JP2011150019A - Light control panel unit, surface light source device, and transmission type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light control panel unit capable of sufficiently and uniformly dispersing light emitted from a point light source, and to provide a surface light source device and a transmission type image display device. <P>SOLUTION: The light control panel unit includes first to fourth light control panels provided in a panel thickness direction. Each of the light control panels includes a plurality of projections extending in one direction on the upper surface thereof, wherein the extending directions of the projections parallel to one another are nearly perpendicular to the extending directions of the projections parallel to one another, and the cross sectional shape of the projection is triangular, and in a u-v coordinate system wherein an axial line passing through both ends of the cross section perpendicular to the extending direction of the projection is denoted as a u-axis, contour shape v(u) of each of the projections satisfies the following expression: 0.95v<SB>o</SB>(u)≤v(u)≤1.05v<SB>o</SB>(u), wherein v<SB>o</SB>(u) satisfies an expression (1). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  As a direct type image display device 40 which is an example of a transmissive image display device, for example, as shown in FIG. 11, a device in which a light source 43 is arranged on the back side of the transmissive image display unit 10 is widely used. Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11. As the light source 43, a plurality of linear light sources such as a straight tube type cold cathode ray tube are arranged in parallel with each other.

  It is desirable that the direct image display device 40 can uniformly illuminate the transmissive image display unit 10 by uniformly dispersing light from the light source 43, and for this reason, between the light source 43 and the transmissive image display unit 10. A light control plate 42 such as a single light diffusing plate having a function of changing the direction of light incident from the light source 43 side and emitting it from the opposite transmissive image display unit 10 side is used. (For example, see Patent Document 1: Japanese Patent Laid-Open No. 7-198913). Since the light output from the light source 43 is emitted as planar light by the light control plate 42, the light source 43 and the light control plate 42 constitute a surface light source device 41.

JP-A-7-198913

  In recent years, it has been studied to use a light emitting diode as a light source from the viewpoint of energy saving instead of a straight tube type cold cathode ray tube. The light emitting diode is usually a point light source, and is used by arranging it in a discrete manner.

  However, when the conventional light control plate is used in a direct type image display device in combination with a point light source such as a light emitting diode, the light from the point light source cannot be made sufficiently uniform, and the transmission type The image displayed by the image display unit has a problem that the brightness differs between the vicinity of the point light source and the position away from the point light source.

  Therefore, an object of the present invention is to provide a light control plate unit, a surface light source device, and a transmissive image display device that can sufficiently uniformly disperse light from a point light source.

ただし、式（１）において、

（式（２）において、ｈ_ａは、０．２０ｗ_ａ以上１．１０ｗ_ａ以下を満たす定数であり、ｋ_ａは−１．００以上且つ０．７５以下を満たす定数である） The light control plate unit according to the present invention can emit light incident from the first surface from the second surface located on the opposite side of the first surface, and extends in one direction. A plurality of convex portions arranged in parallel in a direction substantially orthogonal to the one direction are provided with first to fourth light control plates formed on the second surface. (A) The first light control plate, the second light control plate, the third light control plate, and the fourth light control plate have the second light control plate on the upper side of the first light control plate. And the fourth light control plate is provided in the thickness direction so that the fourth light control plate is positioned above the third light control plate. (B) The first surface of the second light control plate is The first light control plate is located on the second surface side, and (C) the extending direction of the convex portion of the second light control plate and the extending direction of the convex portion of the first light control plate are Are substantially parallel, (D) the first surface of the fourth light control plate is located on the second surface side of the third light control plate, and (E) the convexity of the fourth light control plate The extending direction of the convex portion and the extending direction of the convex portion of the third light control plate are substantially parallel, and (F) the extension of each of the convex portions of the first and second light control plates. Direction of extension and the extension of each of the convex portions of the third and fourth light control plates It is substantially perpendicular to the. Moreover, the cross-sectional shape orthogonal to the extending direction of each of the convex portions of the second and fourth light control plates is a triangle, and each of the convex portions of the first and third light control plates extends. In the cross section perpendicular to the direction, the axis passing through both ends is the u axis, the axis passing through the center between both ends on the u axis is the v axis, and the convex portions of the first and third light control plates When the length in the u-axis direction is w _a , the contour shape of each convex portion of the first and third light control plates in the cross section is −0.475 w _a ≦ u ≦ represented by v (u) satisfying the following formula (1) in 0.475w _a.

However, in Formula (1),

(In the formula (2), _{h a} is a constant satisfying the following 0.20 W _a more 1.10w _{a, k a} is a constant satisfying -1.00 or more and 0.75 or less)

  In this configuration, light that has passed through the first light control plate is incident on the second light control plate, and light that has passed through the third light control plate passes through the fourth light control plate. . Since the convex portions of the first and second light control plates have the above-described cross-sectional shape, the first and second light control plates are convex on the point light source. In the case where the extending directions of the shape portions are arranged substantially in parallel, the light from the point light source can be converted into linear light with uniform luminance. Similarly, since the convex portions of the third and fourth light control plates have the above-described cross-sectional shape, the third and fourth light control plates are arranged on the point light source. When the extending direction of the convex portions of the fourth light control plate is arranged substantially in parallel, the light from the point light source can be converted into linear light with uniform luminance. In the light control plate unit according to the present invention, the extending direction of the convex portions of the first and second light control plates and the extending direction of the convex portions of the third and fourth light control plates are as follows. A set of first and second light control plates and a set of third and fourth light control plates are arranged so as to be substantially orthogonal. Therefore, the light of the point light source incident from the first surface side of the first light control plate is a set of the first and second light control plates, and a set of the third and fourth light control plates. Thus, the light is converted into linear light with uniform luminance in directions substantially orthogonal to each other. As a result, the light control plate unit disperses the light from the point light source uniformly and emits it as planar light that is planar light and has high luminance uniformity on the surface orthogonal to the plate thickness direction. It is possible.

  In the light control plate unit according to the present invention, the cross-sectional shape orthogonal to the extending direction of each of the convex portions of the second and fourth light control plates is an isosceles triangle whose apex angle is substantially a right angle. Is preferred. Accordingly, the first and second light control plates are arranged on the point light source as described above by arranging the first and second light control plate sets and the third and fourth light control plate sets as described above. In each of the set of plates and the set of third and fourth light control plates, the light from the point light source can be reliably converted into linear light with uniform luminance.

  In the light control plate unit according to the present invention, the first surface of each of the first to fourth light control plates may be substantially flat.

The surface light source device according to the present invention includes the light control plate unit according to the present invention and a plurality of point light sources that supply light to the light control plate unit.

  In this surface light source device, light output from a plurality of point light sources is emitted through the light control plate unit according to the present invention. Therefore, the surface light source device can uniformly emit light from a plurality of point light sources and emit the light as planar light.

