JP2015087707A - Optical sheet, el element, illumination device, display device, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical sheet which offers good light extraction efficiency and allows for making effective use of a portion of a light emitting-side surface.SOLUTION: An optical sheet 7A outputs light entering from one surface 7a in a thickness direction from another surface 7b in the thickness direction and includes; a plurality of unit prisms 5A, each having a light incident section 5d located opposite the surface 7a, a light exit surface 5a provided as part of the surface 7b and comprising an area, which is smaller than the light incident section 5d, for outputting light toward outside, and a sloped surface 5c which connects the light incident section 5d and the light exit surface 5a and is sloped such that an area surrounded thereby becomes smaller with a distance from the light incident section 5d; and filling sections 9 that fill gaps among the plurality of unit prisms 5A and form filling section surfaces 9c substantially aligned with the light exit surfaces 5a.

Description

  The present invention relates to an optical sheet, an EL element, a lighting device, a display device, and a liquid crystal display device.

An electroluminescence (EL) element has a structure in which a light-emitting layer containing a fluorescent organic compound is sandwiched between an anode and a cathode on a light-transmitting substrate. 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 used. Leads to light emission.
Conventionally, in these EL elements, when the light emitted from the light emitting layer is emitted from the translucent substrate, there is a problem that the light amount is lost because the light is totally reflected on the translucent substrate and is not emitted to the outside. The light extraction efficiency at this time is generally said to be about 20%. Therefore, there is a problem that the higher the luminance is, the more input power is required. In this case, the load on the element increases and the reliability of the element itself is lowered.
In order to improve the external extraction efficiency of light, a method has been proposed in which fine irregularities are formed on the surface of the substrate of the EL element, and a light component that is totally reflected when there are no irregularities is extracted to the outside. For example, it has been proposed to form a microlens array in which a plurality of microlens elements are arranged in a plane on one surface of a translucent substrate (see Patent Document 1).

JP 2002-260845 A

However, the prior art as described above has the following problems.
When the surface of the EL element is covered with a microlens array as in the technique described in Patent Document 1, the entire surface becomes a light emitting surface, which causes a problem that the surface cannot be used for other purposes.
For example, when an EL element is used for illumination, it is important to enhance the appearance design in addition to the above-described external light extraction efficiency.
In the case of giving design properties to EL elements, a method of giving design characteristics by changing the appearance by covering the EL elements with, for example, Japanese paper or an acrylic plate with a pattern is often adopted. However, in such a method, the EL element is covered with Japanese paper or a patterned acrylic plate, so that light is absorbed by the Japanese paper or acrylic plate, resulting in loss of light, resulting in light utilization efficiency. Will fall.
Thus, an EL element that can change the external appearance of the apparatus without reducing the light use efficiency of illumination light or display light has not been known so far.
Even in applications where design properties are not required, for example, it may be necessary to suppress surface reflection and reflection. In such a case, if the surface is covered with the microlens array, there is a problem that it is difficult to impart necessary reflection characteristics and light absorption characteristics to the surface without reducing the light extraction efficiency of the microlens array.
As described above, the conventional technique has a problem that the light extraction efficiency is lowered when a function other than the function of improving the light extraction efficiency is added to the surface of the EL element.

  The present invention has been made in view of the above problems, and has an optical sheet, an EL element, which has a good light extraction efficiency and can effectively use a part of the surface on the light emitting side. An object is to provide an illumination device, a display device, and a liquid crystal display device.

  In order to solve the above problem, the optical sheet according to the first aspect of the present invention is an optical sheet that emits light incident from one surface in the thickness direction from the other surface in the thickness direction, A light incident portion facing the one surface; and a light emitting surface that is provided on a part of the other surface and emits the light from a region narrower than the light incident portion. And a gap between the plurality of light guide portions, and a plurality of light guide portions inclined so that a side surface between the light entrance surface and the light exit surface is narrowed toward the light exit surface. And a filling portion that forms a surface that fills and substantially aligns with the light exit surface.

  In the optical sheet, it is preferable that a surface layer made of a material that reflects or absorbs external light is formed on the surface of the filling portion.

  In the optical sheet, it is preferable that the light guide portion is formed by arranging unit prisms having a substantially trapezoidal cross-sectional shape along the thickness direction in a one-dimensional direction or a two-dimensional direction.

  In the said optical sheet, it is preferable that the light reflectivity was provided to the side surface of the said light guide part by the said filling part.

  In the optical sheet, it is preferable that the filling portion includes a low refractive index layer in which a refractive index of at least a portion in contact with the side surface is lower than a refractive index of the light guide portion.

  In the optical sheet, it is preferable that the filling portion includes a diffuse reflection layer having light diffusibility at least in a portion in contact with the side surface.

  In the optical sheet, it is preferable that the filling portion includes a light reflection layer at least in a portion in contact with the side surface.

  In the optical sheet, it is preferable that the filling portion has light absorptivity.

  In the optical sheet, the filling portion preferably has a hollow structure.

  In the optical sheet, it is preferable that a light deflecting portion having an uneven shape for deflecting incident light is provided on the one surface.

  An EL device according to a second aspect of the present invention includes a light-emitting structure having an anode and a cathode, a light-emitting layer sandwiched between the anode and the cathode, a translucent substrate that supports the light-emitting structure, An optical sheet, and the optical sheet is bonded to the surface of the translucent substrate in a state where the one surface is directed to the surface of the translucent substrate opposite to the light emitting structure. The configuration is as follows.

  A lighting device according to a third aspect of the present invention includes the EL element as a light emitting unit.

  A display device according to a fourth aspect of the present invention includes the EL element, and a plurality of pixels that can be independently driven are formed by the light emitting structure.

  The liquid crystal display device according to the fifth aspect of the present invention has an image display element using liquid crystal and the EL element arranged on the back surface of the image display element.

  A liquid crystal display device according to a sixth aspect of the present invention is configured such that an image display element using liquid crystal and the lighting device are disposed on the back surface of the image display element.

  According to the optical sheet, the EL element, the illumination device, the display device, and the liquid crystal display device of the present invention, light is emitted between a plurality of light guide portions having a light emission surface narrower than the light incident portion and the plurality of light guide portions. Since the filling portion having the flat portion that is substantially aligned with the emission surface is provided, the light extraction efficiency is good, and an effect that a part of the surface on the light emission side can be used effectively is achieved.

