JP2013254592A - Light guide plate unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate unit capable of attaining luminance enhancement in a front direction and provide a planar light source device, a transmission type image display device, and a light guide plate including this light guide plate unit.SOLUTION: A light guide plate unit 55 includes a side face 51c into which light enters, a rear face 51b which is a face crossing the side face 51c and on which a convex strip part 52 for reflecting light is arranged, and an emission face 51a which is a face on the opposite side to the rear face 51b and emits light. The convex strip part 52 includes a light guide plate 50 which extends in a length direction of the side face 51c and is arranged in a direction orthogonally crossing the extension direction, and a film group 40 including a microlens film 41, a prism film 43, and a diffusion film 45 which are arranged on an emission face 51a side of the light guide plate 50. Each of the plurality of the convex strip parts 52 has an external shape in which a peak angle θ, or an angle having a largest emission intensity in an angular distribution of the light which is made incident from the side face 51c in the light guide plate 50 and is emitted from the emission face 51a, may become 20° or more and 67°or less.

Description

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

  2. Description of the Related Art A transmissive image display device such as a liquid crystal display device generally includes a surface light source device that is disposed on the back side of a transmissive image display unit such as a liquid crystal display panel and supplies a backlight to the transmissive image display unit. As such a surface light source device, an edge light type surface light source device is known (see, for example, Patent Document 1).

  The edge light type surface light source device includes a light-transmitting light guide plate and a light source that is disposed on the side of the light guide plate and supplies light to the side surface of the light guide plate. On the back side of the light guide plate, a plurality of lenticular lenses for reflecting light extend in a direction orthogonal to the incident direction of light and are provided in parallel to each other (for example, see Patent Document 1). In this configuration, the light emitted from the light source enters the light guide plate from the side surface of the light guide plate facing the light source, and propagates while totally reflecting inside the light guide plate. Since a plurality of lenticular lenses are formed on the back side of the light guide plate, the light reflected by the lenticular lens is emitted from the exit surface of the light guide plate on the transmissive image display unit side.

  2. Description of the Related Art Conventionally, in a transmissive image display device, a light guide plate, a transmissive image display unit, In some cases, a microlens film, a prism film, and a diffusion film are disposed between them.

JP 2007-31325 A

  However, when the microlens film, the prism film, and the diffusion film are arranged as described above with respect to the light guide plate having the lenticular lens on the back side (reflection surface side), the luminance in the front direction is sufficiently improved. There was something that could not be done.

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

  The light guide plate unit according to the present invention is an incident surface on which light is incident, a surface intersecting with the incident surface, a reflective surface provided with a ridge that reflects light, and a surface opposite to the reflective surface. A light guide plate that has a light exit surface that emits light, the protrusions extend in the longitudinal direction of the light entrance surface, and are arranged in a direction orthogonal to the extending direction; And a film group including a microlens film, a prism film, and a diffusion film disposed on the surface side, and each of the plurality of ridges is incident from the incident surface of the light guide plate and is emitted from the output surface. In the angular distribution of light, the outer shape is such that the peak angle, which is the angle with the highest emission intensity, is 20 ° or more and 67 ° or less.

  A surface light source device according to the present invention includes the light guide plate unit and a light source unit provided to face an incident surface of the light guide plate in the light guide plate unit.

  A transmissive image display device according to the present invention is provided on the light emitting side of the light guide plate unit, a light source portion provided to face an incident surface of the light guide plate in the light guide plate unit, and a film group in the light guide plate unit. And a transmissive image display unit that displays an image illuminated with light emitted from the film group.

  In the light guide plate unit, the surface light source device, and the transmissive image display device configured as described above, the light incident from the incident surface of the light guide plate propagates while totally reflecting inside the light guide plate. When light propagating in the light guide plate enters the ridges provided on the reflection surface, the light is reflected by the ridges under conditions different from the total reflection conditions. Therefore, the light reflected by the ridges is emitted from the emission surface opposite to the reflection surface, and is transmitted through the film group. In the light guide plate unit, the light incident on the film group from the light guide plate is incident on the film group because the light guide plate unit has a ridge that has a peak angle of 20 ° to 67 °. The ratio of light emitted from the light emission surface in the front direction is high. With these actions, the luminance in the front direction is improved in the light guide plate unit configured as described above. In the transmissive image display device according to the present invention, since the transmissive image display unit is provided on the light guide plate unit, the transmissive image display unit is illuminated with light having a higher luminance in the front direction. As a result, it is possible to improve the luminance of the image displayed on the transmissive image display unit.

  In the light guide plate unit, the surface light source device, and the transmissive image display device according to the present invention, in the light guide plate unit according to the present invention, the peak angle of the light emitted from the light guide plate is 23 ° or more and 43 ° or less. Can do. Thereby, the light emitted from the film group can be further condensed in the front direction.

  In the light guide plate unit, the surface light source device, and the transmissive image display device according to the present invention, the peak angle of the emitted light from the light guide plate can be set to 28 ° to 38 °. Thereby, the light emitted from the film group can be further condensed in the front direction.

  In the light guide plate unit, the surface light source device, and the transmissive image display device according to the present invention, the peak angle of the emitted light from the light guide plate can be set to 28 ° to 33 °. Thereby, the light emitted from the film group can be further condensed in the front direction.

  In the light guide plate unit, the surface light source device, and the transmissive image display device according to the present invention, the film group may be arranged in the order of the microlens film, the prism film, and the diffusion film from the light exit surface side of the light guide plate. it can.

  Moreover, in the light guide plate unit, the surface light source device, and the transmissive image display device according to the present invention, the ridges can be lenticular lenses.

  A light guide plate according to the present invention is a light guide plate disposed to face a light incident surface of a film group including a microlens film, a prism film, and a diffusion film, and includes an incident surface on which light is incident, and an incident surface A reflective surface provided with a convex portion that reflects light, and a surface opposite to the reflective surface, and an output surface that emits light toward the film group. The strips extend in the longitudinal direction of the incident surface and are arranged in a direction perpendicular to the extending direction, and each of the plurality of convex strips is an angular distribution of light incident from the incident surface and emitted from the exit surface. The outer shape has a peak angle that is the angle with the highest emission intensity at 20 ° to 67 °.

  In the light guide plate having the above-described configuration, light incident from the incident surface of the light guide plate propagates while being totally reflected in the light guide plate. When light propagating in the light guide plate enters the ridges provided on the reflection surface, the light is reflected by the ridges under conditions different from the total reflection conditions. Therefore, the light reflected by the ridge is emitted from the emission surface opposite to the reflection surface. At this time, it has a ridge part where the peak angle of the light emitted from the light guide plate is 20 ° or more and 60 ° or less. Such a light guide plate condenses much light emitted from the film group in the front direction when the film group is disposed to face the emission surface. By these actions, the luminance in the front direction is improved.

In the light guide plate according to the present invention, each of the plurality of ridges has a width w _a that is the length of the ridge in the direction orthogonal to the incident surface, and the maximum length of the ridge in the direction orthogonal to the emission surface. is a is height h _a, when the radius of curvature at the tip of the convex portion was set to r, and the ratio of the height h _a to the width w _a (h _a / w _a), the curvature radius r to the width w _a Ratio (r / w _a ) and the bottom angle γ, which is the angle formed between the contour line forming the cross section perpendicular to the extending direction of the ridge and the reflecting surface, for each combination shown in Table 1 below Can be within range.

The light guide plate according to the present invention, the ratio of the maximum height _{h a (h a / w a} ) to the width _{w a,} the ratio of the curvature radius r (r / _{w a)} to the width _{w a,} a bottom angle γ And within the range of each combination shown in Table 2 below.

The light guide plate according to the present invention, the ratio of the maximum height _{h a (h a / w a} ) to the width _{w a,} the ratio of the curvature radius r (r / _{w a)} to the width _{w a,} a bottom angle γ And within the range of each combination shown in Table 3 below.