  A transmissive image display device according to the present invention is irradiated with light control plate unit according to the present invention, a plurality of point light sources that supply light to the light control plate unit, and light emitted from the light control plate unit. And a transmissive image display unit for displaying an image.

  In this transmissive image display device, the transmissive image display unit is illuminated with light output from a plurality of point light sources and emitted through the light control plate unit according to the present invention. As a result, it is possible to illuminate the transmissive image display unit with planar light in which light from a point light source is more uniformly dispersed, so that a higher quality image can be displayed.

  According to the present invention, it is possible to provide a light control plate unit capable of sufficiently uniformly dispersing light from a point light source, a surface light source device including the light control plate unit, and a transmissive image display device. it can.

It is sectional drawing which shows typically the structure of the transmissive image display apparatus which concerns on this invention. It is drawing which shows an example of arrangement | positioning of a point light source. It is drawing which shows the other example of arrangement | positioning of a point light source. It is drawing which shows an example of the light distribution of the point light source used for the transmissive | pervious image display shown in FIG. It is a perspective view which shows one Embodiment of the light control board unit which concerns on this invention. It is drawing which shows the example of the cross-sectional shape of the convex part which the 1st and 3rd light control board of the light control board unit shown in FIG. 5 has. It is drawing which shows the conditions which the cross-sectional shape of the convex part which the 1st and 3rd light control board has satisfies. It is drawing for demonstrating the shape of the convex part which the 2nd and 4th light control board of the light control board unit shown in FIG. 5 has. It is a perspective view which shows other embodiment of the light control board unit which concerns on this invention. It is a perspective view which shows other embodiment of the light control board unit which concerns on this invention. It is sectional drawing which shows typically the structure of the conventional transmissive image display apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent element, and the overlapping description is abbreviate | omitted. The dimensional ratios in the drawings do not necessarily match those described.

(First embodiment)
FIG. 1 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device according to the present invention. FIG. 1 shows the transmissive image display device 1 in an exploded manner.

  The transmissive image display device 1 includes a transmissive image display unit 10 and a surface light source device 20 disposed on the back side of the transmissive image display unit 10 in FIG. In the following description, as shown in FIG. 1, the arrangement direction of the surface light source device 20 and the transmissive image display unit 10 is referred to as a z direction (plate thickness direction), which is two directions orthogonal to the z direction and orthogonal to each other. Two directions are referred to as an x direction and a y direction.

  Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11. In this case, the transmissive image display device 1 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 11 and the polarizing plates 12 and 13, those used in the transmissive image display device 1 such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 11 include known liquid crystal cells such as TFT type and STN type.

  The surface light source device 20 is a so-called direct type surface light source device. The surface light source device 20 includes a light control plate unit 21A and a plurality of point light sources 22 arranged on the back side in FIG.

The light control plate unit 21A includes a first light control plate 30 ₁ , a second light control plate 30 ₂ , a third light control plate 30 _3, and a fourth light, which are sequentially arranged in the plate thickness direction (z direction). a control plate 30 _4.

The planar view shapes (shapes viewed from the z direction) of the _first to _fourth light control plates 30 ₁ to 30 4 constituting the light control plate unit 21A are substantially the same, and are generally rectangular. The planar view shape of the _first to _fourth light control plates 30 ₁ to 30 ₄ , in other words, the size of the planar view shape of the light control plate unit 21 A is suitable for the screen size of the target transmissive image display device 1. Usually, it is 250 mm × 440 mm or more, preferably 1020 mm × 1800 mm or less. The planar view shape of the _first to _fourth light control plates 30 ₁ to 30 ₄ is not limited to a rectangle but may be a square, but in the following, it will be described as a rectangle unless otherwise specified.

FIG. 2 is a drawing showing an example of the arrangement relationship of a plurality of point light sources. As shown in FIG. 2, the plurality of point light sources 22 can be arranged at equal intervals L _{x in the} x direction and at equal intervals L _y in the y direction. In FIG. 2, as an example, the interval Lx in the x direction is larger than the interval Ly in the y direction, but the interval Ly may be larger than the interval Lx, or the interval Lx and the interval Ly may be the same. The space | interval Lx and the space | interval Ly can be made into the distance between the light emission parts of the point light source 22, and are 10 mm-150 mm normally.

  The plurality of point light sources 22 may be arranged in a staggered pattern shown in FIG. Since FIG. 3 can be regarded as a modification of the case of FIG. 2, the distance between the point light sources 22 in the x direction and the y direction can be the same as in the case of FIG. This will be specifically described.

  The rectangular lattice shown in FIG. 2 can be regarded as a plurality of point light source arrays composed of a plurality of point light sources 22 arranged in the x direction arranged in parallel in the y direction. In this case, the staggered arrangement in FIG. 3 is such that adjacent point light source arrays out of a plurality of point light source arrays arranged in the y direction are arranged with a half cycle shift in the x direction. Therefore, also in the arrangement shown in FIG. 3, the interval Ly in the y direction can be the same as the case shown in FIG. 2, that is, the interval between the point light source arrays arranged in parallel in the y direction. In FIG. 3, as an example, the adjacent point light source arrays out of the point light source arrays arranged in parallel in the y direction are shifted by a half cycle in the x direction. However, in the above description, the x direction and the y direction are opposite. There may be.

  An example of the point light source 22 is a light emitting diode. Moreover, as a light emitting diode, what is called side emission, what produces the maximum intensity | strength with respect to a certain angle direction with respect to z direction can be illustrated. FIG. 4 is a drawing showing the light distribution of OSRAM “Golden DRAGON (registered trademark) ARGUS (registered trademark)” as an example of the light distribution of light emitting diodes. In FIG. 4, the horizontal axis indicates the angle θ (see FIG. 1) with respect to the z direction, and the vertical axis indicates the intensity. The intensity is a value normalized with respect to the maximum intensity.

FIG. 5 is a perspective view illustrating the configuration of an embodiment of the light control plate unit. With reference to FIG. 5, the first to fourth light control plates 30 ₁ , 30 ₂ , 30 ₃ , and 30 ₄ constituting the light control plate unit 21A will be described. In Figure 5, for purposes of explanation, although spaced apart first through fourth light control plate ₃₀ 1 to 30 _4, as described later, the second to the first light control plate 30 ₁ on a third light control plate ₃₀ 2-30 ₄ may be provided to two adjacent contacts.