It is typical sectional drawing which shows the structure of the EL element of the 1st Embodiment of this invention. It is the typical perspective view which shows the structure of the light guide layer of the optical sheet of the 1st Embodiment of this invention, and its AA sectional drawing. It is a typical perspective view, a top view, and the BB sectional view showing the composition of the light guide layer of the optical sheet of the modification (the 1st modification) of the 1st embodiment of the present invention. Schematic perspective view, plan view, and CC sectional view, DD sectional view showing the configuration of the light guide layer of the optical sheet of the modified example (second modified example) of the first embodiment of the present invention It is. It is typical sectional drawing which shows the structure of the EL element of the 2nd Embodiment of this invention. It is a typical perspective view which shows the structure of the light guide layer of the optical sheet of the 2nd 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 element 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 a configuration of an EL element according to the first embodiment of the present invention. FIG. 2A is a schematic perspective view showing the configuration of the light guide layer of the optical sheet according to the first embodiment of the present invention. FIG.2 (b) is AA sectional drawing in Fig.2 (a).
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, an EL (electroluminescence) element 101 according to this embodiment has a plurality of pixels that can emit light independently, and these pixels send image signals to a drive unit (not shown). This is a device that is pixel-driven based on a control signal such as the above, and displays an image or video or illuminates by light emission of the driven pixel.
The EL element 101 includes a first substrate 1A (translucent substrate), a second substrate 1B, a light emitting structure 100, and an optical sheet 7A.

The first substrate 1A is a translucent substrate that transmits light generated by the light emitting structure 100 described later toward an optical sheet 7A described later, and the light emitting structure 100 is in close contact with one surface. The transmittance of the first substrate 1A is preferably 50% or more.
The material of the 1st board | substrate 1A will not be specifically limited if it is the material which permeate | transmits the light generated by the light emitting structure 100 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 second substrate 1B is a plate-like or sheet-like member that is disposed to face the first substrate 1A and sandwiches the plurality of light emitting structures 100 with the first substrate 1A. It can be formed of the same material as the substrate 1A.
Moreover, it is preferable that the 2nd board | substrate 1B is provided with the light reflection layer which reflects the light which generate | occur | produced in the light emitting structure 100 toward the 1st board | substrate 1A in the surface in any thickness direction.
Further, the second substrate 1B can be formed of, for example, a metal material having light reflectivity such as aluminum. In this case, the second substrate 1B itself constitutes a light reflection layer. .

The light emitting structure 100 includes an anode 3 disposed on the surface of the first substrate 1A, a cathode 4 disposed on the surface of the second substrate 1B, and a light emitting layer 2 sandwiched between the anode 3 and the cathode 4. It consists of.
In the light emitting structure 100, the light emitting layer 2 emits light by applying a voltage to the anode 3 and the cathode 4, and various conventionally known configurations can be adopted.
In the present embodiment, since the light generated in the light emitting layer 2 is emitted to the first substrate 1A side, at least the anode 3 needs to be a translucent electrode. Examples of such translucent electrodes include ITO (indium tin oxide).
In the present embodiment, the cathode 4 can be made of any suitable metal material having good conductivity, such as aluminum, silver, copper, etc., because it does not matter whether the cathode 4 is translucent or not.

The light emitting layer 2 can be, for example, a white light emitting layer. In this case, the anode 3 is made of ITO, the cathode 4 is made of aluminum, and CuPc (copper phthalocyanine) / α-NPD is doped with 1% rubrene / dioctylanthracene is doped with 1% perylene. A configuration in which Alq3 / lithium fluoride is laminated in this order can be employed.
However, the configuration of the light emitting layer 2 is not limited to this, and an appropriate material that can set the wavelength of light emitted from the light emitting layer 2 to R (red), G (green), and B (blue) is used. Any configuration used may be employed.
When the EL element 101 is used for a full color display, for example, the light emitting layer 2 has a configuration in which three types of light emitting materials corresponding to R, G, and B are separately applied, or a color filter on a white light emitting layer. It is possible to adopt a configuration in which

  In this embodiment, since the EL element 101 is pixel driven, the light emitting structure 100 is formed corresponding to each pixel, and the anode 3 and the cathode 4 of each pixel are wired to a driving unit (not shown). Yes.

The optical sheet 7A has a surface 7a on one side in the thickness direction and a surface 7b constituting the outer surface of the EL element 101 on the other side in the thickness direction, and emits light incident from the surface 7a from the surface 7b. It is a sheet member.
In the present embodiment, the optical sheet 7A is arranged in a positional relationship in which the surface 7a faces the first substrate 1A of the light emitting structure 100, and the surface 7a is opposite to the surface where the anode 3 is arranged on the first substrate 1A. It is joined to the surface on the side via the adhesive layer 6 (joining layer).

The adhesive layer 6 can join the surface 7a of the optical sheet 7A and the first substrate 1A, and has an appropriate pressure-sensitive adhesive or adhesive (hereinafter abbreviated as “viscous / adhesive”) having light transmittance. Can be adopted.
Examples of suitable adhesive / adhesive for the adhesive layer 6 include acrylic, urethane, rubber, and silicone adhesives. In any case, since it is used adjacent to a light source having a high temperature, it is desirable that the storage elastic modulus G ′ at 100 ° C. is 1.0 × 10 ⁴ Pa or more.
If the value of the storage elastic modulus G ′ at 100 ° C. of the adhesive layer 6 is lower than 1.0 × 10 ⁴ Pa, the optical sheet 7A and the first substrate 1A may be displaced during use. If the optical sheet 7A and the first substrate 1A are greatly displaced, the light from the light emitting layer 2 is not efficiently incident on the optical sheet 7A, so that the light use efficiency is lowered.
Further, in order to stably secure the distance between the light emitting layer 2 and the optical sheet 7A, it is possible to mix light-transmitting fine particles such as beads into the adhesive / adhesive constituting the adhesive layer 6. is there. The adhesive / adhesive may be a double-sided tape or a single layer.

With such a layer structure, the light generated in the light emitting layer 2 of the light emitting structure 100 is transmitted through the anode 3, the first substrate 1A, and the adhesive layer 6, and is incident on the surface 7a of the optical sheet 7A. It is emitted to the outside from the side.
Hereinafter, a direction toward the outside along the normal direction of the surface 7b along the thickness direction of the optical sheet 7A is referred to as an irradiation direction F.

The optical sheet 7 </ b> A includes a sheet-like base material 8 having optical transparency and a light guide layer 5 provided by being laminated on the base material 8.
One surface of the substrate 8 constitutes the surface 7 a of the optical sheet 7 </ b> A, and the surface 8 b on the opposite side is a surface on which the light guide layer 5 is joined.
The surface 8b may be a flat surface or a surface having a fine uneven shape for diffusing transmitted light. In this embodiment, a flat surface is adopted as an example.

The light guide layer 5 is a light-transmitting layered portion that is generated in the light emitting layer 2, guides the light transmitted through the anode 3, the adhesive layer 6, and the base material 8 to the surface 7b side and emits the light to the outside. In the optical sheet 7A, a surface layer opposite to the surface 7a is formed.
On one end side in the thickness direction of the light guide layer 5, a bonding surface 5 b that is in close contact with the surface 8 b of the substrate 8 is formed.
As shown in FIGS. 2A and 2B, in the light guide layer 5, a plurality of unit prisms 5A (light guides) are arranged adjacent to each other on the surface opposite to the joint surface 5b. For this reason, the unit prism 5A of this embodiment is an example in the case of being arranged in a one-dimensional direction orthogonal to the extending direction.

