JP2006208930A - Optical sheet, and backlight unit and display using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet (display) capable of uniformizing light from a light source without increasing a portion of the light to be emitted wastefully, and capable of emitting the light while controlling a diffusion range. <P>SOLUTION: The optical sheet is constituted by integrating at least a light scattering layer (a), an adhesive layer or an adhesive layer (b), a light reflective layer (c) which has a surface of high light reflection facing the emission surface side of the light scattering layer (a) and reflects light scattered by the light scattering layer to the light scattering layer side, and a lens sheet (d) of which the back surface (flat surface) is fixed to the other surface of the light reflective layer (c) and the surface has a plurality of unit lenses arranged thereon, in the order from the incident side of illumination light. The optical sheet has an aperture part on the light reflective layer (c) so that a perpendicular drawn from the apex of a protrusion part of each unit lens to the flat surface of the rear surface of the lens sheet passes through the aperture part while being made to correspond to each of the unit lenses of the lens sheet (d) one to one. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of an optical sheet used for illumination light path control in a display backlight unit mainly using a liquid crystal display element, and relates to a backlight unit and a display on which the sheet is mounted.

A display typified by a liquid crystal display device (LCD) is remarkably widespread in a type including a light source necessary for recognizing provided information. In a battery-powered device such as a laptop computer, the power consumed by the light source occupies a substantial portion of the power consumed by the entire battery-powered device.
Thus, reducing the total power required to provide a given brightness increases battery life, which is particularly desirable for battery powered devices.

Brightness Enhancement Film (BE), a registered trademark of 3M, USA
F) is widely used as an optical sheet for solving this problem.

As shown in FIG. 5, BEF is a film in which unit prisms 72 having a triangular cross section are periodically arranged in one direction on a member 70.
The prism 72 has a size (pitch) larger than the wavelength of light.
BEF collects light from “off-axis” and directs this light toward the viewer “on-axis (
on-axis) "redirect" or "recycle".

When using the display (when observing), the BEF increases the on-axis brightness by reducing the off-axis brightness. Here, “on-axis” is a direction that coincides with the visual direction of the viewer, and is generally the normal direction to the display screen (direction F shown in FIG. 8).

When the repetitive array structure of the prisms 72 is arranged in only one direction, only the direction change or recycling in the parallel direction is possible, and in order to control the luminance of the display light in the horizontal and vertical directions, the prism groups are arranged in parallel. Two sheets are stacked and combined so that the directions are substantially orthogonal to each other.

The adoption of BEF allows display designers to achieve the desired on-axis brightness while reducing power consumption.
As patent documents disclosing that a brightness control member having a repetitive array structure of prisms 72 typified by BEF is adopted for a display, as disclosed in Patent Documents 1 to 3, many are known. ing.
Japanese Patent Publication No. 1-378001 JP-A-6-102506 Japanese National Patent Publication No. 10-506500

  In the optical sheet using BEF as a brightness control member as described above, as shown in FIG. 6, the light P from the light source 20 is finally emitted at a controlled angle φ by the refraction action x. Thus, control can be performed to increase the intensity of light in the visual direction F of the viewer. However, at the same time, the light component due to the reflection / refraction action y is unnecessarily emitted in the lateral direction without proceeding in the visual direction F of the viewer.

  Therefore, as shown in FIG. 7, the light intensity distribution emitted from the optical sheet using BEF as shown in FIG. 5 has the light intensity when the viewer's visual direction F, that is, the angle with respect to the visual direction F is 0 °. Although it is most enhanced, there is a problem that the amount of light emitted from the horizontal direction is increased as indicated by a small light intensity peak around ± 90 ° shown in the horizontal axis in the figure.

