG. Graph of the bottom angle of the lens shape; FIG. 20 is a graph illustrating the curvature of the front end portion with respect to the width w _a in the lens shape determined by the values of k _a and the aspect ratio [h _a /w _a ] shown in FIG. 16 a graph of radius r; and FIG. 21 is a diagram illustrating k _a and aspect ratio [h _a /w _a shown in FIG. 17 A graph of the radius of curvature r of the tip end portion with respect to the width w _a among the lens shapes determined by the value.

10‧‧‧Transmissive image display device

20‧‧‧Transmissive image display unit

21‧‧‧ liquid crystal cell

22‧‧‧Linear polarizer

23‧‧‧Linear polarizer

30‧‧‧Spot light source unit/surface light source device

40‧‧‧稜鏡板

40a‧‧‧ front surface

40b‧‧‧Substantially flat rear surface

41‧‧‧稜鏡 unit

41a‧‧‧ apex

50‧‧‧Light guide plate

50a‧‧‧ side

50b‧‧‧ side

51‧‧‧ planar body

51a‧‧‧Outlet surface/first surface

51b‧‧‧Back surface

51c‧‧‧ side

51d‧‧‧ side

52‧‧‧ lens unit

60‧‧‧Light source unit

61‧‧‧ class point light source

70‧‧‧reflection unit

‧‧‧‧顶角

Claims (3)

A light guide plate disposed on a back surface side of a seesaw opposite to a surface of the sill plate, the sill plate having a plurality of ridges extending in a direction formed on each of the surfaces a unit, the plurality of unit are arranged in a row in a direction substantially perpendicular to the extending direction of the unit; the light guide plate comprises: a planar body having a first surface on the side of the seesaw a second surface on the opposite side of the first surface and an incident surface for receiving light intersecting the first surface and the second surface; and a plurality of lens units formed on the second surface And protruding toward a side opposite to the first surface; wherein each of the plurality of lens units has an outer shape such that an incident from the first surface is incident on the incident surface a value obtained by multiplying a ratio of a second luminous flux to a first luminous flux by a light emission efficiency of the light emitted from the first surface by more than 1.055%; wherein the first luminous flux is from the first On a surface a total luminous flux of light emitted in all directions; wherein the second luminous flux is a luminous flux per unit solid angle of light emitted from the point to a predetermined direction; wherein the predetermined direction is substantially perpendicular to the pupil Forming, in a plane of the extending direction of the unit, a direction of an angle of about 30° with a normal of the first surface; Wherein the emission efficiency is a ratio of the amount of light emitted from the first surface to the amount of light incident on the incident surface. A surface light source device for supplying light to a rear surface of a seesaw opposite to a surface of the raft, the raft having a plurality of ones formed on the surface extending in a direction a plurality of 稜鏡 units, the plurality of 稜鏡 units being arranged in a row in a direction substantially perpendicular to the extending direction of the 稜鏡 unit; the surface light source device comprises: a light guide plate, the light guide plate comprising: a planar body Having a first surface on the side of the seesaw, a second surface on the opposite side of the first surface, and an incident surface for receiving light intersecting the first surface and the second surface; And a plurality of lens units formed on the second surface and protruding toward a side opposite the first surface; and a light source unit disposed beside the incident surface of the light guide plate for light Supplying to the incident surface; wherein each of the plurality of lens units has an outer shape such that a second luminous flux of the light incident from the first surface to the incident surface is First A ratio of the luminous flux multiplied by a light emission efficiency of the light emitted from the first surface is greater than 1.055%; wherein the first luminous flux is a total of light emitted from a point on the first surface in all directions a luminous flux; wherein the second luminous flux is a luminous flux per unit solid angle of light emitted from the point to a predetermined direction; Wherein the predetermined direction is a direction forming an angle of about 30[deg.] with a normal of the first surface in a plane substantially perpendicular to the extending direction of the isotropic unit; and wherein the emission efficiency is from The ratio of the amount of light emitted by the first surface to the amount of light incident on the incident surface. A transmissive image display device comprising: a slab having a plurality of 稜鏡 units extending in a direction on each of a surface, the plurality of 稜鏡 units being substantially perpendicular to the One direction of the extending direction of the unit is arranged in a row; a light guide plate is disposed on a back surface side of the yoke opposite to the surface, the light guide plate comprises: a planar body having a first surface on the side of the seesaw, a second surface on the opposite side of the first surface, and an incident surface for receiving light intersecting the first surface and the second surface; and a plurality of lenses a unit formed on the second surface and protruding toward a side opposite the first surface; a light source unit disposed beside the incident surface of the light guide plate for supplying light to the incident surface And a transmissive image display unit disposed on the surface side of the seesaw for displaying an image when illuminated by light emitted from the seesaw; wherein the plurality of lens units are Each lens Having an external shape so that by a second light flux incident to the first surface from the incidence surface of the light emitted by the first light flux with a ratio of one A value obtained by a light emission efficiency of the light emitted from the first surface is greater than 1.055%; wherein the first luminous flux is a total luminous flux of light emitted from a point on the first surface in all directions; wherein The second luminous flux is a luminous flux per unit solid angle of light emitted from the point in a predetermined direction; wherein the predetermined direction is in a plane substantially perpendicular to the extending direction of the isotropic unit and the first A normal to the surface forms a direction of an angle of about 30; and wherein the emission efficiency is the ratio of the amount of light emitted from the first surface to the amount of light incident on the incident surface.