The unit prism 5A of the present embodiment is a trapezoidal prism lens having an isosceles trapezoidal cross section extending in one direction. In the trapezoidal section, a light incident portion 5d extending along the extending direction of the unit prism 5A is formed in the lower bottom portion where the base angle is an acute angle θ (see FIG. 1), and the light incidence portion is incident on the upper bottom portion. A light emission surface 5a having a rectangular shape in plan view, which is narrower than the portion 5d, is formed.
Each of the light incident part 5d and the light emitting surface 5a has a long and narrow rectangular shape when viewed from the upper side in FIG.
The light emitting surface 5a is preferably formed into a shape having a fine uneven shape by, for example, mat processing. In this case, since the total reflection on the light emitting surface 5a is reduced as compared with the case where the light emitting surface 5a is a flat surface, the light extraction efficiency can be further improved.
However, when the light beam component totally reflected by the light emitting surface 5a is small due to the directivity of the light beam incident on the light emitting surface 5a, the surface can be made flat. In this case, when the light emission surface 5a is a flat surface, it is possible to give a glossy appearance.

In addition, a pair of inclined surfaces 5c (side surfaces) inclined so as to sag from the light incident portion 5d toward the light emitting surface 5a is formed in a portion that becomes a leg in the trapezoidal cross section.
The light incident portions 5d of the unit prisms 5A are aligned on a plane parallel to the joint surface 5b, and are adjacent to each other in the direction orthogonal to the extending direction without a gap.
The light emission surface 5a of each unit prism 5A is aligned with the surface 7b of the optical sheet 7A and constitutes a part of the surface 7b.
A groove 5e (see FIG. 2B) having a V-shaped cross section is formed between the inclined surfaces 5c of the adjacent unit prisms 5A.

The width of the light emitting surface 5a in the short direction (the length of the upper base of the trapezoidal cross section) is determined by the brightness distribution and light extraction efficiency of the emitted light from the light emitting surface 5a necessary for illumination and display, and the surface layer 10 described later. Depending on the required area, it can be set appropriately.
For example, the area ratio of the light exit surface 5a with respect to the effective light irradiation region is preferably 10% or more and 50% or less.
If the light exit surface 5a is less than 10%, the light extraction efficiency may be reduced.
If the light emission surface 5a exceeds 50%, the area that can be used as the surface layer 10 becomes narrow, so that the appearance of the appearance by the surface layer 10 is weakened, and it is difficult to form an appearance rich in design.

The inclined surface 5c is provided to guide light that is not directly incident on the light emitting surface 5a to the light emitting surface 5a by internally reflecting the light generated in the light emitting layer 2 and incident on the optical sheet 7A.
For example, as shown in FIG. 1, the light B20 incident obliquely with respect to the thickness direction of the optical sheet 7A repeats internal reflection between the pair of inclined surfaces 5c facing each other, for example, the light B21 Thus, it radiates | emits in the diagonal direction with respect to the irradiation direction F from the light-projection surface 5a.
That is, by repeating the reflection between the inclined surfaces 5c, the incident / exit angle of the light B20 with respect to the reflecting surface gradually increases while the light B20 is guided toward the light emitting surface 5a. For this reason, the traveling direction of the light B20 approaches the irradiation direction F, the light inclination with respect to the normal line of the light emitting surface 5a becomes shallow, and the light B20 is not totally reflected by the light emitting surface 5a.
Further, part of the light that is reflected by the inclined surface 5c and the light emitting surface 5a and returns to the optical sheet 7A is internally reflected within the optical sheet 7A, reenters the light incident portion 5d, and finally emits light. The light is emitted from the surface 5a.

  Thus, according to the unit prism 5A, even if the area of the light emitting surface 5a is smaller than the area of the light incident portion 5d, most of the light incident on the light incident portion 5d is emitted from the light emitting surface 5a. Therefore, a change in light extraction efficiency due to the difference in area is suppressed.

  With such a configuration, the unit prism 5A is provided in a part of the light incident part 5d facing the one surface 7a of the optical sheet 7A and the other surface 7b of the optical sheet 7A and is a region narrower than the light incident part 5d. A light exit surface 5a that emits light to the outside, and an inclined surface 5c that is a side surface between the light incident portion 5d and the light exit surface 5a is recessed from the light incident portion 5d toward the light exit surface 5a. The light guide part which inclines so that it may be comprised is comprised.

Such a base material 8 and the light guide layer 5 can be formed by molding a resin material having optical transparency.
The base material 8 and the light guide layer 5 are formed by, for example, extrusion molding using, for example, a thermoplastic resin or ultraviolet curable resin having light transmittance and a mold having a molding surface for transferring each of the above shapes. It can be produced by molding such as injection molding or UV molding.
As a method for producing a mold for forming the light guide layer 5, first, a diamond bit having various lens shapes is used on a copper plated mold to cut a substantially trapezoidal cross-sectional shape into the unit lens 5A. A corresponding molding surface is produced.

The base material 8 and the light guide layer 5 may be formed as separate bodies and then joined together or may be formed as an integrated product.
The base material 8 is a pre-manufactured film material. The light guide layer 5 is UV-molded by using a mold having a molding surface for transferring the shape of the light guide layer 5 on the surface of the film material. By doing so, it is also possible to form the light guide layer 5 in close contact with the surface of the substrate 8.

When the base material 8 and the light guide layer 5 are joined, for example, the light guide layer 5 does not adhere firmly to the base material 8 depending on the material, or the adhesive force decreases due to external influences such as cold heat and moisture absorption / desorption. There is a possibility.
In this case, a primer layer having high adhesiveness with respect to both materials may be provided between the light guide layer 5 and the base material 8, or the effect of the primer layer may be added to the light guide layer 5. Good.
Moreover, before joining the base material 8 and the light guide layer 5, at least one of the mutual joining surfaces may be subjected to easy adhesion treatment such as corona discharge treatment, for example.

As the resin material used for the base material 8 and the light guide layer 5, a resin material having light transmittance with respect to the wavelength of light emitted from the light emitting layer 2 is used. For example, a plastic material usable for an optical member is used. can do.
However, the resin material of the base material 8 and the resin material of the light guide layer 5 may be the same material or different materials. In order to prevent light incident from the substrate 8 side from causing total reflection at the bonding surface 5b, the refractive index of the material used for the light guide layer 5 is higher than the refractive index of the material used for the substrate 8. It is preferable to do so.
Examples of resin materials that can be suitably used for the base material 8 and the light guide layer 5 include polyester resin, acrylic resin, polycarbonate resin, polystyrene resin, MS (acrylic and styrene copolymer) resin, and polymethyl. Examples thereof include thermoplastic resins such as pentene resins and cycloolefin polymers, and transparent resins such as radiation curable resins composed of oligomers such as polyester acrylate, urethane acrylate, and epoxy acrylate, or acrylates.

