JP2012199104A - Composite light control board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite light control board capable of uniformly dispersing light from a light source, and a planar light source device as well as a transmission type image display device, and a light control board equipped with the above.SOLUTION: In a downright surface light source device of a transmission type image display device, a composite light control board 21A arranged above the light source has a first and a second light control plates 30, 30, each having a first and a second convex parts arranged in parallel in an orthogonal direction to an extension direction, arranged in that order, and the extension directions of the first and the second convex parts 33, 33are arranged in parallel with each other.

Description

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

  As a direct type image display device 40 which is an example of a transmissive image display device, for example, as shown in FIG. 18, a device in which a light source 43 is arranged on the back side of a transmissive image display unit 50 is widely used. Examples of the transmissive image display unit 50 include a liquid crystal display panel in which linearly polarizing plates 52 and 53 are disposed on both surfaces of a liquid crystal cell 51. 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 50 by uniformly dispersing light from the light source 43, and for this reason, between the light source 43 and the transmissive image display unit 50. 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 50 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 such a surface light source device, it is preferable to make the interval between adjacent light sources as long as possible in that the number of light sources can be reduced to save power. Further, the distance between the light source and the light control plate is preferably as short as possible between the light source and the light control plate in that the transmission type image display device can be made thinner. However, in the conventional surface light source device, it is difficult to sufficiently diffuse light from a plurality of light sources if the distance between the light sources is set long or the distance between the light sources and the light control plate is set short. There is a problem that the brightness differs between the vicinity of the light source and the position away from the light source.

  Accordingly, an object of the present invention is to provide a composite light control plate capable of uniformly dispersing light from a light source, a surface light source device, a transmissive image display device, and a light control plate provided with the composite light control plate.

  The composite light control plate 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 perpendicular to one direction are provided with first and second light control plates formed on the second surface, and the second light control plate is the first light. It is provided in the plate thickness direction so as to be located on the upper side of the control plate, the first surface of the second light control plate is located on the second surface side of the first light control plate, and the second The extending direction of the convex portion of the first light control plate and the extending direction of the convex portion of the first light control plate are substantially parallel, and the first and second light control plates have respective convexities. The cross-sectional shape orthogonal to the extending direction is formed in a shape defined below.

Cross-sectional shape of the convex portion included in the first light control plate: in a cross section orthogonal to the extending direction of the convex portion included in the first light control plate, the convex portions included in the first light control plate are arranged in parallel. u _I axis axis passing through both ends with respect to the direction, the u on _I axis an axis perpendicular to the center of the both ends as the u _I axis v _I axis, u convex portion to which the first light control plate has when the length of the _I-axis direction is _{w Ia,} the shape in the range of _{-0.475w Ia ≦ u I ≦ 0.475w Ia} , represented by that satisfy the equation _{(1), v I0 (u} I) .

In the formula (1), v _I0 (u _I ) is defined by the formula (2).

In formula (2), h _Ia is 0.440 w _Ia and k _Ia is −0.550.

Cross-sectional shape of the convex portion included in the second light control plate: in a cross section orthogonal to the extending direction of the convex portion included in the second light control plate, the convex portions included in the second light control plate are arranged in parallel. u _II axis axis passing through both ends with respect to the direction, the u on _II-axis an axis perpendicular to the center of the both ends as the u _II axis v _II axes, u convex portion to which the second optical control plate has when the length of the _II axis direction is _{w IIa,} shape in the range of _{-0.475w IIa ≦ u II ≦ 0.475w IIa} , of formula (3) are satisfied _v II _{(u II).}

In formula (3), v _II0 (u _II ) is defined by formula (4).

In Formula (4), h _IIa is 0.3 w _IIa or more and 1.0 w _IIa or less, and k _IIa satisfies Formula (5).

Here, k _IIa1 and k _IIa2 are represented by Formula (6) and Formula (7).

In the formula (6), α ₁ = 8.62841, β ₁ = −34.85420, χ ₁ = 33.8544, δ ₁ = 17.19255, ε ₁ = −20.25226, φ ₁ = −26.13902 , Γ ₁ = 21.777536,

In the formula (7), α ₂ = 0.03724, β ₂ = 13.29232, χ ₂ = −33.48856, δ ₂ = 20.31892, ε ₂ = 13.56923, φ ₂ = −15.97616, γ ₂ = 2.94948.

In this configuration, the first light control plate included in the composite light control plate has a convex portion having a cross-sectional shape represented by v _I (u _I ) that satisfies the above formula (1) on the second surface. Further, the second light control plate included in the composite light control plate has a convex portion having a cross-sectional shape represented by v _II (u _II ) satisfying the above formula (3) on the second surface. have. Thereby, the light from the light source arranged on the first surface side of the first light control plate can be uniformly dispersed to form planar light.

  The composite light control plate according to the present invention further includes a first isotropic light diffusion plate capable of emitting light incident from the third surface as diffused light from a fourth surface located on the opposite side of the third surface. The first isotropic light diffusing plate is provided in the thickness direction so as to be positioned above the first light control plate, and the third surface of the first isotropic light diffusing plate is You may be located in the 2nd surface side of the 1st light control board.

  In this configuration, light isotropically diffuses by the isotropic light diffusing plate disposed on the second surface side of the first light control plate, so the first surface of the first light control plate The light from the light source arranged on the side can be emitted more uniformly dispersed.

  The composite light control plate according to the present invention further includes a second isotropic light diffusing plate capable of emitting light incident from the third surface as diffused light from a fourth surface located on the opposite side of the third surface. The second isotropic light diffusing plate is provided in the thickness direction so as to be positioned above the second light control plate, and the third surface of the second isotropic light diffusing plate is You may be located in the 2nd surface side of a 2nd light control board.

  In this configuration, light isotropically diffuses by the isotropic light diffusing plate disposed on the second surface side of the second light control plate, so the first surface of the first light control plate The light from the light source arranged on the side can be emitted more uniformly dispersed.

  A surface light source device according to the present invention is disposed apart from the above-described composite light control plate and supplies light to the first surface of the first light control plate constituting the composite light control plate. And a light source unit having the light source.

  In this configuration, since the above-described composite light control plate is provided, the light from the light source can be uniformly dispersed and emitted as planar light with high luminance uniformity on the surface orthogonal to the plate thickness direction. Become.

In the surface light source device according to the present invention, the ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 1.75 or more. In the above equation (6) showing k _IIa1 in the above equation (5) that is less than 25 and defines the cross-sectional shape of the second light control plate, α ₁ = 8.440520, β ₁ = −33.01269, χ ₁ = 29.28857, δ ₁ = 20.44040, ε ₁ = −18.87444, φ ₁ = −29.70226, γ ₁ = 23.1431, which defines the cross-sectional shape of the second light control plate In the above formula (7) indicating k _IIa2 in the above formula (5), α ₂ = 13.97149, β ₂ = −45.65173, χ ₂ = 35.18939, δ ₂ = 25.31623, ε ₂ = − 18.18153, φ ₂ = -33.36581 may be γ ₂ = 23.36307.

In the surface light source device according to the present invention, the ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 2.25 or more. In the above equation (6), which is less than 75 and defines k _IIa1 in the above equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 15.36687, β ₁ = −57.2375, χ ₁ = 52.22981, δ ₁ = 26.86604, ε ₁ = −30.266684, φ ₁ = −36.808847, γ ₁ = 29.94893, which defines the cross-sectional shape of the second light control plate In the equation (7) showing k _IIa2 in the above equation (5), α ₂ = 2.69179, β ₂ = −0.66679, χ ₂ = −8.30041, δ ₂ = 5.774519, ε ₂ = 5 97221, φ ₂ = −4.22110, γ ₂ = −0. 55377.

In the surface light source device according to the present invention, the ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 2.75 or more. In the above formula (6) showing k _IIa1 in the above formula (5) that is less than 25 and defines the cross-sectional shape of the second light control plate, α ₁ = 21.80916, β ₁ = −82.44499, χ ₁ = 110.81252, δ ₁ = −46.020425, ε ₁ = −30.36723, φ ₁ = 40.29250, γ ₁ = −13.64152, which defines the cross-sectional shape of the second light control plate In the above formula (7) showing k _IIa2 in the above formula (5), α ₂ = 2.35575, β ₂ = 0.17987, χ ₂ = −13.991425, δ ₂ = 18.10637, ε ₂ = 4.20522, φ ₂ = -18.52795, It can be ₂ = 8.22009.

In the surface light source device according to the present invention, the ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 3.25 or more. In the above equation (6), which is less than 75 and defines k _IIa1 in the above equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 9.669940, β ₁ = −28.97218, χ ₁ = 21.33353, δ ₁ = 18.009167, ε ₁ = −14.02321, φ ₁ = −23.87926, γ ₁ = 18.17066, which defines the cross-sectional shape of the second light control plate In the above formula (7) indicating k _IIa2 in the above formula (5), α ₂ = 2.778173, β ₂ = −0.12045, χ ₂ = −14.991041, δ ₂ = 18.27412, ε ₂ = 4.68363, φ ₂ = −16.58892, γ ₂ = 6.553802.

  A transmissive image display device according to the present invention includes the above surface light source device and a transmissive image display unit that is illuminated by light output from a plurality of light sources and passed through a composite light control plate. it can.