[First light control board]
The first light control plate 30 ₁ is substantially the (first surface of the first light control plate) 31 ₁ flat lower surface, the convex portion is convex to the second light control plate 30 ₂ side (the first of the convex portion of the light control plate) 33 ₁ is a plate-like body having a second surface) 32 of _the plurality forming top surfaces (first light control plate. The first light control plate 30 ₁ is, for example, a light diffusion plate for dispersing the light by the difference of the emission position of the light from the convex portion 33 _1. Further, the first light control plate 30 _1, since the deflecting direction of light emission by emitting position of light from the convex portion 33 _1, deflecting plate both the shape to adjust the deflection of the light is applied I can say that. Here, although referred to as “plate”, it may be in the form of a sheet or film depending on the thickness. Convex portion 33 ₁ extends substantially parallel to the Y1 direction in the y-direction (first direction of the first light control plate), first in the X1 direction (the first light control plate which is substantially perpendicular to the Y1 direction 2 direction). The X1 direction and the Y1 direction are preferably parallel to the x direction and the y direction, respectively, but may be shifted by about ± 10 ° due to, for example, a manufacturing error. The cross-sectional shape of the plurality of convex portions 33 ₁ is substantially the same between the convex portions 33 ₁ . Further, in the extending direction of the convex portion 33 _1, the cross-sectional shape is substantially uniform. The ends 33a ₁ of the two adjacent convex portions 33 ₁ and 33 ₁ are at the same position in the X1 direction. First thickness d1 of the light control plate 30 ₁ is a z-direction distance between the top portion 33b ₁ of the lower surface 31 ₁ and the convex portion 33 _1, usually a 0.5 mm to 5 mm.

[Second light control board]
The second light control plate 30 ₂ has a substantially flat lower surface (second optical control plate first surface of) 31 _2, the convex portion is convex outward (convex portion of the second light control plate ) 33 ₂ is a second surface) 32 ₂ and the plate-like member having a plurality formed top (second light control plate. Convex portion 33 ₂ in cross section is triangular prism portion. Therefore, the second light control plate 30 ₂ is a so-called prism plate. Here, although referred to as “plate”, it may be in the form of a sheet or film depending on the thickness. Convex portion 33 ₂ extend in substantially parallel Y2 direction in the y direction (first direction of the second light control plate), first in the X2 direction (second light control plate which is substantially perpendicular to the Y2 direction 2 direction). It is preferred X2 direction and the Y2 direction is parallel to the x and y directions, respectively, but as in the case of the first light control plate 30 _1, for example due to a manufacturing error or the like may be offset about ± 10 °. Cross-sectional shape of the plurality of convex portions 33 ₂ is substantially same in the convex portion 33 _2. Further, in the extending direction of the convex portion 33 _2, the cross-sectional shape is substantially uniform. End _33a 2 of two adjacent convex portions ₃₃ 2, 33 _2, 33a ₂ are in the same position in the X2 direction. The second thickness d2 of the light control plate 30 ₂ is a z-direction distance between the top portion 33b ₂ of the lower surface 31 ₂ and the convex portion 33 _2, usually a 0.1 mm to 5 mm.

[Third light control board]
Third light control plate 30 _3, and (first surface of the third light control plate) 31 ₃ substantially flat lower surface, the convex portion is convex outward (convex portion of the third light control plate ) 33 ₃ is a plate-like body having and a second surface) 32 ₃ multiple formed top (third light control plate. Third light control plate 30 _3, a first light control plate 30 ₁ in the same manner as in the light diffusing plate, it can be said that the deflection structure plate. Here, although referred to as “plate”, it may be in the form of a sheet or film depending on the thickness. Convex portion 33 _3, extends substantially parallel to the direction X3 in the x-direction (first direction of the third light control plate), first of Y3 direction (third light control plate substantially perpendicular to the direction X3 2 direction). It is preferred X3 direction and Y3 direction is parallel to the x and y directions, respectively, but as in the case of the first light control plate 30 _1, for example due to a manufacturing error or the like may be offset about ± 10 °. Cross-sectional shape of the plurality of convex portions 33 ₃ are substantially same in the convex portion 33 _3. Further, in the extending direction of the convex portion 33 _3, the cross-sectional shape is substantially uniform. The ends 33a ₃ and 33a ₃ of the two adjacent convex portions 33 ₃ and 33 ₃ are at the same position in the Y3 direction. Third thickness d3 of the light control plate 30 ₃ are the z-direction distance between the lower surface ₃₁₃ and the convex portion 33 ₃ of the top 33b _3, usually a 0.1 mm to 5 mm.

[Fourth light control board]
Fourth light control plate 30 _4, substantially flat lower surface (fourth light control plate first surface of) 31 _4, the convex portion is convex outwardly (protruding portion of the fourth light control plate ) 33 ₄ is a plate-like body having and a second surface) 32 ₄ multi formed top (fourth light control plate. Fourth light control plate 30 _4, like the second light control plate 30 ₂ is a so-called prism plate. Here, it is referred to as “plate”, but it may be in the form of a sheet or a film depending on the thickness. Convex portion 33 _4, extends substantially parallel to the direction X4 in the x-direction (first direction of the fourth light control plate), first in the Y4 direction (fourth light control plate substantially perpendicular to the direction X4 2 direction). It is preferable X4 direction and Y4 direction is parallel to the x and y directions, respectively, but as in the case of the first light control plate 30 _1, for example due to a manufacturing error or the like may be offset about ± 10 °. Cross-sectional shape of the plurality of convex portions 33 ₄ is substantially the same in the convex portion 33 _4. Further, in the extending direction of the convex portion 33 _4, the cross-sectional shape is substantially uniform. The ends 33a ₄ and 33a ₄ of the two adjacent convex portions 33 ₄ and 33 ₄ are at the same position in the Y4 direction. The thickness d4 of the fourth light control plate 30 ₄ is a z-direction distance between the top portion 33b ₄ of the lower surface 31 ₄ and the convex portion 33 _4, usually is 0.1 mm to 5 mm.

[Convex portions of the first and third light control plates]
The shape of the convex portions 33 ₁ and 33 _{3 included in} each of the first and third light control plates 30 ₁ and 30 ₃ will be described.

Convex portion 33 _1, the point light sources 22 first and second light control plate ₃₀ on 1, 30 ₂ is provided on this order, the convex portions ₃₃ 1, 33 ₂ substantially parallel to their extending direction When arranged in such a manner, it has a cross-sectional shape capable of converting light from the point light source 22 into linear light having substantially uniform luminance. Similarly, the convex portion 33 _3, third and fourth light control plate ₃₀ 3, 30 ₄ is provided on this order, the convex portion ₃₃ 3, 33 ₄ of them extending direction on the point light sources 22 Are arranged in parallel, the light from the point light source 22 has a cross-sectional shape that can be converted into linear light with substantially uniform luminance. The cross-sectional shapes of the convex portions 33 ₁ and 33 ₃ will be described with reference to FIG.

Here, the convex portions 33 ₁ and 33 ₃ will be referred to as convex portions 33 _i (i is 1 or 3) unless otherwise specified. In FIG. 6, the uv coordinate system is set with the u-axis as the direction orthogonal to the extending direction of the convex portion 33 _i . U-axis direction corresponding to the convex portion 33 ₁ and the convex portion 33 ₃ are the X1 direction and the Y3 direction. Further, v-axis direction corresponding to the convex portion 33 ₁ and the convex portion 33 ₃ are both a z-direction.

