JP2015108719A - Optical sheet and el device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet which exhibits good optical performance even after being adhered to a target member to be an integral part thereof.SOLUTION: An optical sheet 1 has a light incident surface 3a and a light exit surface 4, from which light entering the light incident surface 3a exits, and includes a first light transmissive layer 2 and a second light transmissive layer 3 laminated between the light incident surface 3a and the light exit surface 4, with a first lens group 5 comprising first lenses 5A, 5B two dimensionally arranged to form the light exit surface 4, and a second lens group 7 comprising second lenses which are located between the light incident surface 3a and the first lens group 5, has a second lens surface 6 to constitute an interface between the first light transmissive layer 2 and the second light transmissive layer 3, which are next to each other in a thickness direction, and are arranged spaced apart from each other in a direction crossing the thickness direction. Viewing from the thickness direction, an area ratio of the first lens group 5 is greater than that of the second lens group 7.

Description

  The present invention relates to an optical sheet and an EL device. For example, backlight, illumination light source, electrical decoration, light source for sign, optical sheet used in display device, heat insulating material for heating element, optical sheet also serving as heat dissipation material, and optical sheet used as adherend, and The present invention relates to an EL device.

Conventionally, optical sheets for obtaining various optical effects have been used in, for example, backlights and illumination light sources.
For example, in a display member, it is used to obtain a diffusion effect that controls the optical characteristics in the horizontal and vertical directions and makes the light source lamp or light guide plate pattern invisible to the viewer. Moreover, in LED illumination, it is used for a cover etc., and is used in order to obtain the diffusion effect for supplying uniform illumination light by erasing the bright point of the light source. Moreover, in an EL illumination device, it is used for the purpose of obtaining a diffusion effect for suppressing color change from an observer by mixing light beams having high angle dependency and for improving light extraction efficiency.
Such an optical sheet is generally produced by providing a specific uneven shape on a translucent substrate.
In order to give a concavo-convex shape on a translucent substrate, for example, the surface of a mold such as a cylinder or a plate is patterned using sculpture represented by a lathe cutting method, corrosion, etc. As a matrix, the concavo-convex shape by the actinic energy curable resin is transferred to the surface of the translucent substrate, or the concavo-convex shape is transferred to the surface during melt molding of the thermoplastic resin by a similar matrix. Moreover, the manufacturing method which forms uneven | corrugated shape by laying microparticles | fine-particles on the translucent base material surface is also used.
Such a concavo-convex shape is given to either the front or back of the optical sheet or both sides, and when used by bonding, the concavo-convex shape is given only to the non-bonding surface of the translucent substrate. (See Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 8-211205 JP 2010-097711 A

However, the prior art as described above has the following problems.
As described above, the conventional optical sheet is used for various purposes. For example, when used in a display, it is used for the purpose of obtaining a light distribution such as a desired viewing angle and imparting a diffusion performance for relaxing a spot-like bright spot caused by a light source lamp.
Conventionally, in order to satisfy such a plurality of requirements at the same time, it was necessary to use a plurality of optical sheets having different concavo-convex shapes.
For this reason, there has been a problem that the number of members of the optical sheet is increased and the component cost is increased. Further, for example, when an environmental load such as temperature and humidity is applied, the deformation behavior of each optical sheet is different, so that there is a problem that reliability as a display is impaired.
It is possible to attach the optical sheet to the light guide plate or the diffusion plate and integrate them. However, in this case, the bonding surface cannot be provided with a surface shape that refracts light rays such as a lens surface. There is a problem that optical performance cannot be obtained.
In addition, since the optical sheet bonded to the light guide plate or the diffusion plate in this way has few optical surfaces, the surface shape of the lens surface provided on the non-bonded surface in order to obtain the necessary optical characteristics is a very complicated pattern. There is a problem of becoming a shape.
For example, in EL illumination, it is common to use an optical sheet bonded to a glass substrate on the surface of an EL panel for the purpose of improving light extraction efficiency. In this case, the concave and convex shape can be given only to one surface on the emission side, and therefore, a sufficient light extraction efficiency improvement function cannot be given, or the color difference for each viewing angle due to insufficient mixing of light rays by the lens There is a problem that it cannot be suppressed.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optical sheet that can exhibit good optical performance even when bonded and integrated with an adherend. .
Another object of the present invention is to provide an EL device capable of improving optical performance by including such an optical sheet.

  In order to solve the above-described problem, the optical sheet according to the first aspect of the present invention is such that the light incident surface and the light emitting surface that emits light incident from the light incident surface to the outside face each other in the thickness direction. An optical sheet formed in such a manner that a plurality of light transmission layers stacked between the light incident surface and the light emitting surface and a plurality of first lenses are arranged in one or two directions. A first lens group forming at least a part of the light emitting surface, and disposed between the light incident surface and the first lens group, and adjacent to the thickness direction of the plurality of light transmission layers. A plurality of second lenses each having a lens surface formed by an interface between the two light transmission layers that are arranged apart from each other in a direction intersecting the thickness direction, and the thickness When viewed from the direction, the area ratio occupied by the first lens group is the second lens group. With high configuration than the area ratio.

  In the optical sheet, the lens surface of the second lens group is formed by a resin molded product constituting one of the two light transmission layers, and the second lens group is formed on the lens surface with the two light beams. It is preferable to be formed by filling an adhesive substance constituting the other of the permeable layer.

  In the optical sheet having the above-mentioned adhesive substance, it is preferable that the adhesive substance also serves as a bonding layer for attaching the resin molded product to the adherend.

  In the optical sheet, it is preferable that light diffusing fine particles are contained in one or more of the plurality of light transmission layers.

  In the optical sheet, it is preferable that the first lens is a prism lens, and the second lens is a dot-like lens in plan view having a dome-shaped lens surface.

  An EL device according to a second aspect of the present invention includes the optical sheet and an EL panel on which the optical sheet is bonded.

According to the optical sheet of the present invention, a plurality of light transmission layers are laminated, and the first lens group provided on one surface and the second lens group provided on the inside thereof are provided. Even if it unites together, there exists an effect that favorable optical performance can be exhibited.
Moreover, according to the EL device of the present invention, the optical performance can be improved by providing the optical sheet of the present invention.

It is typical sectional drawing which shows the structure of the EL apparatus of the 1st Embodiment of this invention. It is typical sectional drawing which shows the structure of the optical sheet of the 1st Embodiment of this invention. It is the typical perspective view which shows the structure of the 1st light transmission layer of the optical sheet of the 1st Embodiment of this invention, its A view, and B view. It is typical sectional drawing which shows the structure of the optical sheet of the modification (1st modification) of the 1st Embodiment of this invention. It is typical sectional drawing which shows the structure of the optical sheet of the modification (2nd modification) of the 1st Embodiment of this invention. It is typical sectional drawing which shows the structure of the optical sheet of the 2nd Embodiment of this invention. It is typical sectional drawing which shows the structure of the optical sheet of the modification (3rd modification) of the 2nd Embodiment of this invention. It is typical sectional drawing which shows the structure of the EL apparatus of the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
An EL device and an optical sheet according to the first embodiment of the present invention will be described.
FIG. 1 is a schematic cross-sectional view showing the configuration of the EL device according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of the optical sheet according to the first embodiment of the present invention. FIG. 3A is a schematic perspective view showing the configuration of the first light transmission layer of the optical sheet according to the first embodiment of the present invention. FIG.3 (b) is A view in FIG.3 (a). FIG. 3C is a B view in FIG.
In addition, since each figure is a schematic diagram, the shape and dimension are exaggerated (the following drawings are also the same).

As shown in FIG. 1, the EL device 100 of the present embodiment includes an EL panel 20 and the optical sheet 1 of the present embodiment. “EL” represents electroluminescence.
The EL panel 20 is a device portion that generates light for displaying an image or video or performing illumination. In this embodiment, the EL panel 20 has a plurality of pixels that can emit light independently. These pixels are pixel-driven based on a control signal such as an image signal sent to a drive unit (not shown), and the driven pixels emit light.
The EL panel 20 is formed in a flat plate shape by laminating an EL panel surface layer 10, a first substrate 14, a light emitting structure 11, and a second substrate 15 in this order.

  The EL panel surface layer 10 is a light-transmitting layered portion that constitutes one surface of the EL panel 20, and is made of, for example, glass or a light-transmitting film. In this embodiment, glass is employed.

