JP2011216414A - El element, lighting device using the same, display device, and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further improve light extraction efficiency through optimizing of the light extraction efficiency.SOLUTION: An EL element 1 includes a first substrate 1A, and a light-emitting layer 2 intervened between an anode 3 and a cathode 4 arranged on one of the surfaces of the first substrate. A light control sheet 5 arranged on a surface at a light-emitting side of the first substrate 1A includes a plurality of first uneven parts 14 forming microlenses arranged at intervals on the surface of a base layer 7, and a plurality of second uneven parts 15 burying gaps of the first uneven parts 14 and made of prisms with lower height than the first uneven parts 14. Provided an area of the surface of the base layer 7 is S1, and a sum of areas of the first uneven parts 14 in contact with the surface is S2, formula (1) of 0.1≤S2/S1≤π/2√3 is satisfied. The first uneven part 14 includes an extraction efficiency of light larger than that of the second uneven part 15, and an extraction efficiency of light becomes larger if an area ratio S2/S1 of the first uneven part 14 becomes larger.

Description

  The present invention relates to an EL element (electroluminescence element) used for a flat panel display, a backlight for liquid crystal, a light source for illumination, an illumination, a light source for signage, and the like, and an illumination device, a display device, and a liquid crystal display using the EL element Relates to the device.

  In general, the organic EL has a structure in which a light emitting layer containing a fluorescent organic compound provided on a light-transmitting substrate is sandwiched between an anode and a cathode. Then, a DC voltage is applied to the anode and the cathode, electrons and holes are injected into the light emitting layer and recombined to generate excitons, and light emission when the excitons are deactivated is utilized. It comes to light emission.

  Conventionally, in these EL elements, when the light emitted from the light emitting layer is emitted from the translucent substrate, a part of the light is totally reflected on the translucent substrate, so that there is a problem that the amount of light emitted to the outside is lost. there were. The light extraction efficiency at this time is generally said to be about 20%. Therefore, there is a problem that more input power is required because it is necessary to increase the amount of light emitted from the light emitting layer as high luminance is required. In this case, there is a problem that the load on the EL element increases and the reliability of the EL element itself is lowered.

  In addition, for the purpose of improving the external extraction efficiency of light in the EL element, fine irregularities are formed on the element substrate, and the light beam lost by re-reflecting the light reflected by the light-transmitting substrate again by the element substrate is exposed to the outside. The technique of taking out is proposed. For example, Patent Document 1 proposes forming a microlens array in which a plurality of microlens elements are arranged in a plane on one surface of a translucent substrate.

JP 2002-260845 A

However, the above-described prior art cannot be said to be sufficient for improving the light extraction efficiency.
The present invention has been made in view of such circumstances, and an EL element capable of further improving the light extraction efficiency by optimizing the light extraction efficiency, and an illumination device and a display using the EL element An object is to provide a liquid crystal display device.

An EL device according to the present invention is an EL device comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate, and the light control sheet is provided on the other surface opposite to the one surface on which the light emitting layer is provided. A plurality of first concavo-convex portions that are arranged on the surface with a space between each other and that constitute each lens, and a lens that is arranged so as to fill the space between the first concavo-convex portions and has a lower height than the first concavo-convex portions. A plurality of second concavo-convex parts to be configured, and the area on the other surface of the light control sheet is S1, and the sum of the areas of the first concavo-convex parts in contact with the other surface of the light control sheet is S2. It satisfies the formula (1).
0.1 ≦ S2 / S1 ≦ π / 2√3 (1)
According to the EL element of the present invention, the first concavo-convex parts arranged in the range of the formula (1) at intervals from each other on the light control sheet and the first concavo-convex parts arranged to fill the gaps between the first concavo-convex parts. By arranging the second concavo-convex part having a height lower than that of the concavo-convex part, the light extraction efficiency can be improved more than a conventional EL element having a directivity-oriented film such as a prism lens sheet as a light control sheet. Can be made. When the area ratio S2 / S1 of the first concavo-convex portion is less than 0.1, the area of the first concavo-convex portion where the external extraction efficiency of light is larger than that of the second concavo-convex portion becomes small, so the external extraction efficiency of light is relatively Becomes smaller, which is not preferable.

An EL device according to the present invention is an EL device comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate, and the light control sheet is provided on the other surface opposite to the one surface on which the light emitting layer is provided. A plurality of first concavo-convex portions that are arranged with a space between each other and each constitute a lens, and a lens that is arranged so as to fill the space between the first concavo-convex portions and have a lower height than the first concavo-convex portions. A plurality of second concavo-convex portions, wherein the area on the other surface of the light control sheet is S1, and the sum of the areas of the first concavo-convex portions in contact with the other surface of the light control sheet is S2, When the height of the part is TM and the height of the second uneven part is TL, the following expressions (2) and (3) are satisfied.
0 <TL / TM ≦ −158.79 × (S2 / S1) ⁵ + 412.89 × (S2 / S1) ⁴
−419.47 × (S2 / S1) ³ + 205.74 × (S2 / S1) ²
−47.492 × (S2 / S1) +4.5014 (2)
0.2 ≦ S2 / S1 ≦ π / 2√3 (3)
According to the EL element of the present invention, the first concavo-convex portions arranged with a space therebetween and the second concavo-convex portion having a height lower than that of the first concavo-convex portions arranged so as to fill a gap between the first concavo-convex portions. And satisfying the above formulas (2) and (3), the area ratio S2 / S1 of the light control sheet is in the range of 0.2 to π / 2√3. The external extraction efficiency of light can be improved as compared with a conventional EL element provided with a diffusion film.

Moreover, it is preferable that the 1st uneven | corrugated | grooved part and 2nd uneven | corrugated | grooved part of a light control sheet satisfy | fill following (4) Formula.
0 <TL / TM ≦ 0.6 (4)
By satisfying the above equation (4) in addition to the equations (2) and (3), the light external extraction efficiency is increased without depending on the area ratio of the first uneven portion.
When the light control sheet is manufactured, the area ratio S2 / S1 of the first uneven portion is a design value due to a small variation in the diameter PM of the first uneven portion, a small variation in the distance between the adjacent first uneven portions, and the like. And may be different. Alternatively, there is a possibility that the area ratio S2 / S1 varies in the plane of the light control sheet due to the above-described variation. Therefore, it is preferable to further satisfy the expression (4) because the external extraction efficiency of light is large and can be stably manufactured without depending on the area ratio S2 / S1 of the first uneven portion.

An EL device according to the present invention is an EL device comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate,
The light control sheet includes a plurality of first concavo-convex portions that are arranged on the other surface opposite to the one surface on which the light emitting layer is provided and are spaced apart from each other, and each constitutes a lens, and the first concavo-convex portions And a plurality of second concavo-convex parts constituting a lens having a height lower than that of the first concavo-convex part, and the area on the other surface of the light control sheet is S1, and the light The sum of the areas of the first concavo-convex portions in contact with the other surface of the control sheet is S2, the height of the first concavo-convex portions is TM, and the height of the second concavo-convex portions is TL. ) Is satisfied.
0 <TL / TM ≦ 37.168 × (S2 / S1) ⁵ −90.138 × (S2 / S1) ⁴
+ 78.959 × (S2 / S1) ³ −32.473 × (S2 / S1) ²
+ 7.3357 × (S2 / S1) −0.0674 (5)
0.3 ≦ S2 / S1 ≦ 0.8 (6)
According to the EL element of the present invention, the first concavo-convex portions arranged with a space therebetween and the second concavo-convex portion having a height lower than that of the first concavo-convex portions arranged so as to fill a gap between the first concavo-convex portions. And satisfying the above formulas (5) and (6), the area ratio S2 / S1 of the light control sheet is in the range of 0.3 to 0.8. The light extraction efficiency can be improved as compared with a conventional EL element having a sheet.

Moreover, it is preferable that the 1st uneven | corrugated | grooved part and 2nd uneven | corrugated | grooved part of a light control sheet satisfy | fill following (7) Formula.
0 <TL / TM ≦ 0.4 (7)
By satisfying the above expression (7) in addition to the expressions (5) and (6), the light external extraction efficiency is increased without depending on the area ratio of the first uneven portion.
When the light control sheet is manufactured, the area ratio S2 / S1 of the first concavo-convex portion is a design value due to a small variation in the diameter PM of the first concavo-convex portion or a minute variation in the distance between the adjacent first concavo-convex portions. May be different. Alternatively, there may be a variation in the area ratio S2 / S1 due to the above-described variation. In particular, when the area ratio S2 / S1 is 0.3 or more, the change in the area ratio S2 / S1 due to a small variation in the diameter PM of the first concavo-convex portion is large, and a deviation of 3 to 10% may occur. . Therefore, by satisfying the expression (7) in addition to the above expressions (5) and (6), the external extraction efficiency of light is increased and stabilized without depending on the area ratio S2 / S1 of the first uneven portion. Manufacture is possible.

Moreover, it is preferable that a 1st uneven | corrugated | grooved part is a substantially hemispherical or substantially elliptical hemispherical microlens.
Since the first concavo-convex part is formed in a substantially hemispherical shape or a substantially elliptical hemispherical shape mainly with a curved shape instead of a linear shape, the inclination angle is not constant and has an arbitrary angle range. In the shape mainly composed of a curved shape, the external extraction efficiency of light is large in a wide angle range, so that the external extraction efficiency is large overall. Therefore, the first concave and convex portion made of a substantially hemispherical or substantially elliptical hemispherical microlens has a large light extraction efficiency, and the light extraction efficiency is also increased by increasing the area ratio S2 / S1 of the first concave and convex portions. Becomes larger.