The base material 8 and the light guide layer 5 may have a configuration in which fine particles are dispersed in the resin material.
As the fine particles to be dispersed, for example, transparent particles having light diffusibility made of an inorganic oxide or a resin can be employed.
Examples of the 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 crosslinked products thereof, melamine-formalin condensate particles, PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy resin), FEP (tetrafluoroethylene). Examples thereof include fluorine-containing polymer particles such as fluoroethylene-hexafluoropropylene copolymer), PVDF (polyfluorovinylidene), and ETFE (ethylene-tetrafluoroethylene copolymer), and silicone resin particles.
These fine particles may be used as a mixture of two or more.
Since these fine particles have light diffusibility, it is possible to adjust the viewing angle of the light emitted from the light emitting surface 5a and reduce the color depending on the observation direction.

The base material 8 and the light guide layer 5 may have a configuration in which an antistatic agent is dispersed in the resin material.
As the antistatic agent, for example, ultrafine particles such as conductive fine particles such as antimony-containing tin oxide (hereinafter referred to as ATO) and tin-containing indium oxide (ITO) can be used.
As described above, by dispersing the antistatic agent in the base material 8 and the light guide layer 5, the antifouling property of the optical sheet 7A can be improved.

When a film material is used as the substrate 8, for example, a thermoplastic resin such as cellulose triacetate, polyester, polyamide, polyimide, polypropylene, polymethylpentene, polyvinyl chloride, polyvinyl acetal, methyl polymethacrylate, polycarbonate, polyurethane, etc. A stretched or unstretched film can be used.
Although the thickness of the film material depends on the rigidity of the film material, it is preferably 50 μm to 300 μm from the viewpoint of handling such as workability.

As shown in FIG. 1, in the optical sheet 7 </ b> A, the groove portion 5 e (see FIG. 2B) of the light guide layer 5 is provided with a filling portion 9 that fills the gap between the groove portions 5 e.
The filling part 9 may fill the groove part 5e with one kind of material, or may be filled with a combination of a plurality of kinds of materials.
In the following, as an example, the filling portion 9 is in contact with the inclined surface 5c and fills the portion surrounded by the reflective layer 9a and the reflective layer 9a that imparts light reflectivity to the inclined surface 5c, and the light emitting surface 5a. And a filling part main body 9b that forms a filling part surface 9c that is substantially aligned with the filling part surface 9c.
Here, “substantially aligned” means being formed in a range of ± 1 μm with respect to the light emitting surface 5a.

The reflective layer 9a can employ an appropriate layer configuration that imparts light reflectivity to the inclined surface 5c.
For example, the reflective layer 9 a can employ a low refractive index layer having a lower refractive index than the material of the light guide layer 5. In this case, the reflectance at the inclined surface 5c can be improved by the difference in refractive index between the material of the reflective layer 9a and the material of the light guide layer 5. As the refractive index difference is larger, the reflectance can be improved.

The reflective layer 9a is, for example, a light made of a reflective film in which a light-reflective metal film such as aluminum or silver is deposited, or a multilayer reflective film in which a low refractive index material and a high refractive index material are alternately formed. It is possible to employ a reflective layer.
Thus, by forming the light reflection layer on the inclined surface 5c, specular reflection occurs on the inclined surface 5c. For this reason, light with strong directivity is emitted from the light exit surface 5a by repeating reflection on the inclined surface 5c.

Moreover, the reflection layer 9a can employ | adopt the diffuse reflection layer which consists of a white particle material which has light diffusibility. Examples of the light diffusing fine particles include barium sulfate and titanium oxide.
In this way, by forming the diffuse reflection layer on the inclined surface 5c, reflection with light diffusion occurs. For this reason, since the light flux colored according to the traveling direction is mixed by the dispersion of the base material 8, the light guide layer 5, etc., the color mixing effect is obtained.

The configuration of the filling portion main body 9b is not particularly limited as long as the groove portion 5e can be filled. For example, it is possible to adopt a configuration in which a resin material or an appropriate additive is contained in the resin material.
As the resin material, for example, all of a thermoplastic resin and an ultraviolet curable resin suitable as the base material 8 and the light guide layer 5 can be adopted.

Examples of the additive include, for example, pigments, hollow particles, bubbles and the like.
When the pigment is added, since the filling portion main body 9b has light absorptivity, light leakage from the filling portion main body 9b to the outside can be suppressed even if light leaking from the inclined surface 5c is incident.
When hollow particles or bubbles are added, air is sealed in the filling portion main body 9b and a hollow structure is formed in the filling portion main body 9b. Therefore, the heat insulation of the filling portion main body 9b can be improved.
In this case, the heat generated in the light emitting structure 100 is not easily transmitted to the surface of the optical sheet 7A, and the temperature of the surface of the EL element 101 can be reduced. For this reason, it is easy to prevent burns even if the EL element 101 can be touched by a person. For example, it is possible to increase the thickness of the optical sheet to enhance the heat insulating property, but if the heat insulating property is imparted to the filling portion main body 9b, the optical sheet 7A can be made thinner. Cost reduction can be achieved.
Further, by adding hollow particles and bubbles, the optical sheet 7A itself can be reduced in weight even when the heat insulation is not required to be improved.
Further, for such a heat insulating effect and weight reduction, the filling portion main body 9b can be formed of a foaming resin.

In the present embodiment, the surface layer 10 is formed on the filling portion surface 9c of the filling portion main body 9b.
The surface layer 10 is a layered layer that adjusts or decorates the appearance of the optical sheet 7A and the appearance of the EL element 101 when the optical sheet 7A is bonded to the EL element 101 by changing the appearance of the filling portion surface 9c. Part.
The surface layer 10 is formed by, for example, printing, transferring, applying, or the like, a material that reflects or absorbs external light.
The surface layer 10 can have a configuration including an appropriate pattern, pattern, character, symbol, or the like, or a configuration with an appropriate color.
Moreover, the surface layer 10 is not limited to the structure which is tinged with color by absorbing a specific wavelength. The surface layer 10 can change the appearance of the filling portion surface 9c by changing the surface property with or without color.
For example, the surface of the surface layer 10 can be a smooth glossy surface.
Further, the surface of the surface layer 10 can be a concavo-convex surface to be a matte surface or an antireflection surface.
Moreover, it is also possible to form the surface layer 10 as a mirror surface by making the material of the surface layer 10 into a high reflectance material. In this case, when the light emitting layer 2 is not emitting light, the surface of the EL element 101 can be used as a mirror, and the convenience of the EL element 101 is improved, which is preferable.
Moreover, when forming the surface layer 10 as an uneven surface, it is also possible to form a diffraction grating or a hologram by forming fine unevenness. In this case, external light is dispersed by the diffractive action and looks like a rainbow color, and the hue changes depending on the viewing direction, so that a beautiful appearance can be obtained.

