JP2011060455A - Lighting unit, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting unit and a display device, capable of enhancing brightness on an observer side by efficiently condensing light emitted from a light source while sufficiently securing a view angle of a display screen. <P>SOLUTION: The lighting unit 55 is provided with a light control sheet 1 equipped with a first prism array with a plurality of first prisms 3 arranged parallel to each other, each of which 3 extends linearly and nearly in the vertical direction on a light-emitting surface side and makes nearly a trapezoid shape in a cross section view crossing the extended direction, and a second prism array with a plurality of second prisms 5 arranged parallel to each other, each of which 5 extends to a direction nearly crossing the extended direction of the first prism at a first top part of the first prism array and makes nearly a triangle shape in a cross section view crossing the extended direction. Further the lighting unit 55 is provided with a light condensing sheet 11 equipped with a third array with a plurality of third lenses extended linearly and arranged parallel to each other. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illumination unit used for illumination optical path control, and a display device using the illumination unit. Specifically, the present invention relates to an illumination unit including a light control sheet that emits control light using light from a light source as incident light, and a condensing sheet that uses the control light as incident light, and a display device using the illumination unit.

  In recent large-sized liquid crystal televisions, a direct type backlight unit (illumination unit) in which a plurality of cold-cathode tubes and LEDs (Light Emitting Diodes) are arranged is employed. In this direct type backlight unit, a diffuser plate having a high light scattering property is used between the image display element and the light source so that a cold cathode tube or an LED as a light source is not visually recognized.

  Since this diffusion plate diffuses light in all directions due to the light diffusion effect, the liquid crystal display device is darkened. Further, the thickness of the diffusion plate usually requires a thickness of about 1 to 5 mm in order to enhance the light scattering property and support the optical film formed on the diffusion plate. Therefore, light absorption occurs not a little with this diffusion plate, and the liquid crystal screen display becomes dark.

  Conventionally, a diffusion plate used in a direct type backlight is intended to diffuse light emitted from a cold cathode tube, which is a light source, and reduce luminance unevenness (lamp image). Therefore, usually, a single or a plurality of optical sheets are arranged on the diffusion plate in order to improve the luminance in the viewer side direction.

  Recently, LEDs (Light Emitting Diode Light Emitting Diodes) have begun to be used instead of cold cathode tubes as light sources, making it possible to make the display brighter than before. Therefore, the edge light system that has been used for notebook computers and portable information terminals and that can be easily reduced in thickness and easily reduced in thickness has begun to be adopted for medium-sized or large-sized liquid crystal display devices of 20 inches or more.

  However, since the edge light system has a structure in which the light source is disposed only on the end face of the light guide plate, the number of light sources installed is limited. Therefore, it is difficult to brighten the entire display as the liquid crystal display device becomes larger. Therefore, the role of the optical sheet for improving the brightness is important.

As an optical sheet for improving the brightness of a liquid crystal display screen, a brightness enhancement film (BEF), which is a registered trademark of 3M USA, is widely used as a lens sheet.
FIG. 13 is a schematic cross-sectional view showing an example of the arrangement of BEF, and FIG. 14 is a perspective view of the BEF. As shown in FIGS. 13 and 14, the BEF 185 is an optical film in which unit prisms 187 having a triangular cross section are periodically arranged in one direction on a member 186. The unit prism 187 has a size (pitch) larger than the wavelength of light.

  The BEF 185 collects light from “off-axis” and redirects this light “on-axis” or “recycle” toward the viewer. can do. That is, the BEF 185 can increase the on-axis brightness by reducing the off-axis brightness when the display is used (observation). Here, “on-axis” is a direction that coincides with the viewer's viewing direction F ′, and is generally on the normal direction side with respect to the display screen.

  When using a lens sheet represented by BEF185, it is effective to use a diffusion film in combination. This diffusion film is configured by applying a diffusion filler on a transparent substrate, and has both functions of diffusion and light collection. By disposing the diffusion film between the diffusion plate and the lens sheet, it is possible to collect the diffused light emitted from the diffusion plate and to suppress the visibility of the light source that cannot be erased only by the diffusion plate. it can.

  Further, the diffusion film can be disposed between the lens sheet and the liquid crystal panel, thereby reducing side lobes and preventing moire interference fringes generated between regularly arranged lenses and liquid crystal pixels. It becomes possible.

By adopting BEF185 like this, a display designer can achieve a desired on-axis brightness while reducing power consumption.
As patent documents disclosing that a luminance control member having a repetitive array structure of prisms represented by BEF185 is adopted for a display, there are many known ones as exemplified in Patent Documents 1 to 3. Yes.

  In the optical sheet using BEF185 as a luminance control member as described above, light incident from the light source is emitted at an angle controlled by refraction. Thereby, it is possible to control to increase the light intensity in the visual direction of the viewer.

Japanese Patent Publication No. 1-378001 JP-A-6-102506 Japanese National Patent Publication No. 10-506500

  However, when BEF 185 is used, a light component due to reflection / refractive action may be unnecessarily emitted in the lateral direction without proceeding to the visual direction F ′ of the viewer. The broken line B in FIG. 14 shows the characteristics of the BEF 185. The light intensity is highest when the angle with respect to the light intensity and the viewing direction F ′ is 0 ° (corresponding to the axial direction), but the angle with respect to F ′ is ± 90. A light intensity peak (side lobe) is generated in the vicinity of °, and the amount of light emitted from the lateral direction is increasing.

  In order to increase the luminance, two luminance control members having a repetitive array structure of prisms represented by BEF185 may be arranged so as to be substantially orthogonal to each other. However, in this case, only the on-axis luminance is excessively improved, and the peak width of the luminance distribution curve is remarkably narrowed so that the viewing area is extremely limited.

  In particular, in recent years, liquid crystal display devices are strongly demanded as market needs for low power consumption, high luminance, and thinning. For this reason, it is required to reduce the number of light sources in both the direct method and the edge light method, and particularly in the edge light method, the number of light sources to be arranged is limited due to the structure, and the total amount of light is reduced. Limited. Therefore, there is a demand for a backlight unit (illumination unit) that effectively uses the light emitted from the light source and improves the luminance, but does not limit the viewing zone.

  The present invention has been made in view of such circumstances, and improves the brightness on the viewer side by efficiently condensing the light emitted from the light source while sufficiently securing the viewing angle of the display screen. An object of the present invention is to provide a lighting unit and a display device that can be used.