In addition, it is preferable that the second concavo-convex part has a lens or prism shape having a convex cross section, extends in a columnar shape in one direction, and is arranged so as to intersect with each other in the gap of the first concavo-convex part.
As the second concavo-convex portion, a columnar convex lens or prism shape is arranged so as to intersect with each other in the gap between the first concavo-convex portions, so that an inclination angle is provided in a two-dimensional direction. Becomes larger. Furthermore, since the light distribution of the light emitted from the second concavo-convex part in the irradiation direction can be adjusted in a two-dimensional direction, the light emitted from the second concavo-convex part is symmetrically distributed by making the second concavo-convex part an arbitrary shape. Distribution or asymmetrical light distribution.

Moreover, it is preferable that the 2nd uneven | corrugated | grooved part arrange | positions the polygonal convex lens part whose bottom part is a polygon, or the polygonal concave lens part whose top part is a polygon without gaps.
Since the polygonal convex lens part including the polygonal pyramidal convex lens or the polygonal concave lens part including the polygonal pyramidal concave lens is arranged without gap as the second concave and convex part, the second concave and convex part which does not contribute to the deflection of the light incident on the second concave and convex part Since the flat portion of the gap can be eliminated, the light extraction efficiency of the EL element can be further increased. Further, since the fine structure is not formed by the flat portion by arranging without gaps, it is possible to prevent the occurrence of color unevenness due to the light diffraction phenomenon.
Furthermore, the polygonal convex lens part or the polygonal concave lens part can deflect the light incident on the second concavo-convex part in substantially the same direction when the inclined surface is linear or planar, so that the light can travel in any direction. Can be condensed. In addition, when the slope is convex or concave, the light incident on the second uneven portion can be deflected at a wide range of angles. Even when the light incident on the second concavo-convex portion has a problem of color misregistration in which the color changes when the angle with respect to the viewing direction is changed, the light from the light emitting layer is deflected at a wide angle to The color of light can be made uniform without depending on the angle with respect to the viewing direction.

The illuminating device according to the present invention is an illuminating device comprising a light emitting means, wherein the light emitting means is any one of the EL elements described above.
By using the above-described lighting device incorporating the EL element of the present invention, a lighting device having high design efficiency and light utilization efficiency can be obtained.

A display device according to the present invention is a display device including any one of the EL elements described above, and is configured such that the EL elements are pixel driven.
By using the display device incorporating the EL element of the present invention, a display device with high light utilization efficiency can be obtained.

The liquid crystal display device according to the present invention is a liquid crystal display device comprising an image display element, wherein any one of the above-described EL elements or the above-described illumination device is disposed on the back surface of the image display element. And
By using the liquid crystal display device incorporating the EL element or the lighting device of the present invention, a liquid crystal display device with high light utilization efficiency can be obtained.

According to the EL element of the present invention, the light control sheet is arranged so as to fill the space between the first concavo-convex portions and the first concavo-convex portions that are arranged with a space therebetween, and is higher than the first concavo-convex portions. By arranging the low second uneven portion, it is possible to improve the external extraction efficiency of light.
Furthermore, by using a lighting device, a display device, and a liquid crystal display device incorporating the EL element of the present invention, it is possible to provide a lighting device, a display device, and a liquid crystal display device that have high design efficiency and use efficiency of light. Become.

It is explanatory drawing which shows schematic structure of the EL element by 1st embodiment of this invention. It is a schematic explanatory drawing of the EL element which does not use a light control sheet in 1st embodiment. The light control sheet | seat by 1st embodiment of this invention is shown, (a) is a principal part perspective view, (b) is a principal part side view. FIG. 4 is a plan view of the light control sheet shown in FIG. 3. The light control sheet | seat by 2nd embodiment of this invention is shown, (a) is a fragmentary perspective view of a 2nd uneven | corrugated | grooved part, (b) is a top view and a side view. The light control sheet by 3rd embodiment of this invention is shown, (a) is a fragmentary perspective view of a 2nd uneven part, (b) is the plane of the light control sheet provided with the 2nd uneven part shown to (a). It is a figure and a side view. It is the top view and side view of the light control sheet | seat by 4th embodiment. It is a fragmentary perspective view of the 2nd unevenness | corrugation part in the light control sheet | seat shown in FIG. (A), (b), (c) is a figure which shows the bottom part of the 2nd uneven | corrugated | grooved part by a modification. It is a figure which shows the bottom part of the 2nd uneven | corrugated | grooved part by another modification. The light control sheet by 4th embodiment is shown, (a) is the fragmentary perspective view of a 2nd uneven | corrugated | grooved part, (b) is the top view and side view of a light control sheet. The light control sheet | seat by 5th embodiment is shown, (a) is a fragmentary perspective view of a 2nd uneven | corrugated | grooved part, (b) is the top view and side view of a light control sheet. It is a figure explaining the relationship between the height ratio of a 1st uneven | corrugated | grooved part and a 2nd uneven | corrugated | grooved part, and the optical external extraction light quantity about the light control sheet by the Example and comparative example of this invention. It is a figure explaining the micro lens filled in the light control sheet | seat, and its clearance gap. It is a perspective view explaining the difference in the height ratio of the 1st uneven part and the 2nd uneven part about the light control sheet by a first embodiment. It is explanatory drawing which shows the case where the height ratio of the 1st uneven | corrugated | grooved part and 2nd uneven | corrugated | grooved part in a light control sheet is too small. It is a figure explaining the relationship between the area ratio of the 1st uneven | corrugated | grooved part and base layer of the light control sheet of this invention, the height ratio of a 1st uneven | corrugated | grooved part and a 2nd uneven | corrugated | grooved part, and light external extraction light quantity. (A), (b), (c) is explanatory drawing which shows one Embodiment of the design pattern which the 1st uneven | corrugated | grooved part in 6th embodiment of this invention comprises. (A), (b) is explanatory drawing of the design pattern which the 1st unevenness | corrugation part in the 1st modification of 6th embodiment comprises. (A), (b) is explanatory drawing of the design pattern which the 1st uneven | corrugated | grooved part in a 2nd modification comprises. It is explanatory drawing of the design pattern which the 1st uneven | corrugated | grooved part by a 3rd modification comprises. It is explanatory drawing of the design pattern which the 1st uneven | corrugated | grooved part by a 4th modification comprises. It is explanatory drawing of the design pattern which the 1st uneven | corrugated | grooved part by a 5th modification comprises.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a diagram showing a configuration of an EL element (electroluminescence element) 1 according to an embodiment of the present invention. As shown in FIG. 1, in the EL element 1, an anode 3 and a cathode 4 are disposed between a first substrate 1A and a second substrate 1B constituting a light-transmitting substrate with a light emitting layer 2 interposed therebetween. The light control sheet 5 is disposed on the surface of the first substrate 1 </ b> A opposite to the light emitting layer 2.
In the light control sheet 5, light is emitted on the side opposite to the surface on which the light emitting layer 2 is installed, and this direction is defined as an irradiation direction F.

An anode 3 is disposed on the surface of the light emitting layer 2 on the light control sheet 5 side, and a cathode 4 is disposed on the opposite surface. The light emitting layer 2 emits light by applying a voltage to the anode 3 and the cathode 4. The light emitting layer 2, the anode 3 and the cathode 4 constitute a light emitting structure 10 as a light source. As the light emitting structure 10, various conventionally known configurations can be employed.
The light emitting layer 2 may be a white light emitting layer, or may be a blue, red, yellow, green or other light emitting layer. In the case of a white light emitting layer, the structure of the light emitting layer 2 is, for example, CuPc (copper phthalocyanine) / α-NPD doped with rubrene 1% / dinactylanthracene perylene 1% doped / Alq 3 / lithium fluoride. To do. What is necessary is just to use indium tin oxide called ITO as the anode 3 arrange | positioned before and behind, and Al as the cathode 4. FIG.

  However, the present invention is not limited to this configuration, and an arbitrary configuration using an appropriate material capable of setting the wavelength of light emitted from the light emitting layer 2 to R (red), G (green), and B (blue). It is possible to adopt. Moreover, when using it for the application of a full color display, full color display is attained by making it separately coat | cover with three types of luminescent materials corresponding to R, G, and B, or overlapping a color filter on white light.

The first substrate 1A is disposed between the anode 3 and the light control sheet 5, and the second substrate 1B is disposed on the surface of the cathode 4 opposite to the light emitting layer 2.
As materials for the first substrate 1A and the second substrate 1B, various glass materials can be used. In addition, a plastic material such as PMMA, polycarbonate, polystyrene, or a metal material such as aluminum can be used. Although various other materials can be used, a cycloolefin polymer is particularly preferable as the material of the first substrate 1A and the second substrate 1B. This polymer is excellent in all of the material properties necessary for the first substrate 1A and the second substrate 1B, such as processability, heat resistance, water resistance, and optical translucency.
In addition, the first substrate 1A is preferably formed of a material capable of making the total light transmittance 50% or more so that light emitted from the light emitting structure 10 can be transmitted as much as possible.