  In this configuration, since the above-described composite light control plate is provided, the light from the light source is uniformly dispersed and emitted as planar light having a high luminance uniformity on the surface orthogonal to the plate thickness direction. The display unit can be illuminated.

  In the light control plate according to the present invention, a plurality of first convex portions extending in one direction and having a cross-sectional shape defined below are formed on the emission surface, and the plurality of first convex portions are formed. A light control plate provided on the exit surface side with respect to the first light control plate arranged in parallel in a direction substantially orthogonal to the extending direction of the first convex portion, and the light emitted from the exit surface Are incident surfaces, opposite to the incident surface, and formed in a plurality of second convex portions extending in one direction and having a cross-sectional shape defined below. The second convex portion has a convex portion forming surface arranged in parallel in a direction substantially orthogonal to the extending direction of the second convex portion, and the extension of the second convex portion The direction is substantially parallel to the extending direction of the first convex portion.

Cross-sectional shape of the first convex portion: In a cross section orthogonal to the extending direction of the first convex portion, an axis passing through both ends with respect to the parallel direction of the first convex portion is a u _I axis and the u _I axis _{when v I} axis an axis perpendicular to the center of the both ends as the _{u I} axis, the _{u I} axis direction of the first convex portion length was _{w Ia} in the above, -0.475w _Ia ≦ u A shape represented by v _I (u _I ) satisfying the formula (8) in the range of _I ≦ 0.475w _Ia .

[In Expression (8), v _I0 (u _I ) is defined by Expression (9).

In formula (9), h _Ia is 0.440 w _Ia and k _Ia is −0.550.

Cross-sectional shape of the second convex portion: In a cross section orthogonal to the extending direction of the second convex portion, the axis passing through both ends of the second convex portion in the parallel direction is the u _II axis and the u _II axis -0.475w _IIa ≤u, where the axis passing through the centers of the both ends and orthogonal to the u _II axis is the v _II axis, and the length of the second convex portion in the u _II axis direction is w _IIa A shape represented by v _II (u _II ) satisfying the formula (10) in the range of _II ≦ 0.475w _IIa .

In formula (10), v _II0 (u _II ) is defined by formula (11).

In Formula (11), h _IIa is 0.3 w _IIa or more and 1.0 w _IIa or less, and k _IIa satisfies Formula (12).

Here, k _IIa1 and k _IIa2 are

In the formula (13), α ₁ = 8.62841, β ₁ = −34.85420, χ ₁ = 33.8544, δ ₁ = 17.19255, ε ₁ = −20.25226, φ ₁ = −26.13902 , Γ ₁ = 21.777536,

In the formula (14), α ₂ = 0.03724, β ₂ = 13.29232, χ ₂ = −33.48856, δ ₂ = 20.31892, ε ₂ = 13.66923, φ ₂ = −15.97616, γ ₂ = 2.94948.

The light control plate has a second convex portion having a cross-sectional shape represented by v _II (u _II ) that satisfies the above formula (10) on the second surface. Thereby, the surface from which the light from the light control plate having the first convex portion having the cross-sectional shape represented by v _I (u _I ) satisfying the above formula (8) is uniformly dispersed on the second surface. Light.

  According to the composite light control plate, the surface light source device and the transmissive image display device, and the light control plate having the same according to the present invention, light from the light source can be uniformly dispersed.

It is a perspective view which shows typically the structure of the transmissive image display apparatus which concerns on this embodiment. It is a perspective view of the light control board unit used for the transmissive image display apparatus shown in FIG. It is drawing which shows the example of the cross-sectional shape of the convex part which a 1st light control board has. It is drawing which shows the conditions which the cross-sectional shape of the convex part which a 1st light control board has satisfy | fills. It is drawing which shows the example of the cross-sectional shape of the convex part which a 2nd light control board has. It is drawing which shows the conditions which the cross-sectional shape of the convex part which a 2nd light control board has satisfy | fills. It is a schematic diagram of the simulation for calculating the shape of the 2nd light control board concerning this embodiment. The figure which shows intensity | strength uniformity distribution when L / D is 1.75 or more and less than 2.25. The figure which shows intensity | strength uniformity distribution when L / D is 2.25 or more and less than 2.75. The figure which shows intensity | strength uniformity distribution when L / D is 2.75 or more and less than 3.25. The figure which shows intensity | strength uniformity distribution when L / D is 3.25 or more and less than 3.75. It is a figure for demonstrating the calculation method of the shape of the 2nd light control board which concerns on this embodiment. It is a perspective view which shows 2nd Embodiment of a light-control board unit. It is a perspective view which shows 3rd Embodiment of a light control board unit. It is a perspective view which shows 4th Embodiment of a light control board unit. It is a perspective view which shows 5th Embodiment of a light control board unit. It is a graph which shows the implementation conditions in each Example and each comparative example, and its intensity | strength uniformity. 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. Further, 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.

(First embodiment)
[Transparent image display device]
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 is an exploded view of a transmissive image display device.

  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-axis direction (plate thickness direction), and is two directions orthogonal to the z-axis direction. Two directions orthogonal to each other are referred to as an x-axis direction and a y-axis 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 a transmissive image display device 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 (Thin Film Transistor) type and STN (Super Twisted Nematic) type.

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

Light control plate unit 21A is a first light control plate 30 ₁ and the second composite light control plate comprising a light control plate 30 ₂ (see FIG. 2). First and second light control plate ₃₀ 1, 30 ₂ are provided in the thickness direction (z-axis direction) to the first light control plate 30 _1, a second order of the light control plate 30 _2. The planar view shapes (the shapes seen from the z-axis direction) of the first and second light control plates 30 ₁ and 30 ₂ constituting the light control plate unit 21A are substantially the same, and are usually rectangular. First and second light control plate 30 _1, 30 ₂ of the plan view shape, in other words, the size of the planar shape of the light control plate unit 21A conforms to the screen size of the transmissive image display device 1 for the purpose However, it is usually 250 mm × 440 mm or more, preferably 1020 mm × 1800 mm or less. Plan view shape of the first light control plate 30 ₁ and the second light control plate 30 ₂ is not limited to a rectangle, it may be square, but in the following, unless otherwise specified, be described as a rectangle.

  The light source 22 is a linear light source extending in a direction (y-axis direction) orthogonal to the arrangement direction (x-axis direction) of the plurality of light sources 22, and is a straight tube like a fluorescent lamp (cold cathode ray lamp). Are illustrated. The plurality of light sources 22 are arranged at intervals so that the central axes of the light sources 22 are located in the same plane P1, and the distance between the central axes of the two adjacent light sources 22 and 22 is L. The distance L is, for example, 10 mm to 150 mm. Here, the light source 22 is linear, but it is also possible to use a point light source such as an LED. Note that the plane P1 shown in FIG. 1 is a virtual plane for convenience of explanation.

When the separation distance between the _first light control plate 301 and the light source 22 included in the light control plate unit 21A is D, the separation distance D is, for example, 3 mm to 50 mm. In the surface light source device 20, in order to reduce the thickness, L / D is 1.5 or more, preferably L / D is 2.0 or more, more preferably L / D is 2.5 or more. The distance L and the separation distance D between the two adjacent light sources 22 and 22 are selected.

  As shown in FIG. 1, the plurality of light sources 22 are preferably arranged in the lamp box 23, and the inner surface 23 a of the lamp box 23 is preferably formed as a light reflecting surface. This is because the light output from each light source 22 is reliably output to the transmissive image display unit 10 side, so that the light from each light source 22 can be used efficiently.

[First light control plate]
The first light control plate 30 _1, as shown in FIG. 2, substantially flat lower surface (first surface) 31 _1, the convex portion is convex to the second light control plate 30 ₂ side (the first (Convex portion) 33 ₁ is a plate-like body having an upper surface (second surface) 32 ₁ on which a plurality of convex portions are formed.

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. The first lower surface 31 ₁ of the light control plate 30 ₁ is usually a flat surface may be a mirror surface may be a surface having a light diffusing property over the entire surface.

Convex portion 33 ₁ extends in the direction Y1 substantially parallel to the y-axis direction, are arranged in parallel in a direction X1 which is substantially orthogonal to the extending direction Y1. The extending direction Y1 and the parallel direction X1 are preferably parallel to the y-axis direction and the x-axis direction, respectively, but may be shifted by about ± 10 ° due to manufacturing errors, for example. 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 and 33a ₁ of the two adjacent convex portions 33 ₁ and 33 ₁ are at the same position in the parallel direction X1. First thickness _{d 1} of the light control plate 30 ₁ is a z-axis direction between the top portion 33b ₁ of the lower surface 31 ₁ and the convex portion 33 _1, typically is 0.1mm or more 5mm or less. The most first light control plate 30 ₁ is disposed at a position closer to the light source 22 side, is desirable not less than a sheet 1mm thick.

[Convex portion of first light control plate]
The shape of the convex portion 33 ₁ in which the first light control plate 30 ₁ has will be described with reference to FIGS. In FIG. 3, are set to _u I _{v I} coordinate system parallel direction X1 orthogonal to the extending direction Y1 of the convex portion 33 ₁ shown in FIG. 2 as _{u I} axis. Here, u _I axis corresponds to an axis parallel (x-axis) (see FIG. 2) in the direction in which the plurality of convex portions 33 ₁ are parallel. v _I axis corresponds to an axis parallel (z-axis) (see FIG. 2) to a second thickness direction of the light control plate 30 _1. In the u _I v _I plane of the u _I v _I coordinate system, the cross-sectional shape of the convex portion 33 ₁ is such that both ends 33a ₁ and 33a ₁ are located on the u _I axis and the top portion 33b ₁ is located on the v _I axis. To do.