In order to solve the above problems, the present invention proposes the following means.
That is, the optical sheet according to the present invention includes a light source that emits light, a light control sheet that controls and emits light incident from the light source, and a light collection that uses light emitted from the light control sheet as incident light. In the illumination unit including the light sheet, the light control sheet extends in a substantially vertical direction linearly on the light exit surface side and has a substantially trapezoidal shape in a cross-sectional view orthogonal to the extending direction. A first prism array in which a plurality of prisms are arranged in parallel to each other; and a substantially triangular shape in a cross-sectional view extending in a direction substantially orthogonal to the first prism at the top of the first prism array and orthogonal to the extending direction. A second prism array in which a plurality of second prisms having a shape are arranged in parallel with each other, and the light collecting sheet has a third lens in which a plurality of third lenses extending linearly are arranged in parallel with each other Featuring an array To.

  According to the illumination unit having such a feature, the second prism of the light control sheet has a triangular prism shape with a high condensing effect, and the first prism has a trapezoidal prism shape that can obtain the same effect as the triangular prism. Therefore, the light collection effect toward the observer side F can be further improved. Further, since the first prism array and the second prism array are substantially orthogonal, a light collecting effect in two directions can be obtained. Furthermore, when the light that has passed through such a light control sheet enters the light collecting sheet, the light collecting effect on the light collecting sheet can be improved.

  In the optical sheet according to the present invention, it is preferable that the light control sheet and the light collecting sheet are arranged so as to extend along a vertical plane, and the third lens extends along a substantially horizontal direction. .

  In the optical sheet according to the present invention, it is preferable that the third lens has a triangular prism shape with an apex angle of 70 degrees to 110 degrees.

  In the optical sheet according to the present invention, it is preferable that an apex angle of the second prism is set in a range of 85 degrees to 115 degrees.

  In the optical sheet according to the present invention, in a cross-sectional view perpendicular to the extending direction of the first prism, an angle formed by the extension lines of the pair of oblique sides constituting the substantially trapezoidal shape is in a range of 65 degrees to 100 degrees. It is preferable that it is set to.

  In the optical sheet according to the present invention, it is preferable that the ratio of the surface area of the second prism array to the surface area of the light control sheet on the exit surface side is set to 0% or more and 40% or less.

  An illumination unit according to the present invention includes a light source that emits light, a light control sheet that controls and emits light emitted from the light source, and a light collecting sheet that uses incident light as light emitted from the light control sheet. The light control sheet includes a first prism having a substantially trapezoidal shape in a cross-sectional view extending in a substantially horizontal direction linearly on the light exit surface side and orthogonal to the extending direction. A plurality of first prism arrays arranged in parallel to each other, and extending in a direction substantially perpendicular to the first prism at the top of the first prism array, and having a substantially triangular shape in a cross-sectional view perpendicular to the extending direction A second prism array in which a plurality of second prisms are arranged in parallel with each other, and the light collecting sheet includes a third prism array in which a plurality of third lenses extending linearly are arranged in parallel with each other. With features That.

  In the optical sheet according to the present invention, it is preferable that the third lens extends along a substantially horizontal direction.

  In the optical sheet according to the present invention, it is preferable that the third lens has a triangular prism shape with an apex angle of 70 degrees to 110 degrees.

  In the optical sheet according to the present invention, it is preferable that the third lens extends along a substantially horizontal direction.

  In the optical sheet according to the present invention, in a cross-sectional view orthogonal to the extending direction of the first prism, the angle formed by the extension lines of the pair of oblique sides constituting the substantially trapezoidal shape is in a range of 85 degrees to 115 degrees. It is preferable that it is set.

  In the optical sheet according to the present invention, it is preferable that an apex angle of the second prism is set in a range of 80 degrees to 100 degrees.

  In the optical sheet according to the present invention, the ratio of the surface area of the second prism array to the surface area of the light control sheet on the emission surface side is preferably set to 20% to 85%.

  In the optical sheet according to the present invention, it is preferable that a plurality of protrusions are formed on the incident surface side of the light control sheet.

A display device according to the present invention includes any one of the illumination units described above and an image display element that performs image display by light irradiation from the illumination unit.
According to the display device having such characteristics, since the light control sheet and the light collecting sheet are provided, the light collecting effect can be improved.

  The display device according to the present invention is characterized in that the image display element defines a display image in accordance with transmission / shading in pixel units.

According to the present invention, the light condensing effect of the light condensing sheet disposed on the viewer side of the light control sheet due to the light condensing effect in the two directions of the first prism and the second prism substantially orthogonal to each other of the light control sheet Can be increased.
In addition, by controlling the incident light to the condensing sheet with the light control sheet, the brightness emitted from the light source is efficiently directed toward the viewer while ensuring a sufficient viewing angle of the display screen. It is possible to provide a lighting unit and a display device that can improve the above.

It is sectional drawing of the display apparatus of embodiment of an edge light system. It is sectional drawing of the display apparatus of embodiment of a direct type. It is a perspective view of a light control sheet. It is (a) (b) side view and (c) top view of a light control sheet. It is sectional drawing of the display apparatus of embodiment of an edge light system. It is sectional drawing of the display apparatus of embodiment of a direct type. It is a perspective view which shows the type | mold used when producing the light control sheet | seat of this embodiment. (A) is the light distribution characteristic figure of the conventional prism, (b) is the light distribution characteristic figure of the light control sheet | seat which concerns on embodiment. (A) The graph which shows the dependence with respect to the area ratio of the 2nd prism array of the half value angle in the arrangement | positioning A of the light control sheet of embodiment, (b) The 2nd prism of the half value angle in the arrangement | positioning B of the light control sheet of embodiment. It is a graph which shows the dependence with respect to the area ratio of an array. (A) is a graph which shows the dependence with respect to the apex angle of the brightness | luminance in arrangement | positioning A of the illumination unit of embodiment, (b) is a graph which shows the dependence with respect to the apex angle of the brightness | luminance in arrangement | positioning B of the illumination unit of embodiment. It is a graph which shows the dependence with respect to the area ratio of the 2nd prism array of the brightness | luminance of the illumination unit of embodiment. It is sectional drawing of the light control sheet | seat which has a projection part in the entrance plane of a base material. It is a cross-sectional schematic diagram which shows an example of arrangement | positioning of BEF by a prior art. It is a perspective view of BEF by a prior art. It is explanatory drawing which shows the light intensity distribution radiate | emitted from the optical sheet using BEF.

  EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail with reference to drawings. In addition, the illumination unit which concerns on embodiment of this invention is demonstrated with a display apparatus.

As shown in FIG. 1 or 2, the display device 70 according to the embodiment includes a liquid crystal display configured by overlapping an image display element 35 on the light emission side of an illumination unit 55 that emits light upward. It is an apparatus, and displays an image by emitting display light whose display is controlled by an image signal from the image display element 35 toward the observer side (upward side in FIG. 1).
The illumination unit 55 and the display device 70 are arranged so that their display surfaces face in the vertical direction, that is, they are arranged so as to stand along a plane including the horizontal direction Ho and the vertical direction Ve. Is done. Thereby, the light control sheet 1 and the light collecting sheet 11 described later are arranged along the vertical plane.
Hereinafter, based on such an arrangement, the upper direction in FIG. 1 or 2 may be simply referred to as the front direction F or the observer side F, and the lower direction may be simply referred to as the back side.
In addition, the size and shape in each figure are exaggerated as appropriate for easy understanding.

  The image display element 35 is preferably an element that displays an image by transmitting / blocking light in pixel units. An image with high image quality can be displayed as long as the image is displayed by transmitting / blocking light in pixel units.

  As the image display element 35, a liquid crystal display element is used in the present embodiment. A liquid crystal display element is a typical element that transmits / shields light in pixel units and displays an image, and can improve image quality and reduce manufacturing cost compared to other display elements. Can do.

  The liquid crystal panel as the image display element 35 is, for example, on the back side of a liquid crystal cell (display element or panel) 32 that controls the light transmission state according to an image signal for each of a plurality of pixel regions formed in a rectangular lattice shape. In addition, polarizing plates 31 and 33 that control the polarization direction of light are stacked on the viewer side. The liquid crystal cell 32 includes a pair of glass substrates and a liquid crystal layer sandwiched between them.

  The image display element 35 is a so-called transmissive display panel in the present embodiment, but may be a transflective display panel. Alternatively, instead of the image display element 35 as a liquid crystal panel including the liquid crystal cell 32, another display panel, for example, a display panel that displays a still image with a light-transmitting coloring pattern may be used.

  The illumination unit 55 is a light emitting device having a light emitting surface having substantially the same area as the display screen of the image display element 35, and the light control sheet 1 and the light collecting sheet 11 are disposed on the light emission direction side of the light source unit 20. It is comprised by laminating in order. Note that a polarization reflection separation sheet or a diffusion sheet may be disposed on the observer side F of the light collecting sheet 11.

  The light source unit 20 emits light toward the front side, and an edge light system is used in FIG. 1, and a direct type is used in FIG.

  In the edge light type light source unit 20 shown in FIG. 1, a plurality of light sources 41 are arranged in a reflecting plate 43, and a light guide plate 25 that emits light incident from the light source 41 to the viewer side F is arranged on the side thereof. Is made up of. Furthermore, a light deflection surface is formed on the surface of the light guide plate 25 opposite to the observer side F. The light deflection surface is a surface that deflects incident light from the light source 41 toward the emission surface, and for example, white diffuse reflection dots are printed thereon. Another example includes a structure such as a microlens shape or a prism shape.

Examples of the light source 41 in the light source unit 20 include a linear light source and a point light source. Examples of the linear light source include fluorescent tubes such as CCFL, HCFL, and EEFL. Examples of the point light source include LEDs, and examples of the LEDs include white LEDs and RGB-LEDs.
In addition, in the light source part 20 of this embodiment, although the light source 41 has shown the example arrange | positioned at the one end surface side of the light-guide plate 25, it is not restricted to this, It arrange | positions at two opposing end surface sides, or The structure arrange | positioned at the four end surface sides may be sufficient. At this time, the shape of the light guide plate 25 may be not only the wedge shape shown in FIG. 1 but also a flat plate shape.

  On the other hand, in the direct type light source unit 20 shown in FIG. 2, a plurality of light sources 41 are arranged in a lamp house (reflecting plate) 43, and further diffused and emitted from the light source 41 on the front side thereof. A plate 26 is provided.

Examples of the light source 41 include a linear light source and a point light source. Examples of the linear light source include fluorescent tubes such as CCFL, HCFL, and EEFL. Examples of the point light source include an LED, and examples of the LED include a white LED and an RGB-LED.
The reflection plate 43 is disposed on the opposite side of the plurality of light sources 41 from the observer side F, and reflects the light emitted in the direction opposite to the observer side F out of the light emitted from the light source 41 in all directions. Can be emitted to the observer side F. As a result, the light H emitted to the observer side F becomes light emitted almost in all directions from the light source 41. By using the reflection plate 43 in this way, the light utilization efficiency can be increased. The reflection plate 43 may be any member that reflects light with high efficiency. For example, a general reflection film, a reflection plate, or the like can be used.

  The diffusion plate 26 is formed by dispersing a light diffusing agent in a transparent resin. Due to the difference in refractive index between the transparent resin and the light diffusing agent dispersed in the transparent resin, sufficient light diffusion characteristics are obtained, and the light emitted from the light source 41 is diffused in all directions.

As shown in FIGS. 1 and 2, the illumination unit 55 and the display device 70 according to the present embodiment can be applied to both the edge light method and the direct type.
In the edge light system, a strong oblique light having a peak at 60 to 80 degrees emitted from the light guide plate 25 when the front direction is set to 0 degree is collected by the light control sheet 1 to be described later. Can be controlled to increase the incident light.
Similarly, in the direct type, light (Lambert light) diffused by the diffusion plate 26 can be controlled to incident light that enhances the light collecting effect of the light collecting sheet 11 by the light control sheet 1 described later. .

Next, the light control sheet 1 will be described with reference to FIGS. 3 and 4.
The light control sheet 1 includes a base material 17, a first prism array 2, and a second prism array 5.

  The base material 17 is made of a transparent resin that transmits light, and is a member having a sheet shape or a plate shape substantially parallel to the display surface of the display device 70, and a surface facing the back surface is an incident surface 17a. A surface facing the observer side F is an emission surface 17b.

The first prism array 2 is formed on the emission surface 17 b of the base material 17 and includes a plurality of first prisms 3.
The first prism 3 extends in one direction along the emission surface 17b of the substrate 17, and has a substantially isosceles trapezoidal shape in a cross-sectional view orthogonal to the extending direction as shown in FIG. There is no. That is, the first prism 3 is connected to the pair of first inclined surfaces 3b and 3b constituting the oblique side of the substantially isosceles trapezoidal shape in cross section, and the pair of first inclined surfaces 3b and 3b, and is substantially isosceles in cross section. And a flat first apex 3a constituting a trapezoidal upper base, and the pair of first inclined surfaces 3b, 3b and the first apex 3a extend in one direction, thereby forming a trapezoidal prism shape. There is nothing.