The light control sheet 5 is integrally formed of a sheet-like base layer 7 and a structural layer 8 formed of a condensing lens group formed on the base layer 7. The light control sheet 5 is fixed to the first substrate 1A through an adhesive layer 6 made of an adhesive.
Examples of the adhesive / adhesive constituting the adhesive layer 6 include acrylic, urethane, rubber, and silicone adhesives. In any case, since the adhesive layer 6 is used adjacent to the light emitting structure 10 that becomes high in temperature, it is desirable that the storage elastic modulus G ′ is 1.0E + 04 (Pa) or more at 100 ° C. If the value of the storage elastic modulus G ′ is lower than this, the light control sheet 5 and the first substrate 1A may be displaced during use. If the light control sheet 5 and the first substrate 1 </ b> A are greatly deviated, light emitted from the light emitting layer 2 does not enter the light control sheet 5 efficiently, so that the light use efficiency decreases.
Further, in order to stably secure a gap between the light emitting layer 2 and the light control sheet 5, transparent fine particles such as beads may be mixed in the contact / adhesive layer constituting the adhesive layer 6. The adhesive layer 6 may be a double-sided tape or may be formed as a single layer.

The light control sheet 5 has a function of deflecting the light from the light emitting layer 2 and emitting it in the irradiation direction F, thereby improving the external extraction efficiency of the light.
That is, as shown in FIG. 1, the light B0 emitted from the light emitting layer 2 passes through the first substrate 1A and enters the light control sheet 5 as light B1. A part of the light B <b> 1 incident on the structural layer 8 of the light control sheet 5 becomes light B <b> 2 emitted from the emission surface of the structural layer 8 to the outside.
As shown in FIG. 2, when the light control sheet 5 has only the sheet-like base layer 7 without the structural layer 8, most of the light B1 is reflected by the flat surface which is the surface 7a of the base layer 7. The light B12 is incident on the first substrate 1A toward the light emitting layer 2 again. The light B12 is lost because it is not deflected in the irradiation direction F.
For this reason, in order to improve the light external extraction efficiency of the EL element 1, it is important to reduce the light B12 and increase the light B1.

As conventional techniques for improving the light extraction efficiency, (1) means for forming a structure such as a prism on the structural layer 8 of the light control sheet 5, or (2) applying a filler to the transparent base layer 7 There are means for installing a diffusion film having an uneven surface, and (3) means for forming a substantially hemispherical microlens. The configurations of (1), (2), and (3) correspond to Comparative Examples 1, 2, and 3 described later.
However, the method (1) for forming a structure such as a prism in the structural layer 8 has the following problems.
That is, in the structure in which the linear shape such as a prism forms most, the inclination angle is constant due to the linear shape, so that it is possible to improve the external extraction efficiency only for light of a specific angle. However, the light other than the above-mentioned specific angle has a problem that the external extraction efficiency is reduced and the external extraction efficiency is reduced overall.

In the method (2) in which a diffusion film in which an uneven surface is formed by applying a filler to a transparent substrate is installed, there are the following problems.
In the case of forming an uneven surface by applying a filler, the shape of the uneven surface is determined by the degree of protrusion of the filler, so that an uneven surface with high accuracy cannot be formed. Therefore, a sufficient shape for controlling light cannot be formed on the uneven surface. For example, when an attempt is made to form a substantially hemispherical shape by raising the filler, the bulge of the filler is insufficient and only a part of the substantially hemispherical shape is formed. That is, when the aspect ratio (height / width) is set to the ratio of the substantially hemispherical height to the width, the aspect ratio becomes small, resulting in a problem that the external extraction efficiency is small.

The method (3) for forming a microlens has the following problems.
The microlens can be molded with higher accuracy than the above-described diffusion filler, and can have a substantially hemispherical array with an increased aspect ratio.
However, since the light emitted from the light emitting layer of the EL element is isotropic, a substantially hemispherical microlens is preferable alone, but the entire surface of the base layer 7 of the light control sheet 5 is filled with a substantially hemispherical microlens group. And a flat surface is generated in the gap between the microlenses. If the light control sheet 5 has a flat surface, light B12 is totally reflected on the flat surface and directed toward the inside of the EL element as shown in FIG. 2, and is not emitted in the external irradiation direction F. Improve usage efficiency.

Moreover, it is possible to fill the entire surface by arranging a close-packed lens group such as a hexagonal arrangement as the structural layer 8 on the surface of the base layer 7 of the light control sheet 5, but creating such a shape In such a case, molding with higher accuracy is required, and problems such as overlapping of microlenses are likely to occur. In addition, if the microlens group is formed so that the gap is reduced, a slight gap distance between the microlenses appears as macro unevenness, which is not preferable. Therefore, in this structure, the substantial area ratio is around 76%.
As a result, since a flat surface remains on about 24% of the surface 7a of the base layer 7, there arises a problem that the external extraction efficiency of light becomes insufficient.

Therefore, in the EL element 1 according to the present embodiment, the light control sheet 5 shown in FIG. 3 is formed on the surface of the EL element 1 in order to improve the external light extraction efficiency.
In the light control sheet 5 in the present embodiment shown in FIG. 3, the structural layer 8 is formed on the front surface 7 a of the base layer 7 and the first substrate 1 </ b> A is bonded to the back surface 7 b through the adhesive layer 6. The structural layer 8 includes a first concavo-convex portion 14 and a second concavo-convex portion 15 for deflecting and emitting the light B0 emitted from the light emitting layer 2 in the irradiation direction F. The first concavo-convex portion 14 and the second concavo-convex portion 15 may be disposed separately on the base layer 7 or may be integrally formed with the base layer 7.

The structural layer 8 shown as an example in FIG. 3 is formed, for example, by a plurality of substantially hemispherical microlenses dispersed as, for example, the first concavo-convex portion 14 on the surface 7 a of the sheet-like translucent base layer 7.
And as the 2nd uneven | corrugated | grooved part 15 is filled with the clearance gap between the 1st uneven | corrugated | grooved parts 14, for example, as shown in FIG.3 (b), the lens or prism lens with a convex cross section is formed. In addition, the prisms having a triangular section which is the second uneven portion 15 have columnar shapes extending in one direction, and these columnar prisms are arranged so as to intersect each other in the gaps of the first uneven portions 14.
In other words, in FIG. 3 (a), a prism lens having a triangular section as a substantially columnar convex member extending in a one-dimensional direction is used as the second concavo-convex portion 15, and the same two directions substantially orthogonal to each other over the entire surface 7a. The microlenses that are the first concavo-convex portions 14 are formed so as to overlap a part of the prism of the second concavo-convex portion 15.

If the second concavo-convex portion 15 is configured as a plurality of columnar shapes that extend only in one direction without intersecting the gaps of the first concavo-convex portion 14, the direction in which the second concavo-convex portion 15 extends. The second concavo-convex portion 15 does not have an inclination angle, that is, has the same effect as a planar effect. In this case, like the light B12 shown in FIG. 2, the light is totally reflected that cannot be extracted to the outside, resulting in a problem that the light extraction efficiency is reduced.
Therefore, the second uneven portion 15 forms a lens having a convex section or a prism lens and has a columnar shape extending in one direction, and the second uneven portion 15 intersects the gap of the first uneven portion 14. By arranging in such a manner, an inclination angle can be provided in a two-dimensional direction. For this reason, the light extraction efficiency is increased, which is preferable.
Furthermore, the light distribution of the light emitted in the irradiation direction F can be adjusted in a two-dimensional direction by the second uneven portions 15 arranged so as to intersect with each other as described above. Therefore, it is preferable to form the second uneven portion 15 in an arbitrary shape because the emitted light from the second uneven portion 15 can have a symmetric light distribution or an asymmetric light distribution.

In FIG. 3A, regarding the first concavo-convex portion 14, the diameter of the bottom surface in contact with the surface 7 a of the base layer 7 is PM, and the height with respect to the surface 7 a of the base layer 7 is TM. The first concavo-convex portions 14 have, for example, a microlens shape, and are regularly arranged at regular intervals or irregularly at irregular intervals. Examples of the shape of the first uneven portion 14 include a substantially semispherical shape and a substantially elliptical shape.
Further, regarding the second concavo-convex portion 15, the width of the bottom surface in contact with the surface 7a is PL, the height from the surface 7a to the top is TM, and the apex angle is θ.

Further, in order to efficiently deflect the light B1 incident on the first uneven portion 14 of the structural layer 8 and improve the external extraction efficiency of the light of the EL element 1, the aspect ratio between the height TM and the diameter (width) PM is increased. It is desirable that TM / PM is 40% or more. By setting the aspect ratio TM / PM to 40% or more, in order to deflect the light B1 in the irradiation direction F, it is preferable that the inclination angle of the slope of the first concavo-convex portion 14 is sufficiently large.
Moreover, the longest diameter PM which is the longest width among the widths along the surface 7a of the base layer 7 of the first concavo-convex portion 14 is set to 20 μm or more and 200 μm or less. When the longest diameter PM is less than 20 μm, diffracted light is generated in the first uneven portion 14 and the efficiency of deflecting the light B1 incident on the first uneven portion 14 in the irradiation direction F is not preferable. When the longest diameter PM exceeds 200 μm, when shaping the shape of the first concavo-convex portion 14, sufficient first ratio to obtain an aspect ratio sufficient to deflect the light B 1 incident on the first concavo-convex portion 14 is obtained. 1 It is not preferable because it becomes difficult to mold the height TM of the uneven portion 14.
The distance between the centers of the bottom surfaces in contact with the surface 7a of the adjacent first uneven portion 14 is preferably 50 μm or more and 5000 μm or less.