  Moreover, in the light-guide plate which concerns on this invention, a protruding item | line part can be made into a lenticular lens.

  According to the present invention, it is possible to provide a light guide plate unit capable of improving luminance in the front direction, a surface light source device including the light guide plate unit, a transmissive image display device, and a light guide plate.

It is a schematic diagram which shows schematic structure of the transmissive image display apparatus to which one Embodiment of the light-guide plate unit which concerns on this invention is applied. It is drawing for demonstrating the shape of a protruding item | line part, Drawing which shows the setting state of the local coordinate system on an output surface, and the definition method of the angle from the z-axis and x-axis in this coordinate system is demonstrated. FIG. It is drawing for demonstrating the example of the external shape of a protruding item | line part. It is a graph which shows the conditions which prescribe | regulate the external shape of a protruding item | line part. FIG. 2 is a partially enlarged view of the transmissive image display device shown in FIG. 1. It is the graph which showed the outgoing angle distribution for every incident angle measured in the experiment example. It is a schematic diagram which shows a simulation model. It is drawing which shows the external shape of the protruding item | line part used for simulation. It is a graph which shows the relationship between the external shape of the protruding item | line part used for simulation, and a peak angle. It is a graph which shows the relationship between the external shape of the protruding item | line part used for simulation, and a peak angle. Shown in FIG. 9 is a table showing the bottom angle of the kurtosis k _a and aspect ratio [h _{a /} w _a] and de determined ridge outer shape. FIG. 11 is a chart showing the bottom angle of the outer shape of the ridge portion determined by the sharpness k _a and the aspect ratio [h _a / w _a ] shown in FIG. 10. 10 is a chart showing the radius of curvature r of the tip portion with respect to the width w _a of the outer shape of the ridge portion determined by the sharpness k _a and the aspect ratio [h _a / w _a ] shown in FIG. 9. Shown in FIG. 10 is a table showing the kurtosis k _a and aspect ratio [h _{a /} w _a] and de determined radius of curvature r of the tip to the width w _a of the outer shape of the convex portion. It is a graph which shows the conditions which prescribe | regulate the external shape of a protruding item | line part. It is a graph which shows the conditions which prescribe | regulate the external shape of a protruding item | line part. It is a graph which shows the conditions which prescribe | regulate the external shape of a protruding item | line part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The dimensional ratios in the drawings do not necessarily match those described. Further, in the description, words indicating directions such as “up” and “down” are convenient words based on the state shown in the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of a transmissive image display device to which an embodiment of a light guide plate unit according to the present invention is applied. In FIG. 1, the sectional configuration of the transmissive image display device 10 is shown in an exploded manner. The transmissive image display device 10 can be suitably used as a display device or a television device of a mobile phone or various electronic devices.

  The transmissive image display device 10 includes a transmissive image display unit 20 and a surface light source device 30 that outputs planar light to be supplied to the transmissive image display unit 20. Hereinafter, for convenience of description, as illustrated in FIG. 1, the direction in which the transmissive image display unit 20 is arranged with respect to the surface light source device 30 is referred to as a Z-axis direction or a front direction. Two directions orthogonal to the Z-axis direction are referred to as an X-axis direction and a Y-axis direction. The X-axis direction and the Y-axis direction are orthogonal to each other.

  The transmissive image display unit 20 displays an image by being illuminated with planar light emitted from the surface light source device 30. An example of the transmissive image display unit 20 is a liquid crystal display panel as a polarizing plate bonding body in which linear polarizing plates 22 and 23 are arranged on both surfaces of a liquid crystal cell 21. In this case, the transmissive image display device 10 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 21 and the polarizing plates 22 and 23, those used in a transmissive image display device such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 21 are a TFT (Thin Film Transistor) type liquid crystal cell, a STN (Super Twisted Nematic) type liquid crystal cell, and the like.

  The surface light source device 30 is an edge light type backlight unit that supplies a backlight to the transmissive image display unit 20. The surface light source device 30 includes a light guide plate unit 55 including a film group 40 and a light guide plate 50, and a light source unit arranged to face side surfaces (incident surfaces) 51c and 51d that are short sides of the light guide plate 50 and face each other. 60, 60.

  The light source unit 60 includes a plurality of point light sources 61 arranged in a line shape (arranged in the Y-axis direction in FIG. 1). An example of the point light source 61 is a light emitting diode. The light source unit 60 may include a reflector as a reflection unit that reflects light on the opposite sides of the side surfaces 51 c and 51 d of the light guide plate 50 in order to efficiently make light incident on the light guide plate 50. Here, the light source unit 60 including the plurality of point light sources 61 is illustrated, but the light source unit 60 may be a linear light source such as a cold cathode fluorescent lamp (CCFL).

  The film group 40 is disposed on the light exit surface 51 a side of the light guide plate 50, which will be described in detail later, and includes a microlens film 41, a prism film 43, and a diffusion film 45. The microlens film 41, the prism film 43, and the diffusion film 45 are arranged in this order from the light guide plate 50 side in the light emission direction (Z-axis direction shown in FIG. 1). The film group 40 is used to collect the light emitted from the light guide plate 50 in the front direction and to emit the light as planar light with high luminance uniformity. The example of the planar view shape of each member which comprises the film group 40 contains a substantially rectangular shape and a substantially square shape.

  The microlens film 41 is a film in which a plurality of microlenses 41b are formed on one surface (outgoing surface) 41a. The microlens 41b has, for example, a dome shape and may have a smooth surface. The microlenses 41b may be regularly arranged in a lattice shape, or may be randomly arranged. The pitch of the microlenses 41b adjacent to each other is normally 10 μm to 500 μm, and can be set to 25.7 μm, for example. Moreover, the height of the microlens 41b is normally 10 μm to 1000 μm, and can be set to 61.1 μm, for example. The total light transmittance Tt of the microlens film 41 is usually 40% to 70%, and can be, for example, 56.5%. The diffuse transmittance Td of the microlens film 41 is usually 30% to 70%, and can be set to 50.7%, for example. The haze Haze of the microlens film 41 is usually 75% to 100%, and can be, for example, 89.7%.

  In the prism film 43, a prism portion 43b extending in one direction (Y-axis direction in FIG. 1) is formed on one surface (outgoing surface) 43a, and is arranged in parallel in a direction orthogonal to the extending direction. It is a film. The prism film 43 is arranged so that the surface on which the prism portion 43b is formed faces the transmissive image display portion 20 side, that is, the light emitting side. The apex angle in the cross-sectional shape orthogonal to the extending direction of the prism portion 43b is usually 85 ° to 95 °. Further, for example, the apex angle is 90 °, and the cross-sectional shape of an isosceles triangle can be obtained. Moreover, the space | interval (pitch) between the prism parts 43b mutually adjacent is 10 micrometers-500 micrometers normally, for example, can be 60 micrometers.

  The prism film 43 is usually made of a translucent resin. Examples of translucent materials are polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin) (refractive index: 1.56-1.59), polystyrene resin (refractive index). : 1.59), AS resin (acrylonitrile-styrene copolymer resin) (refractive index: 1.56-1.59), acrylic ultraviolet curable resin (refractive index: 1.46-1.58), polymethacryl Examples thereof include methyl acid (PMMA) resin (refractive index: 1.49), cycloolefin-based resin (refractive index: 1.51-1.55), polyethylene terephthalate (PET) (refractive index: 1.58), and the like. Moreover, the refractive index of the prism film 43 is normally 1.44 to 1.64, and can be set to, for example, 1.54.

  The diffusion film 45 is a film having a diffusion performance capable of diffusing and emitting incident light. The total light transmittance Tt of the diffusion film 45 is usually 50% to 80%, and can be, for example, 65.8%. The diffusion transmittance Td of the diffusion film 45 is usually 40% to 80%, for example, 61.8%. The haze Haze of the diffusion film 45 is usually 80% to 100%, and can be, for example, 93.9%.