Sectional shape of the convex portion 33 ₁ is represented by _v I _{(u I)} which satisfies the following equation (15).

In Expression (15), v _I0 (u _I ) is defined by Expression (16).

In Formula (16), w _Ia is the length of the convex portion 33 _{1 in} the u _I axis direction, and h _Ia is a convex shape when the convex portion 33 ₁ is shaped as v _I0 (u _I ). corresponding to the maximum height between two ends _33a 1, 33a ₁ parts 33 _1. Further, k _Ia is a parameter indicating the sharpness of the apex 33b ₁ of the convex portion 33 ₁ .

Here, h _Ia is 0.440 w _Ia . The k _Ia is −0.550.

FIG. 4 shows a case where h _Ia is 0.440 w _Ia , k _Ia is −0.550, and v _I (u _I ) = v _I0 (u _I ). In this case, the sectional shape of the convex portion 33 ₁ has a symmetrical contour relative to v _I axis. However, as shown in FIG. 4, when v _I0 (u _I ) is obtained for a certain width w _Ia , the contour line is represented by 0.95 × v _I0 (u _I ), Any contour line may be used as long as it passes through a region between the contour lines indicated by 1.05 × v _I0 (u _I ). In other words, in the above formula _{(15), v I (u} I n) is for any position _{u I} n, corresponding to the height of the convex portion 33 ₁ at the position _{u I} n. Therefore, _v I for any position _{u I} n _{(u I} n) may be satisfies _{0.95 V} I0 to _(u I n) or _1.05v I0 _(u I n).

In consideration of the influence on the manufacturing error and the intensity uniformity distribution at near both ends of the convex portion 33 _1, the cross-sectional shape of the convex portion 33 _1, -0.475w _Ia ≦ _{u I} ≦ 0.475w _{In Ia} , it may be expressed by v _I (u _I ) satisfying the above formula (15). While the molding errors around the skirt of the convex portion 33 ₁ (near end) is in the relatively large tends, influence the shape in the vicinity of the skirt has on the diffusion of light is because small.

Width _{w Ia} of the convex portion 33 _1, since formation of the convex portion 33 ₁ is easy, usually 40μm or more, preferably 250μm or more, the pattern caused by the convex portion 33 ₁ 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 _Ia include w _Ia = 250 μm and w _Ia = 330 μm, but the value of w _Ia is not limited to this.

[Second light control plate]
The second light control plate 30 _2, as shown in FIG. 2, a substantially flat lower surface (first surface) 31 _2, on the side opposite to the first side where the light control plate 30 ₂ is disposed convex portion is convex a (second convex portions) 33 ₂ has multiple forms top surfaces (second surface) 32 ₂ and the plate-like body having a.

The second light control plate 30 _2, 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 _2. The second light control plate 30 _2, since the deflecting direction of light emission by emitting position of light from the convex portion 33 _2, deflecting plate both the shape to adjust the deflection of the light is applied I can say that. Here, although referred to as a “plate”, it may be a sheet having a thickness of 1 mm or more, or may be a film having a thickness of less than 1 mm. The lower surface 31 ₂ of the second light control plate 30 ₂ is typically a flat surface may be a mirror surface may be a surface having a light diffusing property over the entire surface.

Convex portion 33 ₂ extends substantially in a direction parallel (extending direction) Y2 in the y-axis, are arranged in parallel in a direction (parallel direction) X2 substantially perpendicular to the extending direction Y2. The extending direction Y2 and the parallel direction X2 are preferably parallel to the y-axis and the x-axis, respectively, but may be shifted by about ± 10 ° due to manufacturing errors, for example. 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 Y2 of the convex portion 33 _2, the cross-sectional shape is substantially uniform. End _33a 2, 33a ₂ of two adjacent convex portions ₃₃ 2, 33 ₂ are in the same position in the parallel direction X2. Second thickness _{d 2} of the light control plate 30 ₂ is a z-axis direction between the top portion 33b ₂ of the lower surface 31 ₂ and the convex portion 33 _2, typically is 0.1mm or more 5mm or less.

[Convex part of second light control plate]
The shape of the convex portion 33 ₂ having the second light control plate 30 ₂ is described with reference to FIGS. In Figure 5 sets the _u II _{v II} coordinate system parallel direction X2 orthogonal to the extending direction Y2 of the convex portion 33 ₂ shown in FIG. 2 as _{u II} axis. Here, u _II axis corresponds to an axis parallel to the parallel direction of the plurality of convex portions 33 ₂ (x-axis) (see FIG. 2). v _II axis corresponds to an axis parallel (z-axis) (see FIG. 2) to a second thickness direction of the light control plate 30 _2. In _u II _{v II} plane of the _u II _{v II} coordinate system, the cross-sectional shape of the convex portion 33 _2, both ends _33a 2, 33a ₂ is located on the _{u II} axis, top 33b ₂ is positioned on the _{v II} axis To do.

Sectional shape of the convex portion 33 ₂ is represented by _v II _{(u II)} which satisfies the following equation (17).

In formula (17), v _II0 (u _II ) is defined by formula (18).

In the formula _{(18), w IIa} is the length of _{u II-axis} direction of the convex portion 33 _{2, h IIa} is convex in case of the shape shown a convex portion 33 _{2 v} in II0 _{(u II)} corresponding to the maximum height between two ends _33a 2, 33a ₂ parts 33 _{2. Also, k IIa} is a parameter indicating the pointed how the top 33b ₂ of the convex portion 33 _2.

Here, h _IIa is 0.3 w _IIa or more and 1.0 w _IIa or less. Further, k _IIa satisfies the formula (19).

However, _kIIa1 in Formula (19) is represented by Formula (20).

Here, α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , and γ ₁ in equation (20) representing k _IIa1 are as shown in Table 1 below.

Further, k _IIa2 in the above formula (19) is represented by formula (21).

Here, α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , and γ ₂ in the formula (21) representing k _IIa2 are as shown in Table 2 below.

FIG. 6 shows a case where h _IIa is 0.55w _IIa , k _IIa is 0.20, and v _II (u _II ) = v _II0 (u _II ). In this case, the sectional shape of the convex portion 33 ₂ has a symmetrical contour relative v _II axis. However, as shown in FIG. 6, when v _II0 (u _II ) is obtained for a certain width w _IIa , the contour line is expressed by 0.95 × v _II0 (u _II ), _Any contour line may be used as long as it passes through a region between the contour lines indicated by 1.05 × v _II0 (u _II ). In other words, in the above formula _{(17), v II (u} II n) is for any position _{u II} n, corresponding to the height of the convex portion 33 ₂ at position _{u II} n. Therefore, it is only _necessary that v _II (u _II n) for an arbitrary position u _II n satisfy _{0.95v II0} (u _II n) or more and 1.05 _{v II0} (u _II n).

In consideration of the influence on the manufacturing error and the intensity uniformity distribution at near both ends of the convex portion 33 _2, the cross-sectional shape of the convex portion 33 _2, -0.475w _IIa ≦ _{u II} ≦ 0.475w _{In IIa} , it may be represented by v _II (u _II ) that satisfies the above formula (17). While the molding errors around the skirt of the convex portion 33 ₂ (near end) is in the relatively large tends, influence the shape in the vicinity of the skirt has on the diffusion of light is because small.

Width _{w IIa} of the convex portion 33 _2, since the formation of the convex portion 33 ₂ is easy, usually 20μm or more, preferably 40μm or more, the pattern caused by the convex portion 33 ₂ is visually recognized with 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 _IIa include w _IIa = 50 μm, w _IIa = 77 μm, and w _IIa = 100 μm, but the value of w _IIa is not limited thereto.

Range of _h IIa _{/ w IIa} and _{k IIa} in the convex portion 33 ₂ may satisfy the range described above, but the distance between two adjacent light sources 22 is L, the light control plate from a light emitting portion of the light source 22 _Assuming that the distance to the surface of the unit 21A on the light source 22 side is D, parameters for determining a preferable range of k _IIa for L / D, that is, k _IIa1 and k _IIa2 are as shown in the following tables. is there.

(1) When L / D is 1.75 or more and less than 2.25

(2) When L / D is 2.25 or more and less than 2.75

(3) When L / D is 2.75 or more and less than 3.25

(4) When L / D is 3.25 or more and less than 3.75

[Disposition relation of first and second light control plates]
The first and second light control plates 30 ₁ and 30 ₂ are provided in the z-axis direction so as to satisfy the following conditions.
(i) a second light control plate 30 ₂ is located at the first upper optical control plate 30 _1.
(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) a first light control plate 30 ₁ in the extending direction Y1 of the convex portion 33 _1, a second light control plate 30 _{and second} extending direction Y2 of the convex portion 33 ₂ are parallel. Which is preferably parallel to the convex portion 33 ₁ of the extending direction Y1 and the convex portion 33 ₂ in the extending direction Y2, it may be offset approximately 10 °.