The present invention has been made in view of such circumstances, and makes light emitted from a light source uniform without increasing the amount of light emitted unnecessarily and controlling the diffusion range to emit the light. An object of the present invention is to provide an optical sheet capable of satisfying the requirements.
In the following description of the present application, “diffusion” and “scattering” of optical characteristics, “adhesive layer” and “adhesive layer”, and “optical sheet” and “light control film” according to the present application are mixed as synonyms. We will use it.

In order to achieve the above object, the present invention takes the following measures.
That is, the optical sheet of the present invention is
In an optical sheet used for illumination light path control in a backlight unit for display,
In order from the incident light incident side, at least,
(A) A light scattering layer that scatters incident light to the exit surface side that is the non-incident surface side.
(B) Adhesive layer or adhesive layer.
(C) A light reflection layer that has a highly light-reflective surface facing the light exit surface side of the light scattering layer (a) and reflects light scattered by the light scattering layer to the light scattering layer side.
(D) A lens sheet in which a back surface (flat surface) is fixed to the other surface of the light reflecting layer (c) and a plurality of unit lenses are arranged on the surface.
It comprises the above (a) to (d) and is a configuration in which they are integrated,
In the light reflecting layer (c), a perpendicular line passing from the convex vertex of each unit lens to the flat surface on the back surface of the lens sheet passes through the light reflecting layer (c) corresponding to each unit lens of the lens sheet (d). And having an opening.

  As the arrangement relationship between the unit lens and the opening, the vertex of each unit lens of the lens sheet and the center of each cross section when the other surface of the reflective layer of each opening corresponding to each unit lens is taken as a cross section. Each line connected to each other is set to be substantially orthogonal to the cross section.

  According to the present invention, the light from the light source is scattered in the diffusion layer, and the light that has passed through the air layer (opening) provided to face the apex of the lens among the scattered light. Only enters the lens and exits after being diffused by the lens action.

  In other words, since each air layer acts like a slit, only light with a narrowed scattering angle is incident on each lens, so there is no light incident obliquely on the lens, and thus the viewer It is possible to eliminate the light that is emitted in the lateral direction without going in the visual direction.

  The light that could not pass through the air layer is reflected by the reflection layer and returned to the diffusion layer side. Then, after being similarly scattered in the diffusion layer, the incident light enters the lens through the air layer with the scattering angle being reduced, and is emitted after being diffused by the lens.

  In this way, the light from the light source can be scattered and only the light with a narrowed scattering angle can be incident on the lens, and the light that could not be incident on the lens can be re-emitted without being wasted. Since it can be utilized, it is possible to increase the efficiency of utilization of light from the light source, make it uniform, and control the diffusion range to emit light.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a side view showing an example of a light control film according to an embodiment of the present invention.

That is, the light control film 10 according to the embodiment includes the diffusion layer 13 that guides the light P from the light source 20 from the incident surface 11 and scatters the light P toward the emission surface 12 side.
As is well known in the art, the diffusion layer 13 has a structure in which translucent resin contains resin beads and fine particles (fillers) having different refractive indexes, or one of the surfaces is matted. The thing processed into the shape is used.

In addition, the reflective layer 14 is fixed to the emission surface 12 of the diffusion layer 13 by the adhesive layer 18.
As shown in the plan view of FIG. 2, the reflective layer 14 is regularly provided with a plurality of air layers (synonymous with openings).
Further, a lens sheet 17 having a plurality of lenses 16 arranged on the surface thereof is fixed to the other surface of the reflective layer 14 (the upper surface of the reflective layer 14 shown in FIG. 1) by an adhesive layer 18.

The adhesive layer 18 uses an ultraviolet curable resin (hereinafter also referred to as a UV curable pressure sensitive adhesive) or other types of pressure sensitive adhesive, and may contain a diffusing material in order to improve the diffusibility of the diffusing layer. .
In consideration of the stickiness remaining after the production of the optical sheet, it is preferable to use the polymerization adhesiveness of the ultraviolet curable resin because it is less likely to cause deterioration with time and optical characteristics.
The thickness of the adhesive layer 18 is preferably thinner than the reflective layer 14.
This is because when the adhesive layer 18 is formed over the entire surface of the lens sheet, a portion that does not contact the reflective layer 14 enters the air layer 15 and affects the optical characteristics based on the difference in refractive index.