  The surface light source device 30 may include a reflection unit 70 located on the opposite side of the light transmission plate 50 from the transmissive image display unit 20. The reflection unit 70 is for causing the light emitted from the light guide plate 50 to the reflection unit 70 side to enter the light guide plate 50 again. The reflection unit 70 may be a sheet as shown in FIG. Further, the reflection unit 70 may be a bottom surface of the housing of the surface light source device 30 that houses the light guide plate 50 and that is mirror-finished.

  The light guide plate 50 is used for emitting the light emitted from the light source unit 60 to the transmissive image display unit 20 side. Examples of the planar view shape of the light guide plate 50 include a substantially rectangular shape and a substantially square shape.

  The light guide plate 50 is composed mainly of a translucent material (or a transparent material). Examples of the refractive index of the translucent material are 1.46 to 1.62. Examples of the translucent material are a translucent resin material and a translucent glass material. Examples of the translucent resin material include polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin) (refractive index: 1.56-1.59), polystyrene resin (refractive index). Ratio: 1.59), AS resin (acrylonitrile-styrene copolymer resin) (refractive index: 1.56-1.59), acrylic ultraviolet curable resin (refractive index: 1.46-1.58), poly Examples thereof include methyl methacrylate (PMMA) (refractive index: 1.49), cycloolefin resin (refractive index: 1.51-1.55), and the like. As the translucent resin material, PMMA is more preferable from the viewpoint of transparency.

  As shown in FIG. 1, the light guide plate 50 is opposed to the film group 40 and has an emission surface 51 a formed substantially flat, and a back surface (reflection surface) 51 b on which a plurality of ridges 52 described later are formed. And four side surfaces 51c, 51d, 51e, 51f intersecting with the emission surface 51a and the back surface 51b (see FIG. 2). FIG. 1 shows two side surfaces 51c and 51d that face each other in the X-axis direction. The side surfaces 51 c and 51 d face the light source units 60 and 60. In this case, the side surfaces 51c and 51d are incident surfaces on which light from the light source unit 60 is incident.

  Of the four side surfaces 51c, 51d, 51e, and 51f of the light guide plate 50, the remaining two side surfaces 51e and 51f (see FIG. 2) face each other in the Y-axis direction. In FIG. 1, as an example of the arrangement relationship between the side surface 51c and the side surface 51d and the emission surface 51a and the back surface 51b, the side surface 51c and the side surface 51d are substantially orthogonal to the emission surface 51a and the back surface 51b. In the present embodiment, it is assumed that the other side surfaces 51e and 51f of the light guide plate 50 are also orthogonal to the emission surface 51a and the back surface 51b.

  As shown in FIG. 1, the plurality of ridges 52 extend along the Y-axis direction (longitudinal direction) and are arranged in parallel in the X-axis direction. The extending direction of the ridges 52 is also a direction perpendicular to the normal lines of the side surface 51c and the exit surface 51a which are the incident surfaces. The cross-sectional shape orthogonal to the extending direction of the ridges 52 is substantially uniform. The bottom portions 52b, which are the ends of two adjacent ridge portions 52, are at the same position in the X-axis direction. Each ridge 52 is transparent, and is used to emit light propagating through the light guide plate 50 from the emission surface 51a side. The outer shape of each ridge 52 has the shape of a lenticular lens.

The outer shape of each ridge 52 will be described. Ridges 52, if the light reflected by the convex portion 52 is emitted from the emitting surface 51a, that it is outgoing position p peak angle theta _P50 of light emitted (see FIG. 2) is 20 ° or more It has an outer shape that is 67 ° or less. The point p can be, for example, a central point (one point) of the emission surface 51a, that is, the center of the emission surface 51a. The peak angle θ _P50 indicates a direction in which the emission intensity of light incident from the side surface 51c that is the incident surface and emitted from the emission surface 51a is the strongest, and refers to an inclination from the normal line of the emission surface 51a.

  This will be described more specifically with reference to FIG. FIG. 2 is a drawing for explaining the outer shape of the ridge portion 52. FIG. 2A is a diagram showing a local coordinate system setting state on the emission surface 51a. FIG. 2B is a diagram for explaining a method for defining angles from the z axis and the x axis in the coordinate system shown in FIG.

In the xyz coordinate system, the z axis is orthogonal to the exit surface 51a. That is, the z axis corresponds to the normal line of the exit surface 51a. The x axis is substantially parallel to the X axis direction. That is, the x-axis is a direction substantially orthogonal to the side surfaces 51c and 51d that are incident surfaces. In this case, the y axis substantially coincides with the Y axis direction. The x-axis, y-axis, and z-axis correspond to the X-axis direction, the Y-axis direction, and the Z-axis direction as well in FIG. 2B. As shown in FIG. 2B, the angle (declination) formed between the direction of the emitted light from the point p and the z-axis is θ, and the angle (declination) formed between the direction of the emitted light and the x-axis. Is φ. The angle (deflection angle) θ formed with the z-axis indicates the inclination toward the side surface 51d with respect to the z-axis (normal line of the exit surface 51a) as + and the inclination toward the side surface 51c as −. In this setting, the peak angle θ _P50 is an angle θ from the z axis in the xz plane that is a plane orthogonal to the extending direction of the ridges 52. In other words, the peak angle θ _P50 is a direction defined by θ = θ _P50 and φ = 0 °.

  FIG. 3 is a diagram for explaining an example of the outer shape of the ridge portion 52, and is a schematic diagram of a cross-sectional configuration of the light guide plate 50 including the ridge portion 52.

  The top of the ridge 52 is referred to as the tip 52 a of the ridge 52, and the bottom of the ridge 52 is referred to as the bottom 52 b of the ridge 52. In the present embodiment, the outer shape of the ridge portion 52 has an outer shape in which a cross-sectional shape orthogonal to the extending direction is substantially symmetric with respect to the center line C as shown in FIG. Further, the ridge 52 has an outer shape such that the angle formed between the tangential plane contacting the ridge 52 and the back surface 51b monotonously decreases from the bottom 52b side to the tip 52a side of the ridge 52. ing. That is, the surface of the ridge portion 52 can be smooth.

  With reference to FIG. 3, various examples of the outer shape of the ridge portion 52 will be described. Here, the reference plane 51 is defined for convenience of explanation. That is, the reference plane 51 is a plane parallel to a line connecting the bottoms 52b (indicated by a two-dot chain line in FIG. 3) in the cross section of the ridge 52 as shown in FIG. Is defined as a plane that forms In the present embodiment, the exit surface 51a (see FIG. 1) of the light guide plate 50 and the reference surface 51 are parallel to each other.

The outer shape of the ridge 52 where the peak angle θ _P50 (°) satisfies the above range can be a shape defined by any of the combinations in the chart shown in FIG. Hereinafter, the aspect ratio [h _a / w _a ], the radius of curvature [r / w _a ] and the bottom angle γ shown in FIG. 4 will be described.

(I) Aspect ratio [h _a / w _a ]
Aspect ratio _{[h a} / _w a], in FIG. 3, the width of the convex portion 52 _{w a} ([mu] m), the maximum height of the convex portion 52 (the distance between the reference plane 51 and the distal end portion 52a) When h _a (μm), it is the ratio of the maximum height h _a to the width w _a .

(II) Curvature radius relative to width [r / w _a ]
The radius of curvature [r / w _a ] with respect to the width refers to the width w _a when the width of the ridge 52 is w _a (μm) and the radius of curvature of the tip 52a of the ridge 52 is r (μm). It is the ratio of the radius of curvature r. The curvature radius r of the tip 52a represents the degree of bending of the tip 52a as the top of the ridge 52. For example, as shown in FIG. 3, the radius of curvature r of the tip 52a is a radius of a circle assuming a circle (circle indicated by a broken line in FIG. 3) in contact with the tip 52a.