  Such first prisms 3 are continuously arranged on the emission surface 17b of the base material 17 in a direction orthogonal to one direction in which the first prisms 3 extend, whereby the first prism array 2 is formed. It is configured. In the present embodiment, the lower ends of the first inclined surfaces 3b of the adjacent first prisms 3 are in contact with each other, that is, arranged over the entire emission surface so as to fill the emission surface 17b of the base material 17. ing.

The second prism array 5 is formed on the first apex 3 a of the first prism 3 and includes a plurality of second prisms 6.
The second prism 6 extends in a direction orthogonal to the extending direction of the first prism 3, and has a substantially triangular shape in a cross-sectional view orthogonal to the extending direction. That is, the second prism 6 includes a pair of second inclined surfaces 6 a and 6 a that form a hypotenuse having a triangular shape in cross section, and the second inclined surfaces 6 a and 6 a extend in the direction in which the first prism 3 extends. A triangular prism shape is formed by extending in a direction orthogonal to the axis. When the upper ends of the second inclined surfaces 6a and 6a are in contact with each other, a second apex portion 6b extending along the extending direction of the second prism 6 is configured.

  In addition, on both ends of the extending direction of the second prism 6, there are formed third inclined surfaces 6c and 6c that form a triangular shape and extend flush with the first inclined surfaces 3b and 3b of the first prism 3, respectively. Yes. The third inclined surfaces 6c and 6c are connected to the second inclined surfaces 6a and 6a, respectively, and the triangular apexes of the third inclined surfaces 6c and 6c are in contact with both ends of the second apex portion 6b of the second prism 6. .

  The second prism 6 is configured in such a manner that the second prism 6 is continuously arranged on the first apex 3a of the first prism 3 in a direction orthogonal to the one direction in which the second prism 6 extends. Has been. In the present embodiment, the lower ends of the second inclined surfaces 6a of the adjacent second prisms 6 are in contact with each other, that is, the first apex 3a so as to fill the first apex 3a of the first prism 3. It is arranged over the entire surface.

  By providing the first prism array 2 and the second prism array 5 as described above, the light control sheet 1 has a light collecting function in two directions. The angle formed by the pair of first inclined surfaces 3b in the first prism 3 is defined as apex angle θ1, and the angle formed by the pair of second inclined surfaces 6a in the second prism 6 is defined as apex angle θ2.

As shown in FIG. 1 or FIG. 2, the condensing sheet 11 is a member arranged in parallel to the light control sheet 1 on the observer side F of the light control sheet 1, and includes a base 12 and a third prism. And an array (third lens array) 13.
The base material 12 is made of a transparent resin that transmits light, and is a member having a sheet shape or a plate shape substantially parallel to the display surface of the display device 70, and the surface facing the back surface is the incident surface 12 a. A surface facing the observer side F is an emission surface 12b.

The third prism array 13 is formed on the emission surface 12 b of the substrate 12 and is composed of a plurality of third prisms (third lenses) 14.
The third prism 14 is a triangular prism that extends in one direction along the emission surface 12b of the base material 12. In the present embodiment, the third prism 14 extends in the direction in which the first prism 3 of the light control sheet 1 extends. They are arranged in parallel.

The apex angle of the third prism 14 in the condensing sheet 11 is preferably set in the range of apex angle 70 degrees to 110 degrees, and particularly set in the range of apex angle 80 degrees to 100 degrees. preferable. Thereby, the brightness | luminance of the light emitted by improving a condensing effect can be raised.
Note that the third prism 14 may not only have a prism shape, but may have another lens shape.

Further, as shown in FIGS. 1 and 2, the condensing sheet 11 is preferably arranged such that the extending direction of the third prism 14 is along the horizontal direction Ho. By arranging in this way, it is possible to narrow the field of view in the vertical direction Ve rather than the horizontal direction Ho and collect light in the front direction. Since it is desired that the light in the vertical direction Ve is collected in the front direction in the display device 70, the above-described arrangement can satisfy the characteristics required for the display device 70.
Depending on the application, it may be desired to expand the field of view in the vertical direction Ve. In such a case, the arrangement direction of the condensing sheet 11 rotates 90 degrees along the vertical plane, that is, even if the extending direction of the third prism 14 of the condensing sheet 11 is arranged along the vertical direction Ve. Good.

The light control sheet 1 and the light collecting sheet 11 are molded on the light-transmitting base materials 17 and 12 using UV or radiation curable resin, or PET (polyethylene terephthalate), PC (polycarbonate), PMMA ( Polymethyl methacrylate), COP (cycloolefin polymer), PAN (polyacrylonitrile copolymer), AS (acrylonitrile styrene copolymer), etc., and extrusion molding methods and injection molding methods well known in the art Alternatively, it is formed by a hot press molding method.
Moreover, the light control sheet 1 can be manufactured by preparing a mold as shown in FIG. 7 and performing a reverse version of the mold to form a mold. The first prism array unit 4 in FIG. 5 forms the first prism array 2, and the second prism array unit 7 forms the second prism array 5. Or after forming the 1st prism array 2 on the translucent base material 17, the 2nd prism array 5 can also be formed.

The extending direction of the first prism array 2 or the second prism array 5 of the light control sheet 1 may be a direction along either the vertical direction Ve or the horizontal direction Ho of the illumination unit 55. That is, as shown in FIGS. 1 and 2, the extending direction of the first prism array 2 of the light control sheet 1 is along the horizontal direction Ho and the extending direction of the second prism array 5 is along the vertical direction Ve. In addition, as shown in FIGS. 5 and 6, the extension direction of the first prism array 2 of the light control sheet 1 extends along the vertical direction Ve and the extension of the second prism array 5. This is because the light control sheet 1 which may be arranged so that the direction is along the vertical direction Ho can control the emitted light in both the vertical direction Ve and the horizontal direction Ho.

Next, the operation of the illumination unit 55 and the display device 70 configured as described above will be described.
The light emitted from the light source 41 of the light source unit 20 is introduced into the light guide plate 25 or the diffusion plate 26 directly or indirectly through reflection at the lamp house 43, and then directed toward the front direction F. And enters the light control sheet 1. Then, after being condensed in two directions in the light control sheet 1, it is incident on the light condensing sheet 11 and then passes through the image display element 35, so that it is visually recognized by the observer as an image display.