The first substrate 14 is a translucent substrate that transmits light generated by the light emitting structure 11 to be described later toward the EL panel surface layer 10, and the EL panel surface layer 10 is formed on one surface and the other surface. The light emitting structures 11 are in close contact with each other. The transmittance of the first substrate 14 is preferably 50% or more.
The material of the 1st board | substrate 14 will not be specifically limited if it is the material which permeate | transmits the light generated by the light emitting structure 11 mentioned later, For example, various glass materials and plastic materials are employable. Examples of suitable plastic materials include polymethyl methacrylate resin (PMMA), polycarbonate resin (PC), and polystyrene resin.
Particularly preferred plastic materials are cycloolefin-based polymers. This polymer is excellent in all of the workability and material properties such as heat resistance, water resistance, and optical translucency.

The light emitting structure 11 includes an anode 11a disposed on the opposite side of the EL panel surface layer 10 on the first substrate 14, a cathode 11b disposed on the surface of the second substrate 15 described later, and between the anode 11a and the cathode 11b. And the light emitting layer 11c sandwiched between the layers.
The light emitting structure 11 is one in which the light emitting layer 11c emits light by applying a voltage to the anode 11a and the cathode 11b, and various conventionally known configurations can be employed.
In the present embodiment, since light from the light emitting structure 11 is emitted to the first substrate 14 side, at least the anode 11a needs to be an electrode having translucency. Examples of such translucent electrodes include ITO (indium tin oxide).
In the present embodiment, the cathode 11b does not matter whether or not it has translucency, and therefore, an appropriate metal material having good conductivity, such as aluminum, silver, or copper, can be used.

The light emitting layer 11c can be, for example, a white light emitting layer. In this case, the anode 11a is made of ITO and the cathode 11b is made of aluminum, and CuPc (copper phthalocyanine) / α-NPD is doped with 1% rubrene / perylene is doped with 1% perylene in the dioctylanthracene / from the anode 11a side to the cathode 11b. A configuration in which Alq3 / lithium fluoride is laminated in this order can be employed.
However, the configuration of the light emitting layer 11c is not limited to this, and an appropriate material capable of setting the wavelength of light emitted from the light emitting layer 11c to R (red), G (green), and B (blue). Any configuration used may be employed.
Further, when the EL device 100 is used for a full color display, for example, the light emitting layer 11c has a configuration in which three kinds of light emitting materials corresponding to R, G, and B are separately applied, or a color filter on the white light emitting layer. It is possible to adopt a configuration in which

  In this embodiment, since the EL panel 20 is pixel driven, the light emitting structure 11 is formed corresponding to each pixel, and the anode 11a and the cathode 11b of each pixel are wired to a driving unit (not shown). Yes.

The second substrate 15 is a plate-like or sheet-like member that is disposed to face the first substrate 14 and sandwiches the plurality of light emitting structures 11 between the first substrate 14 and is the same as the first substrate 14. It is possible to form with the material of.
The second substrate 15 preferably includes a light reflecting layer that reflects light generated by the light emitting structure 11 toward the first substrate 14 on any surface in the thickness direction.
In addition, the second substrate 15 can be formed of a metal material having light reflectivity. In this case, the second substrate 15 itself constitutes a light reflection layer.

The optical sheet 1 is generated by the light emitting structure 11 and transmitted through the first substrate 14 and the EL panel surface layer 10 from the flat light incident surface 3a, and controls the optical characteristics of the incident light. It is a sheet-like member that emits to the outside from the light exit surface 4 having an uneven shape opposite to the light incident surface.
In the present embodiment, the optical sheet 1 is bonded to the EL panel surface layer 10 and integrated with the EL panel 20.
Here, the “optical characteristics of light” controlled by the optical sheet 1 means one or more characteristics among the emission direction, emission range, color shift, color unevenness, and luminance distribution of the emitted light.
The optical sheet 1 is configured by laminating a plurality of light transmission layers having different refractive indexes. Although the number of light transmission layers is not particularly limited, in this embodiment, as an example, as shown in FIGS. 1 and 2, the second light transmission layer 3 (light transmission layer) and the first light transmission layer are formed on the EL panel surface layer 10. An example in the case of having a two-layer structure in which one light transmission layer 2 (light transmission layer, resin molded product) is laminated in this order will be described.

  As shown in FIGS. 2, 3A, 3B, and 3C, the first light transmission layer 2 is a layered portion formed of a resin molded product, and the light emitting surface 4 of the optical sheet 1 is formed. The first lens group 5 is formed on one surface constituting the surface, and the second lens group 7 is formed on the other surface in close contact with the second light transmission layer 3.

The first lens group 5 can have a configuration in which unit lenses such as microlenses, lenticular lenses, and prism lenses are arranged one-dimensionally or two-dimensionally.
As an example, the first lens group 5 in the present embodiment includes a first lens 5A (first lens) having a constant cross-sectional shape extending in one direction, and a constant cross-sectional shape extending from the first lens 5A. It is composed of two types of unit lenses, a first lens 5B (first lens) extended in a direction crossing the direction.
In the present embodiment, a plurality of first lenses 5A and 5B are closely arranged in a direction orthogonal to the extending direction, and the crossing angle of the first lenses 5A and 5B is 90 as an example. Degree.
For this reason, the light emission surface 4 is an uneven surface formed by any one of the first lenses 5A and 5B.

The cross-sectional shape (hereinafter referred to as the lens cross-sectional shape) along the direction orthogonal to the extending direction of each of the first lenses 5A and 5B is appropriately set according to the optical characteristics of the light emitted from the light exit surface 4. Shape can be adopted.
The first lens group 5 in the present embodiment has a concavo-convex shape so that light that diverges and travels in various directions inside the first light transmission layer 2 can easily pass through the light emitting surface 4, and A shape that controls the emission direction, the emission range, and the luminance distribution is adopted so as to be emitted in a range of a predetermined viewing angle.

In this embodiment, the lens cross-sectional shape of the first lenses 5A and 5B is, for example, a substantially triangular shape (including a triangular shape).
The apex angles of the first lenses 5A and 5B are preferably 30 degrees to 150 degrees.
The top of the first lens 5A, 5B in the lens cross-sectional shape is formed with a rounded shape such as an arc shape or an elliptical arc shape in order to form an appropriate luminance distribution or improve the scratch resistance. It is possible. In addition, the inclined surfaces sandwiching the tops of the first lenses 5A and 5B can adopt a flat surface or a curved surface in order to form an appropriate luminance distribution.
The length of the base (hereinafter referred to as lens width), the height from the base to the top (hereinafter referred to as lens height), and the apex angle in each lens cross-sectional shape of the first lenses 5A and 5B are shown in FIG. ) Shows an example in which they are equal to each other. However, the lens width, the lens height, and the apex angle may be different from each other.

The second lens group 7 can have a configuration in which unit lenses such as microlenses, lenticular lenses, and prism lenses are arranged one-dimensionally or two-dimensionally. However, the area ratio viewed from the thickness direction of the optical sheet 1 is formed such that the area ratio occupied by the first lens group 5 is higher than the area ratio occupied by the second lens group 7.
In the present embodiment, since the first lens group 5 constitutes the entire light emitting surface 4, the area ratio is 100%. On the other hand, the unit lenses constituting the second lens group 7 are spaced apart from each other in the direction orthogonal to the thickness direction of the optical sheet 1, so that the area ratio is less than 100%.

The refractive power of each unit lens of the second lens group 7 may be positive or negative as long as it has a diffusion performance such that the light beam diameter on the light exit surface 4 is larger than the diameter of the unit lens.
As shown in FIGS. 3A and 3C, the unit lens of the second lens group 7 in the present embodiment forms a surface opposite to the light emitting surface 4 in the first light transmission layer 2 as an example. The second lens surface 6 (lens surface, second lens) formed of a concave portion formed on the flat surface 2a is filled with a medium that becomes the second light transmission layer 3 described later.
The second lens surface 6 is a concave portion having a planar dot-like opening such as a circle or an ellipse on the flat surface 2a. For example, a dome-shaped curved surface such as a spherical surface, an elliptical surface, or an aspherical surface may be employed. it can.
The refractive index of the second light transmission layer 3 is preferably lower than the refractive index of the first light transmission layer 2 so that total reflection of light incident from the second light transmission layer 3 does not occur.
The area ratio R6 (%) of the second lens group 7 is R6 = 100 × S7 / (S7 + S2a) where S7 is the total area viewed from the thickness direction of the optical sheet 1 and S2a is the total area of the flat surface 2a. expressed.