ただし、式（３）において、

式（４）において、ｗ_ａはｕ軸方向の凸状部３３_ｉの長さである。ｈ_ａは、凸状部３３_ｉの両端３３ａ_ｉ,３３ａ_ｉ間における最大高さに対応し、ｈ_ａは０．２０ｗ_ａ以上１．１０ｗ_ａ以下を満たす定数である。すなわち、ｈ_ａは、ｈ_ａ／ｗ_ａが０．２０以上１．１０以下を満たす定数である。ｋ_ａは−１．００以上且つ０．７５以下を満たす定数である。凸状部３３_ｉの幅ｗ_aは、凸状部３３_ｉの形成が容易であることから、通常４０μｍ以上、好ましくは２５０μｍ以上であり、凸状部３３_ｉに起因する模様が肉眼で視認されにくいことから、通常８００μｍ以下、好ましくは４５０μｍ以下である。幅ｗ_aとして具体的には、ｗ_a＝４１０μｍ、ｗ_a＝４００μｍおよびｗ_a＝３２５μｍが例示できるが、ｗ_aの値はこれに限定されるものではない。 In the uv coordinate system, the cross-sectional shape of the convex portion 33 _i has both ends 33 a _i and 33 a _i on the u axis, and has a contour line symmetrical to the v axis. This contour line is represented by v (u) that satisfies the following formula (3).

However, in Formula (3),

In Expression (4), w _a is the length of the convex portion 33 _{i in} the u-axis direction. h _a is across 33a _i of the convex portion 33 _i, corresponding to the maximum height between 33a _{i, h a} is a constant satisfying the following 0.20 W _a more 1.10w _a. That, _{h a is,} h _a / _w a is a constant satisfying 0.20 to 1.10. k _a is _a constant satisfying −1.00 and 0.75. Width w _a of the convex portion 33 _i, since formation of the convex portion 33 _i is easy, usually 40μm or more, preferably 250μm or more, the pattern caused by the convex portion 33 _i is visible to the naked eye Since it is difficult, it is usually 800 μm or less, preferably 450 μm or less. Specific examples of the width w _a include w _a = 410 μm, w _a = 400 μm, and w _a = 325 μm, but the value of w _a is not limited to this.

FIG. 6 exemplifies a shape in which v ₀ (u) is expanded and contracted by a predetermined multiple in the v direction within the range satisfying the expression (3) as an example of the cross-sectional shape of the convex portion 33 _i . However, the sectional shape of the convex portion 33 _i, as shown in FIG. 7, when determining the _v 0 (u) for a width _{w a,} contours represented by 0.95v ₀ (u) And a contour line passing through a region between the contour lines represented by 1.05v ₀ (u).

Further, in the above description, it is assumed that the cross-sectional shape of the convex portion 33 _i is represented by v (u) that satisfies Expression (3). However, considering the effect on the manufacturing error and the intensity distribution at near both ends of the convex portion 33 _i, the cross-sectional shape of the convex portion 33 _i has the formula in -0.475w _a ≦ u ≦ 0.475w _a It may be expressed by v (u) that satisfies (3).

Also, h ranges of a _/ w _a and k _a may if they meet the above-mentioned range, but the distance between two adjacent point light sources 22 is L, the light control unit from the light emitting portion of the point light sources 22 When the distance to the surface of 21A on the point light source 22 side (the lower surface 31 _{1 of the first} light control plate 30 ₁ in FIG. 1 or 5) is D, h _a / w is preferable for L / D. range of _a and _{k a} are as in Table 1. L described in Table 1, with respect to the contour shape of the convex portion 33 ₁ corresponds to Lx, for contour shape of the convex portion 33 ₃ and corresponds to Ly.

Convex portion ₃₃ of the first and third light control plate ₃₀ 1, 30 _3, 33 _{3 w a,} h _{a, k} a is may be the same in the convex portion 33 ₁ and the convex portion 33 ₃ May be different. That is, the cross-sectional shapes of the convex portions 33 ₁ and 33 _{3 included in} each of the first and third light control plates 30 ₁ and 30 ₃ may be the same cross-sectional shape, or may be the same. Different cross-sectional shapes may be used as long as the contour lines of the cross-sectional shapes 33 ₁ and 33 ₃ satisfy the above formula (3).

[Convex portions of second and fourth light control plates]
Convex portion ₃₃ 2 of the second and fourth light control plate ₃₀ 2, 30 ₄ has, 33 for ₄ shape described. Here, the convex portions ₃₃ 2, 33 ₄ and convex portion ₃₃ j (j is 2 or 4) referred to as referred to as the second and fourth light control plate ₃₀ 2, 30 ₄ and the light control plate 30 _j. Figure 8 is a view for explaining the shape of the convex portion 33 _j, a side view of the light control plate 30 _j as viewed from the extending direction of the convex portion 33 _j. Since the convex portion 33 _j has a substantially uniform shape in the extending direction, as shown in FIG. 8, the side shape viewed from the extending direction is a cross-section substantially orthogonal to the extending direction of the convex portion 33 _j. Corresponds to the shape.

As shown in FIG. 8, the side surface shape (or cross-sectional shape) of the convex portion 33 _j is a substantially right-angled isosceles triangle in which the apex angle α is substantially a right angle and the lengths of both sides are substantially equal. Here, the apex angle α is preferably 90 °, but may be in the range of 80 ° to 100 °. The pitch P between two adjacent convex portions 33 _j and 33 _j can be 10 μm to 1000 μm, preferably 20 μm to 500 μm, and more preferably 40 μm to 250 μm. What is necessary is just to set the width _| variety of the convex part _{33j so that} the pitch P of the convex part _33j may become the predetermined value of the said range.

The cross-sectional shape of the second and fourth light control plate ₃₀ 2, 30 ₄ of the convex portion 33 _2, 33 ₄ may be the same or may be different.

[Layer structure of first to fourth light control plates]
The first to fourth light control plates 30 ₁ to 30 ₄ may be single-layer plates made of a single transparent material, or have a multilayer structure in which layers made of different transparent materials are laminated. A multilayer board may be sufficient. When the _first to _fourth light control plates 30 ₁ to 304 are multilayer plates, one or both sides of the _first to _fourth light control plates 30 ₁ to 304 are usually 10 μm to 200 μm, preferably 20 μm to It is preferable to use a structure in which a skin layer having a thickness of 100 μm is formed, and a transparent resin material constituting the skin layer to which an ultraviolet absorber is added is used. By adopting such a configuration, it is possible to prevent the _first to _fourth light control plates 30 ₁ to 304 from being deteriorated by the point light source 22 or the ultraviolet rays that may be included in the light from the outside. If the proportion of the light source 22 of ultraviolet rays using a relatively large, because it can prevent deterioration due to ultraviolet rays, it is preferable that the skin layer on the lower surface 31 _{1-31 4} is formed, this time the upper surface 32 ₁ to 32 that the ₄ not formed skin layer, more preferably in terms of cost. When the transparent resin material constituting the skin layer is added with an ultraviolet absorber, the content is usually 0.5% by mass to 5% by mass, preferably 1% by mass to 2% based on the transparent resin material. 0.5% by mass.

