JP5850125B2 - Surface light source device, lighting apparatus and backlight device - Google Patents

Description

  The present invention relates to a surface light source device, and a lighting fixture and a backlight device including the surface light source device.

  The light emitter of the organic electroluminescence element (hereinafter sometimes referred to as “organic EL element”) can have a planar shape, and the color of the light is white or a color close thereto. Therefore, it can be used as a light source of a lighting fixture that illuminates a space such as a living environment or as a backlight of a display device.

  As an example of an organic EL element used for illumination, a white organic EL element is produced. Many of such white elements are laminated layers or light-emitting layers that generate a luminescent color having a complementary color relationship, which are referred to as a laminated type or a tandem type. These light emitting layer laminates are mainly yellow / blue or green / blue / red laminates.

  However, currently known organic EL elements are low in efficiency for use in the above-described illumination applications. Therefore, when the organic EL element is used as a surface light source, it is required to increase its light extraction efficiency. For example, although the light emitting layer itself of the organic EL element has high luminous efficiency, the light amount is reduced due to interference or the like in the layer before it emits light through the laminated structure constituting the element. Such light loss is required to be reduced as much as possible.

  As a method for improving the light extraction efficiency of the organic EL element, it is known to provide various structures on the light extraction substrate. For example, it has been proposed to provide a prism containing a fluorescent compound on the light exit surface of the light source device (Patent Document 1), and to provide a microlens array (Patent Document 2). With these structures, good light collection can be achieved and efficiency is improved. As a means for increasing the light extraction efficiency, for example, Patent Document 3 discloses that a light diffusion medium is provided on the light emission side of the organic EL element to increase the overall luminance.

Japanese Patent Application Laid-Open No. 2002-237381 JP 2003-59641 A JP 2006-528825 A (International Publication No. 2005-18010)

  By the way, as a result of intensive studies by the present inventor, when an organic EL element is used as a surface light source device, in addition to the aforementioned problem of improving the light extraction efficiency, a change in color (color unevenness) due to an observation angle is reduced. Is known to exist as another issue. That is, if the light spectrum changes between when the light exit surface of the surface light source device is observed from the front direction (normal direction of the light exit surface) and when viewed from an oblique direction intersecting the front direction, the color depending on the observation angle This is a problem that the taste changes and is not necessarily suitable as a light source. Note that a certain direction intersecting with another direction means that the certain direction and the other direction are not parallel.

  Such color unevenness also occurs when the structures described in Patent Documents 1 and 2 are employed in the above-described laminated organic EL element for illumination. In this case, the color unevenness is observed when the light emitting surface is observed from the front and from an angle inclined from the front because the depth from the light emitting surface to the light emitting layer differs depending on the light emitting layer of each color. In this case, it is observed as a phenomenon in which the color is greatly different.

  Such a problem of color unevenness can also be improved by the technique of Patent Document 3. However, in this case, the diffusion performance must be greatly increased. Therefore, for example, it is necessary to increase the amount of the diffusing agent to be added. In this case, it is necessary to increase the thickness of the diffusion layer as much as possible, resulting in problems such as inferior productivity due to defects such as bending of the product, and inability to contribute to thinning (miniaturization) of the device.

  Furthermore, when the structure described in Patent Documents 1 and 2 is adopted for a laminated type organic EL element for illumination, and a light-emitting surface of a light source device is provided with a concavo-convex structure such as a prism, the top of the concavo-convex structure is likely to be chipped. There is a problem that it is difficult to increase the mechanical strength.

  The present invention has been made in view of the above, and a first object of the present invention is a surface light source device having high light extraction efficiency, little change in color depending on the observation angle, and high mechanical strength, It is providing a lighting fixture and a backlight apparatus.

  A second object of the present invention is a surface light source device that is excellent in productivity, can contribute to downsizing of the device, and can suppress a change in color depending on an observation angle, and uses this surface light source device. It is providing the lighting fixture and the backlight apparatus using this surface light source device.

  The inventors of the present invention have made extensive studies to solve the above problems. And it discovered that the 1st objective could be achieved by making the light emission surface of a surface light source device into a specific structure, and providing a diffusion member in a surface light source device. Based on this finding, the inventors have completed the first invention.

  Moreover, this inventor discovered that a 2nd objective could be achieved by providing a spreading | diffusion part and a light distribution distribution conversion part collectively. Based on this finding, the present invention has been completed.

That is, according to the first present invention, the following [1] to [10], [21] and [22] are provided.
[1] A surface light source device comprising: an organic electroluminescent element including a light emitting layer; and a light emitting surface structure layer provided in contact with at least one surface of the organic electroluminescent element,
The light-emitting surface structure layer has an uneven structure on the surface of the device light-emitting surface side,
The concavo-convex structure has a plurality of concave portions including slopes, and a flat portion located around each concave portion,
The surface light source device includes a diffusing member that receives light emitted from the light emitting layer and diffuses or transmits or reflects the incident light.
The surface light source device, the diffusion member,
A surface light source provided as a member constituting at least one of a layer constituting part or all of the light exit surface structure layer and a layer provided farther from the light exit surface structure layer than the organic electroluminescence element. apparatus.
[2] The surface light source device, wherein the diffusing member is a member provided as a layer constituting part or all of the light exit surface structure layer, and is a member that transmits incident light in a diffused manner.
[3] The surface light source device, wherein the diffusion member is an adhesive layer interposed between two layers of the light exit surface structure layer.
[4] The light-emitting surface structure layer includes:
A substrate provided in contact with the organic electroluminescence element;
A concavo-convex structure layer provided at a position closer to the device light exit surface than the substrate, the concavo-convex structure layer having the concavo-convex structure on a surface closer to the device light exit surface;
An adhesive layer for adhering the substrate and the concavo-convex structure layer,
The surface light source device includes the adhesive layer as the diffusion member.
[5] The surface light source device, wherein the diffusing member is made of a material containing particles that impart light diffusibility.
[6] The surface light source device, wherein the diffusion member is a member provided at a position farther from the light-emitting surface structure layer than the organic electroluminescence element, and reflects incident light in a diffused manner. .
[7] The ratio of the area occupied by the flat portion to the total area occupied by the flat portion and the area occupied by the recess when the concavo-convex structure is observed from a direction perpendicular to the device light exit surface is 10 to 10%. 75% of the surface light source device.
[8] The concave portion has a pyramid shape, a conical shape, a partial spherical shape, or a combination thereof.
The plurality of recesses are arranged on the device light exit surface along two or more directions intersecting each other,
Between the said recessed parts adjacent, the clearance gap is provided in any direction of the said 2 or more direction, The said surface light source device with which the said clearance gap comprises the said flat part.
[9] The concave portion has a pyramid shape, a cone shape, a partial spherical shape, or a combination thereof,
The plurality of recesses are arranged on the device light exit surface along two or more directions intersecting each other,
The surface light source device, wherein a gap is provided only in one of the two or more directions between the adjacent recesses, and the gap constitutes the flat portion.
[10] The concave portion has a groove shape,
The plurality of recesses are arranged in parallel on the device light exit surface,
The said surface light source device with which a clearance gap is provided between the said adjacent recessed parts, and the said clearance gap comprises the said flat part.
[21] A lighting fixture including the surface light source device according to any one of [1] to [10].
[22] A backlight device including the surface light source device according to any one of [1] to [10].

The second invention provides the following inventions.
(11) An organic electroluminescent element including a first electrode layer, a light emitting layer, and a second electrode layer in this order, and disposed in contact with at least one surface of the organic electroluminescent element, and emits light to the outside. A light-emitting side member having a light-exiting surface, wherein the light-emitting-side member has a light distribution distribution of light emitted from the organic electroluminescence element, and a normal direction of the light-exiting surface from the light-exiting surface. A light distribution distribution converter that converts the chromaticity of the light emitted along the light source and the chromaticity of the light emitted from the light emitting surface along an oblique direction intersecting the normal direction, A surface light source device comprising: a diffusion unit that diffuses light emitted from the organic electroluminescence element.
(12) The surface light source device, wherein the diffusing unit is a layer formed of a composition including particles that are disposed between the light distribution distribution converting unit and the organic electroluminescence element and impart light diffusibility.
(13) The said surface light source device which is a layer comprised by the composition in which the said spreading | diffusion part is provided in the light emission side of the said light distribution distribution conversion part, and provides the light diffusibility.
(14) The surface light source device, wherein the light distribution distribution conversion unit includes an uneven structure layer having an uneven structure formed on a surface thereof.
(15) The surface light source device, wherein the concavo-convex structure layer is composed of a composition containing particles that impart light diffusibility, and also serves as the diffusion portion.
(16) The surface light source device including the light source distribution conversion unit, and a concavo-convex structure layer provided on a surface of the base material and having a concavo-convex structure formed on a surface opposite to the base material. .
(17) The surface light source device, wherein the base material and / or the concavo-convex structure layer is composed of a composition containing particles that impart light diffusibility, and also serves as the diffusion portion.
(18) The surface light source device, wherein the light distribution distribution conversion unit includes a base film and a selective reflection layer provided on at least one surface of the base film.
(19) The surface light source device, wherein the selective reflection layer includes a layer containing a resin having cholesteric regularity.
(20) The said surface light source device with which the said base film is comprised with the composition containing the particle | grains which provide light diffusibility, and serves also as the said diffusion part.
(21) A lighting fixture comprising the surface light source device.
(22) A backlight device including the surface light source device.

The surface light source device of the first aspect of the present invention has high light extraction efficiency, little change in color depending on the observation angle, and high mechanical strength of the light exit surface of the device. It is useful as a backlight of a display device.
Since the lighting apparatus and the backlight device of the first aspect of the present invention have the surface light source device of the first aspect of the present invention, the light extraction efficiency is high, the change in color depending on the observation angle is small, and the mechanical strength is high. It can be set as a lighting fixture and a backlight apparatus.

  The surface light source device according to the second aspect of the present invention is superior in productivity because defects such as bending do not occur in the product, can contribute to downsizing of the device, and can suppress a change in color due to an observation angle. effective. Moreover, since it is a surface light source device which has such an effect, it is useful as the light source of a lighting fixture, the backlight apparatus of a liquid crystal display device, etc.

FIG. 1 is a perspective view schematically showing a surface light source device according to Embodiment 1-1. FIG. 2 is a cross-sectional view showing a cross section of the surface light source device shown in FIG. 1 cut along a plane passing through line 1a-1b in FIG. 1 and perpendicular to the device light exit surface. FIG. 3 is an enlarged partial top view showing the structure of the device light exit surface 10U of the surface light source device 10 shown in FIG. FIG. 4 is a partial cross-sectional view showing a cross section of the concavo-convex structure layer 111 shown in FIG. 3 cut along a vertical plane passing through the line 10a of FIG. FIG. 5 is a partial cross-sectional view showing a modification of the recess shown in FIG. FIG. 6 is a partial cross-sectional view showing another modification of the recess shown in FIG. FIG. 7 is a top view schematically showing the surface light source device according to Embodiment 1-2. FIG. 8 is a cross-sectional view showing a cross section of the surface light source device shown in FIG. 7 cut along a plane passing through line 2a in FIG. 7 and perpendicular to the device light output surface. FIG. 9 is a perspective view schematically showing the surface light source device according to Embodiment 1-3. FIG. 10 is a top view schematically showing the surface light source device according to Embodiment 1-4. FIG. 11 is a cross-sectional view showing a cross section of the surface light source device shown in FIG. 10 cut along a plane that passes through the line 3a in FIG. 10 and is perpendicular to the device light output surface. FIG. 12 is a cross-sectional view showing a cross section of the surface light source device according to Embodiment 1-5 cut along a plane perpendicular to the device light output surface. FIG. 13 is a top view schematically showing the surface light source device according to Embodiment 1-6. FIG. 14 is a cross-sectional view showing a cross section of the surface light source device shown in FIG. 13 cut along a plane passing through line 4a in FIG. 13 and perpendicular to the light output surface of the device. FIG. 15 is a top view schematically showing a concavo-convex structure layer according to a modification of Embodiment 1-6. FIG. 16 is a top view schematically showing the surface light source device according to Embodiment 1-7. 17 is a cross-sectional view showing a cross section obtained by cutting the surface light source device shown in FIG. 16 along a plane passing through a line 11a-11b in FIG. FIG. 18 is a cross-sectional view schematically showing a cross section of the surface light source device according to Embodiment 1-8 cut along a plane perpendicular to the device light output surface. FIG. 19 is a longitudinal sectional view for explaining a surface light source device according to Embodiment 2-1. FIG. 20 is a longitudinal sectional view for explaining a surface light source device according to Embodiment 2-2. FIG. 21 is a graph showing a spectrum of a light emitting layer used in the surface light source device. FIG. 22 is a graph showing the selective reflection characteristics of the selective reflection layer used in the surface light source device according to Embodiment 2-2. FIG. 23 is a graph showing a light distribution of the surface light source device used for comparison with the surface light source device according to Embodiment 2-2. FIG. 24 is a graph showing a light distribution of the surface light source device used for comparison with the surface light source device according to Embodiment 2-2. FIG. 25 is a graph showing a light distribution of the surface light source device according to Embodiment 2-2. FIG. 26 is a longitudinal sectional view for explaining a surface light source device according to an embodiment of the second invention. FIG. 27 is a longitudinal sectional view for explaining a surface light source device according to an embodiment of the second invention. FIG. 28 is a graph showing the relationship between the measurement angle of chromaticity and the chromaticity x and y values according to the measurement result of Comparative Example 1-1. FIG. 29 is a graph showing the relationship between the measurement angle of chromaticity and the chromaticity x and y values according to the measurement result of Example 1-1. FIG. 30 is a graph showing the relationship between the measurement angle of chromaticity and the chromaticity x and y values according to the measurement result of Example 1-2. FIG. 31 is a graph showing the relationship between the flat portion ratio and the load according to the measurement result of Reference Example 1-1.

