JP2009075366A - Optical sheet, backlight unit, and display - Google Patents

Optical sheet, backlight unit, and display Download PDF

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JP2009075366A
JP2009075366A JP2007244346A JP2007244346A JP2009075366A JP 2009075366 A JP2009075366 A JP 2009075366A JP 2007244346 A JP2007244346 A JP 2007244346A JP 2007244346 A JP2007244346 A JP 2007244346A JP 2009075366 A JP2009075366 A JP 2009075366A
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lens
optical sheet
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direction
sheet according
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JP5018371B2 (en
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Hidenori Echizen
Luis Manuel Murillo-Mora
Tomohiro Nakagome
マヌエル ムリジョーモラ ルイス
友洋 中込
秀憲 越前
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Toppan Printing Co Ltd
凸版印刷株式会社
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Abstract

An optical sheet, a backlight unit, and a display device that improve light utilization efficiency and suppress a decrease in light amount due to light absorption.
SOLUTION: A flat substrate 2 and first and second lens arrays 3, 4 provided on one surface of the substrate 2, and the first lens array 3 extends along the X direction on one surface. The second lens array 4 includes a plurality of first lenses 5 that are arranged in parallel with each other, and the second lens array 4 extends along the Y direction on one surface and is arranged in parallel with each other. The second lens 6 has a plurality of sub-lenses 7 disposed in the valleys of the plurality of first lenses 5, the height T1 is greater than or equal to the height T2, and the pitch P1 is greater than or equal to the pitch P2. W1 / P1 is 0.5 or more and 0.8 or less, W2 / P2 is 0.8 or more and 1 or less, and the angle formed by the X direction and the Y direction is 60 ° or more and 120 ° or less. It is.
[Selection] Figure 1

Description

  The present invention relates to an optical sheet, a backlight unit, and a display device.

In recent years, liquid crystal display devices have been used as monitor devices for personal computers and the like. In such a liquid crystal display device, a so-called backlight system is employed in which illumination light is irradiated to the liquid crystal panel from a light source disposed on the back surface of the liquid crystal panel.
As a backlight unit used in the backlight system, a light guide lamp such as a cold cathode fluorescent lamp (CCFL) is roughly divided into a “light guide plate” that performs multiple reflection within a flat light guide plate made of acrylic resin having excellent light transmittance. There are a “light guide system” (so-called edge light system) and a “direct type system” that does not use a light guide plate.

In order to improve the light use efficiency in such a backlight unit, it has been proposed to arrange a prism sheet having a light collecting function between the diffusion plate and the liquid crystal panel (see, for example, Patent Documents 1 to 3). . This prism sheet has a configuration in which a plurality of prisms having a triangular cross section are arranged in parallel on a sheet-like base material. Since such a prism sheet can be expected to improve the light utilization efficiency mainly in the prism arrangement direction, it is used in a state in which two prism sheets having the prism arrangement directions orthogonal to each other are combined.
Japanese Patent Publication No. 1-378001 JP-A-6-102506 Japanese National Patent Publication No. 10-506500

  However, the following problems remain in the conventional optical sheet. That is, in the prism sheet described above, light is unnecessarily emitted in an oblique direction near 90 ° with respect to the front direction of the sheet that is not visually recognized by an observer when the prism sheet is incorporated in the liquid crystal display device. As described above, there is a problem in that the light use efficiency is lowered due to the generation of side lobes that are light emitted from the lateral direction of the sheet. In addition, since two prism sheets are used in combination, there is a problem that the amount of light decreases due to light absorption in the sheets.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optical sheet, a backlight unit, and a display device that improve light utilization efficiency and suppress a decrease in light amount due to light absorption.

  The present invention employs the following configuration in order to solve the above problems. That is, the optical sheet of the present invention includes a flat base material and first and second lens arrays provided on one surface of the base material, and the first lens array extends along one direction on the one surface. A plurality of first lenses that extend in parallel with each other, and the second lens array extends along another direction that intersects the one direction on the one surface and is arranged in parallel with each other A plurality of second lenses, the second lens having a plurality of sub-lenses arranged in valleys of the plurality of first lenses, the pitch of the first lenses being P1, and the first lens being The height is W1, the height of the first lens is T1, the pitch of the second lens is P2, the width of the second lens is W2, and the height of the second lens is T2. T1 is greater than or equal to the height T2, and the pitch P1 is W1 / P1 which is not less than the pitch P2 and is a ratio between the width W1 and the pitch P1 is not less than 0.5 and not more than 0.8, and is a ratio between the width W2 and the pitch P2. However, it is 0.8 or more and 1 or less, and the angle formed by the one direction and the other direction is 60 ° or more and 120 ° or less.

In this invention, the extending direction of each of the first and second lenses is provided by providing a plurality of first lenses extending along one direction and a plurality of second lenses extending along the other direction on one surface. The light condensing and diffusing effect in the orthogonal direction with respect to is sufficiently obtained. Therefore, improvement in light utilization efficiency and reduction in light amount due to light absorption can be suppressed.
That is, each of the plurality of first lenses collects light incident on the optical sheet in a direction orthogonal to the extending direction of the first lens. Each of the plurality of second lenses condenses light incident on the optical sheet in a direction orthogonal to the extending direction of the second lens.
Here, by setting W1 / P1 to be 0.5 or more, it is possible to ensure a viewing angle in a direction orthogonal to one direction which is the extending direction of the first lens. Further, by setting W1 / P1 to 0.8 or less, it is possible to suppress the generation of side lobes that are light that is wasted from the lateral direction of the optical sheet. And by making W2 / P2 0.8 or more, the light emitted from between the plurality of first lenses arranged at intervals is condensed, and the luminance in the front direction of the optical sheet can be improved. it can. Furthermore, by making the angle formed by the extending direction of each of the first and second lenses to be 60 ° or more and 120 ° or less, it is possible to suppress the occurrence of moire in a display device incorporating an optical sheet.

In the optical sheet of the present invention, it is preferable that the first lens is a prism lens having a triangular cross section.
In this invention, the brightness | luminance in the front direction of an optical sheet can be improved by making a 1st lens into a prism lens with a high condensing effect.

In the optical sheet of the present invention, it is preferable that an apex angle of the first lens is 80 ° or more and 105 ° or less.
In the present invention, by setting the apex angle to 80 ° or more and 105 ° or less, the luminance in the front direction of the optical sheet can be sufficiently secured, and the viewing angle in one direction can be secured.

In the optical sheet of the present invention, it is preferable that the second lens is a prism lens having a triangular cross section.
In the present invention, similarly to the above, the luminance in the front direction of the optical sheet can be improved by using the second lens as a prism lens.

In the optical sheet of the present invention, the apex angle of the second lens is preferably 80 ° or more and 105 ° or less.
In the present invention, similarly to the above, by setting the apex angle to 80 ° or more and 105 ° or less, it is possible to maintain the light condensing effect by the lens and improve the front luminance with respect to the optical sheet, and the viewing angle in the other direction. Can be secured.

In the optical sheet of the present invention, it is preferable that an apex angle of the second lens is greater than or equal to an apex angle of the first lens.
In the present invention, by setting the apex angle of the second lens to be equal to or greater than the apex angle of the first lens, it is possible to increase the viewing angle in one direction which is mainly the extending direction of the first lens. That is, when the optical sheet is incorporated in the display device, the viewing angle in the horizontal direction is increased by setting the extending direction of the first lens to a direction along the horizontal direction of the display device.

Further, in the optical sheet of the present invention, the first lens has a top portion having an arcuate surface and a pair of side surface portions extending from the top portion to the one surface, and each of the pair of side surface portions extends from the one surface to the first surface. It is preferable to approach each other toward the top.
In the present invention, since the top portion has a curved surface, it has a higher light diffusion effect than the triangular prism shape, so that a wider viewing angle can be secured in one direction.

In the optical sheet of the present invention, it is preferable that a fitting curvature radius at the top portion of the first lens is not less than 0.15 times and not more than 0.3 times the width W1.
In the present invention, by setting the fitting radius of curvature to be 0.3 times or less of the width W1, the condensing effect by the first lens can be maintained, and the front luminance with respect to the optical sheet can be improved. Further, the moldability of the first lens can be maintained by setting the fitting curvature radius to be 0.15 times or more of the width W1.

In the optical sheet of the present invention, the cross-sectional shape of the first lens has a coefficient when the normal direction of the one surface is the Z axis and the position from the width direction center in the width direction of the first lens is r. Using R, A, B, and C, Z = (r 2 / R) / (1 + √ (1− (1 + k) × (r / R) 2 )) + Ar 2 + Br 4 + Cr 6 and the coefficient (1 / R) is greater than −10 and less than 10, the coefficient A is greater than −5 and less than 5, the coefficient B is greater than −10 and less than 10, and the coefficient C is greater than −30. It is preferably less than 30.
In this invention, the coefficient (1 / R) is larger than −10 and smaller than 10, and the coefficient A is larger than −5 and smaller than 5, so that the fitting curvature radius of the top portion in the outer edge shape of the first lens is 0. 15 times or more and 0.3 times or less.
Further, by setting the coefficient B to be greater than −10 and less than 10 and the coefficient C to be greater than −30 and less than 30, sufficient front luminance can be obtained with the first lens.
The outer edge shape at the top of the first lens is a perfect circle when k is 0, an ellipse when k is greater than -1 and less than 0, a parabola when k is -1, and when k is less than -1. Becomes a hyperbola.

Further, in the optical sheet of the present invention, the second lens has a top portion having an arcuate surface and a pair of side surface portions extending from the top portion to the one surface, and each of the pair of side surface portions extends from the one surface to the one surface. It is preferable to approach each other toward the top.
In the present invention, as described above, since the top portion has a curved surface, a high light diffusion effect is obtained, so that a wider viewing angle can be secured in the other direction.