The first and second light control plates 30 ₁ and 30 ₂ are provided in this order from the light source 22 side in the z-axis direction. The first light control plate 30 ₁ second and the light control plate 30 ₂ is usually superposed via an air layer. 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 the distance in the z-axis direction between the lower surface 31 _2, 5 mm or less can be exemplified. From the viewpoint of the light control plate unit 21A and compact _{ones, d 12} is 0 mm, the first convex portion 33 ₁ of the light control plate 30 ₁ and the second and the lower surface 31 ₂ of the light control plate 30 ₂ You may arrange | position so that it may contact | connect. Thus, in the case of providing in contact with the second light control plate 30 ₂ to the first light control plate 30 ₁ on the second light control plate 30 ₂ a thickness d ₂ first light control it is preferable to use a thinner than the thickness d ₁ of the plate 30 _1. For example, since the second light control plate 30 ₂ If assumed thinner such film form, can be used first light control plate 30 ₁ as the second support bars of the light control plate 30 _2.

The first light control plate 30 ₁ and the second light control plate 30 ₂ constituting the light control plate unit 21A may only have been without simply superimposed be fixed to each other. Further, the light control plate unit 21A, by the positions of respective members constituting them are moved together, the top 33b ₁ and the convex portion 33 ₁ of the first light control plate 30 _1, a second light control plate to prevent the lower surface 31 ₂ of 30 ₂ from being damaged, for example, at the edge, it may be bonded to each other.

[Constituent materials of the first and second light control plates]
The first and second light control plates 30 ₁ and 30 ₂ are made of a transparent material. The refractive index of the transparent material is usually 1.46 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), acrylic ultraviolet curable resin ( Refractive index: 1.46 to 1.58) is exemplified, and polystyrene resin is preferable in terms of cost and low water 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 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 above-described transparent material mainly constituting the first and second light control plates 30 ₁ and 30 ₂ is usually used and 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. .

  In addition, the surface on the light source 22 side can be a surface having light diffusibility in order to reduce moire. For example, the surface on the light source 22 side may be constituted by a skin layer containing fine particles called a matting agent, the surface on the light source 22 side may be embossed or blasted, A matte layer may be formed by applying a coating solution containing a binder.

[Layer structure of the first and second light control plates]
The first and second light control plates 30 ₁ and 30 ₂ may be single-layer plates made of a single transparent material, or may have a structure in which layers made of different transparent materials are laminated. It may be a plate. When the first and second light control plates 30 ₁ and 30 ₂ are multilayer plates, a skin layer having a thickness of usually 10 μm or more and 200 μm or less, preferably 20 μm or more and 100 μm or less is formed on one side or both sides of the light control plate. It is preferable to use a transparent resin material to which an ultraviolet absorber is added as the transparent resin material constituting the skin layer. With this configuration, it is possible to prevent the light source 22 and the first and second light control plates 30 ₁ and 30 ₂ from being deteriorated by ultraviolet rays that may be included in light from the outside. If the proportion of is used relatively large, because it can prevent deterioration due to ultraviolet rays, it is preferable that the lower surface 31 _1, 31 ₂ in the skin layer is formed, in this case the upper surface 32 _1, 32 ₂ It is more preferable in terms of cost that no skin layer is formed. When the transparent resin material constituting the skin layer is added with an ultraviolet absorber, the content is usually 0.5% by mass or more and 5% by mass or less, preferably 1% by mass or more based on the transparent resin material. 2.5% by mass or less.

The first and second light control plates 30 ₁ and 30 ₂ may be coated with an antistatic agent on one side or both sides. By applying this antistatic agent, it is possible to prevent adhesion of dust due to static electricity and the like, and to prevent a decrease in light transmittance due to adhesion of dust.

[Manufacture of first and second light control plates]
The first and second light control plates 30 ₁ and 30 ₂ 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.

Next, the function and effect of the light control plate unit 21A will be described by taking as an example the case where the surface light source device 20 including the light control plate unit 21A as shown in FIG. 2 is applied to a transmissive image display device. In this configuration, the first and second light control plates 30 ₁ , 30 ₂ have the above-described convex portions 33 ₁ , 3 ₂ having the cross-sectional shape, so when these are arranged on the light source 22, light from the light source 22 along the direction (x-axis direction) substantially perpendicular to the first and second light control plate ₃₀ 1, 30 ₂ of the convex portion ₃₃ 1, 33 ₂ in the extending direction (y-axis direction) Is converted into linear light. Thus, the light control plate unit 21A, it is possible to first light from the light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly distributed so with planar light .

Here, when the first and second light control plates having the convex portions 33 ₁ and 33 ₂ having the cross-sectional shape described above are arranged on the light source 22 under predetermined arrangement conditions, the light from the light source 22 is uniformly dispersed. Based on the simulation, it will be described that the light is planar. The simulation was performed by the ray tracing method described below.

FIG. 7 is a schematic diagram showing a simulation model. The simulation on the two light sources 22, 22, the first light control plate 30 ₁ and the second light control plate 30 ₂ having a shape of a predetermined convex portion via a small air layer, convex The first light control plate 30 ₁ and the second light control plate 30 ₂ are arranged in this order so that the extending directions of the parts 33 ₁ and 33 ₂ are parallel to each other, and pass through the _second light control plate 302. The light intensity is calculated. In the simulation, there are three approximations:
(I) performing a simulation in a plane orthogonal to the light source 22;
(Ii) The light source 22 is a point light source, that is, the diameter of the light source is 0, and
(Iii) consider only direct transmitted light,
It was adopted. For convenience of explanation, the two light sources 22 and 22 shown in FIG. 7 are referred to as a light source 22A and a light source 22B, respectively.

In performing the simulation, the following conditions were set.
Distance L between the two light sources 22A and 22B: 45 (mm)
Distance D from light emitting part of light source 22 to light source 22 side surface of light control plate unit 21A: 12.86, 15.00, 18.00, 22.50 (mm)
First thickness of the light control plate _{30 1 d 1: 1.5 (mm} )
The first light control plate 30 ₁ of the refractive index: 1.59
Width _w Ia of the first convex portion of the light control plate 30 _1: 250 (μm)
Height h _Ia of convex portion of _first light control plate ₃₀₁ : 110 (μm)
First kurtosis of the convex portion of the light control plate 30 _{1 k} Ia: -0.550
Thickness d _{2 of second} light control plate 302: 0.25 (mm)
The second light control plate 30 ₂ having a refractive index: 1.59

Under such conditions, the first light control plate 30 ₁ sets a predetermined L / D (L / D = 2.00,2.50,3.00,3.50), this for each set L / D, changing each condition _{(h IIa / w IIa, k} IIa) in a pattern of total 615 that combines the second light control plate 30 ₂ having a shape shown in the following, first the time The intensity uniformity of the light passing through the _second light control plate 302 was calculated. In setting the predetermined L / D, the distance between the two light sources 22A and 22B is constant, and the distance D from the light emitting part of the light source 22 to the surface of the light control plate unit 21A on the light source 22 side is 12 respectively. .86, 15.00, 18.00, 22.50 (mm).
_{(1) h IIa / w IIa} : 0.3~1.0 up at 0.05 intervals 15 pattern ₍₂₎ k IIa: 41 pattern with 0.05 intervals to -1.0 + 1.0

  In calculating the intensity uniformity of the light, the intensity uniformity (%) in the front direction (θ = 0) was calculated for each L / D. The intensity uniformity (%) was calculated as “(minimum intensity) / (maximum intensity) × 100”. Since the intensity for a certain observation angle θ corresponds to the luminance, the intensity uniformity based on the intensity for a certain observation angle θ corresponds to the luminance uniformity.

Based on the intensity uniformity of light calculated by the simulation described above for each L / D of 2.00, 2.50, 3.00, and 3.50, as shown in FIGS. The intensity uniformity distribution was calculated with the vertical axis representing k _IIa and the horizontal axis representing h _IIa / w _IIa . The legend in FIGS. 8 to 11 shows the intensity uniformity. 8 to 11, the shape of the second light control plate (h _IIa / w _IIa ) for each L / D (L / D = 2.00, 2.50, 3.00, 3.50). , K _IIa ) and the intensity uniformity can be confirmed.

For example, when L / D is 2.00, h _IIa / w _IIa is 0.3 or more and 1.0 or less, and the intensity uniformity is 80% or more (shaded area in FIG. 8). Each parameter of k _IIa1 and k _IIa2 that satisfies the above is calculated. These parameters are k _IIa1 parameters (α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , γ ₁ ) shown in Table 3 and k _IIa2 parameters (α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ). Therefore, the second light control plate 30 _2, if it has a range of _{k IIa} indicated by _{k IIa1} and _{k IIa2} defined by the parameters shown in Tables 3 and 4 as the shape of the convex portion, strength uniformity in the front direction of the light emitted from the second light control plate 30 ₂ is 80% or more.

Similarly, when L / D is 2.50, in the intensity uniformity distribution shown in FIG. 9, h _IIa / w _IIa is 0.3 or more and 1.0 or less, and the intensity uniformity is 80% or more. Each parameter of k _IIa1 and k _IIa2 is calculated so as to satisfy the region (the hatched region in FIG. 9). These parameters are k _IIa1 parameters (α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , γ ₁ ) shown in Table 5 and k _IIa2 parameters (α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ). Therefore, the second light control plate 30 _2, if it has a range of _{k IIa} indicated by _{k IIa1} and _{k IIa2} defined by the parameters shown in Tables 5 and 6 as the shape of the convex portion, strength uniformity in the front direction of the light emitted from the second light control plate 30 ₂ is 80% or more.