(III) Bottom angle γ
The bottom angle γ is an angle formed between the tangent plane P of the ridge 52 and the reference plane 51 at the intersection of the outline of the ridge 52 and the reference plane 51 in a cross section passing through the center line C. is there. Further, the bottom of the tip 52a is also the bottom of the ridge 52. Thus, the bottom angle γ is also the skirt angle.

Hereinafter, the conditions of the outer shape that the ridges 52 satisfy according to the case classification based on the aspect ratio [h _a / w _a ] shown in the chart of FIG. 4 will be specifically exemplified.

_{(1) 0.05 ≦ h a /} w a <0.07 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
0.1042 ≦ r / w _a ≦ 4.0625 and 7.00 ≦ γ ≦ 75.97

_{(2) 0.07 ≦ h a /} w a <0.09 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
0.0781 ≦ r / w _a ≦ 3.0469 and 9.30 ≦ γ ≦ 79.97

(3) 0.09 external shape of ≦ _h a _/ w a <0.11 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
0.0625 ≦ r / w _a ≦ 2.4375 and 11.57 ≦ γ ≦ 82.23

_{(4) 0.11 ≦ h a /} w a <0.13 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(4A) 0.0521 ≦ r / w _a ≦ 1.5104 and 13.80 ≦ γ ≦ 41.25
(4B) 1.7188 ≦ r / w _a ≦ 2.0313 and 54.09 ≦ γ ≦ 83.66

(5) 0.13 outer shape of ≦ _h a _/ w a <0.15 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(5A) 0.0446 ≦ r / w _a ≦ 1.2054 and 15.99 ≦ γ ≦ 40.84
(5B) 1.4732 ≦ r / w _a ≦ 1.7411 and 58.14 ≦ γ ≦ 84.64

The outer shape of _{(6) 0.15 ≦ h a /} w a <0.17 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(6A) 0.0391 ≦ r / w _a ≦ 0.9766 and 18.14 ≦ γ ≦ 40.55
(6B) 1.2109 ≦ r / w _a ≦ 1.5234 and 55.55 ≦ γ ≦ 85.36

_{(7) 0.17 ≦ h a /} w a <0.19 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(7A) 0.0347 ≦ r / w _a ≦ 0.7986 and 20.23 ≦ γ ≦ 40.32
(7B) 1.0069 ≦ r / w _a ≦ 1.3542 and 52.71 ≦ γ ≦ 85.90

_{(8) 0.19 ≦ h a /} w a <0.21 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(8A) 0.0313 ≦ r / w _a ≦ 0.5938 and 22.27 ≦ γ ≦ 37.34
(8B) 0.8438 ≦ r / w _a ≦ 1.2188 and 50.97 ≦ γ ≦ 86.33

_{(9) 0.21 ≦ h a /} w a <0.23 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(9A) 0.0284 ≦ r / w _a ≦ 0.4830 and 24.25 ≦ γ ≦ 37.46
(9B) 0.7102 ≦ r / w _a ≦ 1.180 and 49.61 ≦ γ ≦ 86.68

_{(10) 0.23 ≦ h a /} w a <0.25 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(10A) 0.0260 ≦ r / w _a ≦ 0.3906 and 26.17 ≦ γ ≦ 37.55
(10B) 0.5990 ≦ r / w _a ≦ 1.0156 and 48.52 ≦ γ ≦ 86.96

The outer shape of the _{(11) 0.25 ≦ h a /} w a <0.27 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(11A) 0.0721 ≦ r / w _a ≦ 0.3125 and 29.36 ≦ γ ≦ 37.63
(11B) 0.5048 ≦ r / w _a ≦ 0.9375 and 47.63 ≦ γ ≦ 87.20

_{(12) 0.27 ≦ h a /} w a <0.29 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(12A) 0.1116 ≦ r / w _a ≦ 0.2455 and 32.63 ≦ γ ≦ 37.70
(12B) 0.4241 ≦ r / w _a ≦ 0.8705 and 46.88 ≦ γ ≦ 87.41

The outer shape of _{(13) 0.29 ≦ h a /} w a <0.31 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
0.3958 ≦ r / w _a ≦ 0.8125 and 48.84 ≦ γ ≦ 87.59

The outer shape of _{(14) 0.31 ≦ h a /} w a <0.33 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(14A) 0.0586 ≦ r / w _a ≦ 0.0977 and 34.69 ≦ γ ≦ 36.20
(14B) 0.2539 ≦ r / w _a ≦ 0.7617 and 43.50 ≦ γ ≦ 87.74

_{(15) 0.33 ≦ h a /} w a <0.35 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
0.2022 ≦ r / w _a ≦ 0.7169 and 43.18 ≦ γ ≦ 87.87

_{(16) 0.35 ≦ h a /} w a <0.37 where the outer shape of the convex portion 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(16A) 0.1563 ≦ r / w _a ≦ 0.2951 and 42.91 ≦ γ ≦ 51.41
(16B) 0.3299 ≦ r / w _a ≦ 0.6771 and 53.92 ≦ γ ≦ 84.99

(17) 0.37 outer shape of ≦ _h a _/ w a <0.39 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(17A) 0.1480 ≦ r / w _a ≦ 0.2138 and 44.46 ≦ γ ≦ 48.41
(17B) 0.3125 ≦ r / w _a ≦ 0.6414 and 55.38 ≦ γ ≦ 88.10

(18) 0.39 outer shape of ≦ _h a _/ w a <0.41 where ridges 52, r / _{w a} and gamma (°) is a satisfying shape follows.
(18A) 0.1094 ≦ r / w _a ≦ 0.1719 and 44.13 ≦ γ ≦ 47.83
(18B) 0.2969 ≦ r / w _a ≦ 0.6094 and 56.74 ≦ γ ≦ 88.20

An example of the width w _a is 10 μm or more and 2 mm or less, preferably 20 μm or more and 1 mm or less, and more preferably 50 μm or more and 600 μm or less.

  The light guide plate 50 having the above-described configuration may be a single-layer plate-like body made of a single translucent material, or a multi-layer plate in which layers made of different translucent materials are laminated. It may be a body.

  Further, when a translucent resin material is used as the translucent material constituting the light guide plate 50, an ultraviolet absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, a lubricant, etc. are added to the translucent resin material. These additives can also be added. These additives can be used alone or in combination of two or more. Note that it is preferable that an ultraviolet absorber is added to the light guide plate 50 because deterioration of the light guide plate 50 due to ultraviolet rays can be prevented when the light output from the light source unit 60 contains a lot of ultraviolet rays.

  Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers, cyanoacrylate UV absorbers, malonic ester UV absorbers, oxalic anilide UV absorbers, and triazine UV absorbers. Preferred are benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers.

  The translucent resin material is usually used without adding a light diffusing agent as an additive, but may be added with a light diffusing agent as long as it is a slight amount that does not depart from the spirit of the present invention.

  As the light diffusing agent, a powder having a refractive index different from that of the above-described translucent material (or transparent material) mainly constituting the light guide plate 50 can be used, and this can be dispersed in the translucent material. Used. Examples of such a light diffusing agent include organic particles such as styrene resin particles, methacrylic resin particles, and silicone resin particles, and inorganic particles such as potassium carbonate particles, silica particles, titanium oxide particles, and calcium carbonate particles. The diameter is usually 0.8 μm or more and 50 μm or less.

  It is also possible to use a powder having the same refractive index as the above-described translucent material (or transparent material) mainly constituting the light guide plate 50. For example, when the light guide plate 50 has a multilayer structure having a surface layer, a matting agent that is particles having the same refractive index as that of the light-transmitting material (transparent material) constituting the surface layer can be added to the surface layer of the light guide plate 50. Due to the presence of the matting agent in a state of protruding from the surface of the surface layer, the surface is matted (roughened) and provided with diffusion performance.