In the illumination unit 55 of the present embodiment, the condensing sheet 11 disposed on the viewer side from the light control sheet 1 is condensed due to the condensing effect of the first prism array 2 and the second prism array 5 orthogonal to each other. The effect can be increased.
Further, by controlling the incident light to the light collecting sheet 11 by the light control sheet 1, the light emitted from the light source 41 can be efficiently transmitted to the observer side while sufficiently securing the viewing angle of the display screen. The luminance can be improved toward F.

In the light control sheet 1, the second prism 6 has a triangular prism shape with a high light condensing effect, and the first prism 3 has a trapezoidal prism shape that can obtain the same effect as the triangular prism. The light collection effect toward the observer side F can be further improved.
Further, since the first prism array 2 and the second prism array 5 are substantially orthogonal to each other, when the display device 70 is viewed from the observer side F, both the horizontal direction Ho and the vertical direction Ve of the illumination unit 55 are displayed. The light condensing effect can be obtained.

  Here, when the strong oblique light having a peak at 60 to 80 degrees emitted from the light guide plate 25 or the Lambert light diffused by the diffusion slope 26 is directly used as the incident light of the light collecting sheet 11, The light collecting effect cannot be obtained sufficiently. Therefore, conventionally, a diffusion sheet having a diffusion and light collection effect has been arranged between the light guide plate 25 and the light collection sheet 11. However, the light collection effect of the diffusion sheet is not sufficient, and it is difficult to control and emit incident light that enhances the light collection effect of the light collection sheet. In this respect, in the light control sheet 1 of the present embodiment, since the emitted light can be controlled with a high degree of freedom as described later, the effect of the light collecting sheet 11 can be further enhanced. The third prism array 13 of the light collecting sheet 11 may have a lens shape as well as a prism shape.

  Further, for example, when the lens formed on the lens sheet is in one direction, a condensing effect can be obtained only on the lens arrangement direction side, so that there are a direction in which the field of view becomes extremely narrow and a direction in which the field remains wide. In this regard, in the light control sheet 1 of the present embodiment, the viewing angle is adjusted without greatly changing the light collection ratio in two directions by adjusting the widths of the first top 3a and the second top 6b. be able to. This is because the ratio of the first prism array 2 and the second prism array 5 changes by changing the width of the first top portion 3a and the width of the second top portion 6b, and the intensity of the light collecting effect by each prism is increased. This is because it can be changed. That is, it is possible to arbitrarily set the field of view range, such as setting the field of view in the horizontal direction Ho wide, or setting the field of view in the two directions of the horizontal direction Ho and the vertical direction Ve to the same extent. Furthermore, since the apex angle θ1 of the first prism array 2 and the apex angle θ2 of the second prism array 5 can be changed, the light emitted from the light control sheet 1 can be controlled with a high degree of freedom.

  Further, the light control sheet 1 has an advantage that the side lobe generated in the triangular prism hardly occurs because the first prism 3 has a trapezoidal prism shape and the second prism 6 has a triangular prism shape. .

  FIG. 8A shows the viewing angle distribution of a triangular prism having an apex angle of 90 degrees. Since the triangular prism condenses in the front direction, it has a maximum peak at 0 degrees, but a valley Va occurs in the vicinity of 45 degrees, and a small peak (side lobe) occurs when the angle increases further from 45 degrees. This side lobe is emitted light in a direction unnecessary for the display device 70 and also causes a loss of light amount. On the other hand, in the viewing angle distribution of the light control sheet 1, as shown in FIG. 8B, the valley Va near 45 degrees disappears, and unnecessary side lobes can be eliminated and used effectively. That is, this is because a visual field distribution characteristic obtained by combining the vertical Ve visual field distribution and the horizontal Ho visual field distribution of the 90-degree triangular prism shown in FIG.

FIG. 9 shows the vertical direction of the light control sheet 1 when the ratio of the surface area of the second prism array 5 to the surface area of the exit surface of the light control sheet 1 (area ratio R of the second prism array 5) is changed. It is the graph which showed the half value angle of direction Ve and horizontal direction Ho.
Here, the half-value angle represents a viewing angle at which the luminance is 50% when the front luminance in the 0 degree direction (observer side F) is 100%.

  FIG. 9A shows a simulation result when the first prism array 2 is arranged so that the extending direction of the first prism array 2 is the vertical direction Ve and the extending direction of the second prism array 5 is the horizontal direction Ho. FIG. 9B shows a simulation result when the first prism array 2 is arranged such that the extending direction of the first prism array 2 is the horizontal direction Ho and the extending direction of the second prism array 5 is the vertical direction Ve. .

  At this time, the apex angles θ1 and θ2 of the first prism 3 and the second prism 6 were both 90 degrees. The area ratio R of the second prism array 5 which is the horizontal axis in FIG. 9 is the ratio of the width L of the second apex portion 6b to the pitch P of the first prism 3 constituting the first prism array 2 shown in FIG. It is determined by the ratio of (the top width L / P) and the pitch Q of the second prism 6 of the second prism array 5 to the pitch P of the first prism array 2 (prism pitch ratio Q / P).

  When the area ratio of the second prism array 5 is reduced, the light condensing effect of the second prism array 5 is weakened, and the light condensing effect of the first prism array 2 is strengthened. Therefore, in the arrangement of FIG. The half-value angle is narrow, the half-value angle in the vertical direction Ve is wide, and in the arrangement of FIG. 9B, the half-value angle in the horizontal direction Ho is wide, and the half-value angle in the vertical direction Ve is narrow. Conversely, when the area ratio of the second prism array 5 is increased, the light condensing effect of the first prism array 2 is weakened, and the light condensing effect of the second prism array 5 is strengthened. Therefore, in the arrangement of FIG. The half-value angle in the direction Ho is wide, the half-value angle in the vertical direction Ve is narrow, and in the arrangement of FIG. 9B, the half-value angle in the horizontal direction Ho is narrow and the half-value angle in the vertical direction Ve is wide.

The dependency of the optical characteristics on the apex angle θ1 of the first prism array 2 or the apex angle θ2 of the second prism array 5 of the light control sheet 1 varies depending on the direction of the light control sheet 1 and the light collecting sheet 11.
FIG. 10 shows a condensing sheet 11 in which a triangular prism having an apex angle of 90 degrees extends in the horizontal direction Ho. (FIG. 10A, Arrangement A) and horizontal direction Ho (FIG. 10B, Arrangement B), the apex angle θ1 of the first prism array 2 or the apex of the second prism array 5 It is the simulation result which showed the dependence with respect to angle (theta) 2.