  A plurality of second concavo-convex portions 15 are provided so as to fill the gaps between the first concavo-convex portions 14 arranged in this way. In addition, the 1st uneven | corrugated | grooved part 14 is the arrangement | positioning structure which has a clearance gap between the adjacent 1st uneven | corrugated parts 14 mutually, but the 2nd uneven | corrugated part 15 contact | connects the clearance gap between 1st uneven | corrugated parts 14 mutually. A plurality are arranged substantially in parallel (see FIG. 4).

Moreover, as 2nd embodiment, as shown to Fig.5 (a), as for the arrangement structure of the 2nd uneven | corrugated | grooved part 15 in the light control sheet 5, the convex 1st prism 16 formed with the predetermined pitch, You may have the convex 2nd prism 17 formed in the direction substantially orthogonal to this 1st prism 16. As shown in FIG. In this case, one of the first prisms 16 has the same height TL and the same width PL, and is in contact with each other and arranged in parallel. However, the other second prism 17 has a configuration in which the height TL and the width PL are changed. For this reason, the second prisms 17 are arranged in parallel at intervals.
The second uneven portion 15 of the light control sheet 5 according to the second embodiment may have such a configuration.

By the way, the prism sheet in which the prisms are arranged in one direction can control the light distribution in the direction in which the lenses are arranged with the light B1 incident on the second uneven portion 15 of the structural layer 8 by the slope of the prism. . Therefore, when the prisms arranged in one direction are used as the second concavo-convex portion 15, the light distribution can be adjusted one-dimensionally.
However, when the EL element 1 is used for illumination, it is necessary to adjust the light distribution at least two-dimensionally. The reason is that, for example, depending on the installation location of the lighting device, it is not necessary to irradiate in a specific direction, and there is a case where an improvement in luminance in the front direction is required instead of a wide light distribution. Alternatively, it is required that the light B1 incident on the second uneven portion 15 of the structural layer 8 has an asymmetric light distribution, and that the light emitted from the illumination device to the outside is a symmetric light distribution. In this case, it is difficult to make the light distribution of the light emitted from the illumination device a symmetric light distribution by adjusting only the one-dimensional direction. Therefore, the second uneven portion 15 preferably has a configuration according to the present invention that can be adjusted in a two-dimensional direction.

Moreover, in the cross prism in which the prisms in the second concavo-convex portion 15 are arranged substantially orthogonally as in the configuration of the present embodiment, an appropriate lens without adding a new lens sheet in order to spread light in two dimensions. It is possible to adjust the light distribution to a light distribution, and it is possible to reduce the weight, thickness, and cost of the lighting device.
In particular, the light emitted from the light emitting layer 2 is light having a broad directivity with a wide light distribution. Therefore, it is preferable that the second uneven portion 15 is designed so as to deflect the wide light distribution described above in the irradiation direction F.
In the second uneven portion 15 in the light control sheet 5 of the second embodiment shown in FIG. 5, the slopes of the first prism 16 and the second prism 17 are preferably planar (linear). With the planar shape, the light B1 incident on the second concavo-convex portion 15 of the structural layer 8 can be deflected in substantially the same direction, so that the light can be collected in an arbitrary direction.
Further, the shapes and sizes of the first prism 16 and the second prism 17 are different from each other in the second embodiment shown in FIG. 5A, but may be the same.

  Or the 2nd uneven | corrugated | grooved part 15 in 3rd embodiment is the 1st convex cylindrical lens 18 arranged in parallel with a predetermined pitch, and 1st as shown to Fig.6 (a), (b). The cylindrical lens 18 may have a convex second cylindrical lens 19 arranged in a direction substantially orthogonal to the cylindrical lens 18. In this case, the second cylindrical lens 19 is formed to be larger in height and width than the first cylindrical lens 18.

Here, the lenticular lens sheet in which the cylindrical lenses are arranged in one direction can control the light distribution of the light B1 incident on the second uneven portion 15 of the structural layer 8 in the arrangement direction of the cylindrical lenses by the curved surface of the lens. it can. Therefore, when a lenticular lens sheet is used for the second concavo-convex portion 15, the light distribution can be adjusted one-dimensionally.
However, when used for illumination, it is necessary to adjust the light distribution at least two-dimensionally. The reason is that, for example, depending on the installation location of the lighting device, it is not necessary to irradiate in a specific direction, and there is a case where a luminance improvement in the front direction is required instead of a wide light distribution. Alternatively, the light B1 incident on the second uneven portion 15 of the structural layer 8 is required to have an asymmetric light distribution and a light distribution that is symmetric with respect to the light emitted from the illumination device. In this case, since it is difficult to adjust the light distribution in only the one-dimensional direction, the configuration according to the present invention that can adjust the light distribution in the two-dimensional direction is preferable.

In particular, the cross lenticular lens sheet in which the cylindrical lenses 18 and 19 are arranged substantially orthogonally as in the configuration of the second uneven portion 15 in the third embodiment shown in FIG. In order to expand, it is possible to adjust the distribution of light distribution appropriately without adding a new lens sheet, and it is possible to reduce the weight, thickness, and cost of the lighting device.
In particular, the light emitted from the light emitting layer is light having a broad directivity with a wide light distribution. Therefore, it is preferable that the second uneven portion 15 is designed so as to deflect the wide light distribution described above in the irradiation direction F.

The cross-sectional shapes of the first cylindrical lens 18 and the second cylindrical lens 19 of the second concavo-convex portion 15 in the third embodiment are not limited to a complete semicircular shape (spherical lens). A cylindrical lens having a so-called non-semicircular (so-called second-order aspheric shape) cross section such as a parabolic lens (parabolic lens), or a higher-order aspheric shape cross-section having a second-order term or later. The cylindrical lens which has is preferable.
By using a lens having an aspherical cross-sectional shape, the area of a region having an appropriate inclination on the side surface of the lens can be adjusted, and the emitted light can be adjusted more than a complete semicircular lens.
Further, in the second concavo-convex portion 15, the first cylindrical lens 18 and the second cylindrical lens 19 may have the same or different cross-sectional shapes.

7-12, the 2nd uneven | corrugated | grooved part 15 may be a polygonal pyramidal convex lens or a polygonal pyramidal concave lens which has the polygonal base arrange | positioned without the clearance gap on the surface 7a of the base layer 7. FIG. In the drawing, a structure in which the second uneven portions 15 are arranged on the surface 7a of the base layer 7 without a gap is shown.
For example, in the plan view of the light control sheet 5 shown in FIGS. 7 and 8, the quadrangular pyramidal convex lens 15 </ b> A (or the quadrangular pyramidal concave lens) constituting the second concavo-convex portion 15 as the third modified example is formed on the surface 7 a of the base layer 7 without a gap. It is arranged in the vertical and horizontal directions. On the surface 7 a of the base layer 7, microlenses 14 </ b> A constituting the first concavo-convex portion 14 are arranged apart from each other and superimposed on the quadrangular pyramidal convex lens 15 </ b> A.
By arranging the quadrangular pyramidal convex lenses 15A without any gaps, it becomes possible to substantially eliminate the flat portion between the second uneven portions 15 that do not contribute to the deflection of the light B1 incident on the second uneven portion 15 of the structural layer 8. Further, it is possible to increase the efficiency of external extraction of light from the EL element 1. Further, by arranging the quadrangular pyramidal convex lenses 15A without any gaps, the fine structure due to the flat portion is not formed, so that it is possible to prevent the occurrence of color unevenness due to the light diffraction phenomenon.

The 2nd uneven | corrugated | grooved part 15 by the 3rd modification shown in FIG. 8 is arrange | positioned without gap as a quadrangular pyramid convex lens shape in which the bottom face 21 makes a rectangle. When there is a demand to make the light distribution of the light emitted from the EL element 1 symmetrical, it is preferable that the bottom surface 21 is substantially square and the inclination angles of the four inclined surfaces of the quadrangular pyramid convex lens 15A are substantially the same.
If there is a demand for making the light distribution of the light emitted from the EL element 1 asymmetric, the bottom face 21 may be a quadrangular pyramid convex lens 15A having a long side and a short side. By making the bottom surface 21 rectangular, the inclination angle of the short side direction slope and the inclination angle of the long side direction slope in the quadrangular pyramid convex lens 15A are different, and therefore the light distribution of the light emitted from the EL element 1 is changed in the long side direction. And a short side direction can be made asymmetric.

  Further, a modification of the second uneven portion 15 shown in FIG. 9 will be described. Regarding the bottom surface 21 of the second uneven portion 15, in FIG. 9A, the bottom surface 21 </ b> A is a regular hexagon having a honeycomb structure, and in FIG. The bottom surface 21B is formed in a square shape, and in FIG. 8C, the bottom surface 21C is formed in an equilateral triangle. By forming the bottom surfaces 21A, 21B, and 21C of the second concavo-convex portion 15 in this way, the bottom surfaces 21A, 21B, and 21C can be arranged in substantially the same shape in one structural layer 8.