  For example, the surface layer of the light guide plate 50 can be made of PMMA resin with a thickness of 150 μm to 200 μm. Further, for example, 3 to 5% by weight of PMMA resin particles having a particle size of 12 μm can be added to the surface layer as a matting agent. As such a matting agent, for example, organic particles such as styrene resin particles, methacrylic resin particles, and silicone resin particles are used depending on the constituent resin, and the particle diameter is usually 10 μm to 50 μm.

  The emission surface 51a is preferably flat. Further, the emission surface 51a may have a slight surface layer diffusion for reducing moire. For example, by adding the matting agent described above, fine irregularities are formed on the surface of the emission surface 51a, and diffusion performance can be provided.

  The light guide plate 50 provided with the ridges 52 can be manufactured by, for example, a method of scraping a plate material made of a translucent material (or a transparent material). Moreover, when using a transparent resin material as a translucent material, it can manufacture by normal methods, such as an injection molding method, an extrusion molding method, a photopolymer method, a press molding method, for example. Further, when the light guide plate 50 is manufactured using the photopolymer method, an ultraviolet curable resin can be used as the material of the ridge portion 52, and an acrylic ultraviolet curable resin is used as the ultraviolet curable resin. Can do.

(Experimental example)
Next, when the peak angle θ _{P50 of the} light emitted from the light guide plate 50 is set to 20 ° or more and 67 ° or less, the brightness in the front direction can be improved based on the following experimental example. explain. The present invention is not limited to this experimental example. First, the light path after the light emitted from the light source unit 60 enters the light guide plate 50 will be described. FIG. 5 is a partially enlarged view of the transmissive image display apparatus 10 shown in FIG. In FIG. 5, the side surface 51c side is shown enlarged in FIG.

When the point light source 61 included in the light source unit 60 emits light, the light from the point light source 61 enters the light guide plate 50 from the side surface 51 c of the light guide plate 50 facing the point light source 61. The light incident on the light guide plate 50 propagates while being totally reflected in the light guide plate 50. When light propagating in the light guide plate 50 enters the ridge 52, the light is reflected in the ridge 52 under conditions other than the total reflection condition. Therefore, the light reflected by the convex portion within 52 is emitted at an angle theta _o from the exit surface 51a.

The light emitted from the emission surface 51 a is incident at an angle θ ₁ on the microlens film 41 arranged closest to the light guide plate 50 among the members constituting the film group 40. At this time, the exit angle θ _o from the exit surface 51 a of the light guide plate 50 and the incident angle θ ₁ to the microlens film 41 are equal to each other. The light incident on the microlens film 41 is transmitted through the prism film 43 and is incident on the diffusion film 45 disposed closest to the transmission type image display unit 20. Light incident on the diffusion film 45 is emitted at an angle theta ₂ from the diffusion film 45. It can be said that the light is emitted more in the front direction as the light emission angle θ ₂ is closer to 0 °.

Therefore, the microlens film 41, the film unit 40 consisting of a prism film 43 and the diffusion film 45, by the incidence of light from various angles theta _1, the amount of light emitted from the film group 40 and exit angle theta ₂ was measured. A goniophotometer (Nippon Denshoku Industries Co., Ltd .: model number GC-5000L) was used for the measurement. The films used as the microlens film 41, the prism film 43, and the diffusion film 45 are as follows.

(Microlens film 41)
UTE-22 manufactured by MNTtech was used.
(Prism film 43)
A film mounted on LG Electronics TV (42LE5500) having a prism portion apex angle of about 90 °, a base material of PMMA, and a prism portion pitch of about 60 μm was used.
(Diffusion film 45)
It is mounted on a TV (42Z2) manufactured by Toshiba Corporation, and uses a film having a total light transmittance Tt of 65.8%, a diffuse transmittance Td of 61.8%, and a haze haze of 93.9%. did.

Of the measurement results, FIG. 6 shows the distribution of the emission angles of light incident on the film group 40 at a representative angle θ ₁ (every 10 °). The horizontal axis in FIG. 6 indicates the emission angle θ ₂ (°), and the vertical axis indicates the amount of emitted light (cd).

When the peak angle θ _{P40 of} light emitted from the film group 40 is 0 °, the luminance in the front direction becomes the highest, and the luminance in the front direction can be increased as the peak angle θ _P40 is closer to 0 °. For example, as shown in FIG. 6, if the peak angle θ _P40 is in the range of 10 ° or less, the luminance in the front direction can be improved, and if the peak angle θ _P40 is 5 ° or less, the front direction is further increased. The luminance can be improved, and if the peak angle θ _P40 is in the range of 3 ° or less, the luminance in the front direction can be further improved. If the peak angle θ _P40 is in the range of 1 ° or less, the front direction is the most. The luminance can be improved.

In addition, the luminance can be increased as the amount of light emitted from the film group 40 in the direction of the peak angle θ _P40 increases. Even if the peak angle θ _{P40 of the} light emitted from the film group 40 is directed in the direction close to the front direction, if the amount of light emitted from the direction close to the front direction is not sufficient, the front luminance is improved. This is because it cannot be planned.

Thus, the angle θ ₁ to be incident on the film group, which is determined based on the viewpoint of the peak angle θ _P40 of the light emitted from the film group 40 and the light quantity of the light emitted from the film group 40, that is, The angle θ ₀ of the light to be emitted from the light guide plate 50 is as shown in Table 4 below.

As described above, the light is incident on the film group 40 at an angle θ ₁ of 20 ° to 67 °, that is, the light is emitted from the light guide plate 50 at an angle θ ₀ of 20 ° to 67 °. It can be seen that the peak angle θ _{P40 of the} light becomes 10 ° or less, the luminance in the front direction is improved, and a sufficient amount of emitted light can be secured. Therefore, the brightness in the front direction can be improved by forming the convex strip 52 having an outer shape such that the peak angle θ _{P50 of the} light emitted from the light guide plate 50 is 20 ° to 67 °.

Further, the light is incident on the film group 40 at an angle θ ₁ of 23 ° to 43 °, that is, the light is emitted from the light guide plate 50 at an angle θ ₀ of 23 ° to 43 °. It can be seen that the peak angle θ _{P40 of the} light is 5 ° or less, the luminance in the front direction is further improved, and a sufficient amount of emitted light can be secured. Therefore, the brightness in the front direction can be further improved by using the convex ridge portion 52 having an outer shape such that the peak angle θ _{P50 of the} light emitted from the light guide plate 50 is 23 ° to 43 °.

Further, the light is incident on the film group 40 at an angle θ ₁ of 28 ° to 38 °, that is, the light is emitted from the light guide plate 50 at an angle θ ₀ of 28 ° to 38 °. It can be seen that the peak angle θ _{P40 of the} light is 3 ° or less, the brightness in the front direction is further improved, and a sufficient amount of emitted light can be secured. Therefore, the brightness in the front direction can be further improved by using the convex ridge portion 52 having an outer shape such that the peak angle _{θP50 of the} light emitted from the light guide plate 50 is 28 ° to 38 °.

Further, by making light incident on the film group 40 at an angle θ ₁ of 28 ° to 33 °, that is, by emitting light from the light guide plate 50 at an angle θ ₀ of 28 ° to 33 °, the light is emitted from the film group 40. It can be seen that the peak angle θ _{P40 of the} light is 1 ° or less, the brightness in the front direction is most improved, and a sufficient amount of emitted light can be secured. Therefore, the brightness in the front direction can be improved most if the convex strip 52 having an outer shape such that the peak angle θ _{P50 of the} light emitted from the light guide plate 50 is 28 ° to 33 °.

In the above experimental example, it is assumed that light is incident from one side surface. However, even when light is incident from both side surfaces facing each other, the result of the derived peak angle θ _P50 is obtained. Is the same. The amount of emitted light is a result of superimposing the light of each other, and the amount of emitted light in the front direction is further increased.