[I. Description of First Invention]
Hereinafter, although an embodiment, an example thing, etc. are shown and explained in detail about the 1st present invention, the 1st present invention is not limited to an embodiment and an example shown below.

<Embodiment 1-1>
Hereinafter, the first aspect of the present invention will be described in more detail with reference to the drawings.
The surface light source device according to the first aspect of the present invention is provided in contact with at least one surface of an organic EL element including a light emitting layer and the organic EL element, and a light emitting surface structure that defines a concavo-convex structure on the surface on the device light emitting surface side. With layers.
The device light exit surface is a light exit surface as a surface light source device, that is, a light exit surface when light exits from the surface light source device to the outside of the device. The device light exit surface is a surface parallel to the light emitting layer of the organic EL element, and is parallel to the main surface of the surface light source device. However, when viewed microscopically, the surface on the concave portion described later can form an angle non-parallel to the light emitting layer. In the following, unless otherwise noted, being parallel (or perpendicular) to the device exit surface viewed ignoring such recess is simply referred to as “parallel (or perpendicular) to the device exit surface”. Unless otherwise specified, the surface light source device will be described in a state where the device light-emitting surface is placed so as to be parallel to the horizontal direction and upward.
In the first aspect of the present invention, the fact that each component is “parallel” or “perpendicular” may include an error within a range that does not impair the effects of the first aspect of the present invention. May include an error of ± 5 °.

  Embodiment 1-1 is a first embodiment according to the first aspect of the present invention. FIG. 1 is a perspective view schematically showing a surface light source device according to Embodiment 1-1. In Embodiment 1-1, the surface light source device 10 is a device having a rectangular plate-like structure having a device light exit surface 10U. FIG. 2 is a cross-sectional view showing a cross section of the surface light source device 10 shown in FIG. 1 cut along a plane passing through a line 1a-1b in FIG.

  The surface light source device 10 includes an organic EL element 140 and a light-emitting surface structure layer 100 provided in contact with the surface 144 of the organic EL element 140 on the device light-emitting surface 10U side. The surface light source device 10 further includes a sealing substrate 151 as an optional component on the surface 145 side of the organic EL element 140 opposite to the device light exit surface 10U. Although illustration is omitted, an arbitrary substance such as a filler or an adhesive may exist between the surface 145 and the sealing substrate 151, or a gap may exist. As long as there is no inconvenience such as greatly impairing the durability of the light emitting layer 142, air or other gas may be present in the space, or the space may be evacuated.

  The organic EL element 140 includes a first electrode layer 141, a light emitting layer 142, and a second electrode layer 143. In Embodiment 1-1, the first electrode layer 141 is a transparent electrode, and the second electrode layer 143 is a reflective electrode. With such a structure, light from the light-emitting layer 142 passes through the first electrode layer 141 or is reflected by the second electrode layer 143 and passes through the light-emitting layer 142 and the first electrode layer 141. Then, it can go to the light-emitting surface structure layer 100 side.

  The light exit surface structure layer 100 includes a multilayer body 110 including a concavo-convex structure layer 111 and a base film layer 112, a glass substrate 131 as a substrate provided in contact with the organic EL element 140, and the multilayer body 110 and the glass substrate. And an adhesive layer 121 for adhering 131. In the surface light source device 10, at least one of the concavo-convex structure layer 111, the base film layer 112, the adhesive layer 121, and the glass substrate 131 is made of a material containing a diffusing agent (particles that impart light diffusibility). Accordingly, light emitted from the light emitting layer 142 (also referred to as emission) enters the diffusing member, and the diffusing member is configured to diffuse and transmit or reflect the incident light. In the present embodiment, the organic EL element 140 and the glass substrate 131 are in direct contact with each other, but other layers such as a diffusion layer may be interposed therebetween.

  The uneven structure layer 111 is located on the upper surface of the surface light source device 10 (that is, the outermost layer on the device light-emitting surface side of the surface light source device 10). Therefore, the concavo-convex structure layer 111 is provided at a position closer to the device light exit surface 10U than the glass substrate 131. Further, the concavo-convex structure layer 111 has a concavo-convex structure including a plurality of concave portions 113 and flat portions 114 located around the concave portions 113 on the surface near the device light exit surface 10U. In the present embodiment, the surface of the concavo-convex structure layer 111 close to the device light exit surface 10U and the device light exit surface 10U coincide with each other, and the device light exit surface 10U is defined by the concavo-convex structure. The device light exit surface 10U is a plane parallel to other layers in the device such as the flat portion 114 and the glass substrate 131 when viewed macroscopically ignoring the recess 113, but is microscopically defined by the recess 113. It is an uneven surface including an inclined surface. In the present application, since the drawings are schematic illustrations, only a small number of recesses are shown on the device light-emitting surface. However, in an actual device, a single device light-emitting surface is shown here. A much larger number of recesses can be provided.

(Organic EL device)
As exemplified as the organic EL element 140, in the first aspect of the present invention, the organic EL element is provided between two or more electrode layers and these electrode layers, and emits light when a voltage is applied from the electrodes. A light emitting layer.

  In the organic EL element, a layer such as an electrode or a light emitting layer constituting the element is formed on a substrate, a sealing member that covers those layers is further provided, and the layer such as the light emitting layer is sealed with the substrate and the sealing member. Generally, it is configured. Usually, the element that emits light from the substrate side here is called a bottom emission type, and the element that emits light from the sealing member side is called a top emission type. The surface light source device of the first aspect of the present invention may be any of these, and in the case of the bottom emission type, a combination of a substrate for forming a layer and an optional layer as necessary is a light emitting surface. In the case of the top emission type, which constitutes the structural layer, a combination including a structure on the device light emitting surface side such as a sealing member and an optional layer as necessary constitutes the light emitting surface structural layer.

  In the first aspect of the present invention, the light emitting layer constituting the organic EL element is not particularly limited, and a known one can be appropriately selected. The light-emitting material in the light-emitting layer is not limited to one type, and the light-emitting layer is not limited to one layer, and may be a single layer or a combination of a plurality of layers in order to suit the use as a light source. Thereby, light of white or a color close thereto can be emitted.

  The organic EL device may further include other layers such as a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and a gas barrier layer in addition to the light emitting layer between the electrodes. The organic EL element can further include arbitrary components such as a wiring for energizing the electrode and a peripheral structure for sealing the light emitting layer.

  The electrode of the organic EL element is not particularly limited, and a known one can be appropriately selected. As in the organic EL element 140 according to Embodiment 1-1, an organic EL element that emits light to the light-emitting surface structure layer side by using the electrode on the light-emitting surface structure layer side as a transparent electrode and the electrode on the opposite side as a reflective electrode It can be. In addition, both of the electrodes are transparent electrodes, and further have a reflecting member or a scattering member (for example, a white scattering member disposed via an air layer) on the side opposite to the light emitting surface structure layer, thereby providing a light emitting surface structure layer. Light emission to the side can also be achieved.

Although it does not specifically limit as a material which comprises an electrode and the layer provided among them, The following can be mentioned as a specific example.
ITO etc. can be mentioned as a material of a transparent electrode.
Examples of the material for the hole injection layer include a starburst aromatic diamine compound.
Examples of the material for the hole transport layer include triphenyldiamine derivatives.
Examples of the host material for the yellow light-emitting layer include triphenyldiamine derivatives, and examples of the dopant material for the yellow light-emitting layer include tetracene derivatives.
Examples of the material for the green light emitting layer include pyrazoline derivatives.
Examples of the host material for the blue light emitting layer include anthracene derivatives, and examples of the dopant material for the blue light emitting layer include perylene derivatives.
Examples of the material for the red light emitting layer include europium complexes.
Examples of the material for the electron transport layer include an aluminum quinoline complex (Alq).
Examples of the cathode material include lithium fluoride and aluminum, which are sequentially stacked by vacuum film formation.

  By appropriately combining the above or other light-emitting layers, a light-emitting layer that generates a light emission color having a complementary color relationship, which is referred to as a stacked type or a tandem type, can be obtained. The combination of complementary colors can be yellow / blue, green / blue / red, or the like.

(Light emitting surface structure layer)
As exemplified as the light exit surface structure layer 100, in the first aspect of the present invention, the light exit surface structure layer may be composed of a plurality of layers, but may be composed of a single layer. From the viewpoint of easily obtaining a light-emitting surface structure layer having desired characteristics, it is preferably composed of a plurality of layers. For example, like the said light emission surface structure layer 100, the multilayer body which combined the uneven | corrugated structure layer and the base film layer can be included. Thereby, a light-emitting surface structure layer with high performance can be easily obtained.

The resin composition constituting the concavo-convex structure layer and the base film can be a composition containing a transparent resin. That the transparent resin is “transparent” means that it has a light transmittance suitable for use in an optical member. In the first aspect of the present invention, each layer constituting the light exit surface structure layer can have a light transmittance suitable for use in an optical member, and the light exit surface structure layer as a whole has a total light beam of 80% or more. It can have transmittance.
The material of the transparent resin contained in the resin composition is not particularly limited, and various resins that can form a transparent layer can be used. Examples thereof include a thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, and an electron beam curable resin. Among these, thermoplastic resins are preferable because they can be easily deformed by heat, and ultraviolet curable resins have high curability and high efficiency, so that an uneven structure layer can be formed efficiently. Examples of the thermoplastic resin include polyester-based, polyacrylate-based, and cycloolefin polymer-based resins. Examples of the ultraviolet curable resin include epoxy resins, acrylic resins, urethane resins, ene / thiol resins, and isocyanate resins. As these resins, those having a plurality of polymerizable functional groups can be preferably used.

  As the material of the concavo-convex structure layer constituting the multilayer body, a material having a high hardness at the time of curing is preferable from the viewpoint of easily forming the concavo-convex structure on the light exit surface of the device and easily obtaining scratch resistance of the concavo-convex structure. Specifically, when a resin layer having a film thickness of 7 μm is formed on a substrate without a concavo-convex structure, a material having a pencil hardness of HB or higher is preferable, and a material of H or higher is more preferable. The material which becomes 2H or more is more preferable. On the other hand, the material of the base film layer has a certain degree of flexibility in order to facilitate the handling of the multilayer body when forming the concavo-convex structure layer and / or after forming the multilayer body. preferable. By combining such materials, a multilayer body that is easy to handle and excellent in durability can be obtained, and as a result, a high-performance surface light source device can be easily manufactured. Such a combination of materials can be obtained by appropriately selecting the transparent resin exemplified above as the resin constituting each material. Specifically, an ultraviolet curable resin such as acrylate is used as the transparent resin constituting the material of the concavo-convex structure layer, while the alicyclic olefin polymer film (described later) is used as the transparent resin constituting the material of the base film. Zeonor film, etc.) and polyester film can be used, whereby a preferable combination of materials can be obtained.

  When the light exit surface structure layer includes the uneven structure layer and the base film layer as in the light output surface structure layer 100, for example, the refractive index of the uneven structure layer and the base film may be as close as possible. In this case, the difference in refractive index is preferably within 0.1, more preferably within 0.05.

  A resin composition that is a material of a layer that is a constituent element of a light exit surface structure layer such as an uneven structure layer or a base film layer imparts light diffusibility such as particles described later when the layer constitutes a diffusion member. Elements can be included. Furthermore, the resin composition can contain arbitrary components as needed. Examples of the optional component include additives such as phenol-based and amine-based deterioration preventing agents; surfactant-based, siloxane-based antistatic agents; triazole-based, 2-hydroxybenzophenone-based light-resistant agents; be able to.

  In the first aspect of the present invention, the thickness of the concavo-convex structure layer is not particularly limited, but is preferably 1 to 70 μm. Here, the thickness of the concavo-convex structure layer is the distance between the substrate-side surface where the concavo-convex structure is not formed and the flat portion of the concavo-convex structure. Moreover, it is preferable that the thickness of a base film layer is 20-300 micrometers.