  In the arrangement A, when the apex angle θ2 of the second prism array 5 is out of the range of 85 degrees to 115 degrees, a luminance reduction of about 5% is observed compared to the case where the apex angle is 90 degrees. A normal triangular prism has the highest luminance when the apex angle is 90 degrees, and when it deviates from 90 degrees, the luminance decreases around 90 degrees. However, in the case of this arrangement, since the second prism array 5 is arranged in parallel with the third prism of the condensing sheet 11, the apex angle θ2 is set to 90 degrees, and the condensing effect only by the second prism array 5 is prioritized. It is more important to control the incident light to enhance the light collecting effect of the light collecting sheet 11 even if the apex angle θ2 is larger than 90 degrees. Therefore, in the arrangement A, it is desirable that the apex angle θ2 of the second prism array 5 is set within a range of 85 degrees to 115 degrees. Further, when the apex angle θ1 of the first prism array 2 is out of the range of 65 degrees to 100 degrees, a luminance reduction of about 5% is seen compared to the case where the apex angle is 90 degrees. In a normal triangular prism, when the apex angle exceeds 90 degrees, the above-mentioned sidelobe light becomes strong. However, since the first prism array 2 has a trapezoidal shape, side lobe light is not particularly easily generated, and sufficient luminance can be obtained even at an angle smaller than 90 degrees. Therefore, in the arrangement A, it is desirable that the apex angle θ1 of the first prism array 2 is set within a range of 65 degrees to 100 degrees.

  On the other hand, in the arrangement B, when the apex angle θ1 of the first prism array 2 is outside the range of 85 degrees to 115 degrees, a luminance reduction of about 5% is seen compared to the case where the apex angle is 90 degrees. Similarly to the apex angle θ2 in the arrangement A, the light collecting sheet can be obtained even if the apex angle θ1 is larger than 90 degrees, rather than setting the apex angle θ1 to 90 degrees and giving priority to the light condensing effect by the first prism array 2 alone. This is because it is more important to control the incident light to enhance the light collecting effect of No. 11. Therefore, in the arrangement B, it is desirable that the apex angle θ1 of the first prism array 2 is set within a range of 85 degrees to 115 degrees. In addition, when the apex angle θ2 of the second prism array 5 is out of the range of 80 degrees to 100 degrees, a luminance reduction of about 5% is observed as compared with the case where the apex angle is 90 degrees. In this case, unlike the apex angle θ1 in the arrangement A, the light control sheet 1 has a composite shape and thus side lobes hardly occur. However, since the second prism array 5 is a triangular prism, it is more than 90 degrees. At a small angle, side lobes occur, although not as much as a unidirectional triangular prism, and light cannot be used effectively. Therefore, in the arrangement B, it is desirable that the apex angle θ1 of the first prism array 2 is set within a range of 80 degrees to 100 degrees.

  FIG. 11 shows the observer direction F when the area ratio R of the second prism array 5 is changed when the condensing sheet 11 is a triangular prism having an apex angle of 90 degrees extending in the horizontal direction Ho. It is the graph which showed the front luminance. Here, simulation results for the arrangement A (black display) and the arrangement B (white display) are shown.

  In the case of the arrangement A, as the area ratio R of the second prism array 5 is smaller, the influence of the first prism array 2 that collects light in the horizontal direction Ho without the light collection effect of the light collection sheet 11 becomes larger. Therefore, the front luminance is increased as shown in FIG. On the other hand, in the case of the arrangement B, on the contrary, as the area ratio R of the second prism array 5 is larger, the influence of the second prism array 5 that condenses in the horizontal direction Ho without the light condensing effect of the light condensing sheet 11 is larger. Thus, the front luminance is increased. In the arrangement A, when the area ratio R of the second prism array 5 exceeds 40%, the arrangement B has higher luminance regardless of the value of the prism pitch Q / P. Therefore, in the arrangement A, the area ratio R of the second prism array 5 is desirably 40% or less. However, if it is less than 10%, as shown in FIG. 9A, even one light control sheet 1 is strongly condensed in the horizontal direction Ho, and a triangular prism having an apex angle of 90 degrees indicated by a broken line The superior difference of cannot be obtained. That is, the viewing area is extremely limited. Therefore, the area ratio R of the second prism array 5 is desirably 10% or more. On the other hand, in the arrangement B, if the area ratio R of the second prism array 5 is less than 20%, the arrangement B has higher luminance regardless of the value of the prism pitch Q / P. The area ratio R is desirably 20% or more. However, if it exceeds 85%, as shown in FIG. 9B, even one light control sheet 1 is strongly condensed in the horizontal direction Ho, and the viewing area is extremely limited. The area ratio R of the two-prism array 5 is preferably less than 85%.

  Here, the prism pitch ratio Q / P is preferably 0.05 ≦ Q / P ≦ 0.5. As described above, the area ratio R of the second prism array 5 is determined by the top width L / P and the prism pitch ratio Q / P. However, as can be seen from FIG. 8, the luminance is not uniquely determined by the area ratio R of the second prism array 5. This is because the portion where the trapezoidal prism of the first prism array 2 disappears (the height of the prism) varies depending on the value of the prism pitch ratio Q / P. Q / P> 0.5 is not desirable because the reduction in luminance becomes large. In addition, although there is no problem in optical characteristics when Q / P is small, for example, when the pitch Q of the unit lenses constituting the second prism array 5 is 20 μm, when Q / P is 0.05, The pitch P of unit lenses constituting one prism array 2 is 400 μm. If the pitch P of the unit lenses constituting the first prism array 2 is too large, moire interference fringes are likely to occur between the periodic structure of the image display element 35 and the periodic structure of the first prism array 2, which is not desirable. . However, if the pitch P of the unit lenses constituting the first prism array 2 is made small, the pitch R of the unit lenses constituting the second prism array 5 becomes too small and the influence of diffraction is great, which is not desirable. Therefore, it is desirable that 0.05 ≦ Q / P ≦ 0.5.

  As mentioned above, although embodiment in this invention was described in detail, unless it deviates from the technical idea of this invention, it is not limited to these, A some design change etc. are possible.