Next, the operation and effect of the light guide plate unit 55 will be described by taking as an example the case where it is applied to the transmissive image display device 10 as a part of the surface light source device 30 as shown in FIG. Light incident from the side surface 51 c of the light guide plate 50 propagates while totally reflecting inside the light guide plate 50. When the light propagating in the light guide plate 50 is incident on the ridges 52 provided on the back surface 51b, the light is reflected by the ridges 52 under conditions different from the total reflection conditions. Therefore, the light reflected by the ridge portion 52 is emitted from the emission surface 51a opposite to the back surface 51b, and is transmitted through the film group 40 and emitted. In the light guide plate unit 55, the light guide plate 50 has the convex streak portion 52 such that the peak angle θ _{P50 of the} light emitted from the light guide plate 50 is 20 ° or more and 67 ° or less. The ratio of the emitted light to the front direction of the film group 40 is high. With these actions, the luminance in the front direction is improved in the light guide plate unit 55 configured as described above. In the transmissive image display device 10 according to the present embodiment, since the transmissive image display unit 20 is provided on the light guide plate unit 55, the transmissive image display unit 20 can emit light with higher luminance in the front direction. Is illuminated. As a result, the brightness of the image displayed on the transmissive image display unit 20 can be improved.

(Simulation example)
Next, each of the plurality of ridge portions 52 has an outer shape such that the peak angle θ _{P50 of} light incident from the side surface 51c and emitted from the emission surface 51a of the light guide plate 50 is 20 ° or more and 67 ° or less. In other words, when the outer shape of the ridge portion 52 satisfies the condition shown in FIG. 4, the light output in the front direction of the film group 40 in the light guide plate unit 55 is increased based on the simulation results. I will explain. However, the present invention is not limited to these simulations.

FIG. 7 is a schematic diagram showing a simulation model. For convenience of explanation, the components corresponding to the components shown in FIG. 1, described are denoted by the M as a light guide plate 50 _M. In the simulation, as shown in FIG. 7, the point light sources 61 _M and 61 _M are arranged at positions facing the two side surfaces 51 _M c and 51 _M d which are short sides of the light guide plate 50 _M , respectively, and the light guide plate In a model in which a reflection sheet as a reflection portion 70 _M is arranged below 50 _M , the ray tracing method is used. The point light sources 61 _M, in the short-side direction of the light guide plate 50 _M, is located at the center portion of the side surface 51 _M c.

The simulation conditions are as follows.
· The light guide plate 50 _M of the material: PMMA (refractive index: 1.49) assumptions, the light guide plate 50 _M of the plan view shape (shape viewed from a thickness direction): the length of the longer sides of the rectangular-light guide plate 50 _M W1: 540mm
· Light guide plate 50 _M , short side length W2: 20 mm
-Light guide plate 50 _M thickness t: 4 mm
The distance between-the ridge 52 _M of the light guide plate 50 _M and tip 52 _M a and the reflecting portion 70 _M: 0.1 mm
Reflector 70 _M : Assuming a mirror (100% reflectance) Point light source 61 _M : Point light source, assuming isotropic emission Wavelength of light emitted from point light source 61 _M : Assuming 550 nm _-Distance between point light source 61 _M and light guide plate 50 _M : 0.1 mm
Incidentally, assuming a side 51 _M e and side 51 _M f in the periodic boundary conditions of the light guide plate 50 _M. That was a return to all light in the side surface 51 _M e and 51 _M f is reflected guided plate 50 _M. Thus, by providing periodic boundary conditions in the short-side direction of the light guide plate 50 _M (Y axis direction), the length of the short side direction is the simulation that assumes a substantially infinite light guide plate It will be. The thickness t of the light guide plate 50 _M shall not include the thickness of the convex portion 52 _M.

In the simulation, the cross-sectional configuration of the convex portion 52 _M including the center line C of the ridges 52 _M as shown in FIG. 3, showing the contour of the convex portion 52 _M in conic. Specifically, as shown in FIG. 8, it sets the uv coordinate system, the cross-sectional shape of the convex portion 52 _M defined by a conic v (u) represented by the formula (1). v axis of the uv coordinate system corresponds to the center line C of the ridges 52 _M in FIG. Further, the u-axis corresponds to the X-axis direction shown in FIG.

In the formula (1), k _a is a parameter indicating the pointed how conic represented by the formula (1) represents the pointed how tip 52 M _a ridge portions 52 _M (hereinafter, also referred to as a kurtosis _{k a).} For example, when kurtosis _{k a} is 0, the outer shape of the convex portion 52 _M becomes parabolic, when kurtosis _{k a} is 1, the outer shape of the convex portion 52 _M becomes prism shape, kurtosis _{k a} -1 when, the outer shape of the convex portion 52 _M has a shape cut in half an ellipse.

In the simulation model, with a plurality of ridges 52 _M in 100% coverage on the back 51 _M b side of the light guide plate 50 _M. That is, as shown in FIG. 7, the back surface 51 M _b side of the light guide plate 50 _M, ridges 52 _M which are adjacent to each other in the long side direction (X axis direction) are arranged without a gap, adjacent convex position of an end of the ridges 52 _M bottom 52 M _b coincide with each other. The maximum width of the convex portion 52 _M is 500 [mu] m.

In the simulation, first, it sets the convex portion 52 _M having an outer shape defined by Equation (1). Then, the light guide plate 50 _M having a convex portion 52 _M set, from the point light sources 61 _M assuming that light is incident, the emitting surface 51 M _a of the light guide plate 50 _M central portion of the light A point p as an emission position was assumed.

Then, when the convex stripes are formed on the light guide plate 50 _M portions 52 _M of kurtosis _{k a} and the aspect ratio _{h a} / _w a changed respectively, peak angle of light emitted from the light guide plate 50 _M theta _P50 A simulation was carried out. The simulation results are as shown in the charts shown in FIGS. 9 and 10 are graphs showing the relationship between the outer shape of the ridge defined by the kurtosis k _a and the aspect ratio [h _a / w _a ] in Equation (1) and the peak angle of the emitted light. is there. 9 kurtosis _{k a} indicates the range of 0.1 or more and 0.9 or less. Figure 10 is a kurtosis _{k a} indicates a and 0 below the range of -0.9. Cells colored is performed 9 and 10, the peak angle theta _P of light emitted from the light guide plate 50 _M indicates that it is 20 ° or more 67 ° or less. In other words, the coloring is decorated with corresponding cell kurtosis k _a and aspect ratio [h a _{/ w a]} a de defined by the shape of the light emitted from the light guide plate 50 _M having a convex portion 52 _M of Since the peak angle θ _P50 is 20 ° or more and 67 ° or more, the peak angle θ _{P40 of the} light emitted from the film group 40 is 5 ° or less, and the luminance in the front direction is improved and a sufficient amount of emitted light can be secured. Is shown.

Further, in the diagram shown in FIGS. 9 and 10, in addition to the coloring of the cell, according to the value of the peak angle theta _P40 of light emitted from the film group 40 _M, as indicated below, not underlined, wavy Underline, double underline, and bold underline are displayed.
The peak angle θ of the light emitted from the film group 40 _{M The} angle θ of the light emitted from the light guide plate 50 _M corresponding to the shape of the ridge 52 _M where the value of _P40 is greater than 5 ° and 10 ° or less. Only the coloring is given to the cell in which ₀ is described.
The peak angle θ of the light emitted from the film group 40 _{M The} angle θ of the light emitted from the light guide plate 50 _M corresponding to the shape of the ridge 52 _M in which the value of _P40 is greater than 3 ° and 5 ° or less A cell in which ₀ is written is underlined with a wavy line in addition to coloring.
The peak angle θ of the light emitted from the film group 40 _{M The} angle θ of the light emitted from the light guide plate 50 _M corresponding to the shape of the ridge 52 _M where the value of _P40 is greater than 1 ° and 3 ° or less. A cell in which ₀ is written is underlined in addition to coloring.
The angle θ _{0 of the} light emitted from the light guide plate 50 _M corresponding to the shape of the convex portion 52 _M where the value of the peak angle θ _P40 of the light emitted from the film group 40 _M is 1 ° or less is described. The cells are hatched in addition to coloring.