  In the first aspect of the present invention, the light exit surface structure layer can further include a substrate such as a glass substrate 131 in the light exit surface structure layer 100, thereby giving the surface light source device rigidity to suppress deflection. it can. Further, by providing a substrate that is excellent in the performance of sealing the organic EL element as a substrate and that can easily form the layers constituting the organic EL element in the manufacturing process in order, a surface light source The durability of the device can be improved and the manufacture can be facilitated.

  Examples of the material constituting the substrate include resins in addition to glass. Although the refractive index of a board | substrate is not restrict | limited in particular, It can be set to 1.4-2. In the first invention, the thickness of the substrate is not particularly limited, but is preferably 0.1 to 5 mm.

  The light exit surface structure layer may further include an adhesive layer interposed between two layers in the light exit surface structure layer, such as between the multilayer body and the substrate. The adhesive that is the material of the adhesive layer is not only a narrowly-defined adhesive (a so-called hot-melt adhesive having a shear storage modulus of 1 to 500 MPa at 23 ° C. and does not exhibit tackiness at room temperature). A pressure-sensitive adhesive having a shear storage modulus at 1 ° C. of less than 1 MPa is also included. Specifically, a material having a refractive index close to that of the substrate or the transparent resin layer and transparent can be used as appropriate. More specifically, an acrylic adhesive or a pressure-sensitive adhesive can be used. The thickness of the adhesive layer is preferably 5 to 100 μm.

(Diffusion member)
The surface light source device of the first aspect of the present invention is a layer constituting a part or all of the light exit surface structure layer, as a member provided at a position farther from the light exit surface structure layer than the organic EL element, or Both of them further include a diffusing member that diffuses and transmits or reflects incident light. That is, in the first aspect of the present invention, a part or all of the light exit surface structure layer may have a function as a diffusing member. You may have.

  As in the case of the surface light source device 10 in Embodiment 1-1, when one of the electrode layers of the organic EL element is a reflective electrode and the other is a transparent electrode, the diffusing member is a part of the light-emitting surface structure layer. Or it is the member provided as a layer which comprises all, Comprising: It can be set as the member which permeate | transmits the incident light in the diffused aspect. More specifically, by making a part or all of the light-emitting surface structure layers such as the concavo-convex structure layer, the base film, the adhesive layer, and the glass substrate constituting the light-emitting surface structure layer into a layer that diffuses light. A part or all of these layers can be used as a diffusing member.

  Examples of the material for the layer that diffuses light include a material containing particles and a material that is an alloy resin that diffuses light by mixing two or more kinds of resins. From the viewpoint that light diffusibility can be easily adjusted, a material containing particles, particularly a resin composition containing particles, is particularly preferable. In this case, since the particles are particles that impart light diffusibility, the composition containing the particles has light diffusibility.

  The particles contained in the diffusing member may be transparent or opaque. As the material for the particles, metals, metal compounds, resins, and the like can be used. Examples of the metal compound include metal oxides and nitrides. Specific examples of metals and metal compounds include metals having high reflectivity such as silver and aluminum, and metal compounds such as silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, tin-doped indium oxide, and titanium oxide. Can do. On the other hand, examples of the resin include methacrylic resin, polyurethane resin, and silicone resin.

The shape of the particles can be a spherical shape, a cylindrical shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a conical shape, a star shape, or the like.
In the diffusing member, the content ratio of the particles is preferably 1 to 80%, more preferably 5 to 50%, in the volume ratio in the total amount of the material constituting the diffusing member. By setting the content ratio of the particles to be equal to or higher than the lower limit, desired effects such as reduction of a change in color depending on the observation angle can be obtained. Moreover, by setting it as this upper limit or less, aggregation of the particle | grains in a diffusion member can be prevented, and the diffusion member in which the particle | grains were disperse | distributed favorably can be obtained easily.
The particle size of the particles is preferably 0.1 μm or more and 10 μm or less, more preferably 5 μm or less. Here, the particle diameter is a 50% particle diameter in an integrated distribution obtained by integrating the volume-based particle amount with the particle diameter as the horizontal axis. The larger the particle size, the larger the content ratio of particles necessary for obtaining the desired effect, and the smaller the particle size, the smaller the content. Therefore, as the particle size is smaller, desired effects such as a reduction in change in color depending on the observation angle and an improvement in light extraction efficiency can be obtained with fewer particles. When the particle shape is other than spherical, the diameter of the sphere having the same volume is used as the particle size.

  When the particles are transparent particles and the particles are contained in the transparent resin, the difference between the refractive index of the particles and the refractive index of the transparent resin is preferably 0.05 to 0.5. More preferably, it is 07-0.5. Here, either the particle or the refractive index of the transparent resin may be larger. If the refractive index of the particles and the transparent resin is too close, the diffusion effect cannot be obtained and the color unevenness is not suppressed. Conversely, if the difference is too large, the diffusion increases and the color unevenness is suppressed, but the light extraction effect is reduced. It will be.

  When a layer constituting part or all of the light-emitting surface structure layer is used as a diffusing member, which of the layers constituting the light-emitting surface structure layer is not particularly limited and is selected from various viewpoints. can do. For example, from the viewpoint that the degree of diffusion can be easily adjusted, a layer containing a transparent resin is preferably used as the diffusion member.

Furthermore, from the viewpoint of ensuring sufficient light diffusivity without excessively increasing the content ratio of the particles in the layer, it is preferable to use a layer having a thickness of a certain degree, such as 5 μm or more, as the diffusion member.
Here, the concavo-convex structure layer is preferably a material having a high hardness as described above. However, when the film thickness of such a high hardness material is thick, when used in a surface light source device, over time, Undesirable warping can result. Therefore, from this point of view, it is preferable to use a layer other than the concavo-convex structure layer and capable of imparting a property of being easily plastically deformed, for example, a base film or an adhesive layer as the diffusion member.

  On the other hand, management of a manufacturing process can be made easy by using a layer which does not accompany the process of heating materials, such as transparent resin, as a diffusion member in a manufacturing process. For example, it is possible to easily cope with a case where clogging with particles occurs in the resin conveyance path. From this viewpoint, the adhesive layer is preferably a diffusion member. Alternatively, it is also preferable to use a layer other than the adhesive layer and the adhesive layer as the diffusion member. For example, by using an adhesive layer and a base film as a diffusion member and reducing the proportion of particles added to the base film, management in the manufacturing process of the base film is facilitated (for example, how often clogging occurs). Can be reduced).

  Furthermore, layers other than the concavo-convex structure layer, the base film layer, the adhesive layer, and the glass substrate can be additionally provided in the light-emitting surface structure layer, and the additional layer can be used as a diffusion member. For example, between the concavo-convex structure layer and the base film layer, between the adhesive layer and the glass substrate, the surface on the light emitting layer side of the glass substrate, etc. (for example, between the electrode layer constituting the light emitting layer and the glass substrate) Can be formed. Alternatively, both of the additional layer and the concavo-convex structure layer, the base film layer, the adhesive layer, and one or more layers of the glass substrate may be used as the diffusing member.

In the case where the diffusing member is provided as a layer constituting part or all of the light emitting surface structure layer, the degree of diffusion is not particularly limited, but as an example, the diffusing member is part or all between the concavo-convex structure layer and the adhesive layer. In this case, the total light transmittance of the portion from the concavo-convex structure layer to the adhesive layer in a state where the surface of the concavo-convex structure layer is not uneven is preferably 70 to 95%, and more preferably 75 to 90%. preferable.
Moreover, although the refractive index of a diffusion member is not specifically limited, 1.45-2 are preferable, 1.6-2 are more preferable, and 1.7-2 are more preferable. It is preferable that the refractive index of the light emitting side layer from the diffusing member is smaller than the refractive index of the diffusing member, but the refractive index of the light emitting side layer from the diffusing member is selected by increasing the refractive index of the diffusing member as described above. Since the width of is widened, the selectivity of the material can be expanded.

(Uneven structure)
In the first aspect of the present invention, the concavo-convex structure on the light-emitting surface structure layer includes a plurality of concave portions including slopes and flat portions located around the concave portions. Here, the “slope” is a surface that forms an angle that is not parallel to the light output surface of the apparatus. On the other hand, the surface on the flat portion can be a surface parallel to the device light exit surface.

  As an example of the concavo-convex structure, the concavo-convex structure on the device light exit surface of the surface light source device 10 shown in FIGS. 1 and 2 will be described in more detail with reference to FIGS. FIG. 3 is an enlarged partial top view showing the structure of the device light exit surface 10U of the surface light source device 10 defined by the uneven structure layer 111. As shown in FIG. 4 is a partial cross-sectional view showing a cross section of the concavo-convex structure layer 111 taken along a vertical plane passing through the line 10a in FIG.

  Each of the plurality of recesses 113 is a depression having a regular quadrangular pyramid shape. Therefore, the slopes 11A to 11D of the recess 113 have the same shape, and the bases 11E to 11H form a square. The line 10a is a line that passes over all the vertices 11P of the recesses 113 in a row, and is a line parallel to the bottom sides 11E and 11G of the recesses 113.

  The recess 113 is continuously arranged in two orthogonal arrangement directions at a constant interval. One of the two arrangement directions X is parallel to the bases 11E and 11G. In this direction X, the plurality of recesses 113 are aligned at a constant interval 11J. The other direction Y of the two arrangement directions is parallel to the bases 11F and 11H. In this direction Y, the plurality of recesses 113 are aligned at a constant interval 11K.

  The angles formed by the inclined surfaces 11A to 11D constituting each of the concave portions 113 and the flat portion 114 (for the inclined surfaces 11B and 11D, the angles 11L and 11M shown in FIG. 4 respectively) are set to 60 °, for example. The apex angle of the regular quadrangular pyramid that is formed, that is, the angle formed by the opposing inclined surfaces at the apex 11P (the angle 11N shown in FIG. 4 for the angles formed by the inclined surfaces 11B and 11D) is also 60 °.

  As described above, the surface light source device has a configuration including a plurality of concave portions and flat portions positioned around the respective concave portions on the light exit surface of the device, and further includes a combination of predetermined diffusing members to extract light. It is possible to increase the efficiency and reduce the change in color depending on the observation angle, and to prevent the occurrence of chipping of the concavo-convex structure due to an external impact, thereby improving the mechanical strength of the light exit surface of the device. .

  The surface light source device of the first aspect of the present invention has the above-described configuration, and thus takes at least one of the x-coordinate and y-coordinate displacements of the chromaticity coordinates in all hemispherical directions on the light-emitting surface of the device. It can be made smaller than the case where it is not present, for example, it can be halved. For this reason, in the surface light source device, it is possible to suppress a change in color due to the observation angle. As a method for measuring the displacement of chromaticity in all hemispherical directions, for example, when a spectral radiance meter is installed on the normal line (front) of the device light-emitting surface and the normal direction is 0 °, the device light-emitting surface Since a chromaticity coordinate can be calculated from an emission spectrum measured in each direction by providing a mechanism that can rotate the angle from −90 to 90 °, the displacement can be calculated.

  The ratio of the area occupied by the flat portion to the sum of the area occupied by the flat portion and the area occupied by the concave portion when the concavo-convex structure layer is observed from the direction perpendicular to the light exit surface of the device (hereinafter referred to as “flat portion ratio”). The light extraction efficiency of the surface light source device can be improved by appropriately adjusting. Specifically, by setting the flat portion ratio to 10 to 75%, good light extraction efficiency can be obtained, and the mechanical strength of the device light exit surface can be increased.

  In the first aspect of the present invention, the concave portion may have, for example, a cone shape, a partial spherical shape, a groove shape, and a combination thereof in addition to the pyramid shape described above. The pyramid shape may be a quadrangular pyramid having a square bottom surface as exemplified by the recess 113, but is not limited thereto, and may be a pyramid shape such as a triangular pyramid, a pentagonal pyramid, a hexagonal pyramid, or a quadrangular pyramid having a non-square base. You can also.

  Furthermore, the cones and pyramids mentioned in this application include not only ordinary cones and pyramids with sharp points, but also rounded tips or flat chamfered shapes (frustum-shaped shapes, etc.). To do. For example, in the concave portion 113 shown in FIG. 4, the top portion 11 </ b> P of the quadrangular pyramid has a pointed shape, but this may have a rounded shape like the top portion 61 </ b> P of the concave portion 613 shown in FIG. 5. Further, a flat portion 71P may be provided at the top of the pyramid as in the concave portion 713 shown in FIG. 6 to form a flat chamfered shape.

  As shown in FIG. 5, when the top of the pyramid has a rounded shape, the height difference 61R between the top 61P and the top 61Q when the pyramid has a rounded and sharp shape is The pyramid can be 20% or less of the height 61S of the pyramid when the pyramid has a rounded and sharp shape. As shown in FIG. 6, when the top of the pyramid has a flat chamfered shape, the height of the flat portion 71P and the top 71Q when the top of the pyramid is not flat but sharp. The difference 71R can be 20% or less of the height 71S of the pyramid when the apex of the pyramid is not flat but sharp.