In the present embodiment, the plurality of unit lenses 16 are cylindrical lenses. (In the case of a lens sheet in which convex lenses are two-dimensionally arranged or other lens sheets, it does not depart from the gist of the present invention.)
Such a lens sheet 17 is an extrusion molding method well known in the art using PET (polyethylene terephthalate), PC (polycarbonate), PMMA (polymethyl methacrylate), COP (cycloolefin polymer), etc. It is formed by injection molding or hot press molding.
Alternatively, by an ultraviolet curing molding method in which an ultraviolet solidified resin is disposed on a base material of PET (polyethylene terephthalate), PP (polypropylene), PC (polycarbonate), PMMA (polymethyl methacrylate), PE (polyethylene), etc. Form.

The air layer 15 has a refractive index lower than that of the diffusion layer 13 and the lens sheet 17 and is provided at a position corresponding to each of the plurality of lenses 16.
That is, when the vertex of each lens 16 in the lens sheet 17 and the surface of the reflective layer 14 (the upper surface of the reflective layer 14 shown in FIG. 1) of each air layer 15 corresponding to each lens 16 are taken as cross sections, Each line connecting the cross-sectional center G is substantially orthogonal to the surface of the reflective layer 14 (the upper surface of the light reflective layer 14 shown in FIG. 1).
In other words, the opening is formed so that the cross-sectional center G of each air layer 15 exists on a straight line drawn from the apex of each lens 16 along the thickness direction of the optical sheet 10.

As the size of the air layer 15 is increased, scattered light that is not sufficiently narrowed is also incident on the lens 16, and as described above, the component of light that is not emitted in the visual direction F of the viewer is generated. It will increase.
On the other hand, as the size of the air layer 15 is reduced, only the scattered light that is more uniformly focused enters the lens 16, and in some cases, unevenness of the emitted light emitted from the lens 16 increases. .
Therefore, the shape and size of the air layer 15 are design matters determined according to specifications required for the optical sheet 10.

The reflection layer 14 partially penetrated by the plurality of regularly arranged air layers 15 is formed by using a printing method, a transfer method, or a photolithography method well known in the art. To do.
Alternatively, as one method of the photolithography method, a so-called “self-alignment method” is also adopted in which the formation position of the reflective layer (opening) is defined using the light condensing characteristic of the lens itself.
In defining the opening of the present configuration by the self-alignment method, the lens sheet side is arranged on the lens sheet so that the opening corresponding to each unit lens includes a perpendicular drawn from the top of the unit lens to the back surface of the lens sheet. It is required to irradiate the entire surface with parallel light.
In addition, the photosensitive resin layer used in the self-alignment method may remain in the defined opening, but transparency is maintained in consideration of optical characteristics and resistance after the optical sheet is manufactured. It is preferable to use a type of photosensitive resin, and it is more preferable that the refractive index is lower than that of the lens sheet (close to the air layer).

  Next, the effect | action of the light control film which concerns on the said embodiment comprised as mentioned above is demonstrated using FIG.

That is, in the light control film 10 according to the embodiment, the light P from the light source 20 is incident from the incident surface 11 of the diffusion layer 13.
The light P incident on the diffusion layer 13 is randomly scattered here.

Of the scattered light, only the light α that has passed through the air layer 15 is guided to the lens sheet 17.
Since each air layer 15 is provided so as to face the apex of each lens 16 provided on the lens sheet 17, only light focused by the corresponding air layer 15 is guided to each lens 16. It is burned.