The second lens group 7 configured in this manner refracts light incident from the second light transmission layer 3 by the second lens surface 6 and transmits it to the first light transmission layer 2 side by the lens action of each unit lens. Therefore, it has a function of diffusing the luminous flux.
For this reason, when the light incident on the first light transmission layer 2 from the flat surface 2a side passes through the second lens surface 6, the traveling direction of the light is disturbed. As a result, a light beam component that travels straight through the flat surface 2a and a light beam component that travels through the second lens surface 6 and whose traveling direction is disturbed as a convergent light or divergent light reach the light emitting surface 4.
The light beam component that has passed through the flat surface 2a is refracted by the first lens group 5 to be condensed within a certain viewing angle range. However, since the first lens group 5 has dispersion, the observation direction from the outside Depending on the color.
On the other hand, the light beam component transmitted through the second lens surface 6 is similarly affected by dispersion and produces a color depending on the direction. However, since the second lens surface 6 is refracted and diffused, the flat surface 2a. The incident angle distribution with respect to the light exit surface 4 is different from the light flux component that has passed through. For this reason, the appearance of the color depending on the observation direction is different from the light flux component transmitted through the flat surface 2a.
Thereby, by appropriately setting the shape, density, and area ratio of the second lens surface 6, it is possible to reduce or eliminate the change in color depending on the viewing direction.

Of the light incident on the first light transmission layer 2, the light reflected on the back surface of the light output surface 4 is repeatedly reflected in the first light transmission layer 2 and is incident on the light output surface 4 at different incident angles. As a result, the light is emitted to the outside or attenuated while repeating internal reflection.
At this time, the second lens surface 6 acts as a light deflection element for the internally reflected light, and scatters the internally reflected light toward the light emitting surface 4 side. For this reason, compared with the case where the interface with the 2nd light transmissive layer 3 is comprised only by the flat surface 2a, the ratio by which internal reflection light is radiate | emitted outside through the light-projection surface 4 increases. As a result, the light extraction efficiency is improved.

These effects become more significant as the area ratio R6 of the second lens group 7 increases. For this reason, the area ratio R6 of the second lens group 7 is preferably 20% or more and 90%, and more preferably 50% or more and 90% or less.
When the area ratio R6 is less than 20%, the diffusion of incident light becomes insufficient, so that the color depending on the viewing direction cannot be reduced well, and good light extraction efficiency cannot be obtained.
If the area ratio R6 is higher than 90%, it is difficult to fill the second lens surface 6 with the material to be the second light transmission layer 3 without unevenness. For example, the second lens surface 6 and the second light transmission An external space is formed between the layer 3 and the appearance is deteriorated or the reliability is lowered.
Further, as will be described later, a problem corresponding to the method for manufacturing the second light transmission layer 3 is likely to occur.

In addition, the 2nd lens surface 6 which comprises the 2nd lens group 7 may be arranged regularly, and may be arranged so that it may not have regularity. In any case, it is preferable that the distribution density is uniform, but for example, a substantially uniform distribution in which optical performance such as luminance unevenness falls within an allowable range may be employed.
In addition, when the diffusion performance has anisotropy because the shape of the second lens surface 6 is not rotationally symmetric, a distribution with anisotropy is also adopted for the distribution of the second lens surface 6. be able to.

In the present embodiment, as an example, the second lens surface 6 employs a spherical surface so that the diffusion performance is uniform around the optical axis.
A ratio h6 / d6 of a depth h6 (see FIG. 2) from the flat surface 2a of the second lens surface 6 to a diameter d6 (see FIG. 2) of the bottom surface of the second lens surface 6 (an opening in the flat surface 2a) is an aspect ratio. When referred to as α, the aspect ratio α is preferably 0.05 ≦ α ≦ 0.5. When a shape other than a spherical surface is employed as the second lens surface 6, the range of the aspect ratio α is preferably 0.05 ≦ α ≦ 1, and 0.1 ≦ α ≦ 0.8. Is more preferable.
The diameter d6 of the bottom surface of the second lens surface 6 is preferably 10 μm or more and 200 μm or less.
The depth h6 of the second lens surface 6 can be appropriately set according to the required optical performance and the method for manufacturing the second light transmission layer 3 described later, but is preferably 5 μm or more and 100 μm or less. The preferable range according to the manufacturing method will be described together with the manufacturing method described later.

As the material of the first light transmission layer 2, a thermoplastic resin having light transmittance can be adopted. Suitable thermoplastic resins for the first light transmission layer 2 include, for example, acrylic resins, acrylonitrile resins, acrylonitrile polystyrene copolymers, polycarbonate resins, cycloolefin resins, polyester resins, styrene resins, acrylic / A well-known thing, such as a styrene-type copolymer resin, can be used.
In order to form such a first light transmission layer 2, for example, a mother mold having a mold surface obtained by inverting the concavo-convex shape of the light emitting surface 4, and a concavo-convex shape including the flat surface 2 a and the second lens surface 6 are reversed. And a mother die having a finished mold surface. Next, a plate-like or sheet-like base material made of a thermoplastic resin that forms the first light transmission layer 2 is heated and melted, and these matrixes are pressed against the front and back surfaces of the base material, and the surface of the base material Molding is performed to transfer the uneven shape of the mold surface. Thereby, the 1st light transmission layer 2 can be manufactured.

The second light transmission layer 3 fills the inside of the second lens surface 6 of the first light transmission layer 2 and covers the flat surface 2a with a substantially uniform (including a uniform case) thickness. It is a layered part.
In the second light transmission layer 3, the surface opposite to the flat surface 2 a and the second lens surface 6 is a plane parallel to the flat surface 2 a and constitutes the light incident surface 3 a of the optical sheet 1.
The material of the second light transmission layer 3 is not particularly limited as long as the material has a refractive index different from that of the first light transmission layer 2. By providing the refractive index difference in this way, the second lens surface 6 functions as a refractive surface and can have a lens action.
However, in order to prevent total reflection of light from the second light transmission layer 3 toward the first light transmission layer 2, the refractive index of the second light transmission layer 3 is the refractive index of the first light transmission layer 2. Is preferably lower. In this case, since the amount of light incident on the first light transmission layer 2 from the second light transmission layer 3 can be increased, the light utilization efficiency as the optical sheet 1 can be improved.
In addition, the second light transmission layer 3 is preferably made of an adhesive substance that can adhere to the first light transmission layer 2 and the EL panel surface layer 10.

Preferable materials for the second light transmission layer 3 include, for example, resin-based adhesives (adhesive substances) such as acrylic and urethane-based materials.
More specifically, as the acrylic pressure-sensitive adhesive, a pressure-sensitive adhesive obtained by appropriately cross-linking an acrylic polymer can be employed. As an acrylic polymer, an isocyanate compound, an epoxy compound, an aziridine compound etc. can be mentioned, for example. Among these, examples of the isocyanate compound include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.
As specific means of the crosslinking method, a compound having a group capable of reacting with a carboxyl group, a hydroxyl group, an amino group, an amide group or the like appropriately included as a crosslinking base point in an acrylic polymer such as an isocyanate compound, an epoxy compound, or an aziridine compound. There is a method using a so-called cross-linking agent that is added and reacted.
Such a crosslinked acrylic pressure-sensitive adhesive is preferable because of its excellent heat resistance.
In addition, when it is desired to increase the refractive index difference with respect to the first light transmission layer 2, a material in which a part of the material is fluorinated may be adopted, or hollow fine particles may be added to the pressure-sensitive adhesive layer. Is possible. Thereby, since the refractive index of the 2nd light transmissive layer 3 falls more and the refractive power of the 2nd lens group 7 increases, a higher lens effect can be provided.