  The depth of the concave portion in the concavo-convex structure is not particularly limited, but the average roughness of the center line measured on the surface on which the concavo-convex structure is formed along various directions (various directions in a plane parallel to the device light exit surface). The maximum value (Ra (max)) can be in the range of 1 to 50 μm. When the concavo-convex structure is formed on the concavo-convex structure layer, a preferable depth of the concave portion can be determined relative to the thickness of the concavo-convex structure layer. For example, when a hard material that is advantageous for maintaining the durability of the uneven structure layer is used as the material of the uneven structure layer, the thickness of the uneven structure layer is reduced, so that the flexibility of the multilayer body is increased. Handling of the multilayer body in the manufacturing process of the device is facilitated. Specifically, the difference between the depth 16D of the recess shown in FIG. 4 and the thickness 16E of the concavo-convex structure layer 111 is preferably 0 to 30 μm.

  In the first aspect of the present invention, the angle formed by the inclined surface of the recess and the light exit surface of the device is preferably 40 to 70 °, and more preferably 45 to 60 °. For example, when the shape of the recess is a quadrangular pyramid shown in FIGS. 1, 2, 3 and 4, the apex angle (corner 11N in FIG. 4) is preferably 60 to 90 °. Further, from the viewpoint of increasing light extraction efficiency while minimizing the change in color depending on the observation angle, it is preferable that the angle formed by the inclined surface and the light exit surface of the apparatus is large, and specifically, for example, 55 ° or more. Preferably, the angle is 60 ° or more. In this case, the upper limit of the angle can be about 70 ° in consideration of maintaining the durability of the uneven structure layer.

  When the shape of the recess is a rounded or flat chamfered pyramid shape, conical shape or groove shape at the top, the angle of the slope excluding the rounded portion or the chamfered portion, The angle of the slope. For example, in the example shown in FIGS. 5 and 6, the surfaces 613a, 613b, 713a, and 713b are inclined surfaces. By setting the angle of the slope to such an angle, the light extraction efficiency can be increased. The slopes of the concavo-convex structure need not all have the same angle, and slopes having different angles may coexist within the above range. The angle formed between the conical slope and the device light exit surface can be the angle formed between the conical bus and the device light output surface.

  On the device light exit surface, the plurality of recesses can be arranged in any manner. For example, a plurality of concave portions can be arranged along two or more directions intersecting each other on the device light exit surface. More specifically, they can be arranged along two orthogonal directions like the recesses 113 shown in FIGS.

  In the case where the concave portions are arranged in two or more directions, a gap between adjacent concave portions is provided in one or more directions among them, and the flat portion can be constituted by the gap. For example, in the arrangement of the recesses 113 shown in FIG. 3, gaps with intervals 11J and 11K are provided in both directions X and Y that are orthogonal to each other, and the flat part 114 is configured by the gaps. By adopting such a configuration, it is possible to achieve both good light extraction efficiency and mechanical strength of the device light output surface.

(Production method)
Although the manufacturing method of the surface light source device of the first aspect of the present invention is not particularly limited, a surface light source device including the light emitting surface structure layer having the concavo-convex structure layer, the base film, the adhesive layer, and the glass substrate exemplified above is manufactured. In this case, each layer constituting the organic EL element is laminated on one surface of the glass substrate, and thereafter or before that, the multilayer body having the concavo-convex structure layer and the base film on the other surface of the glass substrate is bonded to the adhesive layer. It can manufacture by sticking through.

Manufacture of a multilayer body having a concavo-convex structure layer and a base film can be carried out by preparing a mold such as a mold having a desired shape and transferring this to a layer of a material forming the concavo-convex structure layer. . As a more specific method,
(Method 1) For example, a raw multilayer having a layer of the resin composition A constituting the base film and a layer of the resin composition B constituting the concavo-convex structure layer (the concavo-convex structure has not yet been formed) is coextruded, for example And a method of forming a concavo-convex structure on the surface of the unprocessed multilayer body on the resin composition B side; and (Method 2) applying the resin composition B in a liquid state on the substrate film Then, a method may be mentioned in which a mold is applied to the applied layer of the resin composition B, and the resin composition B is cured in that state to form an uneven structure layer.

In the method 1, the raw multilayer body can be obtained by, for example, extrusion molding in which the resin composition A and the resin composition B are coextruded. An uneven structure can be formed by pressing a mold having a desired surface shape onto the surface of the unprocessed multilayer body on the resin composition B side.
More specifically, a long raw multilayer body is continuously formed by extrusion molding, and the raw multilayer body is pressed with a transfer roll and a nip roll having a desired surface shape, thereby continuously. Manufacturing can be performed efficiently. The pinching pressure between the transfer roll and the nip roll is preferably several MPa to several tens of MPa. The temperature at the time of transfer is preferably Tg or more (Tg + 100 ° C.) or less, where Tg is the glass transition temperature of the resin composition B. The contact time between the unprocessed multilayer body and the transfer roll can be adjusted by the film feed speed, that is, the roll rotation speed, and is preferably from 5 seconds to 600 seconds.

  In Method 2, as the resin composition B constituting the concavo-convex structure layer, it is preferable to use a composition that can be cured by energy rays such as ultraviolet rays. From the light source located on the back side of the coating surface (the side opposite to the surface on which the resin composition B is applied) of the coating surface in a state where the resin composition B is coated on the base film and the mold is applied. By irradiating energy rays such as ultraviolet rays, curing the resin composition B, and then peeling the mold, the coating film of the resin composition B can be used as a concavo-convex structure layer to obtain a multilayer body.

<Embodiment 1-2>
In the surface light source device of the first aspect of the present invention, the shape of the concave portion constituting the device light-emitting surface is not limited to the pyramid shape exemplified as the above-described Embodiment 1-1. For example, as in Embodiment 1-2 shown below, It may be a partial shape of a sphere.
Embodiment 1-2 is a second embodiment according to the first aspect of the present invention. FIG. 7 is a top view schematically showing the surface light source device according to Embodiment 1-2, and FIG. 8 shows the surface light source device shown in FIG. 7 as a device light exit surface passing through line 2a in FIG. It is sectional drawing which shows the cross section cut | disconnected by the perpendicular | vertical surface. As shown in FIGS. 7 and 8, the surface light source device 20 according to Embodiment 1-2 includes the shape of the device light-emitting surface, that is, the surface of the uneven structure layer 211 in the multilayer body 210 constituting the light-emitting surface structure layer 200. Except for the difference in shape, it has the same configuration as the embodiment 1-1.

  The concave portion 213 formed on the surface of the concavo-convex structure layer 211 has a hemispherical shape, and is continuous in three arrangement directions parallel to the lines 2a, 2b, and 2c at a certain interval on the device light-emitting surface 20U. Are arranged. Lines 2a, 2b and 2c are at an angle of 60 ° to each other. A gap is provided between the adjacent recesses 213 in the directions of the lines 2a, 2b, and 2c, and the gap constitutes a flat portion 214.

  Even in the case of having a device light-emitting surface having a structure having a concave portion having a hemispherical shape and a flat portion that is a gap between the concave portions, light is emitted similarly to the pyramid-shaped concave portion in the embodiment 1-1. The extraction efficiency can be increased, the change in color depending on the observation angle can be reduced, and the mechanical strength of the light exit surface of the apparatus can be improved.

<Embodiment 1-3>
In the surface light source device according to the first aspect of the present invention, the shape of the recess constituting the device light exit surface may also be a groove shape as in Embodiment 1-3 described below.
Embodiment 1-3 is a third embodiment according to the first aspect of the present invention. FIG. 9 is a perspective view schematically showing the surface light source device according to Embodiment 1-3. As shown in FIG. 9, the surface light source device 30 according to Embodiment 1-3 has a different shape of the device light exit surface, that is, the surface shape of the concavo-convex structure layer 311 in the multilayer body 310 constituting the light exit surface structure layer 300. Others have the same configuration as the embodiment 1-1.

  Each of the plurality of recesses 313 formed on the surface of the concavo-convex structure layer 311 has a linear, groove-like shape and two flat slopes. Therefore, the cross section obtained by cutting the recess 313 along a plane perpendicular to the extending direction of the groove has a triangular shape having two hypotenuses. The plurality of recesses 313 are arranged in parallel on the device light exit surface 30U. A gap 314 is provided between the adjacent recesses 313, and the gap 314 constitutes a flat portion on the device light exit surface 30U.

  Even in the case of having a device light-emitting surface having such a groove-shaped recess and a flat portion that is a gap between the recesses, light is emitted in the same manner as the pyramid-shaped recess in Embodiment 1-1. The extraction efficiency can be increased, the change in color depending on the observation angle can be reduced, and the mechanical strength of the light exit surface of the apparatus can be improved.

  Here, the groove-like shape of the recess is not particularly limited as long as it includes an inclined surface, and the cross-section exemplified above is not limited to a triangular one, and can take various shapes. For example, the cross-sectional shape of the groove may be another polygonal shape such as a pentagon or a heptagon, or a shape other than a polygon such as a part of a circle. Further, the cross-section of the groove is similar to the shape of the pyramid or the top of the cone, described above in connection with embodiment 1-1, modified to a rounded or flat chamfered shape. The shape may be deformed into a shape with rounded vertices or a flat chamfered shape.

<Embodiment 1-4>
In the surface light source device of the first aspect of the present invention, when the shape of the concave portion constituting the device light-emitting surface is a pyramid shape, the pyramid shape is not limited to the simple pyramid shape exemplified as Embodiment 1-1, For example, like Embodiment 1-4 shown below, in each recessed part, the shape where several pyramids were combined may be sufficient.

  Embodiment 1-4 is a fourth embodiment according to the first aspect of the present invention. 10 is a top view schematically showing the surface light source device according to Embodiment 1-4, and FIG. 11 shows the surface light source device shown in FIG. 10 as a device light exit surface passing through line 3a in FIG. It is sectional drawing which shows the cross section cut | disconnected by the perpendicular | vertical surface. As shown in FIGS. 10 and 11, the surface light source device 40 according to Embodiment 1-4 includes the shape of the device light exit surface 40 </ b> U, that is, in the concavo-convex structure layer 411 in the multilayer body 410 constituting the light output surface structure layer 400. Except for the shape of the recessed part 413 differing from the recessed part 113 in Embodiment 1-1, it has the same structure as Embodiment 1-1.

  Each of the plurality of recesses 413 formed on the surface of the concavo-convex structure layer 411 has three types of inclined surfaces 41T, 41U, and 41V having different inclination angles with respect to the device light exit surface. 41V has the largest inclination, and the four inclined surfaces 41V constitute a quadrangular pyramid. The slope 41U has a smaller slope than the slope 41V, and the slope 41T has a slope smaller than that of the slope 41U. The four-sided slope 41U forms a part of the quadrangular pyramid, and the four-sided slope 41T also forms a part of the quadrangular pyramid. By combining these, the recess 413 has a shape in which three types of quadrangular pyramids or a part thereof are combined. And the flat part 414 located around the recessed part 413 is comprised by the clearance gap provided between the recessed parts in two orthogonal directions similarly to the flat part 114 in Embodiment 1-1.

  By having such a concave portion in which a plurality of pyramids are combined, it may be possible to further reduce the color change due to the observation angle as compared to the pyramid-shaped concave portion in Embodiment 1-1, Similar to Embodiment 1-1, the light extraction efficiency can be increased and the mechanical strength of the device light exit surface can be improved.

<Embodiment 1-5>
In Embodiment 1-1 to Embodiment 1-4 described above, the diffusing member is a member that diffuses and transmits incident light provided as a layer constituting part or all of the light exit surface structure layer. Met. However, the diffusing member in the surface light source device of the first aspect of the present invention is not limited to this, and is provided at a position farther from the light emitting surface structure layer than the organic EL element, as exemplified in Embodiment 1-5 shown below. A member that diffuses and reflects incident light may be used.

  Embodiment 1-5 is a fifth embodiment according to the first aspect of the present invention. FIG. 12 is a cross-sectional view showing a cross section of the surface light source device according to Embodiment 1-5 cut along a plane perpendicular to the device light output surface. As illustrated in FIG. 12, the surface light source device 50 according to Embodiment 1-5 includes an electrode layer 146 that is a second transparent electrode instead of the reflective electrode 143 as a second electrode layer, and a sealing substrate. Instead of 151, it differs from the embodiment 1-1 in that it has a reflecting member 551 and a reflecting member substrate 552, and is otherwise the same as the embodiment 1-1.

  In the surface light source device 50, the reflecting member 551 has a property of reflecting light incident on the reflecting member 551 at the reflecting surface 551U, and the reflecting surface 551U is not flat but has irregularities. Thereby, the reflection member 551 can reflect the incident light in a diffused manner.

  Reflection in a diffused manner on the reflection surface 551U of the reflection member 551 means that at least part of incident light is reflected by non-specular reflection (reflected in a reflection direction different from the reflection direction in specular reflection). That is. As a result, at least part of the light from the light emitting layer 142 is diffused before reaching the device light exit surface 10U.