  In addition, “cells with wavy lines in addition to coloring” than “cells with coloring alone”, “cells with underlining in addition to coloring”, “cells with underlining in addition to coloring”, “ It is shown that the convex part of the shape determined by the sharpness and aspect ratio of the `` cell that is hatched in addition to coloring '' can improve the brightness in the front direction more than the `` cell that is underlined in addition to coloring ''. ing.

11 and 12 are tables showing the bottom angle γ (°) of the outer shape of the ridge determined by the sharpness k _a and the aspect ratio [h _a / w _a ] shown in FIGS. 9 and 10. . 13 and 14 show the curvature radius [r of the tip portion with respect to the width w _a of the outer shape of the ridge portion determined by the sharpness k _a and the aspect ratio [h _a / w _a ] shown in FIGS. / W _a ]. Also in FIGS. 11 to 14, the same processing (coloring, no coloring and no underlining, coloring and wavy underlining, coloring and underlining, coloring and hatching) is applied to the cells corresponding to FIGS. 9 and 10.

In FIG. 11 to FIG. 14, a colored cell is considered. The aspect ratio of the convex portion 52 _M corresponding to these cells [h _{a /} w _a], the curvature radius [r / w _a] and bottom angle γ with respect to the width, in the range of chart shown in FIG. Thus, the aspect ratio shown in FIG. _{4 [h a / w a]} , and the curvature radius [r / _{w a]} and the light guide plate 50 having a ridge 52 _M defined by the combination of the bottom angle gamma _M with respect to the width film in the group 40 light guide plate unit and a _M 55 _M, often the proportion of light emitted in the front direction of the film group 40 _M. Therefore, by adopting the light guide plate unit 55 in the present embodiment, it is possible to illuminate the transmissive image display unit 20 with higher luminance in the transmissive image display device 10. As a result, the brightness of the image displayed on the transmissive image display unit 20 can be improved.

Next, in FIG. 11 to FIG. 14, a cell with coloring and underlined wavy lines will be considered. Aspect ratio corresponding to the colored and wavy underlined cells [h a _{/ w a],} electrical with ridges 52 _M defined by a combination of the curvature radius [r / w _a] and bottom angle γ with respect to the width in the optical plate light guide plate unit including 50 _M 55 _M, the value of the peak angle theta _P40 of light emitted from the film group 40 _M is 3 greater becomes 5 ° or less than °, the peak of the light emitted from the film group 40 _M When the value of the angle theta _P40 is compared with greater than 10 ° and makes the light guide plate unit 55 _M than 5 °, the ratio of the light emitted in the front direction of the film group 40 _M is greater. Therefore, the combination of color and aspect ratio wavy underline corresponding cell represented by [h a _{/ w a],} the radius of curvature to the width [r / w _a] and bottom angle γ is emitted from the film group 40 _M It can be said that this is preferable to the combination shown in FIG. 4 in which the value of the peak angle _θP40 of the light is greater than 5 ° and equal to or less than 10 °. When the combination of the aspect ratio [h _a / w _a ], the curvature radius [r / w _a ] with respect to the width, and the bottom angle γ of the ridges 52 _M corresponding to these cells is calculated, the range of the chart shown in FIG. Inside.

Next, the cells colored and underlined in FIGS. 11 to 14 will be considered. Light guide plate having ridges 52 _M defined by a combination of aspect ratio [h _a / w _a ], radius of curvature [r / w _a ], and bottom angle γ corresponding to the colored and underlined cells In the light guide plate unit 55 _M including 50 _M , the value of the peak angle θ _P40 of the light emitted from the film group 40 _M is greater than 1 ° and 3 ° or less, and the peak angle of the light emitted from the film group 40 _M compared with θ value of _P40 is greater than 3 ° 5 ° or less and comprising the light guide plate unit 55 _M, the proportion of light emitted in the front direction of the film group 40 _M is greater. Therefore, the combination of the color and the aspect ratio underlined corresponding cell represented by [h a _{/ w a],} the radius of curvature to the width [r / w _a] and bottom angle γ is emitted from the film group 40 _M It can be said that it is preferable to the combination shown in FIG. 15 in which the value of the peak angle θ _P40 of light is larger than 3 ° and not larger than 5 °. When the combination of the aspect ratio [h _a / w _a ], the curvature radius [r / w _a ] with respect to the width, and the bottom angle γ of the ridges 52 _M corresponding to these cells is calculated, the range of the chart shown in FIG. Inside.

Next, in FIG. 11 to FIG. 14, a cell colored and hatched will be considered. Light guide plate having ridges 52 _M defined by a combination of aspect ratio [h _a / w _a ], curvature radius [r / w _a ] with respect to width, and bottom angle γ corresponding to cells with coloring and hatching In the light guide plate unit 55 _M including 50 _M , the value of the peak angle θ _P40 of light emitted from the film group 40 _M is 1 ° or less, and the value of the peak angle θ _P40 of light emitted from the film group 40 _M is compared to 3 ° or less and comprising the light guide plate unit 55 _M greater than 1 °, the proportion of light emitted in the front direction of the film group 40 _M is greater. Therefore, the combination of the color and the aspect ratio underlined corresponding cell represented by [h a _{/ w a],} the radius of curvature to the width [r / w _a] and bottom angle γ is emitted from the film group 40 _M It can be said that this is preferable to the combination shown in FIG. 16 in which the value of the light peak angle θ _P40 is greater than 1 ° and 3 ° or less. When the combination of the aspect ratio [h _a / w _a ], the curvature radius [r / w _a ] with respect to the width, and the bottom angle γ of the ridges 52 _M corresponding to these cells is calculated, the range of the chart shown in FIG. Inside.

  In addition, the light guide plate unit 55 including the light guide plate 50 having the protrusion 52 defined by the combination shown in FIG. 4 has the protrusion defined by the combination shown in FIGS. 15, 16, and 17. A light guide plate unit including the light guide plate may be included. In addition, the light guide plate unit including the light guide plate having the convex portion defined by the combination shown in FIG. 15 includes the light guide plate including the light guide plate having the convex portion defined by the combination shown in FIGS. A light plate unit may be included. In addition, the light guide plate unit including the light guide plate having the ridge portion defined by the combination illustrated in FIG. 16 includes the light guide plate unit including the light guide plate having the ridge portion defined by the combination illustrated in FIG. May be included.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the invention.

Further, as illustrated in FIG. 3, the shape of the ridge portion 52 is such that the angle formed between the tangent plane of the ridge portion 52 and the back surface 51 b monotonously decreases from the bottom side to the tip side of the ridge portion 52. It preferably has a shape. However, the ridge 52 has a shape defined by the combination indicated by h _a / w _a , r / w and γ shown in FIG. 4 and the like, so that the peak angle θ of the light emitted from the light guide plate 50 is increased. _{As long as P50} has a shape that is 20 ° or more and 67 ° or less, it may not monotonously decrease toward the tip portion 52a side of the angle formed between the tangential plane of the ridge portion 52 and the back surface 51b. .

  Moreover, about the arrangement | sequence of the protruding item | line part 52, as shown in FIG. 1 etc., the protruding item | line parts 52 adjacent to a long side direction are arrange | positioned without gap, and the bottom part 52b which is an end of the adjacent protruding item | line part 52 is shown. However, the present invention is not limited to this example. For example, the ridges 52 adjacent to each other in the long side direction may be arranged away from each other, and the distance (pitch) between the ridges 52 adjacent to each other in the long side direction changes in the long side direction. It may be arranged to do.