Such a second light transmission layer 3 is a material that becomes the second light transmission layer 3 on the flat surface 2a and the second lens surface 6 of the first light transmission layer 2 (hereinafter referred to as a second light transmission layer forming material). ) Can be applied.
The second light transmission layer 3 is formed by forming the second light transmission layer forming material as a layered body that is thicker than the depth h6 of the second lens surface 6 and easily deformed, and is attached to the flat surface 2a and the second lens surface 6. They can also be formed by drying as necessary.
The second light transmission layer forming material applied or bonded in this way fills the second lens surface 6 and is in close contact with the flat surface 2a. Thereby, the optical sheet 1 is formed.

The optical sheet 1 thus formed has the light incident surface 3a, which is the outer surface of the second light transmission layer 3, bonded to the EL panel surface layer 10 of the EL panel 20, so that the EL device 100 of the present embodiment is bonded. Can be manufactured. The EL panel 20 is an adherent member when the optical sheet 1 is bonded.
When an adhesive substance is used as the material of the second light transmission layer 3, it can be attached using the adhesiveness of the adhesive substance when it is attached to the EL panel surface layer 10 of the EL panel 20. In this case, it can bond together without interposing another bonding layer between EL panel surface layers 10, and a manufacturing process can be simplified and manufacturing cost can be reduced.

The optical sheet 1 in which the second light transmission layer 3 is made of an adhesive substance can be bonded to the EL panel surface layer 10 of the EL panel 20 immediately after the second light transmission layer 3 is formed.
However, in the case where the optical sheet 1 is stored and transported as a sheet body and pasted after a certain time, a protective sheet is pasted on the second light transmitting layer 3 side after the second light transmitting layer 3 is formed. Processing can also be performed.
The optical sheet 1 attached with the protective sheet can be peeled off and attached to the EL panel surface layer 10 of the EL panel 20 as necessary.

Moreover, when the 2nd light transmissive layer 3 consists of materials other than an adhesive substance, it is possible to bond the optical sheet 1 to the EL panel surface layer 10 through a suitable adhesive agent and an adhesive.
Further, the light incident surface 3a and the surface of the EL panel can be obtained by subjecting the light incident surface 3a of the second light transmission layer 3 or the surface of the EL panel surface layer 10 to an easy adhesion treatment such as a corona treatment or a silane coupling treatment. The layer 10 may be bonded.
Moreover, the optical sheet 1 and the EL panel surface layer 10 may be bonded together by thermal lamination or the like by adopting a plastic resin for either the second light transmission layer 3 or the EL panel surface layer 10.

Next, the second light transmission layer forming material and the dimensional conditions of the second lens surface 6 will be described.
The second light transmission layer forming material can be used in a state diluted with a solvent or in a state impregnated with a solvent component.
At that time, it is possible to use only one type of solvent or solvent component, or a mixture of one or more types. In this case, the solvent or solvent component is preferably about 50 ° C. ≦ Ts ≦ 150 ° C., where Ts is the boiling point of the highest boiling component.
When 50 ° C.> Ts, the material applied or pasted on the first light transmission layer 2 is easily dried before filling the second lens surface 6, and a gap is generated between the second lens surface 6 and the second lens surface 6. There is a fear. When joining to the 1st light transmission layer 2 in the state where such a space | gap generate | occur | produced, the defect which a luminescent spot can see in a space | gap part may express. Further, in an environment in which heat is applied, there is a possibility that peeling occurs from the gap portion and a floating defect such that a visible bright spot occurs.
In the case of Ts> 150 ° C., drying after application or pasting to the first light transmission layer 2 becomes insufficient, and foaming may occur in an environment where heat is applied. In this case, there is a possibility that a bright spot appears in the part where the shot is made or a defect such as a float occurs.
In order to prevent such problems, for example, measures such as reducing the coating speed in order to promote drying at the time of application and increasing the temperature of the drying furnace used for drying can be considered, but the cost is increased and the yield is decreased due to heat shrinkage. Such a problem may occur.

Further, when the second light transmission layer material contains a solvent or a solvent component, it is possible to select a material having a slight solubility in the solvent or the solvent component as the material of the first light transmission layer 2.
When such a material is selected, the flat surface 2a and the second lens surface 6 that are in close contact with the second light transmission layer 3 are slightly dissolved, so that the flat surface 2a and the second lens surface 6 can be roughened. It becomes. When the second lens surface 6 is roughened, the diffusion effect on the second lens surface 6 is increased, so that moire caused by the first lens group 5 and the second lens group 7 can be suppressed. For this reason, it becomes easy to select the shape of the arrangement pattern of the lenses in the first lens group 5 and the second lens group 7.
Further, when the flat surface 2a and the second lens surface 6 are roughened, the contact area between the second light transmission layer 3 and the first light transmission layer 2 increases, and therefore the second light transmission layer 3 and the first lens surface 6 are increased. Adhesiveness with the light transmission layer 2 is improved.

When the second light transmission layer forming material is liquid or low in viscosity and the second light transmission layer 3 is manufactured by applying the second light transmission layer formation material to the first light transmission layer 2, the first light The second lens surface 6 of the transmissive layer 2 is preferably formed so as not to be adjacent as much as possible. Moreover, it is more preferable that all of the second lens surfaces 6 are separated from each other via the flat surface 2a.
When the plurality of second lens surfaces 6 are connected adjacent to each other, a flow path is formed by the recesses adjacent to the second lens surfaces 6 when the second light transmission layer forming material is applied. For this reason, the second light transmission layer forming material easily flows along the recesses adjacent to the second lens surface 6. Thereby, for example, the coating thickness on the flat surface 2a may vary, or the filling amount of the second lens surface 6 may be insufficient. If such coating unevenness or filling unevenness occurs, brightness unevenness or the like may occur, resulting in poor appearance.
As the number of isolated second lens surfaces 6 decreases, the number of such flow paths decreases. Therefore, even when the second light transmission layer forming material is liquid or has a low viscosity, it can be applied satisfactorily.
Accordingly, the area ratio R6 of the second lens group 7 is preferably not more than 90% so that the distance between the second lens surfaces 6 can be maintained at a suitable distance.

  In addition, when the second light transmission layer forming material has a high viscosity, a layered body is formed and bonded. Therefore, even if the area ratio R6 exceeds 90%, the second light transmission layer forming material flows and coating unevenness or Although uneven filling does not occur, the amount of deformation of the layered body increases as the second lens surface 6 increases as the area ratio R6 increases. For this reason, for example, uneven filling tends to occur due to uneven pressing force at the time of bonding. Therefore, it is preferable that the area ratio R6 does not exceed 90%.

The shape of the second lens surface 6 is also preferably set to an appropriate dimension according to the viscosity of the second light transmission layer forming material.
For example, when the second light transmission layer forming material has a high viscosity and is bonded to the first light transmission layer 2 after forming a layered body, the second lens surface 6 is filled with the second light transmission layer formation material. In order to facilitate, it is preferable to make the depth h6 of the second lens surface 6 shallow. For example, in this embodiment, h6 is preferably 5 μm or more and 30 μm or less, and more preferably 10 μm or more and 20 μm or less.
If h6 is less than 5 μm, the lens width (the diameter of the lens bottom surface) becomes too small within the range of the aspect ratio that can be molded, and the diffraction effect becomes larger than the lens effect. The optical action cannot be obtained.
When h6 is 5 μm or more and less than 10 μm, when the aspect ratio α exceeds 0.5, the lens width becomes too small, and the diffraction effect becomes larger than the lens effect. Etc. cannot be obtained.
If h6 is greater than 30 μm, the second lens surface 6 may not be filled with the second light transmission layer forming material within the range of the aspect ratio for obtaining the required optical characteristics, resulting in poor appearance and poor floating. To do.
When h6 is larger than 20 μm and 30 μm or less, when the aspect ratio α exceeds 0.5, poor appearance or poor floating tends to occur. In addition, there is a possibility that an air layer that cannot be visually recognized remains between the second light transmission layer forming material and the second lens surface 6. In this case, when an environmental load is applied, there is a possibility of causing a floating defect.