  In the case of the surface light source device 10 of Embodiment 1-1, the layer constituting part or all of the light exit surface structure layer is a diffusing member. However, in the case of the surface light source device 50 of Embodiment 1-5, the reflecting member 551 is used. Since the same effect as that of the diffusing member in the light emitting surface structure layer is obtained by the reflection of the light in the diffused mode, the effect of the first invention can be obtained without providing the diffusing member in the light emitting surface structure layer. Can be obtained. However, if desired, in addition to the reflection member 551, a diffusion member in the light-emitting surface structure layer, such as that provided in Embodiment 1-1, may also be provided as an additional diffusion member.

  A gap 553 between the reflecting surface 551U of the reflecting member 551 and the second transparent electrode 146 can be filled with an arbitrary material such as a filler or an adhesive that does not significantly impair light transmission. Alternatively, air or other gas may be present or a vacuum space may be used if there is no inconvenience such as greatly impairing the durability of the light emitting layer 142.

The material of the reflecting member 551 is not particularly limited, but the reflecting member 551 can be a member including at least a layer of a substance having a property of reflecting incident light, such as a metal such as aluminum or silver. More specifically, a reflective member having fine irregularities can be formed by forming one or a plurality of such metal layers on a substrate having a fine irregular structure. Alternatively, a reflective layer having fine irregularities can be obtained by forming a metal layer on a flat substrate and then processing the metal layer. Alternatively, a reflective member having fine irregularities can be obtained by forming a metal layer on a flat resin substrate and then bending the resin substrate. The reflecting member may have a structure in which a functional layer such as an inorganic thin film or an organic thin film is laminated on the surface of the metal layer for the purpose of improving adhesion, corrosion resistance, scratch resistance, or the like.
The material of the reflecting member 551 is not limited to metal, and for example, a diffusion plate made of an arbitrary material having a white surface may be used to reflect the incident light in a diffused manner.

<Embodiment 1-6>
In the case of arranging the quadrangular pyramids along two directions of the device light-emitting surface in the above-described Embodiment 1-1 and other embodiments, the flat portion has a gap between the quadrangular pyramids adjacent in both of the two directions. However, the first aspect of the present invention is not limited to this. For example, a gap may be provided in only one of the two directions as in Embodiment 1-6 described below.

  Embodiment 1-6 is a sixth embodiment according to the first aspect of the present invention. 13 is a top view schematically showing the surface light source device according to Embodiment 1-6, and FIG. 14 shows the surface light source device shown in FIG. 13 as a device light exit surface passing through line 4a in FIG. It is sectional drawing which shows the cross section cut | disconnected by the perpendicular | vertical surface. As illustrated in FIGS. 13 and 14, the surface light source device 80 according to Embodiment 1-6 includes the shape of the device light exit surface 80 </ b> U, that is, the surface of the concavo-convex structure layer 811 in the multilayer body 810 constituting the light exit surface structure layer 800. The configuration is the same as that of the embodiment 1-1 except that the shape of is different.

  Each of the recesses 813 formed on the surface of the concavo-convex structure layer 811 has the same shape as the recess 113 in the embodiment 1-1, but the gap between the recesses 813 is a direction perpendicular to the line 4a in FIG. As a result, a flat portion 814 extending in a direction parallel to the line 4a is formed. In such a case, as compared with the case of the embodiment 1-1, the scratch resistance when the device light emitting surface is scratched along a certain direction (for example, a direction parallel to the extending direction of the flat portion 814). While the light extraction efficiency can be improved, the light extraction efficiency can be improved.

In the present embodiment, the height of the boundary portion 815 between the adjacent concave portions 813 and the height of the flat portion 814 are the same as the shape of the concave portion 813, but the height of the boundary portion 815 is the height of the flat portion 814. May be different.
Although the example in which the shape of the recess 813 is only a quadrangular pyramid has been taken here, other shapes may be used. For example, as shown in FIG. 15, it can also be set as the structure with which the some ridge roof-like recessed part 816 was located in a line. Note that the uneven structure layer 821 shown in FIG. 15 is a modification of the uneven structure layer 811 according to Embodiment 1-6, and is the same as the uneven structure layer 811 according to Embodiment 1-6, except that the shape of the recesses is different. It has the composition of.

<Embodiment 1-7>
In Embodiment 1-1 to Embodiment 1-6, the flat portion on the concavo-convex structure layer is different in height (that is, the height in a state where the device light-emitting surface is placed parallel to the horizontal direction and upward). However, the first aspect of the present invention is not limited to this, and there is a difference in the height of the flat portion, for example, as in the following Embodiment 1-7. It may be.

  Embodiment 1-7 is a seventh embodiment according to the first aspect of the present invention. FIG. 16 is a top view schematically showing the surface light source device according to Embodiment 1-7, and FIG. 17 shows the device light output through the surface light source device shown in FIG. 16 along the line 11a-11b in FIG. It is sectional drawing which shows the cross section cut | disconnected by the surface perpendicular | vertical to the surface. As illustrated in FIGS. 16 and 17, the surface light source device 90 according to Embodiment 1-7 includes the shape of the device light exit surface 90 </ b> U, that is, the surface of the concavo-convex structure layer 911 in the multilayer body 910 constituting the light exit surface structure layer 900. The configuration is the same as that of the embodiment 1-1 except that the shape of is different.

  Each of the recesses 913 formed on the surface of the concavo-convex structure layer 911 has substantially the same shape as the recess 113 in Embodiment 1-1, but between the recesses 913, a flat portion 914 having a low height and a height are provided. Two types of flat portions, ie, a high flat portion 915, are provided, and the flat portions 914 and 915 are connected by an inclined surface 91W.

  In the present embodiment, two rows of flat portions 914 and one row of flat portions 915 are alternately arranged, whereby the light-emitting surface structure layer 900 has two flat portions 914 and one flat portion 915 in its cross section. , And the repeating unit consisting of the slopes (including the slope 91W) of the three recesses 913 existing between them. In addition to the cross section passing through the lines 11a and 11b shown in FIG. 16, this repetition can occur in a cross section perpendicular to the line and perpendicular to the device light exit surface.

By having such a difference in the height of the flat portion, the scratch resistance of the device light exit surface is slightly reduced, but a favorable effect is produced that rainbow unevenness when the device light exit surface is observed can be suppressed. . That is, when the surface light source device is manufactured by designing the device light exit surface so that there is no difference in height in the flat portion, an error occurs in the height of the flat portion based on the error in forming the flat portion. Interference occurs in the light from the device light exit surface (that is, one or both of the light emitted from the device and the reflected light of the external light from the device light exit surface), and rainbow unevenness may occur. Here, the occurrence of interference is prevented and rainbow unevenness is suppressed by daringly setting the dimensional difference in height between the two types of flat portions 914 and 915 to be a dimensional difference that exceeds the difference that causes light interference. Can do. The dimensional difference exceeding the difference causing interference may be, for example, a dimensional difference of 0.62 times or more, preferably 1.5 times or more of the center wavelength of light emitted from the surface light source device.
In the present embodiment, a predetermined difference (a dimensional difference exceeding a difference that causes interference) is provided in the height of the flat portion. For example, the height of the flat portion is aligned, and the depth of the concave portion is set. A predetermined difference (a dimensional difference exceeding a difference causing interference) may be provided, and in this case, the same effect as described above can be obtained. Moreover, you may provide a difference in both the height of a flat part, and the depth of a recessed part. Thus, the structure which provides a predetermined difference in a flat part or a recessed part is not applied only to this embodiment, but can be applied to all the embodiments in the scope of the present invention.

  The above numerical range is confirmed from the knowledge shown below. In other words, in a concavo-convex structure layer designed so that all the heights of the flat portions are aligned, if an error of 170 nm or more occurs in the height of the flat portions, interference occurs and rainbow unevenness appears. It has been found that the generation of rainbow unevenness can be suppressed by providing a dimensional difference that is at least twice the minimum value of the error to be generated. Further, in the concavo-convex structure layer designed in such a manner that all the heights of the flat portions are aligned, if the flat portion has a standard deviation of σ1 nm (≈60 nm), interference occurs and rainbow unevenness appears. It has been found that the occurrence of rainbow unevenness can be suppressed by deliberately providing a dimensional difference of a height of xσ1 nm (= 360 nm) or more. Based on the above two findings, it can be shown that the dimensional difference exceeding the difference causing interference is 0.62 or more times the center wavelength of the light emitted from the surface light source device.

<Embodiment 1-8>
In the surface light source device of the first aspect of the present invention, not only one surface of the surface light source device is used as the device light exit surface, but both surfaces may be used as the device light exit surface as in the following Embodiment 1-8.

  Embodiment 1-8 is an eighth embodiment according to the first aspect of the present invention. FIG. 18 is a cross-sectional view schematically showing a cross section of the surface light source device according to Embodiment 1-8 cut along a plane perpendicular to the device light output surface. As illustrated in FIG. 18, the surface light source device 1000 according to Embodiment 1-8 includes an electrode layer 146 that is a second transparent electrode in place of the reflective electrode 143, and light output in place of the sealing substrate 151. Unlike the embodiment 1-1 in that the surface structure layer 100 is provided, the other points are the same as those in the embodiment 1-1. In addition, an arbitrary substance such as a filler or an adhesive may exist between the light emitting surface structure layer 100 on the lower side in the drawing and the second transparent electrode 146, or a void exists. May be. As long as there is no inconvenience such as greatly impairing the durability of the light emitting layer 142, air or other gas may be present in the space, or the space may be evacuated.

  Since the second electrode layer 146 is a transparent electrode, the light from the light emitting layer 142 passes through the first electrode layer 141 and the second electrode layer 146 and is emitted from both the upper and lower devices in the figure. Light exits from the surface 10U. Even when light is emitted from both the front surface and the back surface, as in the case of Embodiment 1-1, the light extraction efficiency can be increased and the change in color depending on the observation angle can be reduced. In addition, the mechanical strength of the light exit surface of the device can be improved.

  Further, in the surface light source device 1000 of the present embodiment, normally, light incident on one device light exit surface 10U is transmitted through the surface light source device 1000 and emitted from the other device light exit surface 10U. Therefore, the opposite side can be seen with the naked eye through the surface light source device 1000, and a see-through surface light source device can be realized, so that the design can be diversified.

  In the present embodiment, the example in which the same light exit surface structure layer 100 is provided on both the upper surface and the lower surface in the drawing of the surface light source device 1000 is shown, but different light exit surface structure layers may be provided in combination. For example, the light exit surface structure layer 100 may be provided on the surface of the first electrode layer 141, and the light exit surface structure layer 200 may be provided on the surface of the second electrode layer 146.

<Lighting equipment and backlight device>
The lighting apparatus of the first invention and the backlight device of the first invention both include the surface light source device of the first invention.
The lighting fixture of the first aspect of the present invention has the surface light source device of the first aspect of the present invention as a light source, and can further include arbitrary components such as a member that holds the light source and a circuit that supplies power. The backlight device of the first aspect of the present invention has the surface light source device of the first aspect of the present invention as a light source, and further includes a housing, a circuit for supplying electric power, a diffuser plate for making light emitted more uniform, Arbitrary components, such as a diffusion sheet and a prism sheet, can be included. The backlight device of the first aspect of the present invention is used as a backlight of a display device such as a liquid crystal display device that displays an image by controlling pixels and a display device that displays a fixed image such as a signboard. it can.

The first aspect of the present invention is not limited to the exemplification of the above-described embodiment, and can be modified within the scope of the claims of the present application and equivalents thereof.
For example, in the illustration of the above embodiment, the light emitting surface structure layer is composed of a concavo-convex structure layer, a base film layer, an adhesive layer, and a glass substrate, but the light emitting surface structure layer is a layer having fewer layers than these. It may be configured from the above, or conversely, an arbitrary layer may be further included in addition to these layers. For example, a coating layer may be further provided on the concavo-convex structure layer, and this may define the concavo-convex structure on the device light exit surface.
Moreover, in the illustration of the above embodiment, the concave portions distributed on the entire surface of the device light-emitting surface are shown as those having only the same shape distributed. However, concave portions having different shapes are mixed on the light-emitting surface of the device. May be. For example, pyramid-shaped recesses of different sizes are mixed, pyramid-shaped recesses and cone-shaped recesses are mixed, or a combination of multiple pyramids and a simple pyramid shape are mixed. It may be.
Further, in the illustration of the above embodiment, the width of the flat portion and the interval between the adjacent flat portions are always constant, but even if the width of the flat portion is narrow and wide, it may be mixed. In addition, a portion where the interval between the flat portions is narrow and a portion where the flat portion is wide may be mixed. In such a manner, in one or more elements of the height, width, and interval of the flat portion, a dimensional difference exceeding the difference that causes interference between the emitted light and the reflected light is provided. Unevenness can be suppressed.
Moreover, about the thing which has the reflective electrode layer in the illustration of the said embodiment, even if it replaces a reflective electrode with a transparent electrode and a reflective layer, the apparatus which has the same effect as a reflective electrode can be comprised.