Next, the operation of the EL element 101 will be described focusing on the operation of the optical sheet 7A.
When voltage is applied to the anode 3 and the cathode 4 of the light emitting structure 100, light is emitted from the light emitting layer 2 in various directions as shown in FIG. For example, light B100 traveling along the irradiation direction F from the light emitting layer 2 toward the anode 3, light B101 traveling in an oblique direction intersecting with the irradiation direction F, and the like are generated.
These lights B100, B101, etc. pass through the anode 3, the first substrate 1A, and the adhesive layer 6 and enter the optical sheet 7A. The light incident on the optical sheet 7 </ b> A passes through the base material 8 and enters the light guide layer 5. In these optical paths, since refraction and reflection occur at the interface of each layer according to the refractive index of each layer, the radiation angle distribution in the light emitting layer 2 gradually changes. In particular, when the base material 8 or the light guide layer 5 contains light diffusing fine particles, the light is diffused by the fine particles, so that the light traveling direction is disturbed.
In this way, light traveling in various directions reaches the light incident portion 5d of each unit prism 5A.

The light that has reached each light incident portion 5d travels straight and enters the light exit surface 5a or the inclined surface 5c.
The light (for example, light B10) directly incident on the light emitting surface 5a is transmitted according to the transmittance of the light emitting surface 5a, and the transmitted component (for example, light B11) is emitted to the outside. Since the light guide layer 5 is made of a light transmissive material, most of the light guide layer 5 is emitted to the outside.
When the incident angle with respect to the light emitting surface 5a exceeds the critical angle, total reflection occurs and the light is not emitted to the outside. However, since the unit prism 5A has a trapezoidal shape whose cross-sectional shape is narrow along the irradiation direction F, the incident angle is restricted in the direction orthogonal to the extending direction of the unit prism 5A, and the light directly enters beyond the critical angle. Does not exist or few, if any.

The light (for example, light B20) incident on the inclined surface 5c is reflected on the inclined surface 5c according to the incident angle to the inclined surface 5c and the type of the reflective layer 9a.
For example, when the reflective layer 9a is a low-refractive index layer or a light reflective layer, the reflective layer 9a is reflected toward the inclined surface 5c facing each other with a reflectance corresponding to the incident angle, and is internally formed between the pair of inclined surfaces 5c facing each other. Repeat reflection.
Since each inclined surface 5c of the unit prism 5A is inclined so as to sag along the irradiation direction F, most of the light is guided to the light emitting surface 5a and has an incident angle larger than the critical angle of the light emitting surface 5a. Is incident on the light emission surface 5a and emitted from the light emission surface 5a to the outside like, for example, light B21.
Some of the light is totally reflected by the light exit surface 5a or reflected in a direction away from the light exit surface 5a by the inclined surface 5c, and returns from the light incident part 5d to the substrate 8 side. The return light also repeats internal reflection within the optical sheet 7A. For this reason, except for some loss due to attenuation, the light is finally emitted to the outside from the light emission surface 5a.

In particular, when the light B20 is repeatedly reflected between the inclined surfaces 5c, the traveling direction of the light B20 changes toward the light emitting surface 5a side, and the incident angle with respect to the light emitting surface 5a decreases. For this reason, there is almost no total reflection at the light exit surface 5a, and the light extraction efficiency is further improved.
Also, the light extraction efficiency can be improved by increasing the reflectance of the reflective layer 9a.
Further, when the light emitting surface 5a has a concavo-convex shape such as mat processing, total reflection is less likely to occur. Further, the outgoing light beam is diffused when passing through the light emitting surface 5a, and is emitted within a range of a certain radiation angle with the irradiation direction F as the center.

  Further, when the reflection layer 9a is a diffuse reflection layer, the difference is that the incident light beam diffuses every time it is reflected by the inclined surface 5c, and the light exits from the light exit surface 5a through the same optical path. Is done. At this time, the radiation angle distribution of the emitted light beam from the light exit surface 5a can be widened as compared with the case where the reflective layer 9a is a low refractive index layer or a light reflective layer.

The optical path in the cross section orthogonal to the extending direction of the unit prism 5A has been described above. In an unillustrated cross section that intersects the light emitting surface 5a along the extending direction of the unit prism 5A, the optical sheet 7A is equivalent to a flat plate-like layer portion having a constant thickness.
For this reason, the light generated in the light emitting layer 2 is refracted at the layered interface and travels substantially straight, slightly changing the traveling direction, and reaches the light emitting surface 5a to be emitted to the outside or inside. Reflected. For this reason, the light distribution by the trapezoidal cross section of the unit prism 5A does not work, and the light distribution is different.
For this reason, in the optical sheet 7A, light having a different light distribution is emitted from the striped light emission surface 5a in the extending direction and in the direction orthogonal to the extending direction.

On the other hand, when the light emission of the light emitting structure 100 is stopped, no light is emitted from the light emitting surface 5a.
At this time, when the external light B40 strikes the EL element 101, the surface layer 10 absorbs specific wavelength light in the external light B40 or a part of the external light B40 according to the optical characteristics of the surface layer 10. Alternatively, all of the light is reflected or diffused to form the reflected light B41.
The observer can obtain an impression of the appearance of the EL element 101 according to the optical characteristics of the surface layer 10 by looking at the reflected light B41.

As described above, according to the optical sheet 7A of the present embodiment, the unit prism 5A is provided, and the filling unit 9 is provided with the light reflective reflective layer 9a. Despite the small area, the light extraction efficiency is good.
On the other hand, in the optical sheet 7A, since the filling portion 9 between the striped light emitting surfaces 5a forms the filling portion surface 9c, the surface layer 10 different from the appearance of the filling portion surface 9c is formed on the filling portion surface 9c. By providing in, the appearance of the optical sheet 7A and the EL element 101 can be adjusted or decorated. Such a surface layer 10 can be used in particular to improve the design properties of the optical sheet 7A and the EL element 101.
Since the surface layer 10 is provided without blocking the light emitted from the light emitting surface 5a, the surface of the optical sheet 7A can be effectively used while the light extraction efficiency is good.

[First Modification]
Next, an optical sheet of a modified example (first modified example) of the present embodiment will be described.
FIGS. 3A and 3B are a schematic perspective view and a plan view showing the configuration of the light guide layer of the optical sheet of the modified example (first modified example) of the first embodiment of the present invention. FIG.3 (c) is BB sectional drawing in FIG.3 (b).