In the optical sheet of the present invention, it is preferable that a fitting curvature radius at the top of the second lens is 0.15 times or more and 0.3 times or less of the width W2.
In the present invention, as described above, by setting the fitting curvature radius to be not less than 0.15 times and not more than 0.3 times the width W2, the front luminance with respect to the optical sheet can be improved and the moldability of the second lens can be improved. Can be maintained.

In the optical sheet of the present invention, the cross-sectional shape of the second lens has a coefficient when the normal direction of the one surface is the Z axis and the position from the center in the width direction in the width direction of the second lens is s. Using S, D, E, and F, Z = (s 2 / S) / (1 + √ (1− (1 + j) × (s / S) 2 )) + Ds 2 + Es 4 + Fs 6 and the pitch P2 Is normalized to 1 and the coefficient (1 / S) is greater than −10 and less than 10, the coefficient D is greater than −5 and less than 5, and the coefficient E is greater than −10. It is preferably less than 10, and the coefficient F is preferably greater than −30 and less than 30.
In this invention, the coefficient (1 / S) is larger than −10 and smaller than 10, and the coefficient D is larger than −5 and smaller than 5, so that the fitting curvature radius of the top portion in the outer edge shape of the second lens is 0. 15 times or more and 0.3 times or less.
Further, by setting the coefficient E to be greater than −10 and less than 10 and the coefficient F to be greater than −30 and less than 30, sufficient front luminance can be obtained by the second lens.
The outer edge shape at the top of the second lens is a perfect circle when j is 0, an ellipse when j is greater than -1 and less than 0, a parabola when j is -1, and when j is less than -1. Becomes a hyperbola.

In the optical sheet of the present invention, it is preferable that the second lens is a prism lens having a triangular cross section.
In the present invention, by using the prism lens as the second lens, more sufficient front luminance can be obtained.

In the optical sheet of the present invention, the apex angle of the second lens is preferably 80 ° or more and 105 ° or less.
In the present invention, similarly to the above, by setting the apex angle to 80 ° or more and 105 ° or less, it is possible to maintain the light condensing effect by the lens and improve the front luminance with respect to the optical sheet, and the viewing angle in the other direction. Can be secured.

In the optical sheet of the present invention, it is preferable that the first and second lens arrays are formed of the same material.
In the present invention, the first and second lens arrays are formed of the same material, whereby the manufacturing process of the first and second lens arrays can be simplified.

In the optical sheet of the present invention, it is preferable that at least one of the pitch P1 and the pitch P2 is random.
In the present invention, it is possible to more reliably suppress the occurrence of moire in a display device incorporating an optical sheet by not providing regularity to the arrangement interval of at least one of the first and second lenses. Here, “random” means that the distance between one lens and one lens adjacent to this lens is different from the distance between one lens and the other adjacent lens.

In the optical sheet of the present invention, it is preferable that each of the height T1 and the height T2 is constant.
In the present invention, the occurrence of unevenness in the surface direction of the optical sheet can be suppressed by making the heights of the first and second lenses constant.

In addition, a backlight unit of the present invention includes the above-described optical sheet and a light source that irradiates the optical sheet with illumination light.
In this invention, by providing the optical sheet described above, it is possible to improve the light utilization efficiency and suppress the decrease in the light amount due to light absorption.

According to another aspect of the present invention, there is provided a display device comprising: the above-described backlight unit; and an image display element that is irradiated with the illumination light emitted from the optical sheet and displays a display image.
In the present invention, by providing the above-described backlight unit, it is possible to improve the light utilization efficiency and suppress the decrease in the light amount due to light absorption.

  According to the optical sheet, the backlight unit, and the display device of the present invention, the first and second lens arrays arranged on one surface of the base material sufficiently obtain a light condensing and diffusing effect in the direction orthogonal to the respective extending directions. It is done. Therefore, improvement in light utilization efficiency and reduction in light amount due to light absorption can be suppressed.

[First Embodiment]
Hereinafter, a first embodiment of an optical sheet according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the optical sheet 1 in the present embodiment is a light guide plate used in a backlight unit, and is provided so as to protrude from a flat substrate 2 and one surface of the substrate 2. First and second lens arrays 3 and 4 are provided. In the optical sheet 1, the other surface of the base 2 is an incident surface, and the first and second lens arrays 3 and 4 are each an emission surface.

The substrate 2 is made of, for example, PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), acrylonitrile styrene copolymer, COP (cycloolefin polymer), or the like. The base material 2 is formed by an extrusion molding method, an injection molding method, a hot press molding method, or the like.
In addition, the thickness of the base material 2 is formed of a material in which the first and second lens arrays 3 and 4 are cured by irradiation with energy rays, such as UV (ultraviolet) curable resin or radiation curable resin. In some cases, it is desirable to be larger than 50 μm. Thereby, it is possible to prevent wrinkles and the like from being generated on the base material 2 when the first and second lens arrays 3 and 4 are formed. Moreover, when the optical sheet 1 is used for a display device having a diagonal of 37 inches or more, for example, the thickness of the base material 2 is desirably 0.05 mm or more and 3 mm or less.

  The first and second lens arrays 3 and 4 are made of, for example, UV curable resin, radiation curable resin, PET, PC, PMMA, COP, or the like. The first and second lens arrays 3 and 4 are formed on the base material 2 in the case where the first and second lens arrays 3 and 4 are formed of a material that is cured by irradiation of energy rays such as UV curable resin and radiation curable resin. The resin layer is formed by irradiating energy rays such as ultraviolet rays and radiation. Further, when the first and second lens arrays 3 and 4 are formed of the same material as the base material 2, they are integrally formed with the base material 2 by an extrusion molding method, an injection molding method, a hot press molding method, or the like. Has been.

The first lens array 3 extends along the X direction (one direction) on one surface of the base material 2, and a plurality of first lens arrays 3 are arranged in parallel to each other at intervals in the Y direction that is orthogonal to the X direction. It is formed by the first lens 5.
The first lens 5 is a prism lens having a triangular cross-sectional shape in the width direction. The apex angle α1 that is the angle at the apex of the first lens 5 is not less than 80 ° and not more than 105 °. Further, the first lens 5 has a width W1 of, for example, about 60 μm, and a pitch P1, which is a center interval between other first lenses 5 adjacent in the Y direction, is 1.25 times to 5 times of the width W1, for example, about 100 μm. The height T1 is 20 μm or more and 200 μm or less. Here, W1 / P1, which is the ratio of the width W1 of the first lens 5 to the pitch P1, is 0.5 or more and 0.8 or less.

The second lens array 4 is formed by a plurality of second lenses 6 that extend along the Y direction (the other direction) on one surface of the base material and are arranged in parallel to each other with an interval in the X direction. . That is, the extending direction of the first lens 5 and the extending direction of the second lens 6 are orthogonal to each other, and the angle formed by the extending direction of the first lens 5 and the extending direction of the second lens 6. Is in the range of 60 ° to 120 °.
The second lens 6 has a plurality of sub-lenses 7 arranged along the other direction at the valleys of the plurality of first lenses 5.
Each of the plurality of sub lenses 7 is a prism lens having a triangular cross-sectional shape in the width direction, and its extending direction is the Y direction. Both ends of the sub lens 7 in the extending direction are in contact with the side surfaces of the two first lenses 5 adjacent in the Y direction.
The apex angle α2 that is the angle at the apex of the second lens 6 is not less than 80 ° and not more than 105 °, and is not more than the apex angle α1 of the first lens 5. In addition, the second lens 6 has a width W2 of, for example, about 30 μm, a pitch P2, which is a center interval between other adjacent second lenses 6, is 1 to 1.25 times the width W2, and a height T2 is, for example, 3 μm. The value is 150 μm or less and smaller than the height T1 of the first lens 5. Here, W2 / P2, which is the ratio of the width W2 of the second lens 6 to the pitch P2, is 0.8 or more and 1 or less.

The optical sheet 1 having the above configuration is used in a liquid crystal display device (display device) as shown in FIG.
As shown in FIG. 4, the liquid crystal display device 10 includes a liquid crystal panel (image display element) 11 and a backlight unit 12 that irradiates the liquid crystal panel 11 with illumination light.
The liquid crystal panel 11 includes a pair of substrates 21 and 22 and a liquid crystal layer 23 sealed between the pair of substrates 21 and 22. Each of the pair of substrates 21 and 22 is provided with an electrode (not shown) for driving the liquid crystal layer 23. Then, the polarization state of the light transmitted through the liquid crystal layer 23 changes according to the intensity of the electric field applied to the liquid crystal layer 23.
The liquid crystal panel 11 is provided with a substantially rectangular image display area. In the image display area, a plurality of pixels are arranged in a matrix. The horizontal scanning direction that is the major axis direction of the image display area is substantially parallel to the X direction that is the extending direction of the first lens 5, and the vertical scanning direction that is the minor axis direction is the extending direction of the second lens 6. It is substantially parallel to the Y direction, which is the current direction.
Further, polarizing plates 24 and 25 are provided on both upper and lower surfaces of the liquid crystal panel 11.

The backlight unit 12 includes the optical sheet 1, a plurality of light sources 26, a scattering plate 27, and a light reflection plate 28.
The light source 26 is formed of, for example, a cold cathode fluorescent lamp and has a cylindrical shape. The light source 26 is accommodated in the lamp house 29. The light source 26 emits illumination light toward the other surface of the optical sheet 1.
The scattering plate 27 is disposed between the light source 26 and the optical sheet 1, diffuses the illumination light emitted from the light source 26 and emits it toward the optical sheet 1.
The light reflecting plate 28 is disposed on the back side of the light source 26 and reflects the illumination light emitted from the light source 26 toward the optical sheet 1.

  In the liquid crystal display device 10 configured as described above, the light emitted from the light source 26 is diffused by the scattering plate 27 and is incident on the other surface of the substrate 2 of the optical sheet 1. The light incident on the optical sheet 1 is emitted from the optical sheet 1 toward the liquid crystal panel 11 as light having an optical gain of 1 or more. The light incident on the liquid crystal panel 11 changes its polarization state according to the intensity of the electric field applied to the liquid crystal layer 23 after passing through the polarizing plate 24 and is transmitted or absorbed by the polarizing plate 25. As described above, the image displayed in the image display area of the liquid crystal panel 11 is displayed.