[II. Description of Second Invention]
Hereinafter, although an embodiment, an example thing, etc. are shown and explained in detail about the 2nd present invention, the 2nd present invention is not limited to an embodiment and an example shown below.

<Embodiment 2-1>
The surface light source device according to the first embodiment of the second invention will be described below.
Embodiment 2-1 is the first embodiment according to the second aspect of the present invention. FIG. 19 is a longitudinal sectional view for explaining a surface light source device according to Embodiment 2-1. As shown in FIG. 19, the surface light source device 2001 according to the present embodiment has a light emission surface 2040 </ b> A having a rectangular shape in plan view, and is directly or indirectly on at least one surface of the organic EL element 2020 and the organic EL element 2020. And a concavo-convex structure body 2040 as a light output side member disposed in the.

  The organic EL element 2020 includes a first electrode layer 2022 constituting a reflective electrode, a light emitting layer 2024, and a second electrode layer 2026 as a transparent electrode in this order, and the first electrode layer 2022 and the second electrode layer A voltage is applied between the electrode layers 2026 to cause the light emitting layer 2024 to emit light, which can be used as a light source. Such an organic EL element 2020 can be suitably used for a lighting fixture, a display device, or the like.

  A known material can be used for the light emitting layer 2024. The light-emitting material used for the light-emitting layer 2024 is not limited to one type, and the light-emitting layer is not limited to one layer, and can be a single layer alone or a combination of a plurality of types in order to suit the use as a light source. . Thereby, what emits the light of the color of white or it can be comprised.

  The electrode of the organic EL element 2020 is not particularly limited, and a known one can be appropriately selected. The first electrode layer 2022 is a metal electrode layer. The second electrode layer 2026 is a transparent electrode layer. With such a structure, light emitted from the light-emitting layer 2024 passes through the second electrode layer 2026 or is reflected by the first electrode layer 2022, and passes through the light-emitting layer 2024 and the second electrode layer 2026. The light is transmitted and emitted to the outside of the organic EL element 2020. Note that the first electrode layer 2022 can also be configured as a transparent electrode layer, and in this case, light can be emitted from both surfaces of the organic EL element. In the case where the first electrode layer 2022 is a transparent electrode layer, a reflecting member or a scattering member (for example, a white scattering member disposed via an air layer) is disposed on the side opposite to the light emitting layer 2024 side. It can also be set as the structure to do.

  In addition to the light emitting layer 2024, the organic EL element 2020 includes a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection between the first electrode layer 2022 and the second electrode layer 2026 as necessary. Other layers such as layers and gas barrier layers can be provided. The organic EL element 2020 can also include arbitrary components such as wiring for energizing the electrode layers 2022 and 2026 and a peripheral structure for sealing the light emitting layer.

  Although it does not specifically limit as each electrode layer and the material which comprises each said layer provided in the meantime, The thing similar to the example mentioned in the term of description of 1st this invention is mentioned as a specific example.

  By appropriately combining the above-described or other light-emitting layers, a light-emitting layer that generates a light emission color having a complementary color relationship, which is referred to as a stacked type or a tandem type, can be obtained. The combination of complementary colors can be yellow / blue, green / blue / red, or the like.

  The uneven structure 2040 is provided on the surface of the second electrode layer 2026. The surface of the concavo-convex structure 2040 opposite to the second electrode layer 2026 side is a light exit surface 2040A that emits light to the outside. An uneven structure 2041 is formed on the light exit surface 2040A. The light exit surface 2040A is a surface parallel to the surface of the light emitting layer 2024 of the organic EL element 2020, and is parallel to the main surface of the surface light source device. However, when viewed microscopically, since the concavo-convex structure 2041 is formed on the light exit surface 2040A as described above, these surfaces can be non-parallel to the surface of the light emitting layer. However, unless otherwise specified, it is simply assumed that being parallel (or perpendicular) to the light exit surface viewed ignoring the uneven structure or the like is simply “parallel to (or perpendicular to) the light exit surface”. Unless otherwise specified, the surface light source device will be described in a state where the light exit surface is placed so as to be parallel to the horizontal direction and upward. In the second aspect of the present invention, the fact that each component is “parallel” or “vertical” may include an error within a range that does not impair the effects of the second aspect of the present invention. An error of ± 5 ° from a certain angle may be included.

  The uneven structure 2040 includes, for example, a glass substrate 2042 provided on the surface of the second electrode layer 2026, an uneven structure body 2044, and an adhesive layer 2046 that bonds the substrate 2042 and the uneven structure body 2044. The concavo-convex structure main body 2044 includes a base material 2045 and a concavo-convex structure layer 2047 as a light distribution distribution converter provided on the surface of the base material 2045. In the surface light source device 2001, one or more of the substrate 2042, the base material 2045, the adhesive layer 2046, and the concavo-convex structure layer 2047 are composed of a composition including particles that impart light diffusibility, and the light diffusibility. In the layer having, the light from the light emitting layer 2024 is diffused and transmitted or reflected, so that the layer functions as the diffusion portion of the second aspect of the present invention.

  The substrate 2042 functions as a plate material that provides rigidity for suppressing the deflection of the surface light source device 2001. Further, since the substrate 2042 has excellent performance for sealing the organic EL element 2020 and can easily form the layers constituting the organic EL element 2020 in order in the manufacturing process, the surface light source device 2001 is provided. There is an advantage that the durability can be improved and the manufacturing can be facilitated. The thickness of the substrate 2042 is not particularly limited, but is preferably 0.1 to 5 mm. In this embodiment, the base material 2042 is made of glass, but may be made of resin. In this case, the refractive index of the resin and glass constituting the substrate 2042 can be 1.4-2.

  The base material 2045 can be composed of a composition containing a transparent resin. That the transparent resin is “transparent” means that it has a light transmittance suitable for use in an optical member. In the second aspect of the present invention, each layer constituting the light output side member can have a light transmittance suitable for use in the optical member, and the light output side member as a whole has a total light transmittance of 80% or more. It can have.

  Examples of the transparent resin are the same as those described in the section of the light exit surface structure layer in the description of the first aspect of the present invention.

  The concavo-convex structure layer 2047 is located in the outermost layer on the light output surface side of the surface light source device 2001, and the surface opposite to the substrate 2045 is a light output surface 2040A. The concavo-convex structure layer 2047 has a concavo-convex structure including a plurality of concave portions 2048 including inclined surfaces and a flat portion 2049 formed in a planar shape that is located around the concave portions 2048 and separates the adjacent concave portions 2048. As a material constituting the concavo-convex structure layer 2047, the same material as the base material 2045 described above can be employed. The light exit surface is defined by the uneven structure. Thus, by providing a configuration including a plurality of recesses and a flat part located around each recess, it is possible to increase the light extraction efficiency and prevent the occurrence of chipping of the uneven structure due to external impact, and thus The mechanical strength of the light exit surface can be improved. The “slope” is a surface that forms an angle that is not parallel to the light exit surface. On the other hand, the surface on the flat portion can be a surface parallel to the light exit surface.

  When the concavo-convex structure layer 2047 is observed from a direction perpendicular to the light exit surface 2040A, the ratio of the area occupied by the flat portion 2049 to the total of the area occupied by the flat portion 2049 and the area occupied by the concave portion 2048 (hereinafter referred to as “flat portion ratio”). ”) Is appropriately adjusted, the light extraction efficiency of the surface light source device 2001 can be improved. Specifically, by setting the flat portion ratio to 10 to 75%, good light extraction efficiency can be obtained, and the mechanical strength of the light exit surface 2040A can be increased.

  Each of the plurality of recesses 2048 is a regular quadrangular pyramid shaped recess. For this reason, the inclined surface 2048 </ b> A constituting each concave portion 2048 is the same isosceles triangle. The plurality of recesses 2048 are arranged along two arrangement directions perpendicular to each other at a constant interval, and at this time, the respective recesses 2048 face each other in the same direction. The angle formed by the inclined surface 2048A constituting each of the recesses 2048 and the flat portion 2049 can be set to 60 °, for example. For this reason, the apex angle of the regular quadrangular pyramid constituting the recess 2048 is 60 °. However, the angle between the inclined surface of the concave portion and the flat portion is 40 to 70 ° on average from the viewpoint that the light extraction efficiency can be further increased while minimizing the change in color depending on the observation angle. preferable.

  Further, as a material constituting the concavo-convex structure layer 2047, a material having a high hardness at the time of curing is preferable from the viewpoint of easily forming the concavo-convex structure on the light exit surface and easily obtaining scratch resistance of the concavo-convex structure. Specifically, when a resin layer having a film thickness of 7 μm is formed on a substrate without a concavo-convex structure, a material having a pencil hardness of HB or higher is preferable, and a material of H or higher is more preferable. The material which becomes 2H or more is more preferable. In addition, as a material for the base material 2045, a certain degree of flexibility may be used in order to facilitate handling of the concavo-convex structure main body 2044 when forming the concavo-convex structure layer 2047 and / or after forming the concavo-convex structure main body 2044. Some are preferred. By combining such materials, it is possible to obtain a concavo-convex structure main body 2044 that is easy to handle and has excellent durability. As a result, a high-performance surface light source device can be easily manufactured.

  Such a combination of materials can be obtained by appropriately selecting the transparent resin exemplified above as the resin constituting each material. Specifically, an ultraviolet curable resin such as acrylate is used as the transparent resin constituting the material of the concavo-convex structure layer 2047, while the alicyclic olefin polymer film is used as the transparent resin constituting the material of the substrate 2045. (Zeonor film, etc., described later) or a polyester film can be used, whereby a preferable combination of materials can be obtained.

  In this embodiment, the refractive index difference between the base material 2045 and the uneven structure layer 2047 can be made as small as possible. In this case, the difference in refractive index is preferably within 0.15, more preferably within 0.05. preferable.

  The composition serving as a material of a layer serving as a constituent element such as the base material 2045 and the concavo-convex structure layer 2047 can include particles, which will be described later, imparting light diffusibility when the layer constitutes a diffusion portion. . For example, when one or both of the base material 2045 and the concavo-convex structure layer 2047 are formed of a composition containing particles that impart light diffusibility, the base material 2045 and the concavo-convex structure layer 2047 also serve as a diffusion portion. . Furthermore, the composition may contain optional components as necessary. Examples of the optional component include the same examples as described in the section of the light exit surface structure layer in the description of the first aspect of the present invention.

  In the present embodiment, the thickness of the uneven structure layer 2047 is not particularly limited, but is preferably 1 to 70 μm. Here, the thickness of the concavo-convex structure layer 2047 is the distance between the surface on the substrate side where the concavo-convex structure 2041 is not formed and the flat portion 2049 of the concavo-convex structure 2040. Moreover, it is preferable that the thickness of the base material 2045 is 20-300 micrometers.

  As an adhesive (including a pressure-sensitive adhesive) that is a material for the adhesive layer 2046, an adhesive having a refractive index close to that of the substrate 2045 or the uneven structure layer 2047 and transparent can be used as appropriate. Specifically, examples of the adhesive include an acrylic adhesive (pressure-sensitive adhesive). The thickness of the adhesive layer 2046 is preferably 5 to 100 μm.

  In the surface light source device 2001 according to this embodiment, part or all of the layers constituting the concavo-convex structure 2040 is a layer that diffuses light, so that part or all of these layers are diffused portions. Can do. Examples of the material for the layer that diffuses light include a material containing particles and a material that is an alloy resin that diffuses light by mixing two or more kinds of resins. From the viewpoint that light diffusibility can be easily adjusted, a material containing particles, particularly a resin composition containing particles, is particularly preferable.

  The particles are the same as the particles described in the section of the diffusion member in the description of the first aspect of the present invention. Therefore, for example, the material, content ratio, particle size, refractive index, and the like of the particles are the same as the particles described in the section of the diffusing member in the first description of the present invention.

  In addition, when a layer constituting part or all of the concavo-convex structure is used as the diffusion part, which of the layers constituting the concavo-convex structure is used as the diffusion part is not particularly limited, and can be selected from various viewpoints. can do. For example, from the viewpoint that the degree of diffusion can be easily adjusted, a layer containing a transparent resin is preferably used as the diffusion portion. Furthermore, from the viewpoint of ensuring sufficient light diffusibility without increasing the content ratio of the particles in the layer, it is preferable to use a layer having a thickness of a certain degree, such as 5 μm or more, as the diffusion portion.

  Here, the concavo-convex structure layer is preferably a material having a high hardness as described above. However, if the film thickness of such a material having a high hardness is thick, it is undesirable for the light-emitting surface over time when used in a surface light source device. May cause warping. Therefore, from this point of view, in addition to the concavo-convex structure layer, a layer other than the concavo-convex structure layer that can easily impart plastic deformation (for example, a base material and / or an adhesive layer) is provided, and this layer is diffused. Part.