  That is, since each air layer 15 acts like a slit, only the light α with a narrowed scattering angle is incident on each lens 16, so there is no light incident obliquely on the lens 16, Accordingly, it is possible to eliminate the light that is unnecessarily emitted in the lateral direction without proceeding in the visual direction F of the viewer.

On the other hand, the light β that could not pass through the air layer 15 is reflected by the reflective layer 14 and returned to the diffusion layer 13 side.
Then, after being similarly scattered in the diffusion layer 13, the light α having a narrowed scattering angle is incident on the lens 16 through the air layer 15 and diffused within the predetermined angle φ by the lens 16. It will be emitted later.

  As described above, the light P from the light source 20 is scattered, and only the light α with a narrowed scattering angle can be incident on the lens 16, and the light that could not be incident on the lens 16 is wasted. Since the light can be reused without being emitted, it is possible to emit while controlling the diffusion range while improving the utilization efficiency of the light from the light source 20.

Thereby, as shown in FIG. 7, the light intensity distribution A emitted from the light control film according to the embodiment is changed to the light intensity distribution B emitted from the optical sheet using BEF as shown in FIG. It is possible to eliminate a small light intensity peak around ± 90 ° on the horizontal axis in the figure, and to further increase the light intensity in the visual direction F of the viewer centering on 0 ° shown in the horizontal axis in the figure. Distribution.
Hereinafter, various specific examples of the embodiment will be described.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, an acrylic pressure-sensitive adhesive material (5 μm thickness) is formed as an adhesive layer, and is bonded to a PET film (75 μm thickness) serving as a diffusion layer to create a light control film.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, as an adhesive layer, an acrylic pressure-sensitive adhesive material (5 μm thickness) added with 10% by weight of a spherical acrylic resin filler (average particle size 5 μm) as a diffusion material is provided, and a PET film (75 μm thickness) serving as a diffusion layer And make a light control film.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, as an adhesive layer, a UV curable adhesive material (5 μm thickness) is provided, and a PET film (75 μm thickness) serving as a diffusion layer is bonded to create a light control film.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, as an adhesive layer, a UV curable adhesive material (5 μm thickness) to which 10% by weight of a spherical acrylic resin filler (average particle size 5 μm) was added as a diffusion material was provided, and a PET film (75 μm thickness) serving as a diffusion layer; Create a laminated light control film.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, an acrylic pressure-sensitive adhesive material (5 μm thickness) is provided as an adhesive layer, and a diffusion film (100 μm thickness, haze 90, transmittance 90) to be a diffusion layer and a laminated light control film are prepared.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, as an adhesive layer, an acrylic pressure-sensitive adhesive material (5 μm thickness) added with 10% by weight of a spherical acrylic resin filler (average particle size 5 μm) as a diffusion material is provided, and a diffusion film (100 μm thickness, A haze 90, transmittance 90) and a laminated light control film are prepared.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Further, as the adhesive layer, a UV curable adhesive material (5 μm thickness) is provided, and a diffusion film (100 μm thickness, haze 90, transmittance 90) to be a diffusion layer and a bonded light control film are prepared.

A cylindrical lens group having a unit lens curvature radius of 100 μm and an array pitch of 200 μm is formed on one surface of a PET film (thickness: 75 μm) using a cured product of an acrylic ultraviolet curable resin.
As a reflective layer, a white ink layer (15 μm thick) is formed by a transfer method so that the ratio of the air layer and the reflective layer is 1: 1.
Furthermore, as the adhesive layer, a UV curable adhesive material (5 μm thickness) to which 10% by weight of a spherical acrylic resin filler (average particle size 5 μm) was added as a diffusion material was provided, and a diffusion film (100 μm thickness, haze) serving as the diffusion layer 90, transmittance 90) and a laminated light control film.

<Comparative example>
Product name: BEF3

<Evaluation as backlight unit and display device>
The optical sheets according to Examples 1 to 8 were applied to a backlight unit of a 26-inch liquid crystal television (the following configuration) and evaluated.
Television configuration: Cold cathode tube / light control film group / liquid crystal panel Evaluation was performed by sequentially changing the light control film group (backlight unit).