  The optical gain is one of the indexes indicating the diffusibility of the optical diffusing member, and the luminance of the diffuser that completely diffuses is set to 1, and the optical gain is represented by the ratio of the luminance of the light. When the diffusivity of the diffusing member to be measured is biased depending on the direction, it is possible to show the diffusing characteristic of the diffusing member by calculating the optical gain in each direction. Complete diffusion refers to an ideal diffuser having zero absorption and constant light brightness in all directions. That is, an optical gain of 1 or more indicates that there is an effect of collecting light in the measurement direction, and that the higher the gain, the stronger the light collection effect.

Here, the viewing angle characteristics in the X direction and the Y direction of the optical sheet 1 in this embodiment and the optical sheet on which only the first lens array is formed are shown in FIGS. FIG. 5 and FIG. 6 show the relationship between the angle with respect to the front direction and the luminance in the X direction and the Y direction, respectively.
In the optical sheet on which only the first lens array is formed, W1 / P1 that is the ratio of the width W1 of the first lens to the pitch P1 is set to 1. In the optical sheet 1, W1 / P1 which is the ratio of the width W1 of the first lens 5 to the pitch P1 is 0.6, and W2 / P2 which is the ratio of the width W2 of the second lens 6 to the pitch P2 is 1. The apex angle α1 of the first lens 5 and the apex angle α2 of the second lens 6 are each 90 °.

As shown in FIG. 5, in the optical sheet having only the first lens array, the light is sufficiently condensed in the Y direction by the first lens, but is not condensed in the X direction. Further, in this optical sheet, side lobes are generated in the X direction, and light is hardly emitted in the valleys between the optical lobes.
On the other hand, as shown in FIG. 6, in the optical sheet 1 in the present embodiment, the second lens array 4 in the valley between the side lobe generated in the case of only the first lens array 3 as in the optical sheet described above. Since the light is emitted by the light condensing effect, the luminance does not decrease. Thereby, generation | occurrence | production of a side lobe is suppressed. Moreover, in the optical sheet 1, light is sufficiently condensed in the X direction by the second lens.

FIG. 7 shows the relationship between W1 / P1 which is the ratio of the width W1 of the first lens 5 to the pitch P1 in the optical sheet 1 and the half-value angle in the Y direction of the light emitted from the optical sheet 1. FIG. 8 shows the relationship between W1 / P1 and the half-value angle in the X direction. Here, the half-value angle indicates an angle with respect to the front direction when the luminance in the oblique direction of the optical sheet 1 is half of the luminance in the front direction.
7 and 8 show half-value angles when the value of the apex angle α1 of the first lens 5 is 75 °, 80 °, 85 °, 90 °, 105 °, and 110 °. In the second lens 6, W2 / P2, which is the ratio of the width W2 to the pitch P2, is 1, and the apex angle α2 is the same value as the apex angle α1.
As shown in FIGS. 7 and 8, as W1 / P1 increases, the half-value angle in the Y direction decreases and the half-value angle in the X direction increases. This is because as the W1 / P1 is increased, the light collection effect by the first lens 5 is increased and the light collection effect by the second lens 6 is reduced. Further, as the apex angles α1 and α2 are increased, the half-value angle is increased. This is because if the apex angle α1 is increased, the light condensing effect by the first lens 5 is reduced, and if the apex angle α2 is increased, the light condensing effect by the second lens 6 is reduced.
Generally, in a display device such as a television receiver, it is desired to widen the viewing angle in the X direction, which is the horizontal direction. Therefore, it is desirable that the half-value angle in the X direction is at least about 40 °. Therefore, by setting W1 / P1 to 0.5 or more, a viewing angle in the X direction that is the horizontal direction is sufficiently ensured. When W1 / P1 is 0.5, the half-value angle in the X direction is less than 40 ° when the apex angle is small, but by increasing the apex angle α2 of the second lens 6 as described above. This can be solved.

FIG. 9 shows the relationship between W1 / P1 which is the ratio of the width W1 of the first lens 5 to the pitch P1 in the optical sheet 1 and the luminance of the light emitted from the optical sheet 1 in the front direction of the optical sheet 1. FIG. 9 shows the luminance when the value of the apex angle α1 of the first lens 5 is 75 °, 80 °, 85 °, 90 °, 105 °, and 110 °. In the second lens 6, W2 / P2, which is the ratio of the width W2 to the pitch P2, is 1, and the apex angle α2 is the same value as the apex angle α1.
As shown in FIG. 9, the luminance in the front direction does not change even if W1 / P2 is changed. This is because if W1 / P1 is increased, the light condensing effect by the first lens 5 is increased, and if W1 / P1 is decreased, the light condensing effect by the second lens 6 is increased. Does not change. Further, as shown in FIG. 9, by changing the apex angles α <b> 1 and α <b> 2, the condensing effect in each of the first and second lenses 5 and 6 changes, so that the luminance in the front direction changes.
Therefore, sufficient luminance is ensured by setting the apex angles α1 and α2 to 80 ° to 105 °.

Furthermore, FIG. 10 shows the relationship between W2 / P2 which is the ratio of the width W2 of the second lens 6 to the pitch P2 in the optical sheet 1 and the luminance in the front direction of the optical sheet 1. In FIG. 10, the luminance in the front direction when W2 / P2 is 1 is 1.
As shown in FIG. 10, the luminance decreases as W2 / P2 is decreased. This is because the area where the first and second lenses 5 and 6 are not formed on one surface of the substrate 2 increases as W2 / P2 is decreased.
Therefore, by setting W2 / P2 to 0.8 or more, sufficient luminance is ensured. At this time, W2 / P2 is more preferably 0.9 or more.

Further, the viewing angle characteristics when W1 / P1 which is the ratio of the width W1 of the first lens 5 to the pitch P1 is 0.4, 0.5, 0.7, 0.8, 0.9 are shown in FIG. 11 to FIG. 11 to 15 show the relationship between the angle and the luminance with respect to the front direction in each of the X direction and the Y direction. In the second lens 6, W2 / P2, which is the ratio of the width W2 to the pitch P2, is 1. Further, the apex angle α1 of the first lens 5 and the apex angle α2 of the second lens 6 are each 90 °. The viewing angle characteristics when W1 / P1 is 0.6 are the same as those in FIG.
As shown in FIGS. 6 and 11 to 15, as W1 / P1 increases, the condensing effect by the first lens 5 increases. As shown in FIG. 15, when W1 / P1 is 0.9 or more, Y Side lobes occur in the viewing angle characteristics of directions.
Therefore, by setting W1 / P1 to 0.8 or less, generation of side lobes in the viewing angle characteristic in the Y direction is suppressed.

According to the optical sheet 1, the backlight unit 12, and the liquid crystal display device 10 configured as described above, the first and second lens arrays arranged on one surface of the substrate 2 can be used in directions orthogonal to the respective extending directions. A sufficient light diffusion effect can be obtained. Therefore, improvement in light utilization efficiency and reduction in light amount due to light absorption can be suppressed.
Here, by setting W1 / P1 to be 0.5 or more and 0.8 or less, a viewing angle mainly in the Y direction can be secured, and generation of side lobes can be suppressed. And the brightness | luminance in the front direction of the optical sheet 1 can be improved because W2 / P2 shall be 0.8 or more.
Moreover, the brightness | luminance in the front direction of the optical sheet 1 can be improved by using each of the 1st and 2nd lenses 5 and 6 as a prism lens. And by making each apex angle (alpha) 1 and (alpha) 2 into 80 degrees or more and 105 degrees or less, while being able to improve the front luminance with respect to the optical sheet 1, a viewing angle can be ensured.
Furthermore, the viewing angle in the X direction can be increased by setting the apex angle α2 to the apex angle α1 or more.
Further, by forming the first and second lenses 5 and 6 with the same material, the manufacturing process of each of the first and second lenses 5 and 6 can be simplified.

[Second Embodiment]
Next, a second embodiment of the optical sheet in the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.

The optical sheet 50 in the present embodiment has first and second lens arrays 51 and 52 as shown in FIGS. Each of the plurality of first lenses 53 constituting the first lens array 51 has a curved surface shape. Further, each of the plurality of second lenses 54 constituting the second lens array 52 has a curved surface shape like the first lens 53.
The first lens 53 is a lenticular lens, and has a top portion 53a having an arcuate surface and a pair of side surface portions 53b extending from the top portion 53a to one surface of the substrate 2.

  The fitting curvature radius Rt1 at the top 53a of the first lens 53 is defined as follows. That is, as shown in FIG. 19, at the outer edge of the first lens 53, a position away from the center in the width direction passing through the apex m <b> 1 of the top 53 a of the first lens 53 by 0.1 times the width W <b> 1 of the first lens 53. Let them be points m2 and m3. Then, fitting the radius of a circle passing through the points m2 and m3, centering on the intersection of the normal to the tangent of the outer edge of the first lens 53 at the point m2 and the normal to the tangent of the outer edge of the first lens 53 at the point m3. The curvature radius is Rt1.

  Further, the cross-sectional outer edge shape in the direction orthogonal to the one direction of the first lens 53 is expressed by the following Expression 1. Here, the normal direction of one surface of the substrate 2 is the Z axis, and the position from the center in the width direction in the width direction of the first lens 53 is r. Coefficients R, A, B, and C are correction coefficients.

Here, the coefficient (1 / R) is greater than −10 and less than 10, and the coefficient A is greater than −5 and less than 5. Thereby, the fitting radius of curvature Rt1 at the top 53a of the first lens 53 is 0.15 times or more and 0.3 times or less of the width W1 of the first lens 53. The coefficient B is greater than −10 and less than 10, and the coefficient C is greater than −30 and less than 30.
The outer edge shape of the top 53a of the first lens 53 is a perfect circle when the coefficient k is 0, an ellipse when the coefficient k is greater than -1 and less than 0, a parabola when the coefficient k is -1, and the coefficient k. A hyperbola is obtained when is less than -1.