The first to fourth light control plates 30 ₁ to 30 ₄ may be coated with an antistatic agent on one side or both sides. By applying an antistatic agent, dust adhesion due to static electricity can be prevented, and a decrease in light transmittance due to dust adhesion can be prevented.

  Further, the surface on the point light source 22 side can be a surface having light diffusibility in order to reduce moire. For example, the surface on the point light source 22 side may be configured as described above with a skin layer containing fine particles called a matting agent, or the surface on the point light source 22 side may be embossed or blasted. Alternatively, the mat layer may be formed by applying a coating solution containing a matting agent and a binder.

[Constituent materials]
The first to fourth light control plates 30 ₁ to 30 ₄ are made of a transparent material. The refractive index of the transparent material is usually 1.56 to 1.62. Examples of the transparent material include a transparent resin material and a transparent glass material. Examples of the transparent 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: 1.59), AS resin (acrylonitrile-styrene copolymer resin) (refractive index: 1.56-1.59), etc. Polystyrene resin is preferable in terms of surface and moisture absorption.

  When a transparent resin material is used as the transparent material, additives such as an ultraviolet absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, and a lubricant can be added to the transparent resin material. These additives can be used alone or in combination of two or more.

  Examples of UV absorbers include benzotriazole UV absorbers, benzophenone meter 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 transparent 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 impair the object of the present invention.

As the light diffusing agent, a powder having a refractive index different from that of the transparent material mainly constituting the _first to _fourth light control plates 30 ₁ to 30 4 is generally used, and this is dispersed in the transparent material. Used. As the light diffusing agent, for example, organic particles such as styrene resin particles and methacrylic resin particles, inorganic particles such as potassium carbonate particles, silica particles, and silicone resin particles are used, and the particle diameter is usually 0.8 μm to 50 μm. .

[Method for Manufacturing First to Fourth Light Control Plates]
The first to fourth light control plates 30 ₁ to 30 ₄ can be manufactured by, for example, a method of cutting out from a transparent material. Moreover, when using a transparent resin material as a transparent 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.

[Disposition relationship of first to fourth light control plates]
The first to fourth light control plates 30 ₁ to 30 ₄ are provided in the z direction so as to satisfy the following conditions.
(i) a second light control plate 30 ₂ is first positioned on the upper side of the light control plate 30 ₁ and the fourth light control plate 30 ₄ is positioned on the upper side of the third light control plate 30 ₃ .
(ii) the lower surface ₃₁₂ of the second light control plate 30 ₂ is located at the first upper surface 32 ₁ side of the light control plate 30 _1.
(iii) Fourth underside 31 ₄ of the light control plate 30 ₄ is positioned on the top surface 32 ₃ of the third light control plate 30 _3.
(iv) a first light control plate 30 ₁ of the convex portion 33 ₁ in the extending direction (Y1 direction), the second light control plate 30 _{and second} convex portion 33 ₂ in the extending direction (Y2 direction) and Are substantially parallel.
(v) and the third light control plate 30 ₃ of the convex portion 33 ₃ of the extending direction (X3 direction), the fourth light control plate 30 ₄ of the convex portion 33 ₄ of the extending direction (X4 direction) Are substantially parallel.
(vi) a first light control plate 30 ₁ and a second light control plate 30 ₂ as the first light control plate set, the third light control plate 30, _third and fourth light control plate 30 ₄ second When the second light control plate set is used, the first light control plate set and the second light control plate set are convex with respect to the extending direction of the convex portion 33 ₁ (or the convex portion 33 ₂ ). It arrange | positions so that the extension direction of the part 33 ₃ (or convex part 33 ₄ ) may be substantially orthogonal. The angle formed by the extending direction of the convex portion 33 ₁ (or the convex portion 33 ₂ ) and the extending direction of the convex portion 33 ₃ (or the convex portion 33 ₄ ) is exemplified by 80 ° to 100 °. Preferably, it is 90 degrees.

In the present embodiment, the first to fourth light control plates 30 ₁ to 30 ₄ satisfy the arrangement conditions (i) to (vi), and the first light control plate 30 ₁ and the second light control plate. 30 _2, is provided in the z direction in the order of the third light control plate 30, _third and fourth light control plate 30 _4.

The distance _{d 12} between the first and second light control plate ₃₀ 1, 30 _2, first apex 33b ₁ of the convex portion 33 ₁ of the light control plate 30 ₁ and the second light control plate 30 ₂ it is a z-direction distance between the lower surface 31 _2. Similarly, the second and third light control plate ₃₀ 2, 30 a distance _{d 23} between the _3, the second top portion 33b ₂ of the light control plate 30 _{and second} convex portion 33 ₂ and the third light control plate It is the distance in the z direction between the lower surface 31 _{3 of} 30 ₃ . The third and fourth light control plate ₃₀ 3, 30 a distance _{d 34} between the _4, the third convex portion 33 ₃ of the top portion 33b ₃ of the light control plate 30 _third and fourth light control plate 30 ₄ of the lower surface 31 is the z-direction distance between the _4. d ₁₂ , d ₂₃ and d ₃₄ are, for example, 5 mm or less.

From the viewpoint of the light control plate unit 21A and compact _{ones, d 12, d 23} and _{d 34} are 0 mm, the second light control plate to the first upper convex portion 33 ₁ of the light control plate 30 ₁ 30 _2, third light control plate 30, _third and fourth light control plate 30 _4, the upper bottom surface _{31 2,} 31 3, 31 _4, and the lower convex portion _{33 1,} 33 2, 33 ₃ of the top _{33b 1,} 33b 2, it may be disposed in contact with 33b _3. Thus, the first light control plate 30 ₁ on which is located most point light source 22 side of the light control plate unit 21A, the second to fourth light control plate ₃₀ 2-30 _4, two adjacent When two light control plates 30 ₁ to 30 ₄ are provided so that the upper and lower plates are in contact with each other, the thicknesses d ₂ to d ₄ of the _second to _fourth light control plates 30 ₂ to 304 are set to the first light. it is preferable to use a thinner than the thickness d1 of the control plate 30 _1. For example, when the second to fourth light control plate ₃₀ 2-30 ₄ shall thinner such filmy, supporting the first light control plate 30 ₁ of the second to fourth light control plate ₃₀ 2-30 ₄ This is because it can be used as a stand.

[Arrangement of light control board unit]
Light control plate unit 21A which has first to fourth light control plate ₃₀ 1 to 30 ₄ of the above configuration, the distance D from the point light sources 22 to the lower surface 31 ₁ of the first light control plate 30 _1, usually It arrange | positions with respect to the point light source 22 so that it may become 3 mm-50 mm. In the transmissive image display device 1 or the surface light source device 20, Lx, Ly, and D are values in which Lx / D and Ly / D are 2 or more, respectively, and further 2.5 or more. Is preferable in that it can be made thinner.