  Moreover, although the said embodiment demonstrated the light-guide plate 50 integrally formed including the protruding item | line part 52, the light-guide plate of this invention is not limited to this. For example, by using a photopolymer method, the ridge 52 that is a portion above the reference surface 51 may be formed on the main body that is a portion below the reference surface 51 shown in FIG.

Further, the arrangement position of the light source unit 60, the two sides _51c (51 M c) of the short side as shown in the above embodiments and simulation examples, 51d ₍₅₁ M d) to be limited to a position facing each is not. For example, the light source unit 60 may be disposed in a position facing the one side 51c of the short sides ₍₅₁ M c). In this case, a reflective tape such as a mirror tape or a white diffusion tape for preventing light leakage may be attached to the other side surface facing the side surface on which light is incident.

Further, the light source unit 60 is a side 51c of the short _{side, 51d (51 M c, 51} M d) as well, the side surface 51e of the long side, respectively a position facing _{51f (51 M e, 51 M} f) May be arranged. Moreover, the light source part 60 can also be arrange | positioned in the position which each of three or more side surfaces in a light-guide plate opposes.

  Furthermore, although the film group 40 of the said embodiment gave and demonstrated the example arrange | positioned in order of the micro lens film 41, the prism film 43, and the diffusion film 45 from the light-guide plate 50 side, this invention is limited to this. Is not to be done. For example, from the light guide plate 50 side, the order of the diffusion film 45, the prism film 43, and the microlens film 41, or the order of the prism film 43, the microlens film 41, and the diffusion film 45, or the prism film 43, the diffusion film 45, and the micro The lens films 41 may be arranged in the order. Moreover, the structure by which at least one kind of film of the microlens film 41, the prism film 43, and the diffusion film 45 is arrange | positioned in multiple numbers may be sufficient. In addition to the above three films, other films may be arranged.

In the above embodiment, an example of the light guide plate 50 mounted on the transmissive image display device 10 has been described, but the present invention is not limited to this. For example, the present invention can be applied as a single light guide plate 50 used in combination with the film group 40 used in the above embodiment. In such a light guide plate, each of the plurality of ridges is within the range of each combination shown in Table 5 below, that is, when the value of the “aspect ratio” in the left column is “ It can be the value of “curvature radius relative to width” and the value of “bottom angle” in the right column. For example, when the “aspect ratio” is 0.23 or more and less than 0.25, the “curvature radius with respect to the width” is 0.0260 or more and 0.1823 or less, and the “bottom angle” is 26.17 ° or more and 30.21 ° or less. It can be. The definitions of the width w _a , the height h _a , the aspect ratio (h _a / w _a ), the radius of curvature (r / w _a ) with respect to the width, and the bottom angle γ are as described above.

In such a light guide plate 50, the shape of the ridges is within the range of any combination of the aspect ratio, the radius of curvature with respect to the width, and the bottom angle shown in Table 6 below, thereby further increasing the luminance in the front direction. Can be improved.

In such a light guide plate 50, the shape of the ridges is within the range of any combination of the aspect ratio, the radius of curvature with respect to the width, and the bottom angle shown in Table 7 below, thereby further increasing the luminance in the front direction. Can be improved.

  In the above embodiment, the light guide plate 50 has been described with reference to an example in which the side surface (incident surface) 30c and the side surface 30d, and the side surface 30e and the side surface 30f are orthogonal to the emission surface 51a, as shown in FIG. It is not limited to this, The light-guide plate which mutually cross | intersects may be sufficient.

  DESCRIPTION OF SYMBOLS 10 ... Transmission type image display apparatus, 20 ... Transmission type image display part, 21 ... Liquid crystal cell, 22, 23 ... Polarizing plate, 30 ... Surface light source device, 40 ... Film group, 41 ... Micro lens film, 41b ... Micro lens, 43 ... Prism film, 43b ... Prism part, 45 ... Diffusing film, 50 ... Light guide plate, 51 ... Reference plane, 51a ... Emission surface, 51b ... Back surface (reflection surface), 51c ... Side surface (incident surface), 51d, 51e, 51f ... side face, 52 ... ridge, 52a ... tip, 52b ... bottom, 55 ... light guide plate unit, 60 ... light source, 61 ... point light source, 70 ... reflector.

Claims (13)

An incident surface on which light is incident, a surface intersecting with the incident surface, a reflecting surface provided with a convex portion for reflecting the light, and a surface opposite to the reflecting surface, and emitting the light A light guide plate extending in the longitudinal direction of the incident surface and arranged in a direction orthogonal to the extending direction;
A film group including a microlens film, a prism film, and a diffusion film, disposed on the light exit surface side of the light guide plate;
With
Each of the plurality of ridge portions has a peak angle of 20 ° or more and 67 ° or less that is the angle with the highest emission intensity in the angular distribution of light that is incident from the incident surface and emitted from the output surface of the light guide plate. Has an external shape,
Light guide plate unit. The peak angle is 23 ° or greater and 43 ° or less.
The light guide plate unit according to claim 1. The peak angle is not less than 28 ° and not more than 38 °.
The light guide plate unit according to claim 2. The peak angle is not less than 28 ° and not more than 33 °.
The light guide plate unit according to claim 3. The film group is arranged in the order of the microlens film, the prism film, and the diffusion film from the emission surface side of the light guide plate.
The light-guide plate unit as described in any one of Claims 1-4. The ridge is a lenticular lens,
The light-guide plate unit as described in any one of Claims 1-5. The light guide plate unit according to any one of claims 1 to 6,
A light source unit provided facing the incident surface of the light guide plate in the light guide plate unit;
A surface light source device. The light guide plate unit according to any one of claims 1 to 7,
A light source unit provided facing the incident surface of the light guide plate in the light guide plate unit;
A transmissive image display unit that is provided on the light exit side of the film group in the light guide plate unit, and that is illuminated by light emitted from the film group and displays an image;
A transmissive image display device. A light guide plate disposed facing the light incident side of a film group including a microlens film, a prism film, and a diffusion film,
An incident surface on which light is incident, a surface intersecting with the incident surface, a reflective surface provided with a ridge that reflects the light, a surface opposite to the reflective surface, and the film group An emission surface for emitting the light toward the
The ridges extend in the longitudinal direction of the incident surface and are arranged in a direction perpendicular to the extending direction,
Each of the plurality of ridges has an outer shape such that a peak angle, which is an angle having the highest emission intensity in an angular distribution of light incident from the incident surface and emitted from the output surface, is 20 ° to 67 °. have,
Light guide plate. Each of the plurality of ridges is
The width that is the length of the ridge in the direction orthogonal to the incident surface is w _a , the height that is the maximum length of the ridge in the direction orthogonal to the exit surface is h _a , and the ridge. Where r is the radius of curvature at the tip of
The ratio of the height _{h a} to width _{w a (h a} / _{w a),} the ratio of the radius of curvature r with respect to the width _{w a} and (r / _{w a),} the extending direction of the convex portion The bottom angle γ, which is the angle formed by the contour line forming the orthogonal cross section and the reflection surface, is within the range of each combination shown in Table 1 below.
The light guide plate according to claim 9.
The ratio of the maximum height _{h a} to width _{w a (h a / w a} ), the ratio of the radius of curvature r with respect to the width _{w a (r / w a)} , and said bottom angle γ is, the following Within the range of each combination shown in Table 2,
The light guide plate according to claim 10.
The ratio of the maximum height _{h a} to width _{w a (h a / w a} ), the ratio of the radius of curvature r with respect to the width _{w a (r / w a)} , and said bottom angle γ is, the following It is within the range of each combination shown in Table 3.
The light guide plate according to claim 11.
The ridge is a lenticular lens,
The light guide plate according to any one of claims 9 to 12.