Similar to the first lens 53, the second lens 54 has a plurality of sub-lenses 55 that are lenticular lenses. The sub lens 55 has a top portion 55a having an arcuate surface and a pair of side surface portions 55b extending from the top portion 55a to one surface of the substrate 2.
In addition, the fitting curvature radius Rt2 of the apex portion 55a at the outer edge of the cross section in the direction orthogonal to the other direction which is the extending direction of the second lens 54 is 0.15 times or more and 0.3 times or less of the width W2 of the second lens 54. ing. The definition of the fitting curvature radius Rt2 at the top 54a of the second lens 54 is the same as the above-described fitting curvature radius Rt1.

  In addition, the cross-sectional outer edge shape of the sub lens 55 is expressed by the following Expression 2 similarly to the first lens 53. Here, the position from the width direction center in the width direction of the second lens 54 is s. The coefficients S, D, E, and F are correction coefficients.

Here, the coefficient (1 / S) is greater than −10 and less than 10, and the coefficient D is greater than −5 and less than 5. As a result, the fitting radius of curvature Rt2 at the top 55a of the second lens 54 becomes 0.15 times or more and 0.3 times or less of the width W2 of the second lens 54. Further, the coefficient E is greater than −10 and less than 10, and the coefficient F is greater than −30 and less than 30.
The outer edge shape of the top 55a of the second lens 54 is a perfect circle when the coefficient j is 0, an ellipse when the coefficient j is greater than -1 and less than 0, a parabola when the coefficient j is -1, and the coefficient j. A hyperbola is obtained when is less than -1.

The optical sheet 50 having the above-described configuration also has the same operations and effects as described above. However, by using the first lens 53 as a lenticular lens, the viewing angle in one direction that is the extending direction of the first lens 53 is obtained. Can be widened. Similarly, when the second lens 54 is a lenticular lens, the viewing angle in the other direction that is the extending direction of the second lens 54 can be widened.
At this time, the coefficient (1 / R) in Equation 1 is greater than −10 and less than 10, coefficient A is greater than −5 and less than 5, coefficient B is greater than −10 and less than 10, and coefficient C is greater than −30 and less than 30. And the fitting curvature radius Rt1 at the top 53a is not less than 0.15 times and not more than 0.3 times the width W1 of the first lens 53, whereby the front luminance in the optical sheet 50 can be improved and the first lens 53 moldability can be maintained. Similarly, in Equation 2 above, the coefficient (1 / S) is greater than −10 and less than 10, coefficient D is greater than −5 and less than 5, coefficient E is greater than −10 and less than 10, and coefficient F is greater than −30 and less than 30. When the fitting curvature radius Rt2 at the top 55a is 0.15 times or more and 0.3 times or less of the width W2 of the second lens 54, the front luminance in the optical sheet 50 can be improved, and the second lens 54 formability can be maintained.

[Third Embodiment]
Next, a third embodiment of the optical sheet in the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
As shown in FIGS. 20 to 22, the optical sheet 60 in the present embodiment includes a base material 2, a first lens array 51, and a second lens array 4.

  The optical sheet 60 configured as described above also has the same operations and effects as described above. However, since the first lens 53 is higher than the second lens 6, it is difficult for other members to contact the second lens 6. ing. Therefore, even if the second lens 6 has a prism shape, the shape of the top of the second lens 6 can be maintained without separately providing a film or the like for protecting the second lens 6. Therefore, the number of parts can be reduced and the cost can be reduced.

In the first to third embodiments described above, the extending direction of the first lens and the extending direction of the second lens are orthogonal to each other, but other angles may be used.
In general, in a display such as a liquid crystal display device, pixels are periodically arranged in a matrix in each of the horizontal scanning direction and the vertical scanning direction as described above. On the other hand, in each of the optical sheets in the first to third embodiments, the first and second lenses are periodically arranged. Therefore, high-order moire such as secondary moire that occurs in the periodic array of pixels and the periodic arrays of the first and second lenses may occur. Thereby, the display quality of the display image in a liquid crystal display device will fall.

Therefore, as shown in FIG. 23, for example, in the first and second lens arrays 3 and 4 in the first embodiment, the extending direction of the first lens 5 is inclined by γ1 with respect to the horizontal scanning direction, and the second The extending direction of the lens 6 may be inclined by γ2 with respect to the vertical scanning direction. Thereby, it is possible to suppress a decrease in display quality due to the occurrence of high-order moire. At this time, the angle formed by the extending direction of the first lens 5 and the extending direction of the second lens 6 is β.
Here, it is desirable that the angle β is greater than 60 ° and less than 120 degrees. Accordingly, it is possible to effectively prevent moiré that occurs between the periodic array of pixels in the horizontal scanning direction and the vertical scanning direction and the periodic array of the first and second lenses. However, each of the angles γ1 and γ2 is more preferably 20 ° or less. When each of the angles γ1 and γ2 exceeds 20 °, the condensing effect by the first and second lenses is too inclined with respect to the horizontal scanning direction and the vertical scanning direction, respectively, and thus viewing angle characteristics in the horizontal scanning direction and the vertical scanning direction, respectively. This is because of deterioration.

Further, although the first and second lenses are arranged at equal intervals, the pitches P1 and P2 of the first and second lenses may be random. Also by this, it is possible to suppress deterioration in display quality due to generation of higher-order moire.
Here, the variation degree of the pitch P1 is preferably within ± 20% with respect to the average value of the pitch P1, and more preferably within ± 10%. Similarly, the variation degree of the pitch P2 is preferably within ± 20% with respect to the average value of the pitch P2, and more preferably within ± 10%. At this time, the height of each of the first and second lenses may be random, but the height is preferably constant.

  In addition, the first lens is arranged linearly along the X direction, but may be meandering as long as it is arranged along one direction (X direction). Also by this, it is possible to suppress deterioration in display quality due to generation of higher-order moire. Similarly, the second lens is arranged linearly along the Y direction, but may be meandering as long as it is arranged along the other direction (Y direction).

The first lens has a height T1 higher than the height T2 of the second lens, but the height T1 only needs to be higher than the height T2.
Each of the first and second lenses has apex angles α1 and α2 of 80 ° or more and 105 ° or less, but may be less than 80 ° as long as a sufficient light diffusion effect is obtained. It may be exceeded.
Further, each of the first and second lenses has fitting radii of curvature Rt1 and Rt2 of 0.15 times or more and 0.3 times or less of the widths W1 and W2. It may be less than 15 times and may exceed 0.3 times.
Each of the first and second lenses has a coefficient (1 / R) greater than −10 and less than 10, coefficient A is greater than −5 and less than 5, coefficient B is greater than −10 and less than 10, and coefficient C is −30. Greater than 30, coefficient (1 / S) greater than −10 and less than 10, coefficient D greater than −5 and less than 5, coefficient E greater than −10 and less than 10, coefficient F greater than −30 and less than 30 However, it may be outside this range as long as a sufficient condensing diffusion effect is obtained.

Further, each of the first and second lenses may have dispersed fine particles dispersed therein for adjusting the viewing angle characteristics.
Each of the first and second lenses may be formed of a separate material.
Furthermore, the first lens array has a plurality of first lenses having the same shape, but the first lens array is not limited to the same shape, for example, a combination of a prism-shaped first lens and a lenticular lens-shaped first lens. Similarly, the second lens array has a plurality of second lenses having the same shape, but is not limited to the same shape.

[Fourth Embodiment]
Next, a fourth embodiment of the optical sheet in the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
As shown in FIG. 24, the optical sheet 100 in the present embodiment includes a base material 2, first and second lens arrays 3 and 4 formed on one surface of the base material 2, and first and second lens arrays 3. 4 and an optical film 101 stacked on top of each other.
The optical film 101 is a film material that exhibits a light diffusing and condensing effect by light refraction, transmission, reflection, and polarization, such as a diffusion sheet, a lenticular sheet, a prism sheet, and a polarization separation / reflection sheet. . The optical film 101 is affixed on the first and second lens arrays 3 and 4 by the fixing layer 102.
Here, when the optical film 101 is a diffusion sheet, the optical film 101 preferably has a configuration in which diffusion beads are dispersedly arranged on a sheet-like substrate. Since the diffused beads arranged in a distributed manner have the same effect as the microlens, the viewing angle and the luminance are improved, and a light distribution without cut-off is obtained.

The fixing layer 102 is formed of an adhesive such as a heat curable resin or a UV curable resin, an adhesive, or the like. Here, examples of the adhesive or pressure-sensitive adhesive include acrylic-based, urethane-based, rubber-based, and silicone-based adhesives or pressure-sensitive adhesives. The adhesive or pressure-sensitive adhesive is applied using a coating device such as a comma coater, printing, a dispenser, or a spray.
Further, the storage elastic modulus at 100 ° C. of the fixing layer 102 is desirably 1.0 × 10 4 Pa or more because the optical sheet 100 is applied to the backlight unit. By setting the storage elastic modulus to 1.0 × 10 4 Pa or more, the optical film 101 can be stably fixed when the backlight unit is used. Moreover, in order to improve the stability of the adhesive or the pressure-sensitive adhesive, for example, fine particles such as beads may be dispersed in the adhesive or the pressure-sensitive adhesive.
The fixing layer 102 may be another fixing material such as a double-sided tape. Further, the optical film 101 may be laminated by bonding or welding using excimer laser irradiation or the like without using the fixing layer 102.

The optical sheet 100 having the above configuration also has the same operations and effects as described above. However, by integrating the optical film 101, the number of components and the thickness can be reduced.
In addition, since the optical sheet 100 includes, for example, a diffusion sheet as the optical film 101, the light emitted from the first and second lenses 5 and 6 is sufficiently diffused and then enters the liquid crystal panel 11. Generation can be suppressed.