By making the shape of the bottom surface 21 of the second concavo-convex portion 15 substantially the same, it becomes possible to make the size and shape of the second concavo-convex portion 15 substantially the same, so that an EL element in which unevenness of brightness does not occur is generated. 1 can be created. Therefore, when the EL element 1 that does not cause in-plane unevenness of brightness is required, it is preferable to arrange the second uneven portions 15 having such a bottom surface 21.
In particular, when the bottom surface 21 of the second concavo-convex portion 15 is a regular hexagon, the shape of the connecting portion between the bottom surfaces 21A can be a more complicated zigzag shape instead of a linear shape. In this case, moire that occurs due to interference between the shape of the connecting portion between the bottom surfaces 21 and the pixel pattern of the EL element 1 can be prevented, which is more preferable.

Moreover, like the other modification shown in FIG. 10, the bottom surface of the second concavo-convex portion 15 is formed with different polygonal bottom surfaces 21A and 21B, and these different bottom surfaces 21A and 21B are combined and arranged without gaps. Also good.
When there is a demand for reducing unevenness of brightness within the surface of the EL element 1, the shape of the bottom surface 21 is preferably substantially the same. It is preferable that the shape of the bottom surface 21 is substantially the same because unevenness of the light distribution between the second uneven portions 15 does not occur.

11 and 12 are diagrams showing another embodiment in which the second uneven portion 15 is a polygonal pyramidal convex lens or a polygonal pyramidal concave lens different from the polygonal pyramidal convex lens 15A shown in FIG.
In the fourth embodiment shown in FIG. 11, the second concavo-convex portion 15 is a substantially quadrangular pyramid convex lens 15B, and the top of the quadrangular pyramid convex lens 15B is formed with at least one groove portion 23 having a substantially V-shaped cross section. It has a plurality of divided vertices 24. In the second concavo-convex portion 15 shown in FIG. 11, two groove portions 23 are formed orthogonal to the top of each quadrangular pyramid convex lens 15 </ b> B, and each quadrangular pyramid convex lens 15 </ b> B has four apexes 24. Yes.
However, the shape of the groove portion 23 is not limited to that shown in FIG. 11, and the groove portion 23 having various depths, pitches, and opening angles extending in various directions can be provided.

  As described above, the light distribution can be adjusted by adopting a configuration in which the two groove portions 23 are orthogonal to the top of the substantially quadrangular pyramidal convex lens 15B. In particular, it is possible to adjust the light emitted at a wide angle where the emission angle is 60 degrees or more. Further, by adjusting the shape (depth, inclination angle) of the groove portion 23, it is possible to increase or decrease the light emitted at a wide angle. This is because most of the light emitted at a wide angle is light emitted from the vicinity of the top of the quadrangular pyramidal convex lens 15B.

In the light control sheet 5 according to the fifth embodiment shown in FIG. 12, a quadrangular concave lens 15 </ b> C having a rectangular bottom surface 21 and a substantially quadrangular pyramid-shaped concave portion is formed as the second concave-convex portion 15. Are arranged without gaps on the surface 7a. This quadrangular pyramid concave lens 15C has a shape for extracting the incident light B1 so as to be emitted in the irradiation direction F.
In the second concave and convex portion 15, the quadrangular pyramid convex lens 15A shown in FIG. 8 is a point with the highest apex shape of the second concave and convex portion 15, whereas the quadrangular pyramid concave lens 15C has a substantially rectangular shape at the highest position. Since the ridge line is, the abrasion resistance is improved, which is more preferable. Here, the quadrangular pyramid concave lens 15 </ b> C has the bottom surface 21 of the quadrangular pyramid at the highest position as the top, and the dot-shaped concave portion located on the surface 7 a side of the base layer 7 as the bottom.

When there is a demand to make the light distribution of the light emitted from the EL element 1 symmetrical, the inclination angles of the four downward inclined faces in the quadrangular pyramidal concave lens 15C in which the top of the bottom surface 21 is substantially square are made substantially the same. It is preferable.
When there is a request for making the light distribution of the light emitted from the EL element 1 asymmetric, it is preferable to form a quadrangular pyramidal concave lens 15C in which the top of the bottom surface 21 is a rectangle having a long side and a short side. By making the bottom surface rectangular, the inclination angle of the inclined surface in the short side direction and the inclination angle of the inclined surface in the long side direction of the quadrangular pyramidal concave lens 15C are different, so that the light distribution of the light emitted from the EL element 1 is long. It becomes possible to make it asymmetric between the side direction and the short side direction.

Moreover, when the 2nd uneven | corrugated | grooved part 15 makes a prism lens or the quadrangular pyramid convex lens 15A, the front-end | tip top part may be cut and flattened, or it may be rounded and may be made into a convex curve shape. Further, two side surfaces forming a prism lens shape or four inclined surfaces forming a quadrangular pyramid lens shape may be curved into a convex curved surface shape or a concave curved surface shape.
As described above, the second unevenness of the structural layer 8 is formed by curving each inclined surface of the second uneven portion 15 into a convex curved surface shape or a concave curved surface shape, as compared with the case where the inclined surface is formed in a linear shape or a flat surface shape. The light B1 incident on the portion 15 can be deflected over a wide range of angles. When there is a problem of color misregistration in which the color changes when the angle of the light B1 incident on the second concavo-convex portion 15 of the structural layer 8 is changed with respect to the viewing direction, a convex curved surface in which the light from the light emitting layer 2 is curved Alternatively, it is preferable that the color of light emitted from the light emitting layer 2 can be made uniform without depending on the angle with respect to the viewing direction by deflecting the light from the concave curved surface with a wide range of angles.

Moreover, the shape of the outer peripheral edge in contact with the second concavo-convex portion 15 in the first concavo-convex portion 14 may be arranged to meander at least partially, and the interface between the first concavo-convex portion 14 and the second concavo-convex portion 15 is the first. 2 It may be located not only at the valley portion of the uneven portion 15 but also at the top portion or side surface of the second uneven portion 15.
With the configuration as described above, it is possible to individually change the light distribution of the emitted light from each first uneven portion 14, so that the design property is improved when the EL element 1 is used for illumination. It becomes possible to grant.

The width PL along the surface 7a of the base layer 7 of the second concavo-convex portion 15 is the width of the base of the cross-sectional triangle when the second concavo-convex portion 15 is a prism lens, and the cross-section when cylindrical lenses 18 and 19 are used. This is the width of the maximum outer diameter (straight line portion) of the semi-elliptical shape, and in the case of a quadrangular pyramid shape, it is the width of one side of the bottom surface. These widths PL are set to 20 μm or more and 200 μm or less so that diffracted light is hardly generated in the second uneven portion 15 and is not easily visible from the irradiation direction.
Moreover, in order to improve the external extraction efficiency of the desired light of the light control sheet 5, the height ratio TL / TM of the first uneven portion 14 and the second uneven portion 15 can be adjusted as appropriate.
Further, the area of the surface of the light control sheet 5 (in the plane excluding the first and second uneven portions 14 and 15), that is, the area of the surface 7a of the base layer 7, is the surface of the first uneven portion 14 on the surface in contact with S1 and the surface 7a. The sum of the areas is S2, and the sum of the areas of all the second concavo-convex portions 15 on the surface in contact with the surface 7a is (S1-S2). The ratio of the area S1 of the first concavo-convex portions 14 to the area S1 of the base layer 7 is S2 /. The area ratio (S1-S2) / S1 with respect to the area S1 of the base layer 7 with respect to S1 (hereinafter sometimes referred to as an area ratio) and the similar area sum (S1-S2) of the second uneven portion 15 is appropriately adjusted. Is possible.
The areas S1 and S2 correspond to the area of the light control sheet 5 in plan view.

Next, FIG. 13 shows that the first uneven portion is different from the first uneven portion 14 in that the area ratio S2 / S1 is 0.1 to 0.8 and 0.1 / 2 to π / 2√3. 14 is a result of simulating the relative amount of external extraction (efficiency) of light obtained by changing the height ratio TL / TM between 14 and the second uneven portion 15.
As an example of the light control sheet 5 used in the simulation of FIG. 13, first uneven portions 14 are arranged on the surface 7 a of the base material 7 with gaps at substantially equal intervals, and the second uneven portions 15 are mutually arranged in the gaps. They were arranged so as to be orthogonal. The first uneven portion 14 is a substantially hemispherical microlens.

Then, as shown in FIG. 14, when the microlenses are packed as the first concavo-convex portion 14 so as to be in close contact with the surface 7a of the base layer 7, the area ratio S2 / S1 is as follows. Since the surface that contacts the base layer surface 7a of the microlens 14 is a circle and its radius is PM / 2,
Area of the microlens 14 (semicircular) = π / 2 × (PM / 2) 2 = πPM 2/8
It becomes. Further, as shown in FIG. 14, the triangle Q connecting the centers of the three microlenses 14 in contact with each other is a regular triangle, one side of which is PM, and the height from the apex to the base is √3 × PM / 2. Therefore, the area is as follows.
Area of a triangle Q = 1/2 × PM × √3 × PM / 2 = √3 × PM 2/4
Therefore, the area ratio S2 / S1 = the area of the microlens 14 (semicircle) / the area of a triangle.
Area ratio S2 / S1 = π / 2√3
It becomes. This is the area ratio of the closest packing of the first uneven portion 14 in the light control sheet 5, and this is also plotted in FIG.