Further, the light control plate unit 21A, in the transmissive image display device 1, to the extending direction of the convex portion 33 ₁ may be arranged such that the longitudinal direction of the screen, arranged so as to be laterally May be.

  Next, the function and effect of the light control plate unit 21A will be described by taking as an example the case where the light control plate unit 21A is applied to the transmissive image display device 1 as shown in FIG. Here, it is assumed that the X1, X2, X3, and X4 directions are parallel to the x direction, and the Y1, Y2, Y3, and Y4 directions are parallel to the y direction.

The first convex portion 33 of the light control plate 30 _{1 1} Formula sectional shape represented by v (u) satisfying (3), a second light control plate 30 _{and second} convex portions 33 ₂ Is a prism portion whose cross section is a substantially right-angled isosceles triangle. In this configuration, when the first and second light control plates 30 ₁ and 30 ₂ are arranged on the point light source 22 so that the extending directions of the convex portions 33 ₁ and 33 ₂ are substantially parallel, The first and second light control plates 30 ₁ , 30 ₂ can emit the light output from the point light source 22 by converting it into linear light with uniform luminance. Similarly, the convex portion 33 ₃ of the third light control plate 30 ₃ has a sectional shape which is expressed by v (u) satisfying the expression (3), the fourth light control plate 30 ₄ convex part 33 ₄ is a prism portion is substantially isosceles right triangular cross section. Therefore, as in the case of the first and second light control plates 30 ₁ and 30 ₂ , the third and fourth light control plates 30 ₃ and 30 ₄ also emit light from the point light source 22 with a uniform luminance. It can be converted into a light beam and emitted.

In the light control plate unit 21A, as described above, the first and second light control plates 30 ₁ and 30 _{2 that} can convert the light from the point light source 22 into linear light having substantially uniform luminance. In the z direction, the set and the set of the third and fourth light control plates 30 ₃ and 30 ₄ , the extending direction of the convex portion 33 ₁ (or the convex portion 33 ₂ ) and the convex portion 33 ₃ (or The extending direction of the convex portion 33 ₄ ) is arranged so as to be substantially orthogonal. Therefore, the light from the point light source 22 has a uniform luminance due to the set of the first and second light control plates 30 ₁ and 30 _{2 and} the set of the third and fourth light control plates 30 ₃ and 30 _4. Each is converted into linear light in a substantially orthogonal direction. As a result, the light control plate unit 21A uniformly disperses the light from the plurality of point light sources 22, and is planar light that has higher luminance uniformity on the surface orthogonal to the z direction. Can be emitted.

  Since the surface light source device 20 includes the light control plate unit 21A, the surface light that uniformly distributes the light from the plurality of point light sources 22 and has higher luminance uniformity in the surface orthogonal to the z direction. Can be emitted. In addition, since the transmissive image display device 1 includes the light control plate unit 21A, the luminance uniformity in the plane orthogonal to the z direction is higher because the light from the plurality of point light sources 22 is uniformly dispersed. It is possible to irradiate the transmissive image display unit 10 with planar light. As a result, a higher quality image can be displayed.

In the present embodiment, the _first to _fourth light control plates 30 ₁ to 30 ₄ are sequentially provided in the z direction, but the first to fourth light control plates 30 ₁ to 30 ₄ are arranged according to the arrangement conditions. It only needs to be provided in the z direction so as to satisfy (i) to (vi). Other embodiments of the light control plate unit according to the modified example of the arrangement of the _first to _fourth light control plates 30 ₁ to 304 will be described as second and third embodiments.

(Second Embodiment)
FIG. 9 is a perspective view showing a second embodiment of the light control plate unit according to the present invention. The light control plate unit 21B includes first to fourth light control plates 30 ₁ , 30 ₂ , 30 ₃ , and 30 ₄ as in the case of the first embodiment. First to configuration of the fourth light control plate ₃₀ 1 to 30 ₄ are the same as the first to fourth light control plate ₃₀ 1 to 30 ₄ configuration of the first embodiment, the light control plate unit 21B Is different from the light control plate unit 21 </ b> A in the order of arrangement of the _first to _fourth light control plates 30 ₁ to 304. This difference will be mainly described.

In the light control plate unit 21B, the first light control plate 30 _1, a third light control plate 30 _3, provided in the z direction in the order of the second light control plate 30 ₂ and the fourth light control plate 30 ₄ Yes. The first light control plate 30 ₁ of the convex portion 33 ₁ in the extending direction and the second light control plate 30 ₂ extending direction of the convex portion 33 ₂ is substantially parallel. Also, the third extending direction of the light control plate 30 ₃ of the convex portion 33 ₃ of the extending direction of the fourth light control plate 30 ₄ of the convex portion 33 ₄ are substantially parallel. Further, as in the case of the first embodiment, the first and second light control plates 30 ₁ and 30 ₂ are set as the first light control plate set, and the third and fourth light control plates 30 _{3 are used.} , 30 ₄ is the second light control plate set, the first light control plate set and the second light control plate set are the convex portion 33 ₁ (or the convex portion 33 ₂ ). It arrange | positions so that the extension direction and the extension direction of convex-shaped part 33 ₃ (or convex-shaped part 33 ₄ ) may cross substantially orthogonally. The angle between the extending direction of the convex portion 33 ₁ (or the convex portion 33 ₂ ) and the extending direction of the convex portion 33 ₃ (or the convex portion 33 ₄ ) is exemplified by 80 ° to 100 °, Preferably, it is 90 degrees.

In this configuration, the first to fourth light control plates 30 ₁ to 30 ₄ satisfy the arrangement conditions (i) to (vi) described in the first embodiment.

The first and third light control plate ₃₀ 1, 30 a distance _{d 13} between the _3, first apex 33b ₁ of the light control plate 30 ₁ of the convex portion 33 ₁ and the third light control plate 30 ₃ there der distance in the z-direction between the lower surface 31 _3. Similarly, the distance _{d 32} between the third and second light control plate ₃₀ 3, 30 _2, and the third top 33b ₃ of the convex portion 33 ₃ of the light control plate 30 ₃ second light control plate it is a z-direction distance between the 30 ₂ of the lower surface 31 _2. The distance _{d 24} between the second and fourth light control plate ₃₀ 2, 30 _4, the second light control plate 30 _{and second} convex portion 33 ₂ of the top portion 33b ₂ and the fourth light control plate 30 ₄ of the lower surface 31 is the z-direction distance between the _4. d ₁₃ , d ₃₂ and d ₂₄ are, for example, 5 mm or less.