Here, the optical film 101 is manufactured by the following manufacturing method, for example.
First, the manufacturing method 1 will be described. First, a mixture of silica and a resin filler in a resin material of MS600 (manufactured by Nippon Steel Chemical Co., Ltd.) as a substrate is stretched along a roller having irregularities formed on the surface. And the optical film is manufactured by transferring the uneven shape on the surface of the roller during extrusion by the roller.
Next, manufacturing method 2 will be described. First, an acrylic monomer is polymerized between a pair of metal flat plates whose surfaces have an uneven shape. And an optical film is manufactured by giving the uneven | corrugated shape attached | subjected to the surface of the metal flat plate.

Next, the manufacturing method 3 will be described. First, the diffusion plate is pressurized while being heated between a pair of metal flat plates having an uneven shape on the surface. And an optical film is manufactured by attaching | subjecting the uneven | corrugated shape attached | subjected to the surface of the metal flat plate.
Next, the manufacturing method 4 is demonstrated. First, acrylic, epoxy resin, polyurethane, transparent thermosetting resin, or ultraviolet curable resin is applied on a metal flat plate having a concavo-convex shape on the surface. And an optical film is manufactured by arrange | positioning the metal flat plate with the uneven | corrugated shape on the surface on the apply | coated resin, and hardening | curing resin.

Next, the manufacturing method 5 is demonstrated. First, 20 wt% of a polystyrene filler having a particle size of 15 μm was mixed in a UV curable adhesive, and this was coated on a diffusion plate with a thickness of 15 μm by a roll coater. And an optical film is manufactured by irradiating UV and hardening | curing to the apply | coated adhesive agent.
Next, the manufacturing method 6 will be described. First, a stretched white PP film (manufactured by Tosero Co., Ltd., thickness 30 μm) or a stretched white PET film (manufactured by Toyobo Co., Ltd., thickness 50 μm) and a plate made of styrene methyl methacrylate are bonded together with an adhesive. Thereby, an optical film in which a spherical cavity is formed is manufactured.

[Fifth Embodiment]
Next, a fifth embodiment of the optical sheet in the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
As shown in FIG. 25, the optical sheet 110 in the present embodiment is provided on the other surface of the substrate 2, the first and second lens arrays 3 and 4 formed on one surface of the substrate 2, and the substrate 2. The scattering plate 111 is provided.
The scattering plate 111 includes a transparent resin layer and transparent particles that are dispersed in the transparent resin layer and have a refractive index different from that of the transparent resin. The scattering plate 111 is made of a transparent resin material, and is formed by, for example, an extrusion molding method. Further, the thickness of the scattering plate 111 is, for example, 1 mm or more and 5 mm or less in order to suppress the bending of the scattering plate 111 or a decrease in transmittance.
Here, the refractive index difference between the transparent resin layer and the transparent particles is desirably 0.02 or more in order to obtain a sufficient light scattering effect. Further, the difference in refractive index between the transparent resin layer and the transparent particles is more preferably 0.5 or less.

As the transparent resin constituting the transparent resin layer, for example, PC, acrylic, acrylonitrile styrene copolymer, fluorine acrylic, silicone acrylic, epoxy acrylate, PS (polystyrene), COP, methylstyrene, fluorene, PET, PP ( Resin material such as polypropylene).
Here, the linear expansion coefficients of PC, PS, methylstyrene, and COP are 6.7 × 10 −5 (1 / ° C.), 7 × 10 −5 (1 / ° C.), 7 × 10 −5 (1 / ° C.), 6-7 × 10 −5 (1 / ° C.), which is 7.0 × 10 −5 (1 / ° C.) or less. Thereby, even if it is a case where the base material 2 and each of the first and second lens arrays 3 and 4 are formed of PET having a linear expansion coefficient of 2.7 × 10 −5 (1 / ° C.), the scattering plate 111 is formed. Can be prevented from warping due to heat. In addition, when each of the base material 2 and the first and second lens arrays 3 and 4 is formed of PC, no warpage occurs because the linear expansion coefficients are substantially equal.

The transparent particles include, for example, acrylic particles, styrene particles, styrene acrylic particles and crosslinked products thereof; melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). -Fluoropolymer particles such as hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene-tetrafluoroethylene copolymer), silicone resin particles, and the like. These transparent particles may be used as a mixture of two or more.
The average particle size of the transparent particles is preferably 0.5 μm or more and 10.0 μm or less, and is preferably 1.0 μm or more and 5 μm or less in order to sufficiently scatter the light incident on the scattering plate 111 and emit the light from the scattering plate 111. It is more desirable that the thickness be 0.0 μm or less.

The scattering plate 111 is fixed to the other surface of the substrate 2 by a fixing layer 112 via a gap 113. The fixing layer 112 is an outer edge portion on the other surface of the substrate 2, and is provided at a position where the illumination light transmitted through the scattering plate 111 does not overlap the image display area in the liquid crystal panel 11. Therefore, as shown in FIGS. 26A to 26E, the fixed layer 112 may be provided in a frame shape over the entire periphery of the outer edge portion of the scattering plate 111, and a pair of opposing edges of the scattering plate 111. Each may be provided, may be provided at a corner portion of the scattering plate 111, or may be provided in an island shape along the peripheral edge of the outer edge portion of the scattering plate 111.
Further, the fixing layer 112 is formed of an adhesive or a pressure-sensitive adhesive as described above. The material applicable as an adhesive or a pressure-sensitive adhesive is the same as described above. Here, in order to ensure the gap 113 between the scattering plate 111 and the substrate 2 by the fixed layer 112, fine particles such as beads may be dispersed as spacers in the adhesive or the pressure-sensitive adhesive.

The optical sheet 110 having the above configuration also exhibits the same operations and effects as described above.
In the present embodiment, the scattering plate 111 has a configuration in which transparent particles are dispersedly arranged in the transparent resin layer. However, a configuration in which a scattering function is provided by forming a spherical cavity in the transparent resin layer may also be used. Good. Here, the cavity may be formed by dispersing a foaming agent in the transparent resin and foaming the foaming agent.

[Other forms of the fifth embodiment]
Next, another form of the optical sheet in the fifth embodiment will be described. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
As shown in FIG. 27, the scattering plate 120 in the optical sheet according to this embodiment has a plurality of cylindrical convex portions formed on one surface facing the substrate 2. Here, the shape of the convex portion is not limited to the cylindrical shape, and may be other shapes such as a lens shape, a triangular prism shape, and a microlens shape. Such a scattering plate 120 is formed by an extrusion method, a casting method, or the like.
In this way, by forming irregularities on one surface of the scattering plate 120 facing the substrate 2, a gap between the substrate 2 and the scattering plate 120 can be secured.
In addition, as shown in FIG.28 and FIG.29, you may be the scattering plates 121 and 122 by which multiple cylindrical convex parts were formed in both surfaces. At this time, the extending direction of the plurality of convex portions formed on one surface and the extending direction of the plurality of convex portions formed on the other surface may be substantially parallel or substantially orthogonal to each other. Also good.

[Other forms of the fifth embodiment]
Then, the other form of the optical sheet in 5th Embodiment is demonstrated. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
As shown in FIG. 30, the scattering plate 123 in the optical sheet in this embodiment includes a sheet-like base material 123a and a fine particle layer 123b formed on one surface of the base material 123a. The fine particle layer 123b is formed, for example, by applying and drying transparent ink in which beads or spacers are dispersed. Here, the fine particle layer 123b may be formed on both surfaces of the base material 123a.

[Other forms of the fifth embodiment]
Furthermore, the other form of the optical sheet in 5th Embodiment is demonstrated. In the following description, the same reference numerals are given to the components described in the above embodiment, and the description thereof is omitted.
The optical sheet 130 in this embodiment includes a spacer 131 disposed between the scattering plate 111 and the base 2 as shown in FIG.
The spacer 131 is formed of a transparent resin material, and is provided in an annular shape along the outer edge portion on the other surface of the substrate 2 as described above.
Here, as a resin material for forming the spacer 131, for example, a thermoplastic resin such as PE, acrylic, PC, Ps, methylstyrene, polymethylpentene, COP, an oligomer such as polyester acrylate, urethane acrylate, epoxy acrylate, or acrylate Examples thereof include radiation curable resins made of a system.
Further, fine particles may be dispersed in the resin material forming the spacer 131. Here, examples of the material for forming the fine particles include inorganic substances such as silica, alumina, titanium oxide, carbon black, and glass beads, and organic substances such as resin beads. The fine particles may be uniformly dispersed in the spacer 131 or locally dispersed. The fine particles may have a reflection characteristic by being covered with a reflection film. Furthermore, spherical cavities may be dispersed in the resin material.

In addition, the spacer 131 desirably has appropriate flexibility in order to suppress the warpage of the substrate 2 and the scattering plate 111 even under high temperature due to light irradiation.
The cross-sectional shape of the spacer 131 may be various shapes such as a rectangle, a trapezoid, a triangle, and a circle.
The thickness of the spacer 131 is preferably 200 nm or more in order to avoid optical contact between the scattering plate 111 and the substrate 2. Further, the width of the spacer 131 is preferably 0.1 times or more, more preferably 0.2 times or more of the thickness in order to more reliably prevent the spacer 131 from contacting the scattering plate 111 and the substrate 2. It is more desirable. Further, the width of the spacer 131 is desirably 50 μm or less, and more desirably 30 μm or less, in order to prevent a decrease in visibility from the optical sheet 130.