Similarly, when L / D is 3.00, in the intensity uniformity distribution shown in FIG. 10, h _IIa / w _IIa is 0.3 or more and 1.0 or less, and the intensity uniformity is 80%. Each parameter of k _IIa1 and k _IIa2 is calculated so as to satisfy the above region (the shaded region in FIG. 10). These parameters are k _IIa1 parameters (α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , γ ₁ ) shown in Table 7 and k _IIa2 parameters (α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ). Therefore, the second light control plate 30 _2, if it has a range of _{k IIa} indicated by _{k IIa1} and _{k IIa2} defined by the parameters shown in Tables 7 and 8 as the shape, a second light front direction of the intensity uniformity of the light emitted from the control plate 30 ₂ is 80% or more.

Similarly, when L / D is 3.50, in the intensity uniformity distribution shown in FIG. 11, h _IIa / w _IIa is 0.3 or more and 1.0 or less, and the intensity uniformity is 80%. Each parameter of k _IIa1 and k _IIa2 is calculated so as to satisfy the above region (the shaded region in FIG. 11). These parameters are k _IIa1 parameters (α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , γ ₁ ) shown in Table 9 and k _IIa2 parameters (α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ). Therefore, the second light control plate 30 _2, if it has a range of _{k IIa} indicated by _{k IIa1} and _{k IIa2} defined by the parameters shown in Tables 9 and 10 as a shape, a second light front direction of the intensity uniformity of the light emitted from the control plate 30 ₂ is 80% or more.

In the present embodiment, as described above, k _IIa1 satisfying a region including all regions (shaded regions in FIGS. 8 to 11) in which the intensity uniformity calculated for each L / D is 80% or more, and Each parameter of _kIIa2 is calculated. These parameters are k _IIa1 parameters (α ₁ , β ₁ , χ ₁ , δ ₁ , ε ₁ , φ ₁ , γ ₁ ) shown in Table ₁ and k _IIa2 parameters (α ₂ ) shown in Table _2. , Β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ).

Specifically, each parameter _{k IIa1} in the formula _{(20) (α 1, β} 1, χ 1, δ 1, ε 1, φ 1, γ 1) k and of the formula shown in Table 2 (21) _IIa2 An example of a method for calculating each parameter (α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ) will be described. First, for each L / D, based on the intensity uniformity distribution, the boundary of the region where the intensity uniformity is 80% or more is calculated as a sixth-order polynomial, and as shown in FIG. _Are plotted on a graph with k _IIa and the horizontal axis h _IIa / w _IIa , respectively.

Next, as shown in FIG. 12B, based on the graph obtained by tracing the above four sixth-order polynomials, a boundary that includes all the regions where the intensity uniformity is 80% or more is searched. At this time, as shown in FIG. 12 (b), it can be plotted at a predetermined interval in anticipation of 10 percent the allowable region with respect to k _IIa at the point on the selected boundary. Accordingly, as shown in FIG. _12C , curves satisfying k _IIa1 and k _IIa2 represented by the parameters shown in Table 1 and Table 2 are calculated.

Each parameter _{k IIa1} in the formula _{(20) (α 1, β} 1, χ 1, δ 1, ε 1, φ 1, γ 1) and the parameters of _{k IIa2} of formula (21) shown in Table 2 ( α ₂ , β ₂ , χ ₂ , δ ₂ , ε ₂ , φ ₂ , γ ₂ ) are values calculated in this way, and therefore the first and second light control plates 30 ₁ , 30 ₂ are subjected to the above conditions. (i) when placed in ~ (iii), that the first light from the light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly distributed so with planar light it can.

(Second Embodiment)
FIG. 13 is a perspective view showing a second embodiment of the light control plate unit. Light control plate unit (composite light control plate) 21B has a first light control plate 30 _1, a first isotropic light diffusion plate 30 ₃ and second light control plate 30 _2. Light control plate unit 21B, in the thickness direction, in that the first light control plate 30 ₁ and the first isotropic light diffuser 30 ₃ between the second light control plate 30 ₂ is disposed, light It is different from the control plate unit 21A. Hereinafter, description of the first light control plate 30 ₁ and the second light control plate 30 ₂ included in the light control plate unit 21A is omitted, around the first isotropic light diffusion plate 30 ₃ is the difference Explained.

[First isotropic light diffuser]
First isotropic light diffusion plate 30 ₃ are both substantially flat lower surface (third surface) 31 ₃ and top plate member having a (fourth surface) 32 _3. The first isotropic light diffusing plate 30 ₃ is an optical element that can be emitted from the upper surface 32 ₃ while isotropically scattering the light incident on the lower surface 31 _3. For example, a light diffusing agent is dispersed in a transparent material. And a substrate in which a light diffusing agent is applied to the surface of a substrate made of a transparent material, and a substrate in which a fine circular convex lens is formed on the surface of a substrate made of a transparent material. Further, the thickness d ₃ of the first isotropic light diffusion plate 30 ₃ is usually 0.1 mm or more and 5 mm or less, and may be a film shape of less than 1 mm, or a sheet shape of 1 mm or more. Good.

As the light diffusing agent, a powder having a refractive index different from that of the above-described transparent material mainly constituting the first and second light control plates 30 ₁ and 30 ₂ and the first isotropic light diffusing plate 30 ₃ is usually used. Used and dispersed in a transparent material. 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. .

As a first isotropic light diffusion plate 30 _3, for example, by Keiwa Corp. of light diffusing film (BS-912: Thickness 120 [mu] m, a haze 89%) can be applied. However, isotropic diffusion plate is used as the first isotropic light diffusion plate 30 ₃ is not limited thereto.

[Disposition relationship of the first and second light control plates and the first isotropic light diffusion plate]
The first and second light control plates 30 ₁ and 30 ₂ and the first isotropic light diffusion plate 30 ₃ are provided in the z-axis direction so as to satisfy the following conditions. That is, in addition to the arrangement conditions (i) to (iii) described in the first embodiment, the arrangement conditions (iv) and (v) are also satisfied.
(iv) a first isotropic light diffusion plate 30 ₃ is located on the first upper optical control plate 30 _1.
(v) a first isotropic light diffuser 30 ₃ of the lower surface ₃₁₃ is positioned in the first surface 32 ₁ side of the light control plate 30 _1.

The first light control plate 30 _1, a first isotropic light diffusion plate 30 _3, the second light control plate 30 ₂ is provided from the light source 22 side in the z-axis direction in this order. The first light control plate 30 ₁ and the first isotropic light diffusion plate 30 _3, usually superimposed via an air layer. The distance _{d 13} between the first light control plate 30 ₁ and the first isotropic light diffusing plate 30 _3, the first top 33b ₁ of the convex portion 33 ₁ of the light control plate 30 ₁ and the first isotropic light the distance in the z-axis direction between the lower surface ₃₁₃ of the diffusion plate 30 _3, 5 mm or less can be exemplified. Further, the first isotropic light diffuser 30 ₃ of the second and the light control plate 30 ₂ is usually superposed via an air layer. The distance _{d 32} between the first isotropic light diffusion plate 30 ₃ and the second light control plate 30 ₂ has a first isotropic light diffuser 30 ₃ of the top surface 32 ₃ of the second lower surface of the light control plate 30 ₂ 31 is the distance in the z-axis direction between the _2, 5 mm or less can be exemplified.

As in the first embodiment, from the viewpoint of the light control plate unit 21B and compact _ones, as d _{13, d 32} is 0 mm, the first light control plate 30 ₁ first equal anisotropic light diffusion plate 30 ₃ and the second and the light control plate 30 ₂ may be disposed. For the same reason as that described in the first embodiment, the first first isotropic light diffusion plate 30 ₃ and the second light control plate 30 on the light control plate 30 ₁ which is disposed closest to the light source side when providing, as contact _2, the first isotropic light thickness of the diffusion plate 30 ₃ d ₃ and a second light control plate 30 ₂ thickness d _2, the first light control plate 30 ₁ thickness it is preferable that those be thinner than d _1.

According to the optical control plate unit 21B, similar to the light control plate unit 21A, the light from the first light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly dispersed in a planar It becomes possible to use light. Further, the light from the light source 22 so light isotropically by isotropic light diffusing plate disposed on the first surface 32 ₁ side of the light control plate 30 ₁ is to be spread, by more uniformly dispersed The light can be emitted.

(Third embodiment)
FIG. 14 is a perspective view showing a third embodiment of the light control plate unit. Light control plate unit (composite light control plate) 21C has a first light control plate 30 _1, a first isotropic light diffusion plate 30 ₃ and second light control plate 30 _2. In the light control plate unit 21C, the first light control plate 30 ₁ , the second light control plate 30 ₂ , and the first isotropic light diffusion plate 30 ₃ are arranged in this order from the light source 22 side in the z-axis direction (plate thickness direction). However, the other points are the same.