  Further, as shown in FIG. 3, the second concavo-convex portion 15 forms a prism shape having a triangular cross section and has a columnar shape extending in one direction, and the columnar triangular prism shape is the first concavo-convex portion 14. The gaps are arranged so as to be orthogonal to each other. The second concavo-convex portion 15 was an isosceles triangular cross section in which the apex angle of the cross-sectional triangle was 90 degrees and the inclination angle of the slope was 45 degrees. The heights of the second concavo-convex portions 15 that intersect each other were the same. The aspect ratio TM / PM with the first uneven portion 14 was set to 0.5.

In addition, as Comparative Example 1 related to the above-described prior art (1), a directivity-oriented film in which only the second concavo-convex portions 15 made of the columnar prism lenses orthogonal to each other, for example, are arranged without gaps was used. The directivity-oriented film shape in Comparative Example 1 was a concave quadrangular pyramid shape with an apex angle of 90 degrees and a slope inclination angle of 45 degrees.
As Comparative Example 2 related to the above-described prior art (2), a diffusion film formed by applying a filler to a transparent substrate was used. The shape of the diffusion film was a substantially hemispherical shape with an aspect ratio TM / PM of 0.45 to 0.35, and a part thereof was randomly arranged.
A microlens film was used as Comparative Example 3 related to the above-described prior art (3). The shape of the microlens film was such that the aspect ratio TM / PM was 0.5 and the area ratio was 76%.
S2 / S1 = 0.1 to 0.8, π, where S1 is the total area of the surface 7a of the light control sheet 5 and S2 is the sum of the areas of the bottom surfaces of the first uneven portions 14 in contact with the surface 7a of the light control sheet 5. The simulations of Comparative Examples 1, 2, and 3 were also carried out along with the simulations of the examples according to / 2√3. The simulation result is shown in FIG.

In the graph of the simulation result shown in FIG. 13, the horizontal axis is the height ratio TL / TM of the first uneven portion 14 and the second uneven portion 15, and the vertical axis is the relative light external extraction light amount. The relative light external extraction light quantity with respect to the height ratio TL / TM in each Example and Comparative Examples 1, 2 and 3 according to S2 / S1 = 0.1 to 0.8 and π / 2√3 is shown.
The relative light external extraction light amount when the light external extraction light amount in the directivity-oriented film according to Comparative Example 1 is 1 is shown. As shown in FIG. 13, in order to improve the external extraction efficiency of light compared to Comparative Example 1,
0.1 ≦ S2 / S1 ≦ π / 2√3 (1)
By satisfy | filling, it can confirm that the light extraction light quantity becomes larger than the directivity-oriented film which is the comparative example 1.

The second concavo-convex portion 15 has a higher proportion of linear shape than the first concavo-convex portion 14, and the inclination angle is constant due to the linear shape, so that it is possible to improve the external extraction efficiency only for light of a specific angle. Become. However, the light outside the specific angle described above has a low light extraction efficiency, and overall, the light extraction efficiency is small.
On the other hand, since the 1st uneven | corrugated | grooved part 14 is mainly formed in curve shape instead of linear shape, an inclination angle is not constant and has an arbitrary angle range. In the shape mainly composed of a curved shape, the external extraction efficiency of light is large in a wide angle range, so that the external extraction efficiency is large overall. Therefore, the first concavo-convex portion 14 has a higher light extraction efficiency than the second concavo-convex portion 15.
For the reasons described above, it is preferable that the area ratio S2 / S1 of the first concavo-convex portion 14 is increased because the external extraction efficiency of light is increased.

On the other hand, if the area ratio S2 / S1 of the first concavo-convex portion 14 is less than 0.1, the area of the first concavo-convex portion 14 having a large light extraction efficiency is reduced, which is not preferable because the light extraction efficiency is reduced. .
In addition, the area ratio S2 / S1 when the first concavo-convex portions 14 are arranged hexagonally can be maximized, that is, π / 2√3 in a close-packed structure.
When the area ratio exceeds 76% in the case where the first uneven portion 14 is configured as in the microlens film of Comparative Example 3, the gap between the first uneven portions 14 becomes small, and the first uneven portion. Since a slight gap distance between 14 appears as macro unevenness, it is not preferable.
However, as in this embodiment, by filling the gaps between the first concavo-convex parts 14 with the second concavo-convex parts 15 without gaps, a slight gap between the first concavo-convex parts 14 is formed depending on the shape of the second concavo-convex parts 15. Since the distance shift is not visually recognized, it is possible to prevent the above-described macro unevenness from being visually recognized.

If the ratio TL / TM between the height TL of the second concavo-convex portion 15 and the height TM of the first concavo-convex portion 14 is increased, the light extraction efficiency due to the curved shape of the first concavo-convex portion 14 is reduced, which is not preferable. .
The reason for this is that, as shown in FIG. 15A, when TL / TM is increased, the region having the curved shape of the first uneven portion 14 is relatively small, and the region having the linear shape of the second uneven portion 15 is This is because it becomes larger.
Since the curve shape of the first uneven portion 14 has a higher light extraction efficiency than the linear shape of the second uneven portion 15, the area having the curved shape of the first uneven portion 14 is reduced, so that the outside of the light is reduced. The extraction efficiency is reduced.
On the other hand, as shown in FIG. 15B, when TL / TM is reduced, the region having the curved shape of the first uneven portion 14 is increased, and the region having the linear shape of the second uneven portion 15 is decreased. For this reason, since the TL / TM is reduced, the area of the curved shape of the first concavo-convex portion 14 having a larger light extraction efficiency than the linear shape of the second concavo-convex portion 15 is increased. The external extraction efficiency is increased, which is preferable.

Further, when TL / TM is less than 0.1, it is confirmed that the external extraction efficiency of light is saturated and tends to decrease.
As shown in FIG. 16, when the difference between the height TL of the second uneven portion 15 and the height TM of the first uneven portion 14 is excessive, it is taken out via the second uneven portion 15. This is because the light B3 enters the first uneven portion 14 again to become the light B4, and the light B4 is reflected inside the first uneven portion 14 and returned to the light emitting layer 2 side as the light B5.
For this reason, TL / TM is preferably 0.1 or more.

FIG. 17 is a diagram showing the relationship between the area ratio S2 / S1, the height ratio TL / TM, and the light extraction light quantity of the light control sheet 5 in relation to the simulation results shown in FIG. It is the figure which provided area ratio S2 / S1 and provided height ratio TL / TM on the vertical axis | shaft.
FIG. 17A shows the range of an example having an area ratio S2 / S1 in which the external extraction efficiency of light is larger than the external extraction efficiency of light by the diffusion film of Comparative Example 2.
In FIG. 13, the external extraction amount of light by the diffusion film of Comparative Example 2 is 1.015 times with Comparative Example 1 as the reference value 1. An example in which the amount of outside light extraction is larger than this is from S2 / S1 = 0.2 to π / 2√3. This is expressed by the following equation (3).

Moreover, in the minimum area ratio S2 / S1 = 0.2, the range in which the amount of external light extraction is larger than that in Comparative Example 2 is the height ratio TL / TM = 0 to 0.6. In the range of the height ratio TL / TM = 0 to 0.6, the outside light extraction amount is larger than Comparative Example 2 regardless of the area ratio S2 / S1 of 0.2 to π / 2√3. This region is indicated by a region 501 in FIG.
In addition, in the region exceeding the height ratio TL / TM = 0.6 shown in FIG. 13, the amount of light extracted outside the light from the comparative example 2 in the range of S2 / S1 = 2 to π / 2√3 in FIG. When the height ratio TL / TM having a large value is plotted, the range of the curved portion indicated by the region 500 is obtained. When this curved portion is expressed by an approximate expression, the following expression (2) is obtained.
Thus, in the range which satisfy | fills the following (2) Formula and (3) Formula which prescribe | regulate the area | region 500 and area | region 501 shown to Fig.17 (a), the area | region where the external extraction efficiency of light is larger than the diffusion film of the comparative example 2 It is preferable that it can be confirmed.
0 <TL / TM ≦ −158.79 × (S2 / S1) ⁵ + 412.89 × (S2 / S1) ⁴
−419.47 × (S2 / S1) ³ + 205.74 × (S2 / S1) ²
−47.492 × (S2 / S1) +4.5014 (2)
0.2 ≦ S2 / S1 ≦ π / 2√3 (3)

Furthermore, the following equation (4) 0 <TL / TM ≦ 0.6 (4)
By satisfying the above, only the region 501 shown in FIG. 17A in which the external extraction amount (efficiency) of light is larger than that of the diffusion film of Comparative Example 2 without depending on the area ratio S2 / S1 of the first uneven portion 14. Is preferable.

When the light control sheet 5 is manufactured, the area ratio S2 / S1 of the first concavo-convex portion 14 is a minute variation in the diameter PM of the first concavo-convex portion 14 or a minute variation in the distance between the adjacent first concavo-convex portions 14. It may be different from the design value depending on the reason. Alternatively, there may be a variation in the area ratio S2 / S1 in the plane of the light control sheet 5 due to the above-described variation. In particular, when the area ratio S2 / S1 is 0.3 or more, the change in the area ratio due to minute variations in the diameter PM of the first uneven portion 14 is large, and a deviation of 3 to 10% occurs in the area ratio S2 / S1. there's a possibility that.
Therefore, by satisfying the above formula (4), it is possible to stably manufacture without depending on the area ratio S2 / S1 of the first uneven portion 14, and the external extraction efficiency of light is larger than that of the diffusion film of Comparative Example 2. This is preferable because only the region 501 shown in FIG.