As shown in FIG. 1, the optical sheet 7B of the present modification includes a unit prism 5B (light guide unit) instead of the unit prism 5A in the light guide layer 5 of the optical sheet 7A of the first embodiment.
The optical sheet 7B of this modification can be used in place of the optical sheet 7A in the EL element 101 of the first embodiment.
Hereinafter, a description will be given centering on differences from the first embodiment.

As shown in FIGS. 3A, 3B, and 3C, the unit prism 5B includes the unit prism 5A according to the first embodiment, which includes a prism lens having a trapezoidal cross section extending in one direction. In contrast, the prism lens has a regular quadrangular pyramid shape having a similar trapezoidal cross section.
The unit prisms 5B are arranged adjacent to each other in the direction orthogonal to the base at each base of the regular quadrangular pyramid. For this reason, the unit prisms 5B of this modification are examples in the case where they are arranged in a square lattice pattern in two-dimensional directions orthogonal to each other.

With such a configuration, the light emission surface 5a of the unit prism 5B has a square shape in plan view, and is arranged in a square lattice shape so as to be separated from each other in the two-dimensional direction.
The light incident part 5d of the unit prism 5B has a square shape in plan view, is aligned with a plane parallel to the joint surface 5b, and is adjacent to the light incident part 5d of the adjacent unit prism 5B without a gap.
The inclined surface 5c of the unit prism 5B has an isosceles trapezoidal shape when viewed from the side, and the base angle θ of each trapezoid has the same size as that of the first embodiment.
The groove 5e of the unit prism 5B is formed of a V-shaped groove similar to the unit prism 5A, and is different from the first embodiment in that it is formed in a lattice shape extending in two directions parallel to the arrangement direction of the unit prism 5B. .

As shown in FIG. 1, the groove part 5e is filled with the filling part 9 similarly to the said 1st Embodiment, and the surface layer 10 is formed in the filling part surface 9c.
For this reason, the surface layer 10 according to the present modification is only formed in the region on the filling portion surface 9c having a lattice-like cross structure that surrounds each light emitting surface 5a and extends in two directions. Different from the embodiment.

According to the optical sheet 7B of this modification example, since the shape of the region where the surface layer 10 can be arranged is different, the light extraction efficiency is good and the light is emitted as in the first embodiment. A part of the surface on the side to be used can be used effectively.
In this modification, since the cross-sectional shape along the arrangement direction of the unit prisms 5B is the same in both directions, the light distribution from the light exit surface 5a is also the same in each direction. For this reason, illumination light and display light having a substantially uniform luminance distribution can be obtained in the plane region.
In addition, since the light emission surfaces 5a are arranged in a two-dimensional lattice and the filling portion surface 9c has a cross structure, the arrangement of the surface layer 10 is one compared to the case of having a stripe structure as in the first embodiment. It is not limited to the direction. For this reason, the freedom degree of the formation position of the surface layer 10 improves, and it also becomes possible to form the external appearance which does not have directionality.

[Second Modification]
Next, an optical sheet of a modified example (second modified example) of the present embodiment will be described.
FIGS. 4A and 4B are a schematic perspective view and a plan view showing the configuration of the light guide layer of the optical sheet of the modification (second modification) of the first embodiment of the present invention. 4C and 4D are a CC sectional view and a DD sectional view in FIG.

As shown in FIG. 1, the optical sheet 7C of this modification includes a unit prism 5C (light guide) instead of the unit prism 5B in the light guide layer 5 of the optical sheet 7B of the first modification.
The optical sheet 7C of this modification can be used in place of the optical sheet 7A in the EL element 101 of the first embodiment.
Hereinafter, differences from the first embodiment and the first modification will be mainly described.

As shown in FIGS. 4A and 4B, the unit prism 5C has a truncated cone shape, whereas the unit prism 5B of the first modified example is a prism lens having a regular quadrangular frustum shape. The difference is that it is a prism lens.
The unit prisms 5C are arranged adjacent to each other so that the outer circumferences of the bottom surfaces of the truncated cones are in contact with each other in two directions orthogonal to each other. For this reason, the unit prisms 5C of the present modification are examples in the case where they are arranged in a square lattice pattern in two-dimensional directions orthogonal to each other, like the unit prisms 5B of the first modification.

With such a configuration, the light emission surfaces 5a of the unit prisms 5C are circular in plan view, and are arranged in a square lattice pattern so as to be separated from each other in the two-dimensional direction.
The light incident portion 5d of the unit prism 5C has a circular shape in plan view, is aligned with a plane parallel to the joint surface 5b, is in contact with the adjacent unit prisms 5C in the arrangement direction, and is adjacent to the diagonal in the diagonal direction. Are arranged so as to be separated from each other.
Therefore, as shown in FIG. 4B, a flat surface 5g is formed between the four adjacent unit prisms 5C at a position aligned with the joint surface 5b.
The inclined surface 5c of the unit prism 5C is formed of a conical surface, and the cross-sectional shape including the central axis of the truncated cone has an isosceles trapezoidal shape, and the base angle θ of each trapezoid is the same as that of the first embodiment. Have the same size.
As shown in FIG. 4C, the groove 5e of the unit prism 5C includes a V-shaped groove similar to that of the unit prism 5B of the first modification, as shown in FIG. 4C. In the diagonal cross section, as shown in FIG. 4D, the flat surface 5g is a groove bottom, and the trapezoidal groove expands toward the light emitting surface 5a.

As shown in FIG. 1, the groove portion 5e of the unit prism 5C is filled with the filling portion 9 in the same manner as in the first modification, and the surface layer 10 is formed on the filling portion surface 9c.
Since the groove 5e of the unit prism 5C has a flat surface 5g at the groove bottom, the illustration is omitted, but the reflective layer 9a is also formed on the flat surface 5g, like the inclined surface 5c.

The optical sheet 7C of the present modification is different from the first modification in that the shape of the light guide is different and the flat surface 5g is provided in the diagonal direction of the light guide.
Therefore, the light transmitted through the substrate 8 enters the light incident part 5d or enters the flat surface 5g.
When the light is incident on the light incident portion 5d, the shape of the cross section including the central axis of the unit prism 5C is a trapezoidal cross section similar to the unit prism 5B of the first modified example. Finally, the light is emitted to the outside through the light emitting surface 5a.
When the light is incident on the flat surface 5g, the reflective surface 9a similar to the inclined surface 5c is formed on the flat surface 5g. Therefore, the incident light is reflected and internally reflected in the optical sheet 7C, and then the light incident portion. It will be incident on 5d. For this reason, except for some loss due to attenuation, the light is finally emitted to the outside from the light emission surface 5a.