The contact area between the spacer 131 and the scattering plate 111 is 1% or more to the area of one surface of the scattering plate 111 facing the base material 2 in order to prevent a reduction in fixing strength and luminance between the spacer 131 and the scattering plate 111. % Or less is desirable. Here, the contact area between the spacer 131 and the scattering plate 111 is more preferably 1% or more and 20% or less with respect to the area of the one surface of the scattering plate 111 facing the base material 2 in order to further suppress a decrease in luminance. . Further, the contact area between spacer 131 and scattering plate 111 is desirably in a 2500 [mu] m 2 or less, and more desirably at 900 .mu.m 2 or less.
Similarly, it is desirable that the contact area between the spacer 131 and the substrate 2 is 1% or more and 60% or less with respect to the area of the other surface of the substrate 2.
Further, the spacer 131 is fixed to the scattering plate 111 and the base material 2 by an adhesive or an adhesive. Here, examples of the material used as the adhesive and the pressure-sensitive adhesive include the same materials as described above.

  As described above, by arranging the spacer 131 between the scattering plate 111 and the base material 2, optical contact between the scattering plate 111 and the base material 2 can be easily suppressed, and the optical of the light emitted from the optical sheet can be suppressed. Appearance characteristics are improved by suppressing the occurrence of uneven brightness and Newton rings in the sheet surface.

Here, the spacer 131 is manufactured by the following manufacturing method, for example.
First, the manufacturing method 1 will be described. First, a PC resin, which is a thermoplastic resin, is heated to form a film while being drawn along a roller. Then, the heated film is cooled while being pressurized using a cylinder mold formed into a spacer shape, and the film is cured while the viscosity of the film is reduced and the spacer shape is maintained. Then, a spacer having a width of 60 μm and a height of 100 μm is manufactured by releasing the film from the cylinder mold.

  Next, manufacturing method 2 will be described. First, a UV curable resin (manufactured by Nippon Kayaku Co., Ltd., refractive index: 1.51) is applied on a biaxially stretchable and easy-adhesive PET film having a thickness of about 125 μm, which mainly contains urethane acrylate. Then, using a cylinder mold molded into a spacer shape, the film is cured by irradiating it with ultraviolet rays while transporting the film. Then, a spacer having a width of 60 μm and a height of 100 μm is manufactured by releasing the film from the cylinder mold.

  Next, the manufacturing method 3 will be described. First, a titanium oxide (manufactured by DuPont), which is a reflective material, is dispersed in a weight ratio of 20% with respect to PC, which is a thermoplastic resin, and is heated and stretched along a roller to form a film. Then, the heated film is cooled while being pressurized using a cylinder mold formed into a spacer shape, and the film is cured while the viscosity of the film is reduced and the spacer shape is maintained. Thereafter, the film is released from the cylinder mold to produce a reflective spacer having a width of 60 μm and a height of 100 μm.

  Next, the manufacturing method 4 is demonstrated. First, 20% by weight of titanium oxide (manufactured by DuPont), which is a reflective material, is dispersed on a biaxially stretchable and easily adhesive PET film having a thickness of about 125 μm. Then, a UV curable resin (manufactured by Nippon Kayaku Co., Ltd., refractive index 1.51) is applied thereon as a main component of urethane acrylate which forms a spacer. Furthermore, using a cylinder mold molded into a spacer shape, the film is cured by irradiating it with ultraviolet rays while transporting the film. Thereafter, the film is released from the cylinder mold to produce a spacer having a width of 60 μm, a height of 100 μm, and a pitch interval of 600 μm.

  Next, the manufacturing method 5 is demonstrated. First, a transfer foil (manufactured by Kurz) having a light reflecting function is pressurized and heated on the upper surface of the spacer manufactured in the manufacturing method 1. Then, the transfer foil is transferred to the upper surface to produce a spacer having a reflective surface.

The spacer 131 is provided in a ring shape along the outer edge of the scattering plate 111. However, as long as the optical contact between the scattering plate 111 and the substrate 2 can be suppressed, the spacer 131 may have other shapes such as a rib shape. Good.
Moreover, the adhesive agent or adhesive which fixes the spacer 131, the scattering plate 111, and each base material 2 may contain the reflecting material. Here, the adhesive or pressure-sensitive adhesive containing the reflective material is formed, for example, by dispersing metal particles or transparent particles having a high refractive index.

  The spacer 131 may have reflection characteristics. Here, the reflection characteristic is imparted, for example, by dispersing metal particles or particles having a high refractive index in the resin material constituting the spacer 131 and forming a reflective film on the surface of the spacer 131. For the reflective film, for example, a metal film such as silver, aluminum, or nickel having high light reflectivity is used by a dry film forming method such as vapor deposition or sputtering, or an ink or adhesive in which particles having a high refractive index are dispersed and mixed. It is formed by applying an adhesive, kneading and transferring metal particles or particles having a high refractive index in a binder, laminating white foil or metal foil, and the like. Here, examples of the particles having a high refractive index include titanium oxide, barium sulfate, magnesium carbonate, zinc oxide, clay, aluminum hydroxide, zinc sulfide, silica, and silicone. Examples of the metal particles or metal foil include aluminum and silver. One kind of these particles, metal particles or metal foil may be used, or a plurality of kinds may be used in combination.

In addition to the above methods, the scattering plate 111 and the base material 2 may be fixed using, for example, welding using heat, ultrasonic waves, laser, or other members. Here, for example, in welding using an excimer laser with a wavelength of 178 nm, after irradiating at least one of the laser of the scattering plate 111 and the base material 2, the two may be bonded together while being heated. May be.
The fixed layer 112 and the spacer 131 described above are provided on the outer periphery of the scattering plate 111 so that the illumination light transmitted through the scattering plate 111 does not overlap the image display region in the liquid crystal panel 11. You may provide so that it may overlap. At this time, the light absorptance in the region corresponding to the image display region is desirably 1% or less in order to secure the luminance of the light emitted from the optical sheets 110 and 130.

Next, the optical sheet having the above-described configuration will be specifically described with reference to examples.
First, as Example 1, an optical sheet in which prism-shaped first and second lens arrays made of a UV curable resin were formed on a base material made of a biaxially stretched easily-adhesive PET film was prepared. In this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, and α1 and α2 are each 90 °.
Further, as Example 2, an optical sheet in which a lenticular lens-shaped first lens array and a prism-shaped second lens array made of a UV curable resin are formed on a base material made of a biaxially stretchable easily-adhesive PET film. Created. Here, in this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, and P2 is 30 μm. In this optical sheet, k is −1, (1 / R) is greater than −10 and less than 10, A is greater than −5 and less than 5, Rt1 is 25 μm, and α2 is 90 °.

And as Example 3, the optical sheet by which the prism-shaped 1st and 2nd lens array which consists of UV curable resin was formed on the base material which consists of a biaxially stretched easily-adhesive PET film was created. Here, in this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, α1 is 90 °, and α2 is 100 °.
Further, as Example 4, an optical sheet in which a PC substrate and prism-shaped first and second lens arrays were integrally formed by an extrusion method was prepared. In this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, and α1 and α2 are each 90 °. The thickness of the base material is 200 μm.

  Further, as Example 5, an optical sheet in which a base material made of PC, a lenticular lens-shaped first lens array, and a prism-shaped second lens array were integrally formed by an extrusion method was prepared. Here, in this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, and P2 is 30 μm. In this optical sheet, k is -1, (1 / R) is larger than -10 and smaller than 10, A is larger than -5 and smaller than 5, B is larger than -10 and smaller than 10, C is smaller than -30. It is less than 30 and Rt1 is 25 μm. Further, this optical sheet has α2 of 90 °.

Further, as Comparative Example 1, an optical sheet in which a lenticular lens-shaped first lens array and a prism-shaped second lens array made of a UV curable resin are formed on a base material made of a biaxially stretched easily-adhesive PET film. Created. Here, in this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, and P2 is 30 μm. In this optical sheet, k is -1, (1 / R) is larger than -10 and smaller than 10, A is larger than -5 and smaller than 5, B is larger than -10 and smaller than 10, C is smaller than -30. It is less than 30 and Rt1 is 50 μm. Further, this optical sheet has α2 of 90 °.
Further, as Comparative Example 2, an optical sheet in which prism-shaped first and second lens arrays made of a UV curable resin were formed on a base material made of a biaxially stretched easily adhesive PET film was prepared. In this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, and α1 and α2 are each 120 °.

Further, as Comparative Example 3, an optical sheet in which prism-shaped first and second lens arrays made of a UV curable resin were formed on a base material made of a biaxially stretched easily-adhesive PET film was prepared. In this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, α1 is 70 °, and α2 is 120 °.
Further, as Comparative Example 4, an optical sheet was prepared in which prism-shaped first and second lens arrays made of a UV curable resin were formed on a base material made of a biaxially stretched easily-adhesive PET film. Here, in this optical sheet, W1 / P1 is 0.9, W2 / P2 is 1, P1 is 100 μm, P2 is 30 μm, α1 is 90 °, and α2 is 100 °.

  And as the comparative example 5, the optical sheet by which the 1st and 2nd lens array of the lenticular lens shape which consists of UV curable resin was formed on the base material which consists of a biaxially stretched easily-adhesive PET film was created. Here, in this optical sheet, W1 / P1 is 0.6, W2 / P2 is 1, P1 is 100 μm, and P2 is 50 μm. In this optical sheet, k is -1, (1 / R) is larger than -10 and smaller than 10, A is larger than -5 and smaller than 5, B is larger than -10 and smaller than 10, C is smaller than -30. It is less than 30 and Rt1 is 50 μm. Further, this optical sheet has α2 of 90 °. In this optical sheet, j is -1, (1 / S) is greater than -10 and less than 10, D is greater than -5 and less than 5, E is greater than -10 and less than 10, and F is less than -30. It is less than 30 and Rt2 is 10 μm.

  For each of Examples 1 to 5 and Comparative Examples 1 to 5, the front luminance and viewing angle characteristics were measured using a viewing angle measuring device (EZContrast: manufactured by Eldim). The evaluation results are shown in Table 1.