  On the other hand, management of a manufacturing process can be made easy by making the layer which does not accompany the process of heating materials, such as transparent resin, into a diffusion part in a manufacturing process. For example, it is possible to easily cope with a case where clogging with particles occurs in the resin conveyance path. From this viewpoint, it is preferable that the adhesive layer is a diffusion portion. Moreover, it is also preferable to make a layer other than the adhesive layer and the adhesive layer into the diffusion portion. For example, by making the adhesive layer and the base material a diffusion part and reducing the ratio of particles added to the base material, management in the base material manufacturing process is facilitated (for example, reducing the frequency of clogging). be able to. Although the refractive index of such a diffusion part is not particularly limited, it is preferably 1.45 to 2, more preferably 1.6 to 2, and still more preferably 1.7 to 2. It is preferable that the layer on the light emission side of the diffusion part has a refractive index smaller than that of the diffusion part, but the refractive index of the light emission side of the diffusion part can be selected by increasing the refractive index of the diffusion part as described above. Since the width of is widened, the selectivity of the material can be expanded.

  Furthermore, in the concavo-convex structure, layers other than the concavo-convex structure layer, the base material, the adhesive layer, and the glass substrate can be additionally provided, and the additional layer can be used as a diffusion portion. For example, between the concavo-convex structure layer and the base film layer, between the adhesive layer and the glass substrate, the surface on the light emitting layer side of the glass substrate, etc. (for example, between the electrode layer constituting the light emitting layer and the glass substrate) Can be formed. Alternatively, both the additional layer and the concavo-convex structure layer, the base material, the adhesive layer, and one or more layers of the glass substrate can be used as the diffusion portion.

  When the diffusion portion is provided as a layer constituting part or all of the concavo-convex structure, the degree of diffusion is not particularly limited, but as an example, the diffusion portion is part or all between the concavo-convex structure layer and the adhesive layer In addition, the total light transmittance of the portion from the concavo-convex structure layer to the adhesive layer in a state where the concavo-convex structure layer has no surface unevenness is 70 to 95% from the viewpoint that a sufficient effect of eliminating color unevenness can be secured. Is preferable, and it is more preferable that it is 73 to 90%.

  The surface light source device 2001 of the second aspect of the present invention has the above-described configuration so that the displacement of at least one of the x-coordinate and the y-coordinate of the chromaticity coordinate in all hemispherical directions on the light exit surface 2040A has the above-described configuration. Compared with the case where it does not take, it can be made small, for example, can be reduced to half. For this reason, in the surface light source device 2001, a change in color due to an observation angle can be suppressed. As a method for measuring the displacement of chromaticity in all hemispherical directions, for example, a spectral radiance meter is installed on the normal line (front) of the light output surface 2040A, and the light output is obtained when the normal direction is set to 0 °. By providing a mechanism capable of rotating the surface from −90 to 90 °, the chromaticity coordinates can be calculated from the emission spectrum measured in each direction, and thus the displacement can be calculated.

  Further supplementally, the concavo-convex structure layer 2047 formed on the concavo-convex structure main body 2044 has the light distribution of the incident light when the light emitted from the organic EL element 2020 enters the concavo-convex structure 2041. The difference between the chromaticity of the light emitted from 2040A along the normal direction of the light exit surface 2040A and the chromaticity of the light emitted from the light output surface 2040A along the oblique direction intersecting the normal direction is reduced. It functions as a light distribution distribution conversion unit for converting to. Since such concavo-convex structure 2041 can adjust the chromaticity that varies depending on the observation direction, the diffusion effect in the diffusion portion described above can be supplemented. For example, the amount of particles added to the layer constituting the diffusion portion, for example, This can be reduced as compared with the prior art. For this reason, since the thickness of the layer which comprises a spreading | diffusion part can be made thin or lightweight, it can contribute also to thickness reduction, size reduction, etc. of the surface light source device 2001.

  Although the manufacturing method of the surface light source device 2001 which concerns on this embodiment is not specifically limited, The surface light source device provided with the uneven structure body which has the uneven structure layer, the base material, the contact bonding layer, and glass substrate which were illustrated above. When manufacturing, each layer which comprises an organic EL element is laminated | stacked on one side of a glass-made board | substrate, and an uneven | corrugated structure main body is affixed through the contact bonding layer on the other side of a glass-made board | substrate after that or before that. Can be manufactured.

  The concavo-convex structure main body can be formed by preparing a mold such as a mold having a desired shape and transferring it to a layer of a material forming the concavo-convex structure layer. More specific methods include, for example, Method 1 and Method 2 mentioned in the section of the production method in the description of the first invention.

  The lighting apparatus of the second aspect of the invention and the backlight device of the second aspect of the invention both include the surface light source device. The lighting fixture of the second aspect of the present invention has the surface light source device of the second aspect of the present invention as a light source, and can further include arbitrary components such as a member that holds the light source and a circuit that supplies power. The backlight device of the second aspect of the present invention has the surface light source device of the second aspect of the present invention as a light source, and further includes a housing, a circuit for supplying power, a diffusion plate for making light emitted more uniform, Arbitrary components, such as a diffusion sheet and a prism sheet, can be included. The use of the backlight device of the second aspect of the present invention is to be used as a backlight of a display device for controlling a pixel to display an image, such as a liquid crystal display device, and a display device for displaying a fixed image such as a signboard. it can.

<Embodiment 2-2>
The surface light source device according to the second embodiment of the second invention will be described below.
Embodiment 2-2 is a second embodiment according to the second aspect of the present invention. In addition, about the component which is the same as that of Embodiment 2-1, or equivalent, the same code | symbol is attached | subjected and description is abbreviate | omitted or simplified. FIG. 20 is a longitudinal sectional view for explaining a surface light source device according to Embodiment 2-2. As shown in FIG. 20, the surface light source device 2002 according to the present embodiment has a light emission surface 2040 </ b> A having a rectangular shape in plan view, and is arranged in contact with at least one surface of the organic EL element 2020 and the organic EL element 2020. The light emission side member 2060 is provided.

  The light output side member 2060 includes a selective reflection member 2062, a glass substrate 2042, and a diffusion layer 2070 as a diffusion portion disposed between the selective reflection member 2062 and the glass substrate 2042. The selective reflection member 2062 includes a base film 2064 and a selective reflection layer 2066 provided on the surface of the base film 2064.

  The diffusion layer 2070 is a layer that diffuses light from the organic EL element 2020. Examples of the material constituting the diffusion layer include a material containing particles and a material made of alloy resin that diffuses light by mixing two or more kinds of resins. From the viewpoint that light diffusibility can be easily adjusted, a composition containing particles is preferable, and a resin composition containing particles is particularly preferable.

  The selective reflection layer 2066 is a layer having a property of transmitting specific polarized light and reflecting or absorbing other polarized light in a certain wavelength band. The selective reflection band is a wavelength band in which the selective reflection layer has such properties. The base material 2064 can be configured similarly to the base material 2045 described above.

  Here, since the selective reflection layer 2066 usually has different selective reflection performance depending on the wavelength, the configuration is appropriately selected according to the emission intensity peak of the light emitting layer. As the light emitting layer used in the present embodiment, for example, a light emitting layer having two or more light emission intensity peaks can be adopted, and one or more of the two or more light emission intensity peaks have a wavelength in the range of 500 nm to 650 nm. Is preferred. An example of the spectrum of the light emitting layer having such a light emission intensity peak is shown in FIG. The spectrum shown in FIG. 21 has two peaks at wavelengths of 480 nm and 575 nm. Such two or more emission intensity peaks can be obtained by forming the light emitting layer as a laminate of a plurality of layers having different emission colors or a mixed layer in which a different dye is doped in a certain dye layer.

  The selective reflection layer 2066 includes at least one peak wavelength of the emission intensity peak in the selective reflection band of transmitted light in the front direction. When an example is described in relation to the spectrum of the light emitting element shown in FIG. 21, the selective reflection layer may include at least one of the wavelengths 480 nm and 575 nm in the selective reflection band of transmitted light in the front direction. it can.

Here, the selective reflection band refers to the transmittance (λ) [%] when the maximum transmittance in the visible light range of 380 to 780 nm is a [%] and the minimum transmittance is b [%]:
{A-transmittance (λ)} / {ab} ≧ 0.3
The wavelength range that satisfies

Preferably, the selective reflection layer 2066 has a transmittance T ^F _{Y, N in} the front direction at a wavelength of 575 nm, an average value T ^F _{Y, 60} of a transmittance in the polar angle 60 ° direction at a wavelength of 575 nm, and a transmission in the front direction at a wavelength of 480 nm. The rate T ^F _{B, N} and the average value T ^F _{B, 60} of the transmittance in the direction of the polar angle of 60 ° with the wavelength of 480 nm may satisfy the relationship of the formula [1]. Since the selective reflection layer 2066 has such a selective reflection band, a change in color depending on the observation angle can be reduced.
_{^{(T F Y, 60 / T}} F Y, N)> (T F B, 60 / T F B, N) formula (1)

  More preferably, the selective reflection layer 2066 has one or more selective reflection bands in the wavelength range of 500 nm to 650 nm as the selective reflection band of transmitted light in the front direction. Further, preferably, the selective reflection layer 2066 has one or more selections in a wavelength range of 400 nm to 600 nm as a selective reflection band of transmitted light in a polar angle direction of 60 °, that is, a direction that forms an angle of 60 ° with the front direction. Has a reflection band.

  FIG. 22 shows an example of the selective reflection characteristic having the selective reflection band described above in relation to the spectrum of the light emitting element shown in FIG. As shown in FIG. 22, in the selective reflection characteristic of transmitted light in an angle of 0 °, that is, in the front direction, the light is most reflected at a wavelength of 575 nm, and the selective reflection band of transmitted light in the front direction is 525 nm or more and 635 nm or less. As the angle of the transmitted light increases, the maximum absorption wavelength shifts to the short wavelength side, thereby satisfying the above equation [1], and further in the polar angle 60 ° direction, the maximum absorption wavelength is 490 nm, and the selective reflection band is 580 nm. It is as follows.

  Examples of the suppression of the change in color depending on the observation angle by the selective reflection layer 2066 having such selective reflection characteristics are shown in FIGS. FIG. 25 shows the surface light source device according to the second aspect of the present invention shown in FIG. 20, in which an element having the spectrum shown in FIG. 21 is used as the light emitting element, and the selective reflection layer 2066 has the selective reflection characteristics shown in FIG. 6 is a graph showing a light distribution of blue light having a wavelength of 480 nm and yellow light having a wavelength of 575 nm emitted from the light exit surface 2040A when using the light source. FIG. 24 is a graph showing a light distribution when a light distribution of blue light and yellow light emitted from a glass substrate is observed without providing the diffusion layer 2070. FIG. 23 is a graph showing a light distribution when observed without any of the diffusion layer 2070 and the selective reflection member 2062.

  As shown in FIG. 23, the light emitted from the glass substrate 2042 has a difference in light distribution between blue light and yellow light. On the other hand, as shown in FIG. 24, the light exits through the selective reflection member 2062. The deviation of the light emitted from 2040A is reduced. For this reason, the selective reflection member 2062 has a light distribution distribution of the light emitted from the organic EL element 2020, the chromaticity of the light emitted along the normal direction of the light output surface 2040A, and an oblique direction intersecting the normal direction. Is functioning as a light distribution distribution conversion unit for conversion so that the difference from the chromaticity of the light emitted from the light exit surface 2040A along the line becomes small.

  Furthermore, as shown in FIG. 23, the light emitted from the glass substrate 2042 has a difference in light distribution between blue light and yellow light, whereas as shown in FIG. 25, the diffusion layer 2070 and the selective reflection member 2062 are separated. The light transmitted through the light exit surface 2040A is further reduced in the deviation. For this reason, the selective reflection member 2062 can suppress the color unevenness based on the observation angle, and the diffusion layer 2070 can further suppress the color unevenness. Thus, by using the selective reflection member 2062 and the diffusion layer 2070 in combination, the effect of eliminating color unevenness can be further enhanced as compared with the case where only the diffusion layer 2070 is used or the case where only the selective reflection member 2062 is used. At the same time, the degree of the diffusion effect by the diffusion layer 2070 can be suppressed to a low level, whereby the ratio of addition of, for example, diffusion particles can be suppressed, and the thickness of the diffusion layer can be reduced.

  In the surface light source device 2002 of this embodiment, a part of the light generated from the light emitting layer 2024 is directly transmitted through the second electrode layer 2026, and the other part is reflected by the first electrode layer 2022 before being reflected. The second electrode layer 2026 is transmitted. Light that has passed through the second electrode layer 2026 passes through the glass substrate 2042, the diffusion layer 2070, the selective reflection layer 2066, and the base film 2064, and is emitted. In addition, light reflected downward in the drawing at the interface between the light emitting layer 2024 and the glass substrate 2042 is reflected at the first electrode layer 2022 or another interface and then emitted. Since there is light emitted through such various paths, light interference occurs. The increase / decrease in light due to interference differs depending on the wavelength, and as a result, the relationship between the observation angle and the luminance differs depending on the wavelength of the light, resulting in a change in color depending on the observation angle. By further transmitting such light through the diffusion layer 2070 described above and the selective reflection layer 2066 having the specific selective reflection characteristics described above, it is possible to reduce a change in color depending on the observation angle. In this embodiment, the selective reflection layer 2066 is provided on one surface of the base film 2064. However, even when the selective reflection layer 2066 is provided on both surfaces of the base film 2064, the same advantage can be obtained. it can.