For example, when the second light transmission layer forming material is liquid or has a low viscosity and is applied to the first light transmission layer 2, in this embodiment, h6 is preferably 5 μm or more and 100 μm or less, preferably 10 μm or more. , 80 μm or less is more preferable.
If h6 is less than 5 μm, the lens width (the diameter of the lens bottom surface) becomes too small within the range of the aspect ratio that can be molded, and the diffraction effect becomes larger than the lens effect. The optical action cannot be obtained.
When h6 is 5 μm or more and less than 10 μm, when the aspect ratio α exceeds 0.5, the lens width becomes too small, and the diffraction effect becomes larger than the lens effect. Etc. cannot be obtained.
If h6 is larger than 100 μm, the filling amount of the second lens surface 6 becomes too large, and the filling portion becomes insufficiently dried. For example, it causes a floating defect in an environment where heat is applied.
When h6 is larger than 80 μm and 100 μm or less, when the aspect ratio α exceeds 0.5, the deep part tends to be insufficiently dried. For example, the floating defect is difficult in an environment where heat is applied. Cause the occurrence.

Next, the operation of the optical sheet 1 and the EL device 100 will be described.
The optical sheet 1 has a two-layer structure of a first light transmission layer 2 and a second light transmission layer 3, and a first lens group 5 is formed on the surface of the first light transmission layer 2, and the first light transmission layer A second lens group 7 is formed at the interface between 2 and the second light transmission layer 3.
As described above, since the optical sheet 1 is formed by stacking and integrating a plurality of types of lens groups, conventionally, a plurality of sheets having different optical characteristic control functions can be obtained by changing the optical characteristic control function for each lens group. The function realized by stacking the optical sheets can be realized by a single sheet.

Control of optical characteristics in the present embodiment will be briefly described.
When the EL panel 20 is turned on in the EL device 100, light is generated in the region of the light emitting layer 11c. This light is transmitted directly through the anode 11a, or after being reflected by the cathode 11b and the second substrate 15 and then transmitted through the anode 11a and enters the first substrate 14, and passes through the first substrate 14 and the EL panel surface layer 10. The light is sequentially transmitted and enters the light incident surface 3 a of the optical sheet 1. Thereby, a light beam substantially corresponding to the size of the pixel of the light emitting layer 11 c is emitted from the EL panel 20 toward the optical sheet 1.

The light beam incident on the light incident surface 3 a travels inside the second light transmission layer 3 and reaches the flat surface 2 a or the second lens surface 6 that is an interface with the second lens surface 6.
The light beams that have reached the flat surface 2 a or the second lens surface 6 are refracted according to the difference in refractive index between the second light transmission layer 3 and the first light transmission layer 2. Since the flat surface 2a does not have refractive power, the traveling direction of the light beam only changes according to Snell's law, whereas the second lens surface 6 has refractive power and thus has a lens action. The light beam incident on the lens surface 6 is converged or diverged.
In the present embodiment, since the second lens surface 6 has a negative refractive power, the light beam that has passed through the second lens surface 6 is diverged as a divergent light beam on the lens surfaces of the first lenses 5A and 5B that constitute the light exit surface 4. To reach.

The light beam that has reached the light exit surface 4 is refracted in accordance with the incident angle by the first lenses 5A and 5B, collected within a predetermined viewing angle range, and emitted from the light exit surface 4 to the outside.
At this time, since the first lenses 5A and 5B have a concavo-convex shape including an inclined surface, even if the first lens 5A and 5B are totally reflected by one inclined surface, most of the total reflected light is transmitted from the opposing inclined surface. Thereby, compared with the case where a plane parallel to the light incident surface 3a is formed as the light emitting surface 4, the light extraction efficiency is improved.

  Since the first lens group 5 has dispersion, spectroscopy occurs according to the incident angle. However, the incident angle distribution of the light beam component transmitted through the substantially straight flat surface 2a is different from the incident angle distribution of the light beam component transmitted through the second lens surface 6 diffused by the second lens surface 6 and disturbed in the traveling direction. ing. For this reason, since each light beam component is mixed, the direction in which the color is imparted is not limited to the specific direction, so that the change in the color depending on the observation direction can be reduced or eliminated.

As described above, in the optical sheet 1, the first lens group 5 that mainly improves the light extraction efficiency and the second lens group 7 that mainly reduces or eliminates the change in color depending on the observation direction are integrated. A single sheet has a plurality of characteristic control functions.
Since the second lens group 7 is formed inside the optical sheet 1, the light incident surface 3 a is formed as a flat surface and can be bonded to the EL panel 20 and integrated with the EL panel 20. .
Therefore, unlike a conventional optical sheet in which a lens is formed on one surface and a flat surface for bonding is formed on the other surface, the optical sheet 1 is bonded to the EL panel 20 that is an adherend member. Even if integrated, the second lens group 7 is provided inside, so that good optical performance can be exhibited.
Even if an environmental load occurs, since the first lens group 5 and the second lens group 7 are integrated with the EL panel 20, optical characteristics and reliability are hardly deteriorated due to deformation of the optical sheet 1 or the like. It has become.
Therefore, the optical performance of the EL device 100 can be improved and the performance can be stabilized over time even when an environmental load is applied.

[First Modification]
Next, an optical sheet of a modified example (first modified example) of the present embodiment will be described.
FIG. 4 is a schematic cross-sectional view showing a configuration of an optical sheet of a modification (first modification) of the first embodiment of the present invention.

As shown in FIG. 4, the optical sheet 1 </ b> A of this modification is obtained by dispersing a light diffusing element 8 in the first light transmission layer 2 of the optical sheet 1 of the first embodiment. In the EL device 100 of one embodiment, the optical sheet 1 can be used instead.
Hereinafter, a description will be given centering on differences from the first embodiment.

The light diffusing element 8 is composed of minute elements that scatter light traveling inside the light transmission layer by reflection or refraction.
The first light transmission layer 2 in which the light diffusing element 8 is dispersed is a fine particle material having a refractive index difference from that of the first light transmission layer 2 in the material that becomes the first light transmission layer 2 when the first light transmission layer 2 is formed. It can be formed by adding (light diffusing fine particles) or by mixing microbubbles.
Examples of the fine particle material suitable for the light diffusing element 8 include organic particles, inorganic particles, and pigments.
Examples of organic particles include styrene resins, acrylic resins, silicone resins, urea resins, formaldehyde condensates, and the like.
Examples of inorganic particles include glass beads, silica, alumina, calcium carbonate, metal oxide, and the like.
Since the pigment pigment absorbs a specific wavelength of visible light, it may cause a slight decrease in luminance as compared with the case where no pigment is added, but is suitable for adjusting the emitted light to a desired color.
These light diffusing elements 8 may be of one type, but a plurality of types can be used in appropriate combination.
The size and blending ratio of the light diffusing element 8 can be appropriately set according to the light diffusing characteristics required for the first light transmission layer 2, but the preferred size of the light diffusing element 8 is, for example, The average particle diameter is 0.5 μm to 20 μm, and the preferable blending ratio is, for example, 1% to 40% by volume content.

According to such an optical sheet 1A, when the light beam incident on the first light transmission layer 2 from the second light transmission layer 3 travels inside the first light transmission layer 2, the light diffusing element 8 is positioned at each position. It is reflected or refracted and scattered, whereby the incident light beam is diffused. For this reason, both the light beam component transmitted through the flat surface 2 a and the light beam component transmitted through the second lens surface 6 in the thickness direction of the first light transmission layer 2 before reaching the light emitting surface 4. It spreads as it progresses. Thereby, compared with the case of the said 1st Embodiment, as a result of a light beam being diffused more, the incident angle distribution in the light-projection surface 4 will be disturbed further.
Therefore, the change in color depending on the viewing direction is further reduced as compared with the first embodiment.
Further, the diffusion of the light flux is promoted, so that the image of the light source and the image of the second lens surface 6 are difficult to be visually recognized.
Therefore, even if the lens action of the second lens surface 6 is reduced or the area ratio is reduced, the same action and effect as in the first embodiment can be provided. For this reason, manufacture of the 2nd lens surface 6 in the 1st light transmission layer 2 becomes easy.

  Further, when the first light transmission layer 2 is formed, the light diffusing element 8 is added, so that the releasability from the mother mold is improved. For this reason, molding defects can be suppressed and productivity can be improved.

[Second Modification]
Next, an optical sheet of a modified example (second modified example) of the present embodiment will be described.
FIG. 5 is a schematic cross-sectional view showing a configuration of an optical sheet of a modification (second modification) of the first embodiment of the present invention.

As shown in FIG. 5, in the optical sheet 1B of this modification, a large number of light diffusing elements 8B (light diffusing fine particles) are dispersed in the second light transmission layer 3 of the optical sheet 1 of the first embodiment. In the EL device 100 according to the first embodiment, the optical sheet 1 can be used instead.
Hereinafter, a description will be given centering on differences from the first embodiment.