Next, FIG. 17B shows the range of an embodiment having an area ratio S2 / S1 in which the external extraction efficiency of light is larger than the external extraction efficiency of light by the microlens film of Comparative Example 3.
In FIG. 13, the amount of external light extraction in Comparative Example 3 is 1.025 based on Comparative Example 1. Since the example which can obtain the optical external extraction amount exceeding the optical external extraction amount of Comparative Example 3 is S2 / S1 = 0.3 to 0.8, the following equation (6) is obtained. In addition, when the minimum area ratio S2 / S1 = 0.3, the range in which the amount of external light extraction is larger than that of Comparative Example 3 is the height ratio TL / TM = 0 to 0.4. In the range of the height ratio TL / TM = 0 to 0.4, the outside light extraction amount is larger than Comparative Example 3 regardless of the size of the area ratio S2 / S1 of 0.3 to 0.8. This region is indicated by a region 503 in FIG.

Further, in the region where the height ratio TL / TM = 0.4 shown in FIG. 13, in FIG. 17B, the amount of light extracted outside the light from Comparative Example 3 in the range of S2 / S1 = 0.3 to 0.8. When the height ratio TL / TM with a large value is plotted, a range of a curved portion indicated by a region 502 is obtained. When this curved portion is expressed by an approximate expression, the following expression (5) is obtained.
As described above, the region where the external extraction efficiency of light is larger than the microlens film of Comparative Example 3 within the range satisfying the following formulas (5) and (6) that define the region 502 and the region 503 shown in FIG. It can be confirmed that it is preferable.
0 <TL / TM ≦ 37.168 × (S2 / S1) ⁵ −90.138 × (S2 / S1) ⁴
+ 78.959 × (S2 / S1) ³ −32.473 × (S2 / S1) ²
+ 7.3357 × (S2 / S1) −0.0674 (5)
0.3 ≦ S2 / S1 ≦ 0.8 (6)

Furthermore, the following formula (7) 0 <TL / TM ≦ 0.4 (7)
By satisfying the above, the external extraction efficiency of light becomes larger than the microlens film of Comparative Example 3 without depending on the area ratio S2 / S1 of the first uneven portion 14, which is preferable.
When the light control sheet 5 is manufactured, the area ratio S2 / S1 of the first concavo-convex portion 14 is a small variation in the diameter PM of the first concavo-convex portion 14 or a small distance between the adjacent first concavo-convex portions 14. It may be different from the design value due to variations. Alternatively, there may be a variation in the area ratio S2 / S1 within the surface of the light control sheet 5 due to the above-described variation.
In particular, when the area ratio S2 / S1 is 0.3 or more, the change in the area ratio S2 / S1 due to a small variation in the diameter PM of the first uneven portion 14 is large, and the area ratio S2 / S1 is 3 to 10%. Misalignment may occur.
Therefore, satisfying the above expression (7) enables stable production without depending on the area ratio S2 / S1 of the first concavo-convex portion 14, and the external extraction efficiency of light from the microlens film of Comparative Example 3 This is more preferable because only the region 503 shown in FIG.

Next, as shown in FIGS. 18 to 23, the light control sheet 5 can form a design pattern by the arrangement configuration of the first uneven portions 14. These will be described as the light control sheet 5 according to the sixth embodiment of the present invention.
For example, as shown in FIG. 18, for example, a plurality of first concavo-convex portions 14 having a substantially hemispherical shape may be arranged on the surface 7 a of the base layer 7 at substantially uniform intervals to provide a design pattern that does not cause unevenness. In this case, the arrangement of the first uneven portions 14 may form a square lattice as shown in FIG. 18A, or may form a triangular lattice as shown in FIG. 18B. In the case of forming a triangular lattice, it is possible to arrange with a shorter minimum distance between adjacent first uneven portions 14 compared to a square lattice, and to increase the maximum value of the density of the first uneven portions 14. This is preferable.
Moreover, as shown in FIG.18 (c), you may arrange | position the some 1st uneven | corrugated | grooved part 14 irregularly entirely. By arranging the first uneven portions 14 irregularly, when a pixel pattern is provided on the EL element 1, moire generated due to interference between the design pattern of the first uneven portion 14 and the pixel pattern of the EL element 1 is prevented. This is more preferable.

Further, as a design pattern in which the first uneven portion 14 is uniformly arranged on the surface 7a of the base layer 7, as shown in FIG. 19A, the first uneven portion 14 is a mixture of a substantially hemispherical shape and a substantially elliptical spherical shape. You may comprise on the surface 7a of the base layer 7. FIG. Here, the substantially uneven hemispherical first uneven portion 14 in the first uneven portion 14 is denoted by reference numeral 14D.
When the first concavo-convex portion 14 includes the first concavo-convex portion 14D having a substantially elliptical hemispherical shape, it is possible to obtain a desired luminance distribution by controlling the ratio of orienting the major axis of the ellipse in the same direction.
For example, as shown in FIG. 19A, the light distribution in the direction in which the major axis of the first elliptical hemisphere of the first concave-convex portion 14D faces is larger than the direction in which the minor axis of the substantially elliptical hemisphere faces. Tend to have a wide light distribution. This is based on the difference between the elliptical inclination rates. This makes it possible to create an EL element 1 in which the light distribution of emitted light is asymmetric.
Further, as shown in FIG. 19 (b), the first uneven portion 14 is similar in shape such as an inclination angle and dispersed in different sizes (outer diameter PM and height TM). You may arrange.

Further, as shown in FIGS. 20 to 23, by designing the arrangement pattern of the first uneven portions 14 on the surface 7 a of the base layer 7 in the light control sheet 5, design patterns such as specific characters, marks, designs, patterns, etc. May be formed.
For example, FIG. 20 is an example in which a design pattern is formed depending on the presence or absence of the first uneven portion 14.
In FIG. 20A, on the surface 7a of the base layer 7, a region X1 in which the first uneven portions 14 are arranged and a region Y1 in which the first uneven portions 14 are not provided are formed, and the first uneven portions 14 are not provided. A design pattern of the letter “T” is formed on Y1. In the region Y1 where the first uneven portion 14 is not provided, the second uneven portion 15 is arranged. In FIG. 20B, contrary to FIG. 20A, the design pattern of the letter “T” is formed in the region X1 in which the first uneven portions 14 are arranged.
With the configuration as described above, when a design pattern is formed on the light control sheet 5 with the first concavo-convex portion 14 and the second concavo-convex portion 15, a design pattern having a high contrast can be formed. It is preferable when making it conspicuous.

FIG. 21 is an example in which a design pattern is formed by the difference in density of the arrangement of the first uneven portions 14.
In FIG. 21, the region “X2” where the density of the first concavo-convex portions 14 is relatively high and the region Y2 where the density of the first concavo-convex portions 14 is relatively small are arranged separately on the surface 7a of the base layer 7 to thereby form the character “T The design pattern is formed.
When the design pattern is formed on the light control sheet 5 with the configuration as described above, the contrast of the design pattern can be arbitrarily adjusted by an arbitrary density difference. Moreover, since it becomes possible to form a design pattern with small contrast, it is preferable when forming a light design pattern.

FIG. 22 is an example in which a design pattern is formed due to a difference in shape of the first uneven portion 14. In FIG. 22, by dividing the region X3 in which the first concavo-convex portion 14 formed in a hemispherical shape is arranged from the region Y3 in which the first concavo-convex portion 14D formed in a semi-elliptical sphere shape is divided, the character “T” A design pattern is formed.
When the design pattern is formed with the above-described configuration, the design pattern can be formed by the difference in light distribution emitted from the first uneven portions 14 and 14D due to the difference in shape. When the design pattern is formed by the difference in the light distribution, it is possible to emphasize the design pattern especially when the angle with respect to the viewing direction is changed. Therefore, it is preferable when the design pattern differs depending on the observation position.

FIG. 23 is an example in which a design pattern is formed by the size difference of the first uneven portion 14. In FIG. 23, the design pattern of the letter “T” is formed by the region X4 in which the first uneven portions 14S having a relatively small size are arranged and the region Y4 in which the first uneven portions 14 having a relatively large size are arranged. is doing.
When the design pattern is formed by the difference in size as described above, the design pattern is formed by combining the presence / absence of the first uneven portion 14 and the combination of the first uneven portion 14 having a different shape. Thus, by making the inclination angles of the first concavo-convex portions 14 substantially the same and making them similar to each other, it is possible to reduce unevenness of the light distribution in the surface of the EL element 1 and to form a design pattern. Furthermore, since a difference in height occurs between the first uneven portion 14S in the region X4 and the first uneven portion 14 in the region Y4, the design pattern can be confirmed not only visually but also by touch.