Comparative Configuration 1: Diffuser / Diffusion Film / BEF3 / Reflective Polarization Separation Film (trade name = DBEF manufactured by 3M)
Comparative Configuration 2: Lower Diffusion Film 1 / Lower Diffusion Film 2 / BEF3 / Upper Diffusion Film Implementation Configuration 1: Single Example 1 Implementation Configuration 2: Single Example 2 Implementation Configuration 3: Single Example 3 Implementation Configuration 4: Example 4 Single unit Implementation unit 5: Example unit 5 Example configuration 6: Example unit 6 Unit configuration 7: Example unit 7 Unit configuration 8: Example unit 8 Unit configuration 9: Bottom diffusion film 1 / Example 1
Implementation Configuration 10: Example 1 / DBEF
Implementation Configuration 11: Example 1 / Upper Diffusion Film Implementation Configuration 12: Bottom Diffusion Film 1 / Example 1 / DBEF
Implementation configuration 13: Lower diffusion film 1 / Example 1 / Upper diffusion sheet Implementation configuration 14: Lower diffusion film 1 / Example 2
Implementation Configuration 15: Example 2 / DBEF
Implementation Configuration 16: Example 2 / Upper Diffusion Film Implementation Configuration 17: Lower Diffusion Film 1 / Example 2 / DBEF
Implementation configuration 18: Lower diffusion film 1 / Example 2 / Upper diffusion sheet Implementation configuration 19: Lower diffusion film 1 / Example 3
Implementation Configuration 20: Example 3 / DBEF
Implementation Configuration 21: Example 3 / Upper Diffusion Film Implementation Configuration 22: Lower Diffusion Film 1 / Example 3 / DBEF
Implementation configuration 23: Lower diffusion film 1 / Example 3 / Upper diffusion sheet Implementation configuration 24: Lower diffusion film 1 / Example 4
Implementation configuration 25: Example 4 / DBEF
Implementation Configuration 26: Example 4 / Upper Diffusion Film Implementation Configuration 27: Lower Diffusion Film 1 / Example 4 / DBEF
Implementation configuration 28: Lower diffusion film 1 / Example 4 / Upper diffusion sheet

In the above, the “upper diffusion film” and the “lower diffusion film” have directivity in light scattering (diffusion), and incident light has many scattered emission components in the upper direction of the screen or much in the lower direction. It is a difference in the characteristics of whether it has a scattered emission component.
Each specification is as follows.
Lower diffusion film 1: film thickness 2 mm, haze 95, transmittance 80
Lower diffusion film 2: film thickness 100μ, haze 90, transmittance 90
Upper diffusion film 3: film thickness 100μ, haze 40, transmittance 90

The image evaluation of the display device was performed with the above-described comparison configuration and implementation configuration.
All the implementation configurations had surface brightness and horizontal / vertical viewing angles equal to or higher than those of the comparative example.

  The present invention is not limited to a liquid crystal television with a relatively large screen having a direct light source, but also effective in application to a medium to small display device having a backlight unit having an edge light source and a light guide plate. is there.

The side view which shows an example of the optical sheet which concerns on embodiment of this invention. The top view which shows stripe-like arrangement | positioning of a light reflection layer and an air layer. Explanatory drawing of the optical effect | action of the optical sheet which concerns on the same embodiment. Explanatory drawing which shows the light intensity distribution with respect to the angle with respect to the visual direction of the optical sheet which concerns on the embodiment. The perspective view which shows the structural example of BEF. Explanatory drawing about the optical action of BEF. Explanatory drawing which shows light intensity distribution with respect to the angle with respect to a visual direction of BEF.