For this reason, a good light extraction efficiency can be obtained in substantially the same manner as in the first modification.
Further, since the filling portion surface 9c surrounds the circular light emitting surface 5a and is formed between the light emitting surfaces 5a, the surface layer 10 can be arranged in a region substantially similar to the first modification. is there. Therefore, the optical sheet 7C has good light extraction efficiency and can effectively use a part of the surface on the light emitting side, as in the first modification.
Further, since the unit prism 5C has a rotationally symmetric shape, the anisotropy of the light distribution is further reduced as compared with the unit prism 5B of the first modified example. For this reason, the light distribution of the emitted light from the light emitting surface 5a becomes a uniform distribution around the central axis of the truncated cone. Thereby, illumination light and display light having a substantially uniform luminance distribution can be obtained in the plane region.
Also in the present modified example, since the light emitting surfaces 5a are arranged in a two-dimensional lattice and the filling portion surface 9c has a cross structure, the arrangement of the surface layer 10 is unidirectional as in the first modified example. Without being limited, the degree of freedom of the formation position of the surface layer 10 is improved, and it is possible to form an appearance having no directionality.

[Second Embodiment]
Next, the optical sheet and EL element of the 2nd Embodiment of this invention are demonstrated.
FIG. 5 is a schematic cross-sectional view showing the configuration of the EL element according to the second embodiment of the present invention. FIG. 6 is a schematic perspective view showing the configuration of the light guide layer of the optical sheet according to the second embodiment of the present invention.

As shown in FIG. 5, the EL element 102 of this embodiment includes an optical sheet 7D of this embodiment instead of the optical sheet 7A of the EL element 101 of the first embodiment.
The optical sheet 7D is obtained by adding a light deflection unit 11 to the optical sheet 7A of the first embodiment.
Hereinafter, a description will be given centering on differences from the first embodiment.

The light deflection unit 11 deflects light generated in the light emitting layer 2 and traveling in an oblique direction to reach the adhesive layer 6, and forms a direction along the irradiation direction F or a shallower angle with respect to the irradiation direction F. Is provided on the surface 7a.
The light deflection unit 11 can adopt an appropriate uneven shape having a light deflection action. For example, a configuration of a lens array in which a plurality of unit lenses having a dome-shaped uneven surface are two-dimensionally arranged, and a lenticular lens having a dome-shaped uneven surface extended in one direction intersects the extending direction as a unit lens For example, a configuration in which a prism lens having a triangular cross section extended in one direction is used as a unit lens, and a configuration in which the prism lens is arranged in a direction crossing the extending direction can be employed. These unit lenses may be arranged apart from each other, or may be arranged adjacent to each other without a gap.

In this embodiment, as shown in FIG. 6, as an example of the light deflection unit 11, an arc-shaped or elliptical arc-shaped cross section that protrudes from the surface 7 a of the base material 8 toward the adhesive layer 6 is extended in one direction. A configuration is adopted in which a plurality of lenticular lenses are spaced apart in a direction orthogonal to the extending direction.
In FIG. 6, the extending direction of the light deflecting unit 11 is made to coincide with the extending direction of the unit prism 5 </ b> A, but may be arranged so as to intersect the extending direction of the unit prism 5 </ b> A.
The light deflection unit 11 may be formed by integral molding when the base material 8 is molded, or may be molded or transferred onto the surface 7a of the base material 8 formed in a film shape. is there.
The material of the light deflection unit can be appropriately selected from the resin materials having light permeability suitable for the base material 8 described above.

According to the EL element 102 having such a configuration, as shown in FIG. 5, for example, the adhesive layer 6 is irradiated with light (for example, light B <b> 101) emitted from the light emitting layer 2 with a large inclination with respect to the irradiation direction F. The light B30 incident at a large incident angle reaches.
When such light B30 is incident on the light deflection unit 11, it is refracted by the light deflection unit 11 and travels at a shallower angle with respect to the direction along the irradiation direction F or the irradiation direction F like the light B31. . For this reason, for example, when the light B31 reaches the inclined surface 5c, the incident angle is large. Therefore, after the light B31 is reflected by the inclined surface 5c, the incident angle with respect to the light emitting surface 5a becomes small. The light is emitted from the surface 5a.
Even when the light B31 directly enters the light emitting surface 5a, the light B31 travels at a shallower angle with respect to the direction of the irradiation direction F or the irradiation direction F, so that the incident angle with respect to the light emitting surface 5a is also reduced. .
In this way, in any case, the light deflected by the light deflecting unit 11 has a smaller incident angle on the light emitting surface 5a than when the light deflecting unit 11 is not provided on the light emitting surface 5a. For this reason, the light exit surface 5a can be efficiently transmitted.
For this reason, light extraction efficiency can be improved.

In the above description of each embodiment and each modification, an example in which the optical sheet includes the base material 8 and the light guide layer 5 has been described. However, the refractive indexes of the base material 8 and the light guide layer 5 are as follows. Since they may be the same, the optical sheet may be integrally formed with a single material. When the optical deflection unit 11 is provided as in the second embodiment, the optical deflection unit 11 can also be formed by integral molding.
Further, when the optical sheet is composed of the base material 8 and the light guide layer 5, a configuration in which the unit prism is directly formed on the base material 8 and the light incident part is formed on the joint surface with the base material 8 is also possible. is there.

  In the description of each of the embodiments and the modifications described above, an example in which the filling portion 9 includes the filling portion main body 9b and the reflective layer 9a has been described. However, the filling portion main body 9b is formed of the same material as the reflective layer 9a. Thus, it is possible to have a configuration that does not have a boundary between the filling portion main body 9b and the reflective layer 9a.

In the description of each of the above embodiments and each modification, the example in which the cross-sectional shape of the unit lens of the light guide unit is an isosceles trapezoid has been described. The shape of the surface 5c) may be any shape as long as it is inclined so as to sag from the light incident portion 5d toward the light emitting surface 5a, and the cross-sectional shape is not limited to an isosceles trapezoid.
For example, a trapezoid other than an isosceles trapezoid, or a substantially trapezoidal shape with curved leg portions and upper base can be employed.
For example, when the leg portion has a curved shape, the inclination angle of the leg portion gradually increases from θ as it goes from the light incident portion 5d to the light emitting surface 5a, and is a concave curve that becomes maximum in the vicinity of the light emitting surface 5a. Shape can be adopted.
In this case, since the inclination increases as the light is reflected at a position closer to the light exit surface 5a, the effect of increasing the exit angle becomes significant. Thereby, since the incident angle with respect to the light-projection surface 5a can be made smaller, light extraction efficiency improves.
At this time, since the area of the light incident part 5d can be increased as compared with the case where the base angle θ is constant and is similarly large, the area ratio of the light emitting surface 5a with respect to the light incident part 5d is further reduced. be able to. Thereby, since the area of the filling part surface 9c can be increased, the area of the surface layer 10 can be increased.