  The light diffusing element 8B can employ a configuration excluding the case where the light diffusing element 8 of the first modified example is composed only of bubbles. That is, the light diffusing element 8B includes, for example, a configuration including one or more kinds of light diffusing fine particles such as organic particles, inorganic particles, and pigments, or a configuration in which air bubbles having light diffusibility are mixed. be able to.

According to such an optical sheet 1B, when the light beam incident from the second light transmission layer 3 travels inside the second light transmission layer 3, light is diffused in the light diffusing element 8B. For this reason, the light beam is diffused before reaching the flat surface 2 a or the second lens surface 6.
For this reason, the incident angle distribution of the light incident on the flat surface 2a and the second lens surface 6 is disturbed, and as a result, the degree of light diffusion of the light flux reaching the light exit surface 4 also increases.
Therefore, it is possible to further reduce the change in color depending on the viewing direction as compared to the first embodiment.
Further, since the diffusion of the light flux is promoted, the image of the light source becomes difficult to be visually recognized. Therefore, it is preferable that the image of the light source is not visually recognized.

Further, according to the optical sheet 1B, the light diffusing element 8B is mixed in the second light transmission layer 3 to be bonded to the EL panel surface layer 10, and therefore, for example, the second light transmission layer 3 is formed of an adhesive substance. Moreover, the adhesive force on the light incident surface 3a can be adjusted by the blending amount of the light diffusing element 8B. That is, since the amount of the light diffusing element 8B exposed to the light incident surface 3a increases, the surface area of the adhesive substance that contributes to the bonding is reduced, or fine irregularities are formed on the light incident surface 3a. The adhesive force on the light incident surface 3a changes.
In addition, by reducing the adhesive force of the light incident surface 3a as described above, even when the bonding position is shifted, it is possible to peel off and perform the bonding again. For this reason, the working efficiency of the bonding work is improved.

[Second Embodiment]
Next, an optical sheet according to the second embodiment of the present invention will be described.
FIG. 6 is a schematic cross-sectional view showing the configuration of the optical sheet according to the second embodiment of the present invention.

As shown in FIG. 6, the optical sheet 1 </ b> C of the present embodiment replaces the first light transmission layer 2 of the optical sheet 1 of the first embodiment with a first light transmission layer 22 (light transmission layer), the first A second light transmission layer 23 (light transmission layer) and a third light transmission layer 24 (light transmission layer) are provided. Instead of the second light transmission layer 3, a fourth light transmission layer 25 (light transmission layer) is provided.
The optical sheet 1C can be used in place of the optical sheet 1 in the EL device 100 of the first embodiment.
Hereinafter, a description will be given centering on differences from the first embodiment.

The first light transmissive layer 22, the second light transmissive layer 23, and the third light transmissive layer 24 are layered members stacked in close contact in this order, and have the same outer shape as the first light transmissive layer 2.
That is, the surface exposed to the outside of the first light transmission layer 22 is formed by the light emission surface 4 similar to the first light transmission layer 2 of the first embodiment, and faces the light emission surface 4. It is a light-transmitting layered portion having a flat surface 22a.
The second light transmission layer 23 is a light-transmitting layered portion having a constant thickness, and both end surfaces in the thickness direction are flat surfaces 23 a bonded in close contact with the flat surfaces 22 a of the first light transmission layer 22. And a flat surface 23b which is in close contact with and bonded to the third light transmission layer 24.
The third light transmission layer 24 is formed in a flat surface 24b that is in close contact with the flat surface 23b of the second light transmission layer 23 and is formed at a position facing the flat surface 24b in the first embodiment. This is a light-transmitting layered portion having the same flat surface 2 a and second lens surface 6 as the one light-transmitting layer 2.

The first light transmission layer 22, the second light transmission layer 23, and the third light transmission layer 24 may have the same refractive index, or may have two or more different refractive indexes.
However, when having two or more different refractive indexes, it is preferable to have a refractive index magnitude relationship such that light incident from the fourth light transmission layer 25 side does not cause total reflection at the mutual interface.
For example, when the refractive indexes of the first light transmission layer 22, the second light transmission layer 23, and the third light transmission layer 24 are represented by n22, n23, and n24, respectively, it is preferable that n22 ≦ n23 ≦ n24 is satisfied.

The materials used for the first light transmission layer 22, the second light transmission layer 23, and the third light transmission layer 24 can be selected from the same materials as the first light transmission layer 2 of the first embodiment. .
It is also possible to use actinic ray curable resin for the first light transmission layer 22 and the third light transmission layer 24 and a film of thermoplastic resin for the second light transmission layer 23.
Examples of materials that can be suitably used for the first light transmission layer 22 and the third light transmission layer 24 include an ultraviolet curable resin containing an acrylic resin and a thermosetting resin containing an epoxy resin. .
Examples of suitable materials for the second light transmission layer 23 include examples of synthetic resins such as polyester resins, polyolefin resins, polystyrene resins, methacrylic resins, polycarbonate resins, vinyl chloride resins, cycloolefin polymers, and composites thereof. be able to.

The fourth light transmission layer 25 is a layered portion similar to the second light transmission layer 3 of the first embodiment, and is filled in the second lens surface 6 of the third light transmission layer 24, and 3 is a light-transmitting layered portion that covers the flat surface 2a of the light-transmitting layer 24 with a substantially uniform thickness (including a uniform case).
In the fourth light transmission layer 25, the surface opposite to the flat surface 2a and the second lens surface 6 is a plane parallel to the flat surface 2a, and constitutes the light incident surface 3a of the optical sheet 1C.
The material of the fourth light transmission layer 25 is not particularly limited as long as the material has a refractive index different from that of the third light transmission layer 24. By providing the refractive index difference in this way, the second lens surface 6 functions as a refractive surface and can have a lens action.
However, in order to prevent total reflection of light from the fourth light transmission layer 25 toward the third light transmission layer 24, the refractive index of the fourth light transmission layer 25 is the refractive index of the third light transmission layer 24. Is preferably lower. In this case, since the amount of light incident on the third light transmission layer 24 from the fourth light transmission layer 25 can be increased, the light utilization efficiency as the optical sheet 1C can be improved.
The fourth light transmission layer 25 is preferably made of an adhesive substance that can adhere to the third light transmission layer 24 and the EL panel surface layer 10.
Examples of the material suitable for the fourth light transmission layer 25 include the same materials as those suitable for the second light transmission layer 3 of the first embodiment.

Regarding the manufacturing method of the optical sheet 1C having such a configuration, in the example in which the first light transmission layer 22 and the third light transmission layer 24 are made of active ray curable resin and the fourth light transmission layer 25 is made of an adhesive. explain.
First, a stacked body of the first light transmission layer 22, the second light transmission layer 23, and the third light transmission layer 24 is formed.
For this reason, a mother die having a mold surface that is obtained by reversing the uneven shape of the light emitting surface 4 and a mother die having a mold surface obtained by reversing the uneven shape composed of the flat surface 2a and the second lens surface 6 are manufactured.
Next, the second light transmission layer 23 is formed from a film member having a certain thickness, and an active ray curable resin is applied to the surface of the second light transmission layer 23 using the film member as a base material. In addition, before performing this application | coating, it is also possible to perform surface treatments, such as providing an easily bonding layer, for example, surface treatments, such as an easily bonding process and a corona treatment, to at least one surface of the 2nd light transmission layer 23. It is.
In this case, the adhesion between the first light transmission layer 22 or the third light transmission layer 24 and the second light transmission layer 23 formed on the easy adhesion layer can be improved by the easy adhesion layer.
Next, in a state where the matrix is pressed against the applied actinic radiation curable resin, for example, actinic radiation such as ultraviolet rays is irradiated to cure the actinic radiation curable resin. When the actinic radiation curable resin is cured, the mold is removed from the matrix.
Thereby, the shape of the light emitting surface 4 in which the irregular shape of the matrix is inverted, and the shapes of the flat surface 2 a and the second lens surface 6 are transferred to the actinic radiation curable resin on the second light transmission layer 23.
In this manner, a stacked body of the first light transmission layer 22, the second light transmission layer 23, and the third light transmission layer 24 can be formed.