From the viewpoint of the light control plate unit 21B and compact _ones, d _{13, d 32} and _{d 24} are 0 mm, the third light control plate to the first upper convex portion 33 ₁ of the light control plate 30 ₁ 30 _3, a second light control plate 30 ₂ and the fourth light control plate 30 _4, the upper bottom surface _{31 3,} 31 2, 31 ₄ lower convex portion _{33 1,} 33 3, 33 ₂ of the top portion 33b ₁ , 33b ₃ , and 33b ₂ may be arranged so as to be in contact with each other as in the case of the first embodiment. Further, the first to fourth light control plate ₃₀ 1 to 30 first light control plate 30 ₁ second to fourth light control plate ₃₀ 2-30 ₄ located closest to the point light source 22 side of the _four It is preferable to make it thicker. In this case, for example, the _second to _fourth light control plates 30 ₂ to 304 can be formed into a film shape as in the case of the first embodiment.

The light control plate unit 21B shown in FIG. 9 can be applied to the surface light source device 20 and the transmissive image display device 1 instead of the light control plate unit 21A in FIG. In this case, the transmission type image display device 1, the light control plate unit 21B is to the extending direction of the convex portion 33 ₁ may be arranged such that the longitudinal direction of the screen, arranged to be laterally May be.

In the optical control plate unit 21B, and a second light control plate 30 ₂ is provided satisfy the placement condition (ii) and (iv) a first upper optical control plate 30 _1, a third light control fourth light control plate 30 ₄ are provided meets the arrangement conditions (iii) and (v) to the upper plate 30 _3. In this arrangement, the first and second light control plates 30 ₁ and 30 ₂ can convert the light from the point light source 22 into linear light with substantially uniform luminance, and the third and fourth light control plates. 30 ₃ and 30 ₄ can also convert light from the point light source 22 into linear light having substantially uniform luminance.

In the light control plate unit 21B, the first and second light control plates 30 ₁ and 30 ₂ and the third and fourth light control plates 30 ₃ and 30 ₄ are arranged according to the arrangement condition (vi ) Is arranged. That is, the set of the first and second light control plates 30 ₁ and 30 _{2 and} the set of the third and fourth light control plates 30 ₃ and 30 ₄ are the convex portion 33 ₁ (or the convex portion 33). The extending direction of ₂ ) and the extending direction of the convex part 33 ₃ (or the convex part 33 ₄ ) are arranged so as to be substantially orthogonal to each other.

  Therefore, when the light control plate unit 21B is used instead of the light control plate unit 21A of FIG. 1, the light from the plurality of point light sources 22 is the light control plate unit as in the case of the first embodiment. By passing through 21B, it is possible to generate planar light that is uniformly dispersed and, as a result, has a higher luminance uniformity in a plane orthogonal to the z direction.

  Therefore, the surface light source device 20 and the transmissive image display device 1 including the light control plate unit 21B and the plurality of point light sources 22 also have the same operational effects as in the case of the first embodiment.

Further, the light control plate unit 21B, the first to fourth light control plate ₃₀ 1 to 30 _4, the convex portion ₃₃ 1 in the _z-direction, 33 _2, 33 3, 33 ₄ in the extending direction is substantially alternately It arrange | positions so that it may orthogonally cross. Therefore, Moire fringes is unlikely to occur to a fourth planar light emitted from the light control plate 30 _4. Therefore, even in the surface light source device 10 including the light control plate unit 21 </ b> B and the plurality of point light sources 22, planar light with suppressed moire fringes can be emitted. Furthermore, the transmission type image display device 1 including the light control plate unit 21B and the plurality of point light sources 22 can display a higher quality image.

(Third embodiment)
FIG. 10 is a perspective view showing a third embodiment of the light control plate unit according to the present invention. The light control plate unit 21C includes first to fourth light control plates 30 ₁ , 30 ₂ , 30 ₃ , and 30 ₄ as in the case of the first embodiment. First to configuration of the fourth light control plate ₃₀ 1 to 30 ₄ are the same as the first to fourth light control plate ₃₀ 1 to 30 ₄ configuration of the first embodiment, the light control plate unit 21C Is different from the light control plate unit 21 </ b> A in the order of arrangement of the _first to _fourth light control plates 30 ₁ to 304. This difference will be mainly described.

In the light control plate unit 21C, the first light control plate 30 _1, a third light control plate 30 _3, the order of the fourth light control plate 30 ₄ and second light control plate 30 _2, a first embodiment It is provided in the z direction so as to satisfy the arrangement relationships (ii) to (vi) described in the above. Then, the first light control plate 30 _1, a third light control plate 30 _3, the order of the fourth light control plate 30 ₄ and second light control plate 30 _2, so provided in z-direction, the In the embodiment, the arrangement relationship (i) described in the first embodiment is also satisfied.

The distance _{d 42} between the fourth and second light control plate ₃₀ 4, 30 _2, the fourth convex portion 33 ₄ top 33b ₄ of the light control plate 30 ₄ and the second light control plate 30 _This is a distance in the z direction between the lower surface 312 of ₂ and 5 mm or less. Since the distance d ₁₃ between the first and third light control plates 30 ₁ and 30 ₃ is the same as that in the second embodiment, the description thereof is omitted. Further, the distance d ₃₄ between the third and fourth light control plates 30 ₃ and 30 ₄ is the same as that in the first embodiment, and thus the description thereof is omitted.

From the viewpoint of the light control plate unit 21C and compact _ones, d _{13, d 34} and _{d 42} are 0 mm, the third light control plate to the first upper convex portion 33 ₁ of the light control plate 30 ₁ 30 _3, a fourth light control plate 30 ₄ and second light control plate 30 _2, the upper bottom surface _{31 3,} 31 4, 31 ₂ convex lower shaped portion _{33 1,} 33 3, 33 ₄ of the top 33b ₁ , 33b ₃ , and 33b ₄ may be arranged so as to be in contact with each other as in the case of the first embodiment. Further, the first to fourth light control plate ₃₀ 1 to 30 first light control plate 30 ₁ second to fourth light control plate ₃₀ 2-30 ₄ located closest to the point light source 22 side of the _four It is preferable to make it thicker. In this case, for example, the _second to _fourth light control plates 30 ₂ to 304 can be formed into a film shape as in the case of the first embodiment.

The light control plate unit 21C shown in FIG. 10 can be applied to the surface light source device 20 and the transmissive image display device 1 in place of the light control plate unit 21A in FIG. In this case, the transmission type image display device 1, the light control plate unit 21C is to the extending direction of the convex portion 33 ₁ may be arranged such that the longitudinal direction of the screen, arranged to be laterally May be.

In the optical control plate unit 21C, the second light control plate 30 ₂ to the first upper light control plate 30 ₁ is provided satisfy the placement condition (ii) and (iv), the third light on the upper side of the control plate 30 ₃ fourth light control plate 30 ₄ are provided meets the arrangement conditions (iii) and (v). In this arrangement, the first and second light control plates 30 ₁ and 30 ₂ can convert the light from the point light source 22 into a linear light source having substantially uniform luminance, and the third and fourth light control plates. 30 ₃ and 30 ₄ can also convert the light from the point light source 22 into a linear light source having substantially uniform luminance.