In the light control plate unit 21C, the first light control plate 30 _1, the second light control plate 30 ₂ and the first isotropic light diffusion plate 30 ₃ are provided from the light source 22 side in the z-axis direction in this order In addition to the arrangement conditions (i) to (iii) described in the first embodiment, the arrangement conditions (iv) and (v) are also satisfied.

The first light control plate 30 ₁ second and the light control plate 30 ₂ is usually superposed via an air layer. The first distance _{d 12} between the light control plate 30 ₁ and the second light control plate 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 the distance in the z-axis direction between 30 ₂ of the lower surface 31 _2, 5 mm or less can be exemplified. The second light control plate 30 ₂ and the first isotropic light diffusion plate 30 _3, usually superimposed via an air layer. The second light control plate 30 ₂ and the first isotropic light diffusion plate 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 first isotropic light the distance in the z-axis direction between the lower surface ₃₁₃ of the diffusion plate 30 _3, 5 mm or less can be exemplified.

As in the first embodiment, from the viewpoint of the light control plate unit 21C compact _ones, as d _{12, d 23} is 0 mm, the first light control plate 30 ₁ second light control plate 30 ₂ and the first isotropic light diffuser 30 ₃ may be disposed. For the same reason as that described in the first embodiment, the first light control plate 30 ₁ on the second light control plate 30 ₂ and the first isotropic light diffusing plate disposed closest to the light source 30 when providing ₃ in contact with the second light control plate 30 ₂ having a thickness d ₂ and a first thickness d ₃ of the isotropic light diffusion plate 30 _3, the first light control plate 30 ₁ thickness it is preferable that those be thinner than d _1.

According to the optical control plate unit 21C, like the light control plate unit 21A, the light from the first light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly dispersed in a planar It becomes possible to use light. Further, the light from the light source 22 so light isotropically by isotropic light diffusing plate disposed on the first surface 32 ₁ side of the light control plate 30 ₁ is to be spread, by more uniformly dispersed The light can be emitted.

(Fourth embodiment)
FIG. 15 is a perspective view showing a fourth embodiment of the light control plate unit. Light control plate unit (composite light control plate) 21D, the first light control plate 30 _1, a first isotropic light diffusion plate 30 _3, the second light control plate 30 ₂ and the second isotropic light diffuser 30 ₄ Have Light control plate unit 21D differs from the light control plate unit 21B in that the second upper light control plate 30 ₂ second isotropic light diffuser 30 ₄ are disposed. Hereinafter, the description of the first light control plate 30 ₁ , the first isotropic light diffusing plate 30 ₃ , and the second light control plate 30 ₂ included in the light control plate unit 21B is omitted, and the difference is described above. It will be mainly described second isotropic light diffuser 30 _4.

[Second isotropic light diffuser]
The second isotropic light diffuser 30 ₄ are both substantially flat lower surface (third surface) 31 ₄ and a top plate member having a (fourth surface) 32 _4. The second isotropic light diffuser 30 ₄ while isotropically scatter the light incident on the lower surface 31 ₄ an optical element which can be emitted from the upper surface 32 _4, a light diffusing agent is dispersed in a transparent material And a substrate in which a light diffusing agent is applied to the surface of a substrate made of a transparent material, and a substrate in which a fine circular convex lens is formed on the surface of a substrate made of a transparent material. The second thickness _{d 4} of the isotropic light diffuser 30 ₄ is usually at 0.1mm or 5mm or less, may be a 1mm less than film-like, even more than 1mm sheet Good.

A second isotropic light diffuser 30 _4, for example, by Keiwa Corp. of light diffusing film (BS-912: Thickness 120 [mu] m, a haze 89%) can be applied. However, isotropic light diffusion plate used as the second isotropic light diffuser 30 ₄ is not limited thereto.

Usually as the light diffusing agent, the first and second light control plate 30 _1, 30 _2, and the transparent material as described above which is the main constituent of the first and second isotropic light diffusion plate 30 _3, 30 ₄ Powders having different refractive indexes are used, which are dispersed in a transparent material. 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. .

[Disposition relationship of first and second light control plates and first and second isotropic light diffusion plates]
The first and second light control plates 30 ₁ and 30 ₂ and the first and second isotropic light diffusion plates 30 ₃ and 30 ₄ are provided in the z-axis direction so as to satisfy the following conditions. That is, in addition to the arrangement conditions (i) to (v) described in the second embodiment, the arrangement conditions (vi) and (vii) are also satisfied.
(vi) a second isotropic light diffuser 30 ₄ is located on the second upper optical control plate 30 _2.
(vii) a second isotropic light diffuser 30 ₄ of the lower surface 31 ₄ is positioned on the second upper surface 32 ₂ side of the light control plate 30 _2.

The first light control plate 30 _1, a first isotropic light diffusion plate 30 _3, the second light control plate 30 _2, the second isotropic light diffuser 30 ₄ is provided from the light source 22 side in this order in the z-axis direction It has been. The first light control plate 30 ₁ and the first isotropic light diffusion plate 30 _3, usually superimposed via an air layer. The distance _{d 13} between the first light control plate 30 ₁ and the first isotropic light diffusing plate 30 _3, the first top 33b ₁ of the convex portion 33 ₁ of the light control plate 30 ₁ and the first isotropic light the distance in the z-axis direction between the lower surface ₃₁₃ of the diffusion plate 30 _3, 5 mm or less can be exemplified. The distance _{d 32} between the first isotropic light diffusion plate 30 ₃ and the second light control plate 30 _2, first isotropic light diffuser 30 ₃ of the top surface 32 ₃ and the second light control plate 30 ₂ of the distance in the z-axis direction between the lower surface 31 _2, 5 mm or less can be exemplified. Further, the second light control plate 30 ₂ and the second isotropic light diffuser 30 _4, usually superimposed via an air layer. The distance _{d 24} between the second light control plate 30 ₂ and the second isotropic light diffuser 30 _4, the second top portion 33b ₂ of the light control plate 30 _{and second} convex portion 33 ₂ and the second isotropic light the distance in the z-axis direction between the lower surface 31 ₄ of the diffusion plate 30 _4, 5 mm or less can be exemplified.

As in the first embodiment, from the viewpoint of the light control plate unit 21D compact _ones, as _{d 13,} d 32, d ₂₄ is 0 mm, the first light control plate 30 _1, the 1 isotropic light diffusion plate 30 _3, the second light control plate 30 _2, the second isotropic light diffuser 30 ₄ may be disposed. For the same reason as that described in the first embodiment, the first light control plate 30 first on _one isotropic light diffuser 30 3 which is disposed closest to the light source _side, a second light control plate 30 ₂ and if the second isotropic light diffusion plate 30 ₄ contact so providing, the first isotropic light diffuser 30 ₃ having a thickness of d _3, the thickness of the second light control plate 30 ₂ d ₂ and the isotropic light diffuser 30 ₄ thick d ₄ 2, it is preferable that the first of less than the thickness d ₁ of the light control plate 30 _1.

According to the optical control plate unit 21D, similarly to the light control plate unit 21A, the light from the first light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly dispersed in a planar It becomes possible to use light. Moreover, isotropic light diffusing plate disposed on the first surface 32 ₁ side of the light control plate 30 _1, isotropically by the second isotropic light diffusing plate disposed on the upper surface 32 ₂ side of the light control plate 30 ₂ Since the light is diffused, the light from the light source 22 can be more uniformly dispersed and emitted.

(Fifth embodiment)
FIG. 16 is a perspective view showing a fifth embodiment of the light control plate unit. Light control plate unit 21E includes a first light control plate 30 _1, a first isotropic light diffusion plate 30 _3, the second light control plate 30 ₂ and the second isotropic light diffuser 30 _4. In the light control plate unit 21E, the first light control plate 30 _1, a second light control plate 30 _2, the first isotropic light diffusion plate 30 _3, the second isotropic light diffuser 30 ₄ of the plate thickness direction, Although it is different from the light control plate unit 21D in that it is arranged in this order from the light source 22 side, the other points are the same.

In the light control plate unit 21E, the first light control plate 30 _1, a second light control plate 30 _2, the first isotropic light diffusion plate 30 _3, and the second isotropic light diffuser 30 ₄ of the light source in the z-axis direction Since they are provided in this order from the 22 side, in addition to the arrangement conditions (i) to (v) described in the second embodiment, the arrangement conditions (vi) and (vii) are also satisfied.

The first light control plate 30 ₁ second and the light control plate 30 ₂ is usually superposed via an air layer. The first distance _{d 12} between the light control plate 30 ₁ and the second light control plate 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 the distance in the z-axis direction between 30 ₂ of the lower surface 31 _2, 5 mm or less can be exemplified. The second light control plate 30 ₂ and the first isotropic light diffusion plate 30 _3, usually superimposed via an air layer. The second light control plate 30 ₂ and the first isotropic light diffusion plate 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 first isotropic light the distance in the z-axis direction between the lower surface ₃₁₃ of the diffusion plate 30 _3, 5 mm or less can be exemplified. The distance d ₃₄ between the first isotropic light diffusion plate 30 ₃ and the second isotropic light diffuser 30 _4, a first isotropic light diffuser 30 ₃ of the top surface 32 ₃ of the second isotropic light diffuser plate 30 ₄ is the distance in the z-axis direction between the lower surface 314 and ₄ mm or less.