In each light control sheet 5 according to the sixth embodiment, even when designability is imparted as described above, the width PM of the first uneven portions 14, 14D, and 14S is set to 20 um or more and 200 um or less, and the second uneven portion. The width PL of 15 is set to 20 μm or more and 200 μm. In this range, the widths PM and PL are set so that the ratio of the width PM of the first uneven portion 14 to the width PL of the second uneven portion 15 is in the range of 1.1 to 10.
When the ratio PM / PL of the width is less than 1.1, the first concavo-convex portion 14 is almost covered with the second concavo-convex portion 15, and thus it is difficult to visually identify the first concavo-convex portion 14. Become. Therefore, it is not preferable because the design pattern cannot be identified by the first uneven portion 14. On the other hand, when the ratio PM / PL of the width exceeds 10, the first uneven portion 14 is easily visible, but the second uneven portion 15 has an excessively fine structure, and thus is diffracted by the second uneven portion 15. Light increases and light utilization efficiency decreases.
In this respect, in the light control sheet 5 according to the sixth embodiment, since the width ratio PM / PL is set in the range of 1.1 to 10, the design pattern by the first uneven portion 14 is visually recognized. At the same time, it is possible to prevent the light utilization efficiency from being reduced due to the diffraction of the second uneven portion 15.

As a material for molding the light control sheet 5, a material having optical transparency with respect to the wavelength of light emitted from the light emitting layer 2 is used. For example, a plastic material that can be used for an optical member is used. Can do.
Examples of the material of the light control sheet 5 include thermoplastic resins such as polyester resin, acrylic resin, polycarbonate resin, polystyrene resin, MS (acrylic and styrene copolymer) resin, polymethylpentene resin, and cycloolefin polymer. Or a transparent resin such as a radiation curable resin made of an oligomer such as polyester acrylate, urethane acrylate, epoxy acrylate, or acrylate. Further, depending on the application, fine particles may be dispersed in the transparent resin.

As the fine particles, particles made of an inorganic oxide or particles made of a resin can be used. For example, transparent particles made of an inorganic oxide include particles made of silica, alumina, titanium oxide, or the like.
The transparent particles made of resin include acrylic particles, styrene particles, styrene acrylic particles and cross-linked products thereof, melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Examples thereof include fluorine-containing polymer particles such as fluoroethylene monohexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene monotetrafluoroethylene copolymer), and silicone resin particles. These fine particles may be used as a mixture of two or more.

The light control sheet 5 is molded by pouring the material as described above into a mold and solidifying it. As a method for producing this mold, first, a lacquer in which carbon black is dispersed in a resin is applied to a copper plated mold by a spray method, and then an infrared laser with a wavelength of 1060 nm is irradiated to sublimate the lacquer. .
Thereafter, a die is attached to the iron chloride chromic acid solution to corrode copper in an isotropic shape in the depth direction and the width direction, so that a portion corresponding to the first uneven portion 14 is produced. Next, the die is cut into a triangular shape using a diamond tool having various lens shapes, and a portion corresponding to the second uneven portion 15 is produced.

  In addition to the method for producing the light control sheet 5 using the mold described above, the first concavo-convex portion 14, the second concavo-convex portion 15, and the base layer 7 may be formed using a thermoplastic resin, an ultraviolet curable resin, or the above-described shape. Using a shaped mold, it can be molded by extrusion molding, injection molding, UV molding, or the like. At this time, the first concavo-convex portion 14, the second concavo-convex portion 15 and the base layer 8 may be molded separately or may be molded as an integrated product. Further, when molding the first concavo-convex portion 14, the second concavo-convex portion 15 and the base layer 8, a diffusing agent such as a filler can be dispersed therein and molded.

As the antistatic agent, ultrafine particles such as antimony-containing tin oxide (hereinafter referred to as ATO) or tin-containing indium oxide (ITO), which are conductive fine particles, may be dispersed. By dispersing the antistatic agent, the antifouling property of the light control sheet 5 can be improved.
When the structural layer 8 and the base layer 7 are molded separately as in the UV molding method, the base layer 7 is a transparent film, cellulose triacetate, polyester, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl A stretched or unstretched film of a thermoplastic resin such as acetal, polymethyl methacrylate, polycarbonate, or polyurethane can be used.
Although the thickness of the base layer 7 depends on the rigidity of the base layer 7, it is preferably 50 to 300 μm from the viewpoint of handling such as workability.

In addition, when the structural layer 8 does not adhere firmly to the base layer 7 or the adhesive force is reduced due to external influences such as cold, moisture absorption and desorption, both materials are placed between the structural layer 8 and the base layer 7. On the other hand, a primer layer with high adhesiveness may be provided, or the action of the primer layer may be added to the structural layer 8.
Alternatively, an easy adhesion process such as a corona discharge process may be performed.
In addition, although the typical example about the light control sheet 5 has been described, if the optical characteristics of the present embodiment can be achieved, the light control sheet 5 can be manufactured using materials, structures, processes, and the like other than those described above. .

DESCRIPTION OF SYMBOLS 1 EL element 1A 1st board | substrate 1B 2nd board | substrate 2 Light emitting layer 3 Anode 4 Cathode 5 Light control sheet 6 Adhesive layer 7 Base layer 7a Front surface 7b Back surface 8 Structural layer 10 Light emitting structure 14, 14D, 14S 1st uneven part 15 Second uneven portion 15A, 15B Square pyramidal convex lens (second uneven portion)
15C square pyramid concave lens (second irregularity)
16 1st prism (2nd uneven part)
17 Second prism (second uneven portion)
18 First Cylindrical Lens 19 Second Cylindrical Lens 21, 21A, 21B, 21C Bottom Surface θ Apex Angle 500-503 Region

Claims (11)

An EL element comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate,
The light control sheet has a plurality of first concavo-convex portions that are arranged at intervals on the other surface opposite to the one surface on which the light emitting layer is provided, and each constitute a lens,
A plurality of second concavo-convex parts that are arranged so as to fill between the first concavo-convex parts and constitute a lens having a height lower than that of the first concavo-convex parts;
The area of the other surface of the light control sheet is defined as S1, and the sum of the areas of the first concavo-convex portions in contact with the other surface of the light control sheet is defined as S2, and the following expression (1) is satisfied. EL element.
0.1 ≦ S2 / S1 ≦ π / 2√3 (1) An EL element comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate,
The light control sheet has a plurality of first concavo-convex portions that are arranged at intervals on the other surface opposite to the one surface on which the light emitting layer is provided, and each constitute a lens,
A plurality of second concavo-convex parts that are arranged so as to fill between the first concavo-convex parts and constitute a lens having a height lower than that of the first concavo-convex parts;
The area on the other surface of the light control sheet is S1, the sum of the areas of the first uneven portions in contact with the other surface of the light control sheet is S2, the height of the first uneven portion is TM, An EL element satisfying the following formulas (2) and (3), where TL is the height of the second uneven portion.
0 <TL / TM ≦ −158.79 × (S2 / S1) ⁵ + 412.89 × (S2 / S1) ⁴
−419.47 × (S2 / S1) ³ + 205.74 × (S2 / S1) ²
−47.492 × (S2 / S1) +4.5014 (2)
0.2 ≦ S2 / S1 ≦ π / 2√3 (3)
The EL device according to claim 2, wherein the first uneven portion and the second uneven portion of the light control sheet satisfy the following expression (4).
0 <TL / TM ≦ 0.6 (4) An EL element comprising a light-transmitting substrate and a light-emitting layer provided on one surface of the light-transmitting substrate and sandwiched between an anode and a cathode,
A light control sheet is provided on the other surface opposite to the one surface of the translucent substrate,
The light control sheet has a plurality of first concavo-convex portions that are arranged at intervals on the other surface opposite to the one surface on which the light emitting layer is provided, and each constitute a lens,
A plurality of second concavo-convex parts that are arranged so as to fill between the first concavo-convex parts and constitute a lens having a height lower than that of the first concavo-convex parts;
The area on the other surface of the light control sheet is S1, the sum of the areas of the first uneven portions in contact with the other surface of the light control sheet is S2, the height of the first uneven portion is TM, An EL element satisfying the following formulas (5) and (6), where the height of the second uneven portion is TL.
0 <TL / TM ≦ 37.168 × (S2 / S1) ⁵ −90.138 × (S2 / S1) ⁴
+ 78.959 × (S2 / S1) ³ −32.473 × (S2 / S1) ²
+ 7.3357 × (S2 / S1) −0.0674 (5)
0.3 ≦ S2 / S1 ≦ 0.8 (6) The EL device according to claim 2, wherein the first uneven portion and the second uneven portion of the light control sheet satisfy the following expression (7).
0 <TL / TM ≦ 0.4 (7)   The EL device according to claim 1, wherein the first uneven portion is a micro lens having a substantially hemispherical shape or a substantially elliptical hemispherical shape.   The second concavo-convex portion is a lens or prism shape having a convex cross section, extends in a columnar shape in one direction, and is arranged so as to intersect each other in a gap between the first concavo-convex portions. The EL element according to claim 1.   The said 2nd uneven | corrugated | grooved part has the polygonal convex lens part whose bottom part is a polygon, or the polygonal concave lens part whose top part is a polygon are arranged without the gap, It was described in any one of Claim 1 thru | or 6 characterized by the above-mentioned. EL element. An illumination device comprising a light emitting means,
The lighting device according to claim 1, wherein the light emitting means is an EL element according to claim 1. A display device comprising the EL element according to any one of claims 1 to 8,
A display device, wherein the EL element is configured to be driven by a pixel. A liquid crystal display device comprising an image display element,
A liquid crystal display device, wherein the EL element according to any one of claims 1 to 8 or the illumination device according to claim 9 is disposed on a back surface of the image display element.

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