In the light control plate unit 21C, the first and second light control plates 30 ₁ and 30 ₂ and the third and fourth light control plates 30 ₃ and 30 ₄ are arranged according to the arrangement condition (vi ) Is arranged. That is, the extending direction of the convex portion 33 ₁ (or the convex portion 33 ₂ ) and the extending direction of the convex portion 33 ₃ (or the convex portion 33 ₄ ) are arranged so as to be substantially orthogonal.

  Therefore, when the light control plate unit 21C is used instead of the light control plate unit 21A of FIG. 1, the light from the plurality of point light sources 22 is the light control plate unit as in the case of the first embodiment. By passing through 21C, it is possible to generate planar light that is uniformly dispersed and, as a result, has a higher luminance uniformity in a plane orthogonal to the z direction.

  Therefore, the surface light source device 20 and the transmissive image display device 1 including the light control plate unit 21C and the plurality of point light sources 22 also have the same operational effects as in the case of the first embodiment.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. In the above embodiment, the arrangement examples of the plurality of point light sources 22 are shown in FIGS. 2 and 3. For example, a square lattice, that is, between the point light sources 22 adjacent to each other in the x direction and the y direction as described above. The interval may be the same. Moreover, although the end 33a ₁ in the cross-sectional shape of the adjacent convex portion 33 ₁ has been described as overlapping in the arrangement direction of the convex portion 33a ₁ , it is slightly flat between the ends 33a _{1 of the} adjacent convex portions 33 _1. A part (for example, a part caused by a manufacturing error) may be generated. This also applies to each of the arrangement of the convex portion ₃₃ 2-33 _4.

The light control plate units 21A to 21C may further include an optical film such as a diffusion film or a microlens film on the transmissive liquid crystal display unit 10 side (for example, the liquid crystal panel side). The transmissive image display device 1 may further include an optical film such as the above-described diffusion film or microlens film between the light control plate units 21 </ b> A to 21 </ b> C and the transmissive liquid crystal display unit 10. it can.

  Furthermore, the surface light source device 20 and the transmissive image display device 1 may include a reflection unit such as a reflection plate that reflects the light output from the point light source 22 toward the light control plate units 21A to 21C. In the schematic diagram shown in FIG. 1, the reflection means may be provided on the side opposite to the light control plate units 21 </ b> A to 21 </ b> C with respect to the point light source 22. The light source mounting surface can be a reflecting surface.

Further, the first to fourth light control plate ₃₀ 1 to 30 _4, the first and second light control plate ₃₀ 1, 30 ₂ of the combination and the third and fourth light control plate ₃₀ 3, 30 ₄ In order to more uniformly disperse the light output from the plurality of point light sources 22 in combination to generate linear light, convex portions 33 ₁ , convex portions 33 ₂ , convex shapes are formed on the light emission side. part 33 ₃ and the convex portion 33 ₄ may if the shaped plate-like optical component, respectively. In this case, the light control plate unit may be configured such that the four optical components are arranged in the relationship described using the light control plate units 21A, 21B, and 21C. In addition, although demonstrated as plate shape, the thing of a film form and a sheet form is also included according to thickness.

1 ... transmission type image display apparatus, 10 ... transmission type image display unit, 20 ... surface light source device, 21A to 21C ... light control plate unit, 22 ... point light source, ₃₀ 1 to 30 4 _... first to fourth light Control plate, 31 _{1 to} 31 ₄ ... Lower surface of first to fourth light control plates (first surface of first to fourth light control plates), 32 _{1 to} 32 ₄ ... Upper surface of control plate (second surface of first to fourth light control plates), 33 _{1 to} 33 ₄ ... Convex portion of first to fourth light control plates, 33 _i . , Convex portion of the third light control plate), 33a _{1 to} 33a ₄ ... end of the convex portion (end of the convex portion of the first to fourth light control plates), 33a _i ... end of the convex portion. (Ends of convex portions of the first and third light control plates), Y1... Extension direction of the convex portions of the first light control plate, X1... Direction substantially orthogonal to the Y1 direction, Y2. Extension direction of convex part of light control plate, X2... Y Direction substantially orthogonal to the direction, X3... Extension direction of the convex portion of the third light control plate, Y3... Direction substantially orthogonal to the X3 direction, X4. , Y4... Direction substantially orthogonal to the X4 direction.

Claims (5)

Light incident from the first surface can be emitted from the second surface located on the opposite side of the first surface, and extends in one direction and is substantially perpendicular to the one direction. A plurality of convex portions arranged in parallel are provided with first to fourth light control plates formed on the second surface,
The first light control plate, the second light control plate, the third light control plate, and the fourth light control plate have a second light control plate on the upper side of the first light control plate. And is provided in the plate thickness direction so that the fourth light control plate is located above the third light control plate,
The first surface of the second light control plate is located on the second surface side of the first light control plate;
The extending direction of the convex part included in the second light control plate and the extending direction of the convex part included in the first light control plate are substantially parallel to each other. The first surface is located on the second surface side of the third light control plate,
The extending direction of the convex portion included in the fourth light control plate and the extending direction of the convex portion included in the third light control plate are substantially parallel.
The extending direction of each of the convex portions of the first and second light control plates and the extending direction of each of the convex portions of the third and fourth light control plates are substantially orthogonal. And
The cross-sectional shape orthogonal to the extending direction of each of the convex portions of the second and fourth light control plates is a triangle,
In the cross section perpendicular to the extending direction of each of the convex portions of the first and third light control plates, an axis passing through both ends is defined as a u axis, and the u passes through the center between the both ends on the u axis. When the axis perpendicular to the axis is the v-axis and the length in the u-axis direction is w _a for each of the convex portions of the first and third light control plates, the first and The contour shape of each of the convex portions of the third light control plate is represented by v (u) satisfying the following formula (1) when −0.475 w _a ≦ u ≦ 0.475 w _a . Light control board unit.

However, in the formula (1),

(In Formula (2), h _a is _a constant satisfying 0.20 w _a to 1.10 w _a and k _a is _a constant satisfying −1 and 0.75)   2. The light control plate unit according to claim 1, wherein a cross-sectional shape perpendicular to the extending direction of each of the convex portions of the second and fourth light control plates is an isosceles triangle having a substantially perpendicular vertex. .   The light control plate unit according to claim 1 or 2, wherein the first surface of each of the first to fourth light control plates is substantially flat. The light control plate unit according to any one of claims 1 to 3,
A plurality of point light sources for supplying light to the light control plate unit;
A surface light source device comprising: The light control plate unit according to any one of claims 1 to 3,
A plurality of point light sources for supplying light to the light control plate unit;
A transmissive image display unit that displays an image irradiated with light emitted from the light control plate unit;
A transmissive image display device comprising:

Images