Next, in the same manner as in the first embodiment, a material that becomes the fourth light transmission layer 25 is applied or bonded to the flat surface 2 a and the second lens surface 6 on the third light transmission layer 24. The fourth light transmission layer 25 can be formed.
Thus, the optical sheet 1C is formed. The optical sheet 1C can be bonded to the EL panel surface layer 10 of the EL panel 20 in the same manner as the optical sheet 1 of the first embodiment, whereby the EL device 100 using the optical sheet 1C can be manufactured. .

  The optical sheet 1 </ b> C is different from the optical sheet 1 of the first embodiment only in that four optical transmission layers are laminated, and the first optical sheet 1 </ b> C provided on one surface is the same as the optical sheet 1 of the first embodiment. A lens group 5 and a second lens group 7 provided inside are provided. For this reason, similarly to the optical sheet 1, even if it is bonded to and integrated with the adherend member, good optical performance can be exhibited.

[Third Modification]
Next, an optical sheet of a modified example (third modified example) of the present embodiment will be described.
FIG. 7 is a schematic cross-sectional view showing a configuration of an optical sheet of a modification (third modification) of the second embodiment of the present invention.

As shown in FIG. 7, the optical sheet 1D of the present modification is similar to the first modification in the first light transmission layer 22 and the third light transmission layer 24 of the optical sheet 1C of the second embodiment. The light diffusing element 8 is dispersed and can be used in place of the optical sheet 1 in the EL device 100 of the first embodiment.
Hereinafter, a description will be given focusing on differences from the second embodiment.

  Such an optical sheet 1D has a light diffusibility as a material that becomes the first light transmission layer 22 (third light transmission layer 24) when the first light transmission layer 22 (third light transmission layer 24) is formed. It can be manufactured in the same manner as the optical sheet 1C of the second embodiment except that a fine particle material to be the element 8 is added or minute bubbles are mixed.

According to such an optical sheet 1D, since the light diffusing element 8 is dispersed in the third light transmission layer 24 and the first light transmission layer 22, the light exit surface enters from the fourth light transmission layer 25. The light beam emitted from 4 is reflected or refracted by the light diffusing element 8 and scattered and diffused.
In the same manner as in the first modification, the incident angle distribution on the light exit surface 4 is disturbed, and the change in color depending on the viewing direction is further reduced compared to the second embodiment.
Further, the diffusion of the light flux is promoted, so that the image of the light source and the image of the second lens surface 6 are difficult to be visually recognized.
Therefore, even if the lens action of the second lens surface 6 is reduced or the area ratio is reduced, the same action and effect as in the second embodiment can be provided. For this reason, manufacture of the 2nd lens surface 6 in the 3rd light transmissive layer 24 becomes easy.

  Moreover, when the 1st light transmissive layer 22 and the 3rd light transmissive layer 24 are shape | molded, since the light diffusable element 8 is added, the mold release property from a mother mold | die improves. For this reason, molding defects can be suppressed and productivity can be improved.

[Third Embodiment]
Next, an EL device and an optical sheet according to the third embodiment of the present invention will be described.
FIG. 8 is a schematic cross-sectional view showing the configuration of the EL device according to the third embodiment of the present invention.

As shown in FIG. 8, an EL device 101 according to the present embodiment includes an optical sheet 41 according to the present embodiment, instead of the optical sheet 1 of the EL device 100 according to the first embodiment.
The optical sheet 41 is replaced with the 1st light transmissive layer 2 and the 2nd light transmissive layer 3 of the said 1st Embodiment, respectively, and the 1st light transmissive layer 42 (light transmissive layer, a resin molded product), and a 2nd light transmissive layer, respectively. The layer 43 (light transmission layer) is provided.
Hereinafter, a description will be given centering on differences from the first embodiment.

Similar to the first light transmission layer 2, the first light transmission layer 42 includes the first lens group 5 that constitutes the light emission surface 4, and instead of the second lens surface 6 that constitutes the second lens group 7, A second lens surface 46 (lens surface, second lens) for constituting a unit lens of the second lens group 47 is provided.
The 1st light transmissive layer 42 consists of a resin molded product manufactured by shape | molding the resin material similar to the 1st light transmissive layer 2 of the said 1st Embodiment.

Similar to the second lens group 7 of the first embodiment, the second lens group 47 is a lens group for diffusing a light beam incident on the first light transmission layer 42. The first light transmission layer 42 is formed by being filled with a material that becomes the second light transmission layer 43 having a refractive index different from that of the first light transmission layer 42.
The second lens surface 46 has a circular opening on the flat surface 2a, and a cross section along the thickness direction of the first light transmission layer 42 is a concave portion having a triangular shape.
The second lens surface 46 is different from the second lens surface 6 of the first embodiment only in the shape of the lens surface, and the area ratio and depth are set to appropriate values similar to those of the second lens surface 6. .

The second light transmission layer 43 fills the second lens surface 46 of the first light transmission layer 42 and covers the flat surface 2a with a substantially uniform (including uniform) thickness. It is a layered part.
In the second light transmission layer 43, the surface opposite to the flat surface 2 a and the second lens surface 46 is a plane parallel to the flat surface 2 a and constitutes the light incident surface 3 a of the optical sheet 41.

  Thus, the optical sheet 41 of the present embodiment has the second lens group 47 as the second lens group 47, whereas the optical sheet 1 of the first embodiment has the second lens group 7 which is a concave lens group. The only difference is that it has a convex conical prism lens on the light exit surface 4 side.

  According to the optical sheet 41, the first lens group 5 provided on one surface and the second lens group 47 provided inside are provided in the same manner as the optical sheet 1 of the first embodiment. For this reason, similarly to the optical sheet 1, even if it is bonded to and integrated with the adherend member, good optical performance can be exhibited.

  In the above description of each embodiment and each modification, an example in which the optical sheet has two lens groups has been described, but two or more formed inside by providing three or more light transmission layers. It is possible to form a total of three or more lens groups using these interfaces.

  In the description of each of the embodiments and the modifications described above, an example in which the second lens surface constituting the second lens group is a concave surface with respect to the light incident surface has been described. It is also possible to constitute a convex surface with respect to the incident surface.

In the description of each of the embodiments and the modifications described above, the example in which the lens cross-sectional shape of the first lens group is a prism lens having a substantially triangular shape has been described. However, the lens cross-sectional shape of the first lens group is not limited thereto. . For example, the shape of a microlens or lenticular lens in which the lens cross-sectional shape is a circle, an ellipse, or other curves can be employed.
Further, the crossing angle of the first lenses 5A and 5B is not limited to 90 degrees, and an angle of 0 degrees or more and less than 180 degrees can be adopted as necessary. Here, when the crossing angle is 0 degree, the unit lens is one-dimensionally arranged.

  In the description of each of the embodiments and the modifications, the example in which the area ratio occupied by the first lens group is 100% has been described. However, the area ratio occupied by the first lens group is the area ratio occupied by the second lens group. If it is higher than 100%, it may be less than 100%.

Hereinafter, Examples 1 to 15 corresponding to the above embodiment will be described.
[Examples 1 to 4]
Table 1 below shows the main conditions and evaluation results of Examples 1 to 4.

Examples 1 to 4 are examples in the case where the height of the second lens group 7 is fixed and the area ratio of the second lens group 7 is changed in the optical sheet 1 of the first embodiment. .
In each of Examples 1 to 4, the first light transmission layer 2 was formed by molding a polycarbonate having a refractive index of 1.58. Each of the first lenses 5A and 5B of the first light transmission layer 2 is a prism lens having an apex angle of 90 degrees, a lens width of 100 μm, and a lens height of 50 μm. The crossing angle of the first lenses 5A and 5B was 90 degrees. The first lenses 5 </ b> A and the first lenses 5 </ b> B are arranged adjacent to each other without a gap therebetween, whereby the area ratio occupied by the first lens group 5 is set to 100%.
The layer thickness from the flat surface 2a to the bottom surface of the first lens group 5 was 200 μm.
The second lens surface 6 was a hemispherical concave surface having a bottom diameter of 100 μm and a depth h6 of 50 μm.
The second light transmission layer 3 was formed by applying an acrylic adhesive having a refractive index of about 1.49 on the flat surface 2 a and the second lens surface 6. The height of the second light transmission layer 3 from the flat surface 2a was 30 μm. As a result, the second lens surface 6 is filled with the acrylic adhesive, the second lens having a hemispherical lens having a height of 50 μm from the flat surface 2a and an aspect ratio α of 0.5 as a unit lens. Group 7 was formed.
As shown in [Table 1], the area ratio of the second lens group 7 in each example is 20% in Example 1, 50% in Example 2, 80% in Example 3, and 90% in Example 4. It was. In the second lens group 7, the adjacent distance between the unit lenses is made substantially constant so that an equal area ratio can be obtained.