  For example, as illustrated in FIG. 12, a protrusion 29 may be formed on the incident surface 17 a of the base material 17 of the light control sheet 1. The protrusions 29 can alleviate damage on the incident side of the light control sheet 1 and, when arranged on the light guide plate 25, the air layer does not enter between the light guide plate 25 and the light control sheet 1. This is because it is possible to prevent optical adhesion.

  As the protrusion 29, a cylindrical shape having a central axis extending in a direction parallel to the thickness direction of the light control sheet 1, a thin cylindrical tip, a round cylindrical tip, a microlens shape May be a trapezoidal shape with a thin tip, a polygonal shape, a cylinder with two steps, a cylinder with a thin tip with two steps, a combination of a column and a microlens, etc. . Among these, a shape in which the cross-sectional area decreases as the distance from the incident surface 17a increases is more desirable. This is because when the protrusion 29 is formed, its shapeability and releasability from the mold are improved, so that productivity is improved.

  The protrusions 29 may be arranged at a constant pitch, but are desirably random. Furthermore, although the arrangement of the protrusions 29 is random, the ratio of the total area of the areas in contact with the incident surface 17a of the protrusions 29 included in the unit area of the incident surface 17a is substantially constant regardless of the location. Is desirable. This is because there is no difference in the optical characteristics depending on the location, and moire interference fringes with the structure of the light deflection surface of the light guide plate 25, other lens sheets, and color filters can be prevented. However, even if they are arranged at a constant pitch, they can be solved by shifting them within a range of 30 degrees or less from the direction of the periodic structure such as the first prism array 2, the second prism array 5, and the image display element 35.

  Further, when a diffusing sheet or a polarization reflection separating sheet is disposed on the observer side F of the light collecting sheet 11, the viewing angle distribution of the light emitted from the light collecting sheet 11 can be made smoother. Because. The polarization separation / reflection sheet has a function of transmitting a polarization component in one direction and reflecting a polarization component orthogonal to the polarization component out of the light incident on the polarization separation / reflection sheet. The image display element 35 constituting the liquid crystal display device 70 of the present embodiment has a configuration in which the liquid crystal cell 32 is sandwiched between two polarizing plates 31 and 33, and only light having a polarization component in one direction is used. Therefore, the polarization component orthogonal thereto is absorbed by the polarizing plates 31 and 33 and cannot be used. The polarized light reflection separation sheet reflects polarized light components that are not used in the image display element 35 and diffuses and reuses the polarization direction in the reflection plate 43 constituting the illumination unit 55, so that light can be used effectively ( Recycling), it is possible to improve the luminance of the lighting unit of the present invention. Further, it is desirable that the polarization separating / reflecting sheet has a diffusion performance.

Example 1
The light control sheet 1 was produced by an extrusion molding method using a polycarbonate resin with a base material 17 having a thickness of 250 μm. The first prism array 2 has a trapezoidal prism shape with an apex angle of 90 degrees, a lens pitch of 100 μm, and a width L of the first apex portion 3a of 10 μm. The second prism array 5 has an apex angle of 90 degrees and a lens pitch of 25 μm. Triangular prism shape. Further, the light collecting sheet 11 was produced by an extrusion molding method using a polycarbonate resin with a thickness of the substrate 17 of 250 μm. A triangular prism shape having an apex angle of 90 degrees and a lens pitch of 50 μm was used.

As an example of the direct system, a CCFL is used for the light source 41, a reflecting plate 43 is disposed on the side opposite to the observer side F, and the diffuser plate 26 and the light control sheet are directed from the light source 41 toward the observer side F. 1, the condensing sheet | seat 11, and the diffusion sheet were arrange | positioned in order. At this time, the extending direction of the light collecting sheet 11 is made to coincide with the horizontal direction Ho, and the extending direction of the first prism array 2 of the light control sheet 1 is made to coincide with the substantially vertical direction Ve (Example 1-1) or horizontal. It was made to correspond with direction Ho (Example 1-2).
As an example of an edge light system, white LEDs are arranged on four sides of an acrylic light guide plate 25 on which a white dot pattern is formed, and the light control sheet 1 is directed from the light guide plate 25 toward the viewer side F. The condensing sheet 11 and the diffusion sheet were arranged on the light guide plate 25 in this order. At this time, the extending direction of the light collecting sheet 11 is matched with the horizontal direction Ho of the illumination unit, and the extending direction of the first prism array 2 of the light control sheet 1 is matched with the vertical direction Ve of the lighting unit (1-3 ) Or the horizontal direction Ho (1-4).

As a comparative example, a microlens sheet was disposed instead of the light control sheet 1 of the illumination unit 55 described above (Comparative Example 1-1 as a direct type and Comparative Example 1-3 as an edge light system).
As another comparative example, another light condensing sheet 11 was disposed instead of the light control sheet 1 (Comparative Example 1-2 as a direct type and Comparative Example 1-4 as an edge light system). At this time, the two condensing sheets 11 were arranged so that the extending directions were substantially orthogonal.

  And the image display element 35 was arrange | positioned to the illumination unit 55 of an Example and a comparative example, and the display apparatus 70 was produced. The front luminance of the display device 70 was measured with a spectral radiance meter SR-3A manufactured by Topcon. Further, the light distribution was measured with EZContrast manufactured by ELDIM. The results are shown in Table 1.

According to Table 1, both of Examples 1-1 and 1-2 have a luminance improvement of about 10% as compared with Comparative Example 1-1 while sufficiently securing a horizontal viewing angle of about 40 degrees. It turns out that the effect was able to be acquired. Also, in Examples 1-3 and 1-4, it is possible to obtain a brightness improvement effect of about 12% compared to Comparative Example 1-3 while sufficiently securing a horizontal viewing angle of about 40 degrees. I understand that.
On the other hand, Comparative Example 1-2 and Comparative Example 1-4 obtain a brightness improvement effect of about 11% more than that of Examples 1-1 and 1-2 and Examples 1-3 and 1-4, respectively. However, the horizontal viewing angle was too narrow at 32 degrees.

(Example 2)
As Example 2, the vertex angle of the first prism array 2 of the light control sheet 1 was changed from 60 degrees to 120 degrees at intervals of 10 degrees, and the vertex angle of the second prism array 5 was changed from 70 degrees to 120 degrees. Each was changed at intervals of 10 degrees. The lens pitch of the first prism array 2 was 100 μm, the width L of the first apex 3 a was 30 μm, and the lens pitch of the second prism array 5 was 25 μm. Further, the same light collecting sheet 11 as that in Example 1 was used.