As in the first embodiment, from the viewpoint of making the light control plate unit 21E compact, the first light control plate 30 ₁ , the _first light control plate 30 ₁ , the second light control plate 30 ₁ , the second light d so that d ₁₂ , d ₂₃ , and d ₃₄ are 0 mm. 2 of the light control plate 30 _2, the first isotropic light diffusion plate 30 _3, the second isotropic light diffuser 30 ₄ may be disposed. For the same reason as that described in the first embodiment, the first light control plate 30 ₁ second light control plate 30 2 on which is disposed closest to the light source _side, a first isotropic light diffusion plate 30 ₃ and if the second isotropic light diffusion plate 30 ₄ contact so providing the second thickness d ₂ of the light control plate 30 _2, and the first isotropic thickness of the light diffusing plate 30 ₃ d ₃ the isotropic light diffuser 30 ₄ thick d ₄ 2, it is preferable that the first of less than the thickness d ₁ of the light control plate 30 _1.

According to the optical control plate unit 21E, similarly to the light control plate unit 21A, the light from the first light control plate 30 ₁ of the light source 22 arranged on the lower surface 31 ₁ side, uniformly dispersed in a planar It becomes possible to use light. Moreover, isotropic light diffusing plate disposed on the first surface 32 ₁ side of the light control plate 30 _1, isotropically by the second isotropic light diffusing plate disposed on the upper surface 32 ₂ side of the light control plate 30 ₂ Since the light is diffused, the light from the light source 22 can be more uniformly dispersed and emitted.

  Hereinafter, Examples 1 to 4 and Comparative Examples 1 to 8 will be described with reference mainly to the diagram of FIG. FIG. 17 is a chart showing implementation conditions and intensity uniformity (luminance uniformity) in each example and each comparative example.

Example 1
In Example 1, the following were prepared.
<Light diffusion plate, isotropic light diffusion plate>
(1) Light control plate 100
A light control plate 100 was prepared as a first light control plate. The thickness d ₁ , refractive index n _{1 of} the light control plate 100, and w _Ia , h _Ia / w _Ia , and k _Ia of the convex portions in the light control plate 100 were as follows.
Thickness d ₁ : 1.5 (mm)
Refractive index n ₁ : 1.59
Width w _Ia : 250 (μm)
Aspect ratio h _Ia / w _Ia : 0.440
Sharpness k _Ia : −0.550

(2) Light control plate 200
A light control plate 200 was prepared as a second light control plate. The thickness d ₂ and refractive index n _{2 of} the light control plate 200 and the w _IIa , h _IIa / w _IIa and k _IIa of the convex portions in the light control plate 200 were as follows.
Thickness d ₂ : 0.25 (mm)
Refractive index n ₂ : 1.59
w _IIa : 50 (μm)
Aspect ratio h _IIa / w _IIa : 0.70
Sharpness k _IIa : 0.30

(3) Isotropic light diffusion plate 300
Thickness d ₃ : 0.12 (mm)
Refractive index n ₃ : 1.576
Haze 89%

<Light source>
The following light sources were prepared as light sources.
Light source: CCFL (Cold Cathode Fluorescent Lamp) light source

  Next, as in the first to fifth embodiments, the light control plate 100 and the light control plate 200 are placed in this order from the light source side in the plate thickness direction (z-axis direction) on the light source disposed in the lamp box. Provided. The light source distance is set so that L / D is 2.00, where L is the distance between the central axes of two adjacent light sources and D is the distance between the light control plate 100 and one light source. L and separation distance D were set.

  Next, the intensity uniformity in the front direction of the light control plate 200 was calculated by simulation using the ray tracing method. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 97.9% as shown in the chart of FIG.

(Comparative Example 1)
In Comparative Example 1, the light control plate 100 and the light control are the same as in Example 1 except that h _IIa / w _IIa in the convex portion of the light control plate 200 is 0.50 and k _IIa is 1.00. The plate 200 was placed, and the strength uniformity was calculated in the same manner as in Example 1. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 75.7% as shown in the chart of FIG.
(Comparative Example 2)
In Comparative Example 2, the intensity uniformity was calculated in the same manner as in Example 1 except that the isotropic light diffusing plate 300 was disposed as the second light control plate. At this time, the intensity uniformity in the front direction of the light emitted from the isotropic light diffusing plate 300 was 45.3% as shown in the chart of FIG.

(Example 2)
Example 2 is the same as Example 1 except that L / D is 2.50, h _IIa / w _IIa is 0.90, and k _IIa is 0.40 in the convex portion of the light control plate 200. In addition, the light control plate 100 and the light control plate 200 were arranged, and the intensity uniformity was calculated in the same manner as in Example 1. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 94.3% as shown in the chart of FIG.
(Comparative Example 3)
In Comparative Example 3, the light control plate 100 and the light control are the same as in Example 2 except that h _IIa / w _IIa in the convex portion of the light control plate 200 is 0.50 and k _IIa is 1.00. The plate 200 was placed, and the strength uniformity was calculated in the same manner as in Example 2. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 74.8% as shown in the chart of FIG.
(Comparative Example 4)
In Comparative Example 4, the intensity uniformity was calculated in the same manner as in Example 2 except that the isotropic light diffusing plate 300 was disposed as the second light control plate. At this time, the intensity uniformity in the front direction of the light emitted from the isotropic light diffusion plate 300 was 31.0% as shown in the chart of FIG.

(Example 3)
Example 3 is the same as Example 1 except that L / D is 3.00, h _IIa / w _IIa is 1.00 and k _IIa is 0.45 in the convex portion of the light control plate 200. In addition, the light control plate 100 and the light control plate 200 were arranged, and the intensity uniformity was calculated in the same manner as in Example 1. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 91.6% as shown in the chart of FIG.
(Comparative Example 5)
In Comparative Example 5, the light control plate 100 and the light control are the same as in Example 3 except that h _IIa / w _IIa in the convex portion of the light control plate 200 is 0.50 and k _IIa is 1.00. The plate 200 was placed, and the strength uniformity was calculated in the same manner as in Example 3. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 60.9% as shown in the chart of FIG.
(Comparative Example 6)
In Comparative Example 6, the intensity uniformity was calculated in the same manner as in Example 3 except that the isotropic light diffusion plate 300 was disposed as the second light control plate. At this time, the intensity uniformity in the front direction of the light emitted from the isotropic light diffusing plate 300 was 21.8% as shown in the chart of FIG.

Example 4
Example 4 is the same as Example 1 except that L / D is 3.50, h _IIa / w _IIa is 1.00 and k _IIa is 0.55 in the convex portion of the light control plate 200. In addition, the light control plate 100 and the light control plate 200 were arranged, and the intensity uniformity was calculated in the same manner as in Example 1. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 86.1% as shown in the chart of FIG.
(Comparative Example 7)
In Comparative Example 7, the light control plate 100 and the light control are the same as in Example 4 except that h _IIa / w _IIa in the convex portion of the light control plate 200 is 0.50 and k _IIa is 1.00. The plate 200 was placed, and the intensity uniformity was calculated in the same manner as in Example 4. At this time, the intensity uniformity in the front direction of the light emitted from the light control plate 200 was 47.5% as shown in the chart of FIG.
(Comparative Example 8)
In Comparative Example 8, the intensity uniformity was calculated in the same manner as in Example 4 except that the isotropic light diffusion plate 300 was disposed as the second light control plate. At this time, the intensity uniformity in the front direction of the light emitted from the isotropic light diffusion plate 300 was 16.4% as shown in the chart of FIG.

(Evaluation results)
The examples and comparative examples were compared for each L / D. For example, when the intensity uniformity between Example 1 and Comparative Example 1 or Comparative Example 2 was compared, it was confirmed that the intensity uniformity in Example 1 was higher than the intensity uniformity in Comparative Example 1 or Comparative Example 2. . As a result, it was confirmed that the light from the light source can be uniformly dispersed by arranging the second light control plate having the convex portion having a predetermined shape.

  Similarly, for example, the intensity uniformity in Example 2 and Comparative Example 3 or Comparative Example 4, Example 3 and Comparative Example 5 or Comparative Example 6, Example 4 and Comparative Example 7 or Comparative Example 8 were compared. Also in this case, the intensity uniformity in Examples 2, 3, and 4 may be higher than that in Comparative Example 3 or Comparative Example 4, Comparative Example 5 or Comparative Example 6, Comparative Example 7 or Comparative Example 8, respectively. confirmed. As a result, the light from the light source can be uniformly dispersed by disposing the second light control plate having the convex portion of the predetermined shape on the first light control plate having the shape described above. I was able to confirm that it was possible.

  As mentioned above, although the Example was described, this invention is not limited to the said Example. The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 ... Transmission type image display apparatus, 10 ... Transmission type image display part, 11 ... Liquid crystal cell, 12, 13 ... Polarizing plate, 20 ... Surface light source device, 21A-21E ... Light control board unit (composite light control board), 22 ... light source, 23 ... lamp box, 30 ₁ ... first light control plate, 30 ₂ ... second light control plate, 30 ₃ ... first isotropic light diffusion plate, 30 ₄ ... second isotropic light diffusion plate, 31 ₁ ... lower surface (first surface), 31 ₂ ... lower surface (first surface, incident surface), 31 ₃ ... lower surface (third surface), 31 ₄ ... lower surface (third surface), 32 ₁ ... Upper surface (second surface, emission surface), 32 ₂ ... Upper surface (second surface, convex portion forming surface), 32 ₃ ... Upper surface (fourth surface), 32 ₄ ... Upper surface (fourth surface), 33 ₁ ... convex portion (first convex portion), 33 ₂ ... convex portion (second convex portion), 100 ... light control plate (first light control plate), 200 ... light control plate (Second light control plate), 300... Isotropic light diffusion plate.