[Evaluation]
Evaluations of Examples 1 to 4 were performed by attaching the light incident surface 3a of each optical sheet to the EL panel surface layer 10 made of glass to manufacture the EL device 100, and then evaluating the appearance and evaluating the light extraction efficiency. And went.
Appearance evaluation evaluated whether unevenness, such as a horizontal stage at the time of application | coating of the 2nd light transmission layer 3, a stripe, foaming, can be visually recognized when the EL apparatus 100 was turned on.
In the “Appearance” column of [Table 1], “◯” (good) is shown when unevenness cannot be visually recognized, and “X” (no good) when unevenness is visible.
As a comparative example, the light extraction efficiency is evaluated by removing the second lens surface 6 to form the first light transmission layer 2 including only the flat surface 2a, and applying the second light transmission layer 3. An optical sheet having only one lens group 5 was formed.
The optical sheet of this comparative example was affixed to the EL panel 20, the light extraction efficiency used as a reference was measured, and compared with the light extraction efficiency of the optical sheets 1 of Examples 1 to 4.
In the “Efficiency” column of [Table 2], when the light extraction efficiency is improved by 2% or more compared to the comparative example, “◎” (very good) exceeds 0% compared to the comparative example, and 2% When it improved only by less than "(circle)" (good) and inferior to a comparative example, it described as "x" (no good).

  According to [Table 1], the appearance evaluations of Examples 1 to 4 were all “◯”, and the light extraction efficiency was evaluated as “◯” in Example 1, and “◎” in Examples 2 to 4. It was.

[Examples 5 to 8]
Table 2 below shows the main conditions and evaluation results of Examples 5 to 8.

Examples 5 to 8 are examples in which, in the optical sheet 1 of the first embodiment, the area ratio of the second lens group 7 is fixed to 50%, and the height of the second lens group 7 is changed. It is.
Example 5 differs from Example 2 only in that the height of the unit lens of the second lens group 7 of Example 2 is set to 10 μm.
Example 6 differs from Example 2 only in that the height of the unit lens of the second lens group 7 of Example 2 is set to 30 μm.
Example 7 is the same as Example 2 described above.
Example 8 differs from Example 2 only in that the height of the unit lens of the second lens group 7 of Example 2 is set to 80 μm.

[Evaluation]
Evaluation of Examples 5-8 performed the evaluation of light extraction efficiency similar to the above, and reliability evaluation.
In the reliability evaluation, each optical sheet was affixed to the EL panel 20 and then allowed to stand for 240 hours in an 80 ° C. environment, and then visually evaluated for appearance.
In the “Reliability” column of [Table 2], “o” (good) is described when no appearance defect occurs, and “x” (no good) when an appearance defect occurs.
When it was inferior to an example, it described as "x" (no good).

  According to [Table 2], all of the reliability evaluations of Examples 5 to 8 were “◯”. The evaluation of light extraction efficiency was “◯” for Example 5 and “「 ”for Examples 6-8.

[Examples 9 to 11]
Table 3 below shows the main conditions and evaluation results of Examples 9 to 11.

In Examples 9 to 11, when the second light transmission layer 3 is formed in the optical sheet 1 of the first embodiment, a layered body of an acrylic adhesive is formed, and the flat surface 2a and the second lens surface 6 are formed. In this embodiment, the area ratio of the second lens group 7 is fixed to 50%, and the height of the second lens group 7 is changed.
Example 9 differs from Example 2 only in the method of manufacturing the second light transmission layer 3.
Example 10 differs from Example 9 only in that the height of the unit lens of the second lens group 7 of Example 9 is set to 15 μm.
Example 11 differs from Example 9 only in that the height of the unit lens of the second lens group 7 of Example 9 is set to 20 μm.

[Evaluation]
Evaluation of Examples 9-11 performed the external appearance evaluation similar to the above, reliability evaluation, and evaluation of light extraction efficiency.
According to [Table 3], the appearance evaluation and the reliability evaluation of Examples 9 to 11 were both “◯”. The light extraction efficiency was evaluated as “◯” in Example 9 and “◎” in Examples 10 and 11.

[Examples 12 to 15]
Table 4 below shows the main conditions and evaluation results of Examples 12 to 15.

In Examples 12 to 15, when the second light transmission layer 3 is formed in the optical sheet 1 of the first embodiment, a layered body of an acrylic pressure-sensitive adhesive is formed, and the flat surface 2a and the second lens surface 6 are formed. In this embodiment, the height of the second lens group 7 is fixed to 15 μm and the area ratio of the second lens group 7 is changed.
Example 12 differs from Example 10 only in that the area ratio of the second lens group 7 of Example 10 is set to 20%.
The thirteenth embodiment is the same as the tenth embodiment.
Example 14 differs from Example 12 only in that the area ratio of the second lens group 7 of Example 12 is set to 80%.
Example 15 differs from Example 12 only in that the area ratio of the second lens group 7 of Example 12 is set to 90%.

[Evaluation]
Evaluation of Examples 12-15 performed the external appearance evaluation similar to the above, and evaluation of light extraction efficiency.
According to [Table 4], the appearance evaluations of Examples 12 to 15 were all “◯”. The evaluation of the light extraction efficiency was “◯” in Example 12 and “◎” in Examples 13-15.

  The present invention can be used to improve the light extraction efficiency from the light emitting layer when an EL element is used as a backlight, an illumination light source, electrical decoration, and a sign light source, particularly an EL element as an illumination light source. In addition, it can be used as an optical sheet that can be used in a display device and can improve the luminance and reduce a change in color depending on an observation angle.

1, 1A, 1B, 1C, 1D, 41 Optical sheet 2, 42 First light transmission layer (resin molded product)
2a, 22a, 23a, 23b, 24b Flat surfaces 3, 23, 43 Second light transmission layer (light transmission layer)
3a Light entrance surface 4 Light exit surface 5 First lens group 5A, 5B First lens (first lens, prism lens)
6, 46 Second lens surface (lens surface, second lens)
7, 47 Second lens group 8 Light diffusing element 8B Light diffusing element (light diffusing fine particles)
10 EL panel surface layer 11 Light emitting structure 20 EL panel (adhering member)
22 1st light transmission layer (light transmission layer)
24 Third light transmission layer (light transmission layer)
25 Fourth light transmission layer (light transmission layer)
100, 101 EL device

Claims (6)

An optical sheet in which a light incident surface and a light emitting surface for emitting light incident from the light incident surface to the outside are formed facing each other in the thickness direction,
A plurality of light transmission layers stacked between the light incident surface and the light emitting surface;
A first lens group in which a plurality of first lenses are arranged along one or two directions and forms at least a part of the light exit surface;
A plurality of second lenses disposed between the light incident surface and the first lens group and having a lens surface formed by an interface between two light transmission layers adjacent to each other in the thickness direction among the plurality of light transmission layers. A second lens group in which the lenses are arranged apart from each other in a direction intersecting the thickness direction,
With
When viewed from the thickness direction, the area ratio occupied by the first lens group is higher than the area ratio occupied by the second lens group.
Optical sheet. The lens surface of the second lens group is formed by a resin molded product constituting one of the two light transmission layers,
The optical sheet according to claim 1, wherein the second lens group is formed by filling the lens surface with an adhesive substance constituting the other of the two light transmission layers. The adhesive substance is
The optical sheet according to claim 2, which also serves as a bonding layer for bonding the resin molded product to an adherent member. The optical sheet according to any one of claims 1 to 3, wherein light diffusing fine particles are contained in one or more of the plurality of light transmission layers. The first lens is a prism lens,
5. The optical sheet according to claim 1, wherein the second lens is a dot-like lens in plan view having a dome-shaped lens surface. The optical sheet according to any one of claims 1 to 5,
An EL panel having the optical sheet bonded to the surface;
An EL device.

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