As shown in Table 1, in the optical sheets in Examples 1 to 5, each of luminance, half-value angle, side lobe, and cutoff was good.
On the other hand, in the optical sheet in Comparative Example 1, the front luminance was low because Rt1 of the first lens array was too large.
In the optical sheet in Comparative Example 2, the front luminance was low because the apex angles α1 and α2 of the first and second lens arrays were too large.
In the optical sheet in Comparative Example 3, the half angle is narrowed because the apex angle α1 of the first lens array is too small, side lobes are generated, and the front angle is low because the apex angle α2 of the second lens array is too large. became.
Furthermore, in the optical sheet in Comparative Example 4, side lobes were generated because W1 / P1 of the first lens array was too large, and a sharp decrease in luminance occurred in the Y direction.
Moreover, in the optical sheet in Comparative Example 5, the front luminance was low because Rt1 of the first lens array was too large.

Subsequently, the optical sheet as described above will be specifically described with reference to examples.
First, as Example 6, an optical sheet having prism-shaped first and second lens arrays and having an angle of 95 ° between the extending direction of the first lens and the extending direction of the second lens was manufactured. In this optical sheet, the angle between the extending direction of the first lens and the horizontal scanning direction of the liquid crystal panel is 10 °, and the angle between the extending direction of the second lens and the vertical scanning direction is 15 °. Arranged.
Further, as Example 7, an optical sheet having prism-shaped first and second lens arrays and having an angle of 65 ° between the extending direction of the first lens and the extending direction of the second lens was manufactured. . In this optical sheet, the angle between the extending direction of the first lens and the horizontal scanning direction of the liquid crystal panel is 10 °, and the angle between the extending direction of the second lens and the vertical scanning direction is −15 °. Arranged.

As Comparative Example 6, the optical system has prism-shaped first and second lens arrays, and the angle formed by the extending direction of the first lens and the extending direction of the second lens is 150 ° (30 °). A sheet was produced. In this optical sheet, the angle between the extending direction of the first lens and the horizontal scanning direction of the liquid crystal panel is -25 °, and the angle between the extending direction of the second lens and the vertical scanning direction is 45 °. Arranged.
Further, as Comparative Example 7, an optical sheet having prism-shaped first and second lens arrays and having an angle of 90 ° between the extending direction of the first lens and the extending direction of the second lens was manufactured. . In this optical sheet, the angle between the extending direction of the first lens and the horizontal scanning direction of the liquid crystal panel is 30 °, and the angle between the extending direction of the second lens and the vertical scanning direction is 30 °. Arranged.

For each of Examples 6 and 7 and Comparative Examples 6 and 7, the presence or absence of moiré in each of the 32-inch liquid crystal panel and the 37-inch liquid crystal panel was evaluated. As a result, moire was not confirmed in the liquid crystal display devices including the optical sheets in Examples 6 and 7.
On the other hand, in the liquid crystal display device including the optical sheet in Comparative Example 6, moire was confirmed. Further, in the liquid crystal display device including the optical sheet in Comparative Example 7, moire was not confirmed, but the half-value angle in each of the horizontal scanning direction and the vertical scanning direction was reduced, and the display quality was deteriorated.

Subsequently, the optical sheet as described above will be specifically described with reference to examples.
First, as Example 8, an optical sheet in which a surface diffusion film was laminated on the upper surfaces of the first and second lens arrays in the optical sheet in Example 2 described above was manufactured.
Further, as Example 9, an optical sheet was manufactured by laminating a polarization separation / reflection sheet on the upper surfaces of the first and second lens arrays in the optical sheet in Example 2 described above using an adhesive.
And as Example 10, the optical sheet which laminated the optical sheet in Example 2 on the upper surface of the 1st and 2nd lens array in the optical sheet in Example 1 mentioned above using the adhesive was manufactured.

  About each of the above Examples 8-10, evaluation of each brightness | luminance and a half value angle was performed. As a result, in the optical sheet in Example 8, the half-value angle was increased, and the luminance decrease in the oblique direction with respect to the optical sheet was moderated. Further, in the optical sheet in Example 9, the front luminance significantly increased and the half-value angle increased, and the luminance decrease in the oblique direction with respect to the optical sheet was moderated. And in the optical sheet in Example 10, the front luminance increased, and the decrease in luminance in the oblique direction with respect to the optical sheet became gentle.

Subsequently, the optical sheet as described above will be specifically described with reference to examples.
First, as Example 11, an optical sheet was manufactured as follows. First, an adhesive whose main component is an acrylic resin is applied to an end portion 5 mm of a 700 mm × 900 mm diffuser plate (65HLW (PC) manufactured by Teijin Chemicals Ltd.) (application amount: 5 g / m 2). )did. And the base material in which the 1st and 2nd lens array was formed on the diffusion plate is coat | covered with a laminator, and it is made to heat for 30 minutes in 80 degreeC and a 50% drying furnace. Thereafter, the adhesive was cured to produce an optical sheet.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the substrate on which the first and second lens arrays were formed were not peeled off, and no bubbles were generated from the adhesive.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

Next, as Example 12, an optical sheet was manufactured as follows. First, a double-sided tape (manufactured by Sumitomo 3M Co., Ltd.) was affixed to an end portion 5 mm of a 700 mm × 900 mm diffusion plate (manufactured by Teijin Chemicals Ltd., 65HLW (PC)). And the base material in which the 1st and 2nd lens array was formed on the diffusion plate was bonded together, and the optical sheet was manufactured.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

Next, as Example 13, an optical sheet was manufactured as follows. First, the 1st and 2nd lens array which consists of UV curable resin was formed on the base material which consists of a biaxially stretched easily-adhesive PET film. Then, a diffusion plate (Teijin Chemicals Limited) having a linear expansion coefficient of 7.0 × 10 −5 (1 / ° C.) by an adhesive sheet previously applied at 5 g / m 2 on the first and second lens arrays. Made of 65HLW (PC)) to produce an optical sheet.
Further, as Example 14, an optical sheet was manufactured as follows. First, the base material made of PC and the first and second lens arrays were integrally formed by an extrusion method. Then, a diffusion plate (Teijin Chemicals Limited) having a linear expansion coefficient of 7.0 × 10 −5 (1 / ° C.) by an adhesive sheet previously applied at 5 g / m 2 on the first and second lens arrays. Made of 65HLW (PC)) to produce an optical sheet.
And these optical sheets were thrown into the environment of normal temperature to 80 degreeC, and the curvature by a temperature change was confirmed. The warpage was measured by placing an optical sheet on a flat table so that the base material was on the bottom surface, and measuring the amount of floating from the table at four corners. In addition, it was 0 mm in each corner before introduction.
The warpage occurred in the optical sheet of Example 13 after being put in the 80 ° C. environment. The amount of warpage at this time was 10 to 15 mm. Further, no warpage occurred in the optical sheet of Example 14.
This test reproduces the situation where the temperature is high when the backlight is lit, but in each optical sheet, each corner is warped so that it floats from the table, and is directed toward the first and second lens arrays. It is not warped to become convex. Therefore, even if the display image is pressed when it is incorporated in the liquid crystal display device, it is considered that no abnormality occurs in the display image.

Next, as Example 15, an optical sheet was manufactured as follows. First, similarly to Example 14 described above, a base material made of PC and the first and second lens arrays were integrally formed by an extrusion method. A diffusion plate (Teijin Chemicals Ltd.) having a linear expansion coefficient of 7.2 × 10 −5 (1 / ° C.) by an adhesive sheet previously applied at 5 g / m 2 on the first and second lens arrays. Made of 65HLW (PC)) to produce an optical sheet.
Moreover, as Comparative Example 8, as in Example 13 described above, first and second lens arrays made of UV curable resin were formed on a base material made of a biaxially stretched easily-adhesive PET film. A diffusion plate (Teijin Chemicals Ltd.) having a linear expansion coefficient of 7.2 × 10 −5 (1 / ° C.) by an adhesive sheet previously applied at 5 g / m 2 on the first and second lens arrays. Made of 65HLW (PC)) to produce an optical sheet.
And these optical sheets were thrown into the environment of normal temperature to 80 degreeC, and the curvature by a temperature change was confirmed.
Warpage occurred in each of the optical sheets in Example 15 and Comparative Example 8 after being put in the 80 ° C. environment. The amount of warpage at this time was about 5 mm for the optical sheet in Example 15 and about 40 mm for the optical sheet in Comparative Example 8.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, in the optical sheet in Example 15, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off. On the other hand, in the optical sheet in Comparative Example 8, the diffusion plate and the substrate on which the first and second lens arrays were formed were peeled off.