Claims (10)

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 and second light control plates formed on the second surface,
The second light control plate is provided in the plate thickness direction so as to be positioned above the first 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 portion of the second light control plate and the extending direction of the convex portion of the first light control plate are substantially parallel.
Each of the convex portions of the first and second light control plates is formed in a shape in which a cross-sectional shape orthogonal to the extending direction is defined below.
Composite light control board.
Cross-sectional shape of the convex portion included in the first light control plate: In the cross section orthogonal to the extending direction of the convex portion included in the first light control plate, the convex portion included in the first light control plate. u _I axis axis passing through the ends for parallel direction, on the u _I axis an axis perpendicular to the center of the both ends as the u _I axis v _I axis, the convex portion in which the first light control plate has when the length of u _I axis direction is _{w Ia,} in the range of _{-0.475w Ia ≦ u I ≦ 0.475w Ia} , formula (1)

[In Formula (1), v _I0 (u _I ) is defined by Formula (2)

(In Formula (2), h _Ia is 0.440 w _Ia and k _Ia is −0.550)
Defined by ]
A shape represented by v _I (u _I ) satisfying
Cross-sectional shape of the convex portion of the second light control plate: In the cross section orthogonal to the extending direction of the convex portion of the second light control plate, the convex portion of the second light control plate has u _II axis axis passing through the ends for parallel direction, an axis perpendicular to the center of the both ends as the u _II axis on the u _II axis v _II axis, the convex portion in which the second light control plate has In the range of −0.475w _IIa ≦ u _II ≦ 0.475w _IIa , where u _II- axis length is w _IIa , the formula (3)

[In Formula (3), v _II0 (u _II ) is represented by Formula (4)

(In Formula (4), h _IIa is 0.3 w _IIa or more and 1.0 w _IIa or less, and k _IIa is Formula (5).

Meet. Here, k _IIa1 and k _IIa2 are

In the formula (6), α ₁ = 8.62841, β ₁ = −34.85420, χ ₁ = 33.8544, δ ₁ = 17.19255, ε ₁ = −20.25226, φ ₁ = −26.13902 , Γ ₁ = 21.777536,

In the formula (7), α ₂ = 0.03724, β ₂ = 13.29232, χ ₂ = −33.48856, δ ₂ = 20.31892, ε ₂ = 13.56923, φ ₂ = −15.97616, γ ₂ = 2.94948. )
Defined by ]
A shape represented by v _II (u _II ) satisfying A first isotropic light diffusing plate capable of emitting light incident from the third surface as diffused light from a fourth surface located on the opposite side of the third surface;
The first isotropic light diffusing plate is provided in the plate thickness direction so as to be positioned above the first light control plate,
The third surface of the first isotropic light diffusing plate is located on the second surface side of the first light control plate;
The composite light control board according to claim 1. A second isotropic light diffusing plate capable of emitting light incident from the third surface as diffused light from a fourth surface located opposite to the third surface;
The second isotropic light diffusing plate is provided in the plate thickness direction so as to be positioned above the second light control plate,
The third surface of the second isotropic light diffusing plate is positioned on the second surface side of the second light control plate;
The composite light control board according to claim 2. The composite light control plate according to any one of claims 1 to 3,
A light source unit that is disposed apart from each other and includes a plurality of light sources that supply light to the first surface of the first light control plate constituting the composite light control plate;
A surface light source device. The ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 1.75 or more and less than 2.25,
In the equation (6) showing the k _IIa1 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 8.440520, β ₁ = −33.01269, χ ₁ = 29 28857, δ ₁ = 20.44040, ε ₁ = -18.87444, φ ₁ = -29.70226, γ ₁ = 23.1431,
In the equation (7) indicating k _IIa2 in the equation (5) defining the cross-sectional shape of the second light control plate, α ₂ = 13.97149, β ₂ = −45.65173, χ ₂ = 35 18939, δ ₂ = 25.31623, ε ₂ = −18.18153, φ ₂ = −33.36581, γ ₂ = 23.36307,
The surface light source device according to claim 4. The ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 2.25 or more and less than 2.75,
In the equation (6) indicating the k _IIa1 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 15.36687, β ₁ = −57.20375, χ ₁ = 52 22981, δ ₁ = 26.86604, ε ₁ = −30.26684, φ ₁ = −36.808847, γ ₁ = 29.94893,
In the equation (7) indicating k _IIa2 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₂ = 2.69179, β ₂ = −0.66679, χ ₂ = − 8.30041, δ ₂ = 5.74519, ε ₂ = 5.99721, φ ₂ = −4.222110, γ ₂ = −0.55377,
The surface light source device according to claim 4. The ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 2.75 or more and less than 3.25,
In the equation (6) indicating the k _IIa1 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 21.80916, β ₁ = −82.444499, χ ₁ = 110 81252, δ ₁ = −46.020425, ε ₁ = −30.36723, φ ₁ = 40.29250, γ ₁ = −13.64152,
In the equation (7) indicating the k _IIa2 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₂ = 2.35575, β ₂ = 0.17987, χ ₂ = −13 .91425, δ ₂ = 18.10637, ε ₂ = 4.252022, φ ₂ = −18.52795, γ ₂ = 8.22009.
The surface light source device according to claim 4. The ratio (L / D) between the distance D between the first surface of the first light control plate and the light source unit and the distance L between the light sources is 3.25 or more and less than 3.75,
In the equation (6) indicating the k _IIa1 in the equation (5) that defines the cross-sectional shape of the second light control plate, α ₁ = 9.669940, β ₁ = −28.97218, χ ₁ = 21 .33353, δ ₁ = 18.009167, ε ₁ = −14.02321, φ ₁ = −23.87926, γ ₁ = 18.17066,
In the formula (7) indicating the k _IIa2 in the formula (5) defining the cross-sectional shape of the second light control plate, α ₂ = 2.778173, β ₂ = −0.12045, χ ₂ = − 14.91041, δ ₂ = 18.27412, ε ₂ = 4.668363, φ ₂ = -16.588892, γ ₂ = 6.553802.
The surface light source device according to claim 4. A surface light source device according to any one of claims 4 to 8,
A transmissive image display unit illuminated by light output from the plurality of light sources and passed through the composite light control plate;
A transmissive image display device. A plurality of first convex portions extending in one direction and having a cross-sectional shape defined below are formed on the exit surface, and a plurality of the first convex portions are formed on the first convex portions. A light control plate provided on the exit surface side with respect to the first light control plate arranged in parallel in a direction substantially orthogonal to the extending direction,
An incident surface on which light emitted from the emission surface is incident;
A surface opposite to the entrance surface, and a plurality of second convex portions extending in one direction and having a cross-sectional shape defined below are formed, and the plurality of second convex shapes A convex portion forming surface in which the portions are arranged in parallel in a direction substantially orthogonal to the extending direction of the second convex portion;
Have
The light control board in which the extending direction of the second convex portion is substantially parallel to the extending direction of the first convex portion.
Cross-sectional shape of the first convex portion: In a cross section orthogonal to the extending direction of the first convex portion, the axis passing through both ends of the first convex portion in the parallel direction is the u _I axis, and the u _{I when v I} axis an axis perpendicular to the center of the both ends as the _{u I} axis, the _{u I} axis direction of the first convex portion length was _{w Ia} on an axis, -0.475w _Ia ≦ In the range of u _I ≦ 0.475 w _Ia , the formula (8)

[In Formula (8), v _I0 (u _I ) is defined by Formula (9)

(In Formula (9), h _Ia is 0.440 w _Ia and k _Ia is −0.550)
Defined by ]
A shape represented by v _I (u _I ) satisfying
Cross-sectional shape of the second convex portion: In a cross section orthogonal to the extending direction of the second convex portion, the axis passing through both ends of the second convex portion in the parallel direction is the u _II axis, and the u _II -0.475w _IIa ≤ when the axis passing through the center of the both ends on the axis is perpendicular to the u _II axis is the v _II axis, and the length of the second convex portion in the u _II axis direction is w _IIa In the range of u _II ≦ 0.475 w _IIa , the formula (10)

[In Formula (10), v _II0 (u _II ) is represented by Formula (11)

(In Formula (11), h _IIa is 0.3 w _IIa or more and 1.0 w _IIa or less, and k _IIa is Formula (12).

Meet. Here, k _IIa1 and k _IIa2 are

In the formula (13), α ₁ = 8.62841, β ₁ = −34.85420, χ ₁ = 33.8544, δ ₁ = 17.19255, ε ₁ = −20.25226, φ ₁ = −26.13902 , Γ ₁ = 21.777536,

In the formula (14), α ₂ = 0.03724, β ₂ = 13.29232, χ ₂ = −33.48856, δ ₂ = 20.31892, ε ₂ = 13.66923, φ ₂ = −15.97616, γ ₂ = 2.94948. )
Defined by ]
A shape represented by v _II (u _II ) satisfying