  In the description of each of the embodiments and the modifications described above, the example in which the surface layer 10 is formed on the entire filling portion surface 9c has been described. However, the surface layer 10 is partially formed on the filling portion surface 9c. Alternatively, when there is no need to change the appearance of the filling portion surface 9c, the surface layer 10 can be deleted.

In the description of the first modification, the example in which the unit prism 5B has a regular quadrangular pyramid shape has been described. However, the light incident portion 5d and the light emission surface 5a may have a rectangular quadrangular pyramid shape other than a square shape. In addition, the base angle of the trapezoid in the cross section in two directions can be set to different sizes.
In this case, since the cross-sectional shape differs depending on the arrangement direction, anisotropy can be imparted to the light distribution of the emitted light from the light emitting surface 5a and the area of the filling portion surface 9c.

In the description of the first and second modified examples, the case where the unit lenses constituting the light guide unit are arranged in a square lattice shape has been described. However, the arrangement form of the unit lenses is not limited to this.
For example, a triangular lattice arrangement is also possible. For example, when the triangular lattice arrangement is employed in the second modification, a denser arrangement than the square lattice arrangement is possible. For this reason, while being able to make the space | interval of the adjacent unit prism 5B into an equal space | interval, the area of the flat surface 5g can be reduced more.

  In the description of the first and second modified examples, the case where the unit lens has a quadrangular pyramid shape and a truncated cone shape has been described. However, the shape of the unit lens is not limited to this, for example, other than the quadrangular pyramid shape. A polygonal frustum or an elliptical frustum is possible.

In the description of each of the above embodiments and each modification, an example in which adjacent unit lenses are adjacent to each other in the unit lens constituting the light guide unit has been described, but a configuration in which adjacent unit lenses are separated is also possible. is there.
In this case, the separation distance is not necessarily constant and can be changed as appropriate. For example, the separation distance may be changed depending on the arrangement location, and the arrangement of the unit lenses may be increased or decreased. In this case, since the distribution of illumination light and display light and the area ratio of the filling portion surface 9c can be changed, a more varied appearance can be formed.

In the description of each of the above-described embodiments and modifications, the example has been described in which the filling portion 9 includes the reflective layer 9a between the inclined surface 5c, but it is not essential to include the reflective layer 9a.
For example, when there is a margin in the light amount of the light emitting structure 100 and the light extraction efficiency can be reduced, a light absorbing layer is provided instead of the reflective layer 9a, or the reflective layer 9a is deleted to fill the filling body 9b. May be made of a light-absorbing material.
In this case, since the reflection on the inclined surface 5c is suppressed, the radiation angle distribution of the emitted light from the light emitting surface 5a can be reduced.

In the above description of each embodiment and each modification, an example in which an optical sheet is used as an EL element has been described. However, an illumination device can be configured using an EL element including the optical sheet of the present invention as a light emitting unit. It is.
In addition, a display device including such an EL element and including a plurality of pixels that can be driven independently can be formed using a light-emitting structure of the EL element.
Further, it is possible to constitute an image display element using liquid crystal and a liquid crystal display device in which the EL element of the present invention is disposed on the back surface of the image display element.

Moreover, all the components described above can be implemented by appropriately changing or deleting the combination within the scope of the technical idea of the present invention.
For example, the light deflection unit 11 in the second embodiment can be added to the optical sheets 7A, 7B, and 7C.

  The EL element of the present invention, and a lighting device, a display device, and a liquid crystal display device using the EL element may be used in the lighting field, display field, and the like.

1A First substrate (translucent substrate)
2 Light emitting layer 3 Anode 4 Cathode 5 Light guide layer 5a Light exit surface 5A, 5B, 5C Unit prism (light guide part)
5c Inclined surface (side surface)
5d Light incident part 5e Groove part 5g Flat surface 6 Adhesive layer 7A, 7B, 7C, 7D Optical sheet 7a, 7b Surface 8 Base material 9 Filling part 9a Reflective layer 9b Filling part main body 9c Filling part surface 10 Surface layer 11 Light deflection part 100 Light emitting structure 101, 102 EL element B40 Outside light F Irradiation direction

Claims (15)

An optical sheet that emits light incident from one surface in the thickness direction from the other surface in the thickness direction,
A light incident portion facing the one surface; and a light emitting surface that is provided on a part of the other surface and emits the light from a region narrower than the light incident portion. And a plurality of light guide portions inclined so that a side surface between the light incident surface and the light emitting surface is narrowed from the light incident portion toward the light emitting surface;
A filling portion that fills the gaps between the plurality of light guide portions and forms a surface that is substantially aligned with the light exit surface;
An optical sheet comprising: The optical sheet according to claim 1, wherein a surface layer made of a material that reflects or absorbs external light is formed on the surface of the filling portion. The light guide is
3. The optical sheet according to claim 1, wherein unit prisms having a substantially trapezoidal cross-sectional shape along the thickness direction are arranged in a one-dimensional direction or a two-dimensional direction. The side surface of the light guide is
The optical sheet according to claim 1, wherein light reflectivity is imparted by the filling portion. The filling part is
The optical sheet according to claim 4, further comprising a low refractive index layer having a refractive index of at least a portion in contact with the side surface lower than a refractive index of the light guide unit. The filling part is
The optical sheet according to claim 4, further comprising a diffuse reflection layer having light diffusibility at least at a portion in contact with the side surface. The filling part is
The optical sheet according to claim 4, further comprising a light reflecting layer at least at a portion in contact with the side surface. The filling part is
It has a light absorptivity, The optical sheet of any one of Claims 1-3 characterized by the above-mentioned. The filling part is
The optical sheet according to any one of claims 1 to 8, wherein a hollow structure is formed. The optical sheet according to any one of claims 1 to 9, wherein a light deflecting portion having an uneven shape for deflecting incident light is provided on the one surface. A light emitting structure having an anode and a cathode, and a light emitting layer sandwiched between the anode and the cathode;
A translucent substrate that supports the light emitting structure;
The optical sheet according to any one of claims 1 to 10,
With
The optical sheet is
The EL element, wherein the one surface is bonded to the surface of the light transmitting substrate in a state where the surface is directed to the surface of the light transmitting substrate opposite to the light emitting structure.   A lighting device comprising the EL element according to claim 11 as a light emitting means. An EL element according to claim 11 is provided,
A display device in which a plurality of independently drivable pixels are formed by the light emitting structure. An image display element using liquid crystal;
The liquid crystal display device by which the EL element of Claim 11 is arrange | positioned on the back surface of the said image display element. An image display element using liquid crystal;
The liquid crystal display device by which the illuminating device of Claim 12 is arrange | positioned on the back surface of the said image display element.

Images