Next, as Example 16, an optical sheet was manufactured as follows. First, 20% by weight of a polystyrene filler having a particle diameter of 15 μm was mixed in a UV curable adhesive, and this was thickened on a 700 mm × 900 mm diffusion plate (65HLW (PC) manufactured by Teijin Chemicals Ltd.) using a roll coater. Application was at 30 μm. And it was hardened by irradiating UV light once until the tack remained. Then, the base material in which the 1st and 2nd lens array was formed on the diffusion plate was bonded together, and the optical sheet was manufactured.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the substrate on which the first and second lens arrays were formed were not peeled off, and no bubbles were generated from the adhesive.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

Next, as Example 17, an optical sheet was manufactured as follows. First, the substrate on which the first and second lenses are formed is irradiated with excimer UV light having a wavelength of 172 nm for 30 seconds, and a lenticular lens having a lens pitch of 140 μm and a lens height of 60 μm is formed. The plates were bonded with a laminator to produce an optical sheet.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the substrate on which the first and second lens arrays were formed were not peeled off, and no bubbles were generated from the adhesive.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

Next, as Example 18, an optical sheet was manufactured as follows. First, a base material on which the first and second lens arrays are formed is prepared in advance in a large size (1000 mm × 1000 mm), and this and a diffusion plate are overlapped. And it lightly pressed with the static elimination brush so that it may not float between the base material in which the 1st and 2nd lens array was formed, and the diffusion plate, and laser-cutting to the size of 500 mm x 500 mm with the carbon dioxide laser cutting machine. Note that the color of the lens sheet was slightly changed to yellow at the end portion of about 5 mm cut by laser irradiation. Therefore, a 25 μm easy-adhesive PET film was laminated as a protective film on the surfaces of the base material on which the first and second lens arrays were formed in advance and the diffusion plate, and laser cutting was performed in the same manner. Thereafter, when the protective film was peeled off, the base material on which the first and second lens arrays were formed and the diffusion plate were not discolored.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the substrate on which the first and second lens arrays were formed were not peeled off, and no bubbles were generated from the adhesive.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

Next, as Example 19, an optical sheet was manufactured as follows. A through hole was formed in each of the base material on which the first and second lens arrays were formed and the diffusion plate. And a base material and a diffusion plate were fixed to this through-hole through the wire, and the optical sheet was manufactured.
The optical sheet thus produced was heated at 80 ° C. for 24 hours in the same manner as the temperature when the backlight was turned on. As a result, the diffusion plate and the substrate on which the first and second lens arrays were formed were not peeled off, and no bubbles were generated from the adhesive.
Further, the manufactured optical sheet was incorporated into a liquid crystal display device. The liquid crystal display device is vibrated at a frequency of 5 to 50 Hz with an acceleration of 1 G for 70 minutes in the vertical direction (Z direction), 20 minutes in the horizontal direction (X direction), and 20 minutes in the horizontal direction (Y direction). The state was reproduced. As a result, the diffusion plate and the base material on which the first and second lens arrays were formed were not peeled off.

In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, an optical sheet is used in a backlight unit used in a display device, but for controlling the viewing angle and improving the contrast of a display device such as a liquid crystal display device, an EL (electroluminescence) display device, or a plasma display. You may use for other uses, such as a sheet material of this, the film for light control for solar cells, and a projection screen.
The light source of the backlight unit is not limited to a cold cathode tube, but may be another light source such as an LED, an EL, or a semiconductor laser. Here, when using an LED as a light source, an array of red, green, and blue LEDs is used, and light emitted from the red, green, and blue LED arrays is mixed with a light guide plate or the like to uniformly emit white light. It is good also as composition to do. Moreover, it is good also as a structure which mixes the light inject | emitted from the LED array of red, green, and blue using a diffuser board etc., and inject | emits uniformly.
Further, the backlight unit is not limited to a direct type backlight unit, and may be a side edge type backlight unit.

It is a perspective view which shows the optical sheet in 1st Embodiment. It is a top view of FIG. (A) is X1-X1 arrow sectional drawing of FIG. 1, (b) is Y1-Y1 arrow sectional drawing. It is a schematic block diagram which shows the liquid crystal display device of this invention. It is a graph which shows the viewing angle characteristic of an optical sheet. Similarly, it is a graph which shows the viewing angle characteristic of an optical sheet. It is a graph which shows the relationship between W1 / P1 and the half value angle in a X direction. It is a graph which shows the relationship between W1 / P1 and the half value angle in a Y direction. It is a graph which shows the relationship between W1 / P1 and the brightness | luminance in a front direction. It is a graph which shows the relationship between W2 / P2 and the brightness | luminance in a front direction. It is a graph which shows the viewing angle characteristic of an optical sheet. Similarly, it is a graph which shows the viewing angle characteristic of an optical sheet. Similarly, it is a graph which shows the viewing angle characteristic of an optical sheet. Similarly, it is a graph which shows the viewing angle characteristic of an optical sheet. Similarly, it is a graph which shows the viewing angle characteristic of an optical sheet. It is a perspective view which shows the optical sheet in the 2nd Embodiment of this invention. FIG. 17 is a plan view of FIG. 16. (A) is X2-X2 arrow sectional drawing of FIG. 16, (b) is Y2-Y2 arrow sectional drawing. It is an enlarged view sectional view showing the top part of the 1st lens. It is a perspective view which shows the optical sheet in 3rd Embodiment. It is a top view of FIG. (A) is X3-X3 arrow sectional drawing of FIG. 20, (b) is Y3-Y3 arrow sectional drawing. It is a top view which shows the other arrangement | positioning state of a 1st and 2nd lens array. It is a schematic block diagram which shows the liquid crystal display device which has an optical sheet in 4th Embodiment. It is a schematic block diagram which shows the liquid crystal display device which has an optical sheet in 5th Embodiment. It is a top view which shows the formation location of the fixed layer in a scattering plate. It is a perspective view which shows the scattering plate in the other form of FIG. Similarly, it is a perspective view which shows the scattering plate in the other form of FIG. Similarly, it is a perspective view which shows the scattering plate in the other form of FIG. Similarly, it is a perspective view which shows the scattering plate in the other form of FIG. Similarly, it is a perspective view which shows the scattering plate in the other form of FIG.

Explanation of symbols

1, 50, 60 Optical sheet 2 Base material 3, 51 First lens array 4, 52 Second lens array 5, 53 First lens 6, 54 Second lens 7, 55 Sub lens 10 Liquid crystal display device (display device)
11 Liquid crystal panel (image display element)
12 Backlight unit 26 Light source 53a, 55a Top part 53b, 55b Side face part A, B, C, D, E, F, j, k, R, S Coefficient P1, P2 Pitch Rt1, Rt2 Fitting radius of curvature T1, T2 Height W1, W2 width α1, α2 apex angle

Claims (19)

  1. A flat substrate, and first and second lens arrays provided on one surface of the substrate,
    The first lens array includes a plurality of first lenses that extend along one direction on the one surface and are arranged in parallel to each other.
    The second lens array includes a plurality of second lenses extending along another direction intersecting the one direction on the one surface and arranged parallel to each other.
    The second lens has a plurality of sub-lenses arranged in valleys of the plurality of first lenses;
    The pitch of the first lens is P1, the width of the first lens is W1, the height of the first lens is T1, the pitch of the second lens is P2, the width of the second lens is W2, and the second lens. When the height of T2 is T2,
    The height T1 is not less than the height T2,
    The pitch P1 is equal to or greater than the pitch P2.
    W1 / P1, which is the ratio of the width W1 to the pitch P1, is 0.5 or more and 0.8 or less,
    W2 / P2, which is a ratio of the width W2 and the pitch P2, is 0.8 or more and 1 or less,
    An optical sheet, wherein an angle formed by the one direction and the other direction is 60 ° or more and 120 ° or less.
  2.   The optical sheet according to claim 1, wherein the first lens is a prism lens having a triangular cross section.
  3.   The optical sheet according to claim 2, wherein an apex angle of the first lens is 80 ° or more and 105 ° or less.
  4.   The optical sheet according to claim 2, wherein the second lens is a prism lens having a triangular cross section.
  5.   The optical sheet according to claim 4, wherein an apex angle of the second lens is 80 ° or more and 105 ° or less.
  6.   6. The optical sheet according to claim 4, wherein an apex angle of the second lens is equal to or greater than an apex angle of the first lens.
  7. The first lens has a top portion having an arcuate surface and a pair of side portions extending from the top portion to the one surface,
    2. The optical sheet according to claim 1, wherein each of the pair of side surface portions comes closer to each other from the one surface toward the top portion.
  8.   8. The optical sheet according to claim 7, wherein a fitting curvature radius at the top of the first lens is not less than 0.15 times and not more than 0.3 times the width W1.
  9. The cross-sectional shape of the first lens uses coefficients R, A, B, and C where the normal direction of the one surface is the Z axis and the position from the center in the width direction in the width direction of the first lens is r. Z = (r 2 / R) / (1 + √ (1− (1 + k) × (r / R) 2 )) + Ar 2 + Br 4 + Cr 6
    When the pitch P1 is normalized to 1,
    The coefficient (1 / R) is greater than −10 and less than 10;
    The coefficient A is greater than -5 and less than 5;
    The coefficient B is greater than −10 and less than 10;
    The optical sheet according to claim 8, wherein the coefficient C is greater than −30 and less than 30.
  10. The second lens has a top portion having an arcuate surface and a pair of side portions extending from the top portion to the one surface,
    The optical sheet according to any one of claims 7 to 9, wherein each of the pair of side surface portions comes closer to each other from the one surface toward the top portion.
  11.   11. The optical sheet according to claim 10, wherein a fitting curvature radius at the top of the second lens is not less than 0.15 times and not more than 0.3 times the width W <b> 2.
  12. The cross-sectional shape of the second lens uses coefficients S, D, E, and F, where the normal direction of the one surface is the Z axis and the position from the width direction center in the width direction of the second lens is s. Z = (s 2 / S) / (1 + √ (1− (1 + j) × (s / S) 2 )) + Ds 2 + Es 4 + Fs 6
    When the pitch P2 is normalized to 1,
    The coefficient (1 / S) is greater than −10 and less than 10;
    The coefficient D is greater than -5 and less than 5,
    The coefficient E is greater than −10 and less than 10;
    The optical sheet according to claim 11, wherein the coefficient F is greater than −30 and less than 30.
  13.   The optical sheet according to any one of claims 7 to 9, wherein the second lens is a prism lens having a triangular cross section.
  14.   The optical sheet according to claim 13, wherein an apex angle of the second lens is 80 ° or more and 105 ° or less.
  15.   The optical sheet according to claim 1, wherein the first and second lens arrays are made of the same material.
  16.   The optical sheet according to any one of claims 1 to 15, wherein at least one of the pitch P1 and the pitch P2 is random.
  17.   The optical sheet according to any one of claims 1 to 16, wherein each of the height T1 and the height T2 is constant.
  18. The optical sheet according to any one of claims 1 to 17,
    A backlight unit comprising: a light source that irradiates the optical sheet with illumination light.
  19. The backlight unit according to claim 18;
    A display device comprising: an image display element that is irradiated with the illumination light emitted from the optical sheet and displays a display image.
JP2007244346A 2007-09-20 2007-09-20 Optical sheet, backlight unit and display device Expired - Fee Related JP5018371B2 (en)

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