Explanation of symbols

F ... Visual direction 10 ... Optical sheet 11 ... Incident surface 12 ... Outgoing surface 13 ... Light scattering layer 14 ... Light reflecting layer 15 ... Low refractive index region 16 ... Lens 17 ... Lens sheet 18 ... Adhesive layer 20 ... Light source 70 ... Member 72 …prism

Claims (15)

In an optical sheet used for illumination light path control in a backlight unit for display,
In order from the incident light incident side, at least,
(A) A light scattering layer that scatters incident light to the exit surface side that is the non-incident surface side.
(B) Adhesive layer or adhesive layer.
(C) A light reflection layer that has a highly light-reflective surface facing the light exit surface side of the light scattering layer (a) and reflects light scattered by the light scattering layer to the light scattering layer side.
(D) A lens sheet in which a back surface (flat surface) is fixed to the other surface of the light reflecting layer (c) and a plurality of unit lenses are arranged on the surface.
It comprises the above (a) to (d) and is a configuration in which they are integrated,
The light reflecting layer (c) has a 1: 1 correspondence with each unit lens of the lens sheet (d) so that a perpendicular line passing from the convex vertex of each unit lens to the flat surface on the back side of the lens sheet passes. An optical sheet having an opening. The lens sheet (d) is a lenticular sheet having a lens portion in which semi-cylindrical convex cylindrical lens groups are arranged in one direction,
When a parallel light beam is incident on the lenticular sheet from the lens unit side, a light-transmitting stripe is formed on the flat surface of the back surface so as to include a portion where the incident light beam is collected by the condensing function of the lens unit. A non-opening has a stripe-shaped light reflection layer (c),
2. The optical sheet according to claim 1, wherein the parallel pitch of the semi-cylindrical convex cylindrical lenses as unit lenses is equal to the formation pitch of the stripe-shaped openings.   The optical sheet according to claim 1 or 2, wherein the opening contacting the back surface (flat surface) of the lens sheet (d) is an air layer.   3. The optical sheet according to claim 1, wherein a layer made of a material having a lower refractive index than that of the lens sheet (d) is provided in an opening portion in contact with the back surface (flat surface) of the lens sheet (d).   The optical sheet according to any one of claims 1 to 4, wherein the adhesive layer or the adhesive layer (b) is any one of an ultraviolet curable resin layer, a pressure-sensitive adhesive layer, and a heat-sensitive adhesive layer.   The optical sheet according to claim 1, wherein the adhesive layer or the pressure-sensitive adhesive layer (b) has a structure containing light diffusing fine particles in the layer.   The optical sheet according to any one of claims 1 to 6, wherein the adhesive layer or the pressure-sensitive adhesive layer (b) is thinner than the light reflecting layer (c).   The optical sheet according to any one of claims 1 to 7, wherein the light reflection layer (c) is any one of white ink, a metal foil, and a metal vapor deposition layer.   The optical sheet according to any one of claims 1 to 8, wherein the lens sheet (d) is a monolithic molded body by press molding or extrusion molding using a thermoplastic resin.   The optical lens according to any one of claims 1 to 9, wherein the lens sheet (d) has a laminated structure in which a lens portion made of a cured product of a radiation curable resin is polymerized and bonded to the surface of the base sheet. Sheet.   An optical device comprising a light scattering layer made of a sheet or film having light scattering properties on the light emitting surface side (lens portion side) of the optical sheet according to claim 1. Sheet.   An optical sheet comprising a reflection type polarization separation film on the light exit surface side of the optical sheet according to claim 1. On the back of the image display element that defines the display image,
A display backlight unit comprising at least a direct light source and the optical sheet according to claim 1. On the back of the image display element that defines the display image,
A display backlight unit comprising at least an edge light source and a surface light source including a light guide plate, and the optical sheet according to claim 1. An image display element comprising a liquid crystal display element that defines a display image according to transmission / shading in pixel units;
A light source using a cold cathode ray tube or LED;
A liquid crystal display comprising the backlight unit according to claim 13.

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