  The front luminance was measured with a spectral radiance meter SR-3A manufactured by Topcon using the same display device 70 as that of the edge light system of Example 1. The arrangement in which the extending direction of the first prism array 2 is in the substantially vertical direction Ve of the illumination unit is referred to as arrangement A, and the arrangement in which the extending direction in the substantially horizontal direction Ho is in arrangement B. The apex angle is the name of the arrangement in which the front luminance is 0.95 or more when the front luminance in each arrangement of the light control sheet 1 of 90 degrees for each of the first prism 3 and the second prism 6 is 1. , A or B are shown in Table 2. A case where the arrangements A and B were both less than 0.95 was marked as x.

  In the case of arrangement A, when the first prism apex angle θ1 is 70 degrees to 100 degrees and the first prism apex angle θ2 is 90 degrees to 110 degrees, a front luminance of 0.95 or more can be obtained. In the case of arrangement B, when the first prism apex angle θ1 is 90 ° to 110 ° and the first prism apex angle θ2 is 80 ° to 100 °, a front luminance of 0.95 or more can be obtained. In both the arrangements, the luminance drop of 5% or more was not observed when both the apex angles θ1 and θ2 were either 90 degrees or 100 degrees.

(Example 3)
As Example 3, the area ratio R of the second prism array 5 of the light control sheet 1 was about 20%, 40%, and 60%. In the light control sheet 1 having an area ratio R of about 20%, 40%, and 60%, the width L of the first top portion 3a of the first prism array 2 is 10 μm, 30 μm, and 50 μm, respectively. The lens pitch of the array 2 was 100 μm, and the lens pitch of the second prism array 5 was 25 μm. Further, the same light collecting sheet 11 as that in Example 1 was used.

  Using the same liquid crystal display device 70 as in the edge light system of Example 1, the front luminance was measured with a spectral radiance meter SR-3A manufactured by Topcon. The results are summarized in Table 3. The name of the arrangement is the same as in the second embodiment.

  Those having higher front luminance in the arrangement A had an area ratio R of 20%, and those in the arrangement B had a higher area ratio R of 40% and 60%. However, when the area ratio R was 20% or 40%, it was confirmed that the difference in luminance in the arrangement was slight.

DESCRIPTION OF SYMBOLS 1 Light control sheet 2 1st prism array 3 1st prism 3a 1st top part 3b 1st inclined surface 5 2nd prism array 6 2nd prism
6a 2nd inclined surface 6b 2nd top part 6c 3rd inclined surface 11 Condensing sheet 12 Base material 12a Incident surface 12b Output surface 13 3rd prism array (3rd lens array)
14 Third prism (third lens)
17 Base material 17a Incident surface 17b Output surface 20 Light source unit 25 Light guide plate 26 Diffuser plate 31 Polarizing plate 32 Liquid crystal cell 33 Polarizing plate 35 Image display element 41 Light source 43 Lamp house (reflecting plate)
55 Illumination unit 70 Display device

Claims (15)

In an illumination unit comprising: a light source that emits light; a light control sheet that controls and emits light incident from the light source; and a light collecting sheet that uses incident light as light emitted from the light control sheet.
The light control sheet is
A first prism array in which a plurality of first prisms extending in a substantially vertical direction linearly on the light exit surface side and having a substantially trapezoidal shape in a cross-sectional view orthogonal to the extending direction are arranged in parallel to each other;
A plurality of second prisms extending in a direction substantially orthogonal to the first prism at the top of the first prism array and having a substantially triangular shape in a cross-sectional view orthogonal to the extending direction are arranged in parallel to each other. Two prism arrays,
The said light collection sheet | seat is equipped with the 3rd lens array which arrange | positions the 3rd lens extended in a straight line in parallel mutually, The illumination unit characterized by the above-mentioned. The light control sheet and the light collecting sheet are arranged so as to extend along a vertical plane,
The lighting unit according to claim 1, wherein the third lens extends along a substantially horizontal direction.   The illumination unit according to claim 1, wherein the third lens has a triangular prism shape with an apex angle of 70 degrees to 110 degrees.   4. The illumination unit according to claim 1, wherein an apex angle of the second prism is set in a range of 85 degrees to 115 degrees. 5.   In a cross-sectional view orthogonal to the extending direction of the first prism, an angle formed by the extension lines of the pair of hypotenuses constituting the substantially trapezoidal shape is set in a range of 65 degrees to 100 degrees. The lighting unit according to any one of claims 1 to 4.   6. The ratio of the surface area of the second prism array to the surface area on the emission surface side of the light control sheet is set to 0% or more and 40% or less. 6. The lighting unit according to one item. In an illumination unit comprising: a light source that emits light; a light control sheet that controls and emits light emitted from the light source; and a condensing sheet that uses incident light as light emitted from the light control sheet.
The light control sheet is
A first prism array in which a plurality of first prisms extending in a substantially horizontal direction linearly on the light exit surface side and having a substantially trapezoidal shape in a cross-sectional view orthogonal to the extending direction are arranged in parallel to each other;
A plurality of second prisms extending in a direction substantially orthogonal to the first prism at the top of the first prism array and having a substantially triangular shape in a cross-sectional view orthogonal to the extending direction are arranged in parallel to each other. Two prism arrays,
The illumination unit includes a third prism array in which a plurality of third lenses extending linearly are arranged in parallel to each other.   The lighting unit according to claim 7, wherein the third lens extends along a substantially horizontal direction.   The illumination unit according to claim 7 or 8, wherein the third lens has a triangular prism shape with an apex angle of 70 degrees to 110 degrees.   In a cross-sectional view orthogonal to the extending direction of the first prism, an angle formed by the extension lines of the pair of oblique sides constituting the substantially trapezoidal shape is set in a range of 85 degrees to 115 degrees. The lighting unit according to any one of claims 7 to 9.   The lighting unit according to any one of claims 7 to 10, wherein an apex angle of the second prism is set in a range of 80 degrees to 100 degrees.   12. The ratio of the surface area of the second prism array to the surface area of the light control sheet on the exit surface side is set to 20% or more and 85% or less. The lighting unit according to one item.   The lighting unit according to any one of claims 1 to 12, wherein a plurality of protrusions are formed on an incident surface side of the light control sheet. The lighting unit according to any one of claims 1 to 13,
An image display element that displays an image by irradiating light from the illumination unit.   The display device according to claim 14, wherein the image display element defines a display image according to transmission / shielding in pixel units.

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