  As long as the selective reflection layer 2066 has the selective reflection band, any material may be used and selective reflection of any principle may be performed. The thing containing a polarization separation sheet can be mentioned. When the selective reflection layer has a circularly polarized light separating sheet, the selective reflection layer transmits only specific circularly polarized light and reflects other light (other circularly polarized light, linearly polarized light, etc.) in the selective reflection band. .

  Examples of the circularly polarized light separating sheet include a layer comprising a resin having cholesteric regularity. For example, a composition capable of exhibiting a cholesteric liquid crystal phase (cholesteric liquid crystal composition) is applied to a transparent resin substrate to obtain a liquid crystal layer, and then cured by at least one light irradiation and / or heating treatment. The circularly-polarized-light separation sheet which can be mentioned can be mentioned. As the cholesteric liquid crystal composition, a composition containing a rod-like liquid crystal compound that can be cured by itself or with other substances can be used. Specifically, for example, a rod-like liquid crystal compound having a refractive index anisotropy Δn of 0.10 or more and having at least two or more reactive groups in one molecule can be given.

  The manufacturing method of a cholesteric liquid crystal composition is not specifically limited, It can manufacture by mixing the said essential component and arbitrary components. As a method of forming a selective reflection layer using the cholesteric liquid crystal composition, the cholesteric liquid crystal composition is applied to a base film 2064 to obtain a liquid crystal layer, and then at least one time of light irradiation and / or heating. The method of hardening by a process is mentioned.

  The material of the base film 2064 is not particularly limited, and a base material having a thickness of 1 mm and a total light transmittance of 80% or more can be used. Specifically, alicyclic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, modified acrylic polymer, epoxy resin, Examples thereof include a single layer or laminated film made of a synthetic resin such as polystyrene or acrylic resin. Among these, an alicyclic olefin polymer or a chain olefin polymer is preferable, and an alicyclic olefin polymer is particularly preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like. In addition, similar to the diffusion layer 2070, particles or the like that impart light diffusibility can also be added to the base film 2064. According to such a configuration, the base film 2064 is composed of a composition containing particles that impart light diffusibility, and also serves as a diffusion portion, so that the thickness of the diffusion layer 2070 can be reduced. There is.

  The said base film can have an orientation film as needed. By having the alignment film, the cholesteric liquid crystal composition applied thereon can be aligned in a desired direction. The thickness of the alignment film may be any film thickness that provides desired alignment uniformity of the liquid crystal layer, and is preferably 0.001 to 5 μm, and more preferably 0.01 to 2 μm. Application | coating of the liquid-crystal composition to the said base film can be performed by well-known methods, such as reverse gravure coating, direct gravure coating, die coating, and bar coating. Before curing the coating layer obtained by the coating, an orientation treatment can be performed as necessary. The alignment treatment can be performed, for example, by heating the coating layer at 50 to 150 ° C. for 0.5 to 10 minutes. By performing the alignment treatment, the cholesteric liquid crystal layer can be aligned well.

A cured liquid crystal layer that is a cured product of the cholesteric liquid crystal composition can be obtained by curing the cholesteric liquid crystal composition after performing an alignment treatment as necessary. The curing step can be performed by a combination of one or more light irradiations and a heating treatment. Specifically, the heating conditions are, for example, a temperature of 40 to 200 ° C., preferably 50 to 200 ° C., more preferably 50 to 140 ° C., and a time of 1 second to 3 minutes, preferably 5 to 120 seconds. it can. The light used for light irradiation in the second invention includes not only visible light but also ultraviolet rays and other electromagnetic waves. Specifically, the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 second to 3 minutes. Further, for example, a weakly irradiated ultraviolet ray of 0.01 to 50 mJ / cm ² and heating may be alternately repeated a plurality of times to obtain a circularly polarized light separating sheet having a wide reflection band. After extending the reflection band by the above-mentioned weak ultraviolet irradiation, etc., a relatively strong ultraviolet ray of 50 to 10,000 mJ / cm ² is irradiated to completely polymerize the liquid crystalline compound to form a cured liquid crystal layer. it can. The expansion of the reflection band and the irradiation with strong ultraviolet rays may be performed in the air, or a part or all of the process may be performed in an atmosphere in which the oxygen concentration is controlled (for example, in a nitrogen atmosphere). .

  In the second aspect of the present invention, the step of applying and curing the cholesteric liquid crystal composition on the transparent resin substrate is not limited to one time, and repeating the application and curing a plurality of times to form two or more cured liquid crystal layers. You can also.

  In the selective reflection layer, the dry thickness of the cured liquid crystal layer is preferably 0.5 μm to 10.0 μm, more preferably 1.0 μm to 5.0 μm. If the dried film thickness of the cured liquid crystal layer is thinner than 0.5 μm, sufficient selective reflection performance cannot be obtained. Conversely, if it is thicker than 10.0 μm, light absorption in the cured liquid crystal layer increases, which is not preferable. The dry film thickness refers to the total film thickness of each layer when the cured liquid crystal layer is two or more layers, and the film thickness when the cured liquid crystal layer is one layer.

  Through the above steps, a laminated structure having the base film 2064 and the selective reflection layer 2066 is obtained. By attaching this to the glass substrate 2042 via the diffusion layer 2070, the surface light source device 2002 shown in FIG. 20 can be obtained.

  The lighting apparatus of the second aspect of the invention and the backlight device of the second aspect of the invention both include a surface light source device as in the embodiment 2-1, and exhibit the same effects as those in the embodiment 2-1. Can do.

<Modification>
The second aspect of the present invention is not limited to the above embodiments.
In Embodiment 2-1, the concave-convex structure includes a concave portion. However, the present invention is not limited to this, and the concave-convex structure may include a convex portion. In the case of including a convex portion, the same flat portion may be provided between adjacent convex portions, or may not be provided.

  Further, in Embodiment 2-1, the shape of the concave portion is a regular quadrangular pyramid, but a polygonal pyramid shape such as a triangular pyramid or an octagonal pyramid, a conical shape, a polygonal frustum shape, a truncated cone shape, a hemispherical shape, or a groove shape. Or a combination of these. In addition, when the concavo-convex structure is configured to include a polygonal pyramid shape or a polygonal frustum shape, the slope of each polygonal pyramid does not necessarily have to be a strict plane, and has a curved surface shape including some fluctuations. It may be formed. Further, in the case where the concavo-convex structure includes a cone, as in the case of the polygonal pyramid shape, the generatrix of the cone is not necessarily a strict straight line but may be a curved line including a slight fluctuation. Moreover, when it is set as a polygonal pyramid shape or a conical shape, the apex angle part may be a round shape even if it is a convex shape or a concave shape. Further, in the case of a polygonal pyramid shape or a conical shape, it is not limited to a so-called straight cone, and may be an oblique cone.

  Moreover, in the said Embodiment 2-1, although the several recessed part was made into the same shape altogether, the recessed part of a different shape may be mixed. For example, pyramid-shaped recesses of different sizes are mixed, pyramid-shaped recesses and cone-shaped recesses are mixed, or a combination of multiple pyramids and a simple pyramid shape are mixed. It may be.

  In the embodiment 2-1, the concave portions are arranged along two directions orthogonal to each other. However, the concave portions may be arranged along non-orthogonal directions, or may be arranged along one or more directions. Moreover, although the flat part was provided in either direction of the said 2 direction between adjacent recessed parts, you may provide only in any one direction, and does not need to provide in both directions. However, the configuration in which the flat portion is provided has an advantage that both good light extraction efficiency and mechanical strength of the light output surface can be achieved.

In Embodiment 2-2, the selective reflection layer is a layer containing a resin having cholesteric regularity, but is not limited thereto, and may be a dielectric multilayer film. Examples thereof include a band-pass filter that exhibits strong reflection or transmission characteristics at a specific wavelength using TiO ₂ as a material and SiO ₂ as a low refractive index material. The characteristics of these selective reflection layers are common in that the wavelength range showing the selective reflection characteristics shifts when the observation angle is changed, and the transmittance of light having a wavelength in the visible light range is also common. The characteristics that change with the shift are utilized.

  In each of the above embodiments, the surface light source device may further include an arbitrary layer. For example, a coating layer may be further provided on the concavo-convex structure layer, and this may define the concavo-convex structure on the light exit surface. Further, a sealing substrate may be provided on the surface of the organic EL element opposite to the light exit surface 2040A.

  In each said embodiment, although the uneven structure body or the selective reflection member was used as a light distribution distribution conversion part, it is not limited to this, For example, you may use a diffraction structure etc. The diffractive structure can strongly diffuse a specific wavelength by selecting an appropriate pitch, and in this case as well, the color unevenness can be further eliminated by combining with another diffusion layer as in the above embodiments. effective.

  In the present embodiment, the light emission side member is provided on only one surface of the organic EL element 2020, but may be provided on both surfaces. In this case, the first electrode layer described above is also preferably configured as a transparent electrode. Examples of such cases are shown in FIGS.

  FIG. 26 and FIG. 27 are longitudinal sectional views for explaining the surface light source device according to the second embodiment of the present invention. A surface light source device 2003 shown in FIG. 26 includes a first electrode 2028 as a transparent electrode instead of the first electrode 2022 as a reflective electrode, and an uneven structure body 2040 on both surfaces of the organic EL element 2020. Unlike the embodiment 2-1, the other points are the same as those of the embodiment 2-1. In addition, the surface light source device 2004 shown in FIG. 27 includes a first electrode 2028 as a transparent electrode instead of the first electrode 2022 as a reflective electrode, and the light emitting side on both surfaces of the organic EL element 2020. It differs from the embodiment 2-2 in that the member 2060 is provided, and is otherwise the same as the embodiment 2-2. Note that an arbitrary substance such as a filler or an adhesive may exist between the first electrode 2028 and the substrate 2042, or a gap may exist. As long as there is no inconvenience such as greatly impairing the durability of the light emitting layer 142, air or other gas may be present in the space, or the space may be evacuated.

In the surface light source devices 2003 and 2004, since the first electrode layer 2028 is a transparent electrode, light from the light-emitting layer 2024 passes through the first electrode layer 2028 and the second electrode layer 2026, and the upper side in the drawing. The light exits from both of the light exit surfaces 2040A on the lower side. Thus, even in the surface light source devices 2003 and 2004 in which light is emitted from both the front surface and the back surface, the same effects as those of the embodiment 2-1 and the embodiment 2-2 are obtained.
In the surface light source devices 2003 and 2004, light incident on one light exit surface 2040A normally passes through the surface light source devices 2003 and 2004 and exits from the other light exit surface 2040A. Accordingly, the opposite side can be seen with the naked eye through the surface light source devices 2003 and 2004, and a see-through surface light source device can be realized, so that the design can be diversified.

  In addition, although the example provided with the same light emission side member (uneven | corrugated structure 2040 or the light emission side member 2060) in both the upper surface and the lower surface in the figure of the surface light source device 2003, 2004 was shown here, it combines and provides a different light emission side member. You may do it. For example, the uneven structure 2040 may be provided on the surface of the first electrode 2028 and the light emission side member 2060 may be provided on the surface of the second electrode layer 2026.

  Further, for example, a layer formed of a composition containing particles that impart light diffusibility may be provided on the light exit side of the concavo-convex structure layer 2047 or the selective reflection member 2062, and this layer may be used as a diffusion portion.

  Hereinafter, based on an Example and a comparative example, it demonstrates still in detail about this invention. In addition, this invention is not limited to the following Example. The refractive index of the resin described below is the refractive index after curing.

[Description of Examples and Comparative Examples Related to First Invention]
<Comparative Example 1-1>
(C1-1: Formation of organic EL element, production of surface light source device (no multilayer))
A transparent electrode layer 100 nm, a hole transport layer 10 nm, a yellow light emitting layer 20 nm, a blue light emitting layer 15 nm, an electron transport layer 15 nm, an electron injection layer 1 nm on one main surface of a 0.7 mm thick glass substrate (refractive index 1.53). And a reflective electrode layer of 100 nm were formed in this order. The hole transport layer to the electron transport layer were all made of an organic material. The yellow light emitting layer and the blue light emitting layer have different emission spectra.

The material forming each layer from the transparent electrode layer to the reflective electrode layer is as follows:
-Transparent electrode layer; tin-added indium oxide (ITO)
Hole transport layer; 4,4′-bis [N- (naphthyl) -N-phenylamino] biphenyl (α-NPD)
・ Yellow light emitting layer: 1.5% by weight of rubrene added α-NPD
Blue light-emitting layer; iridium complex added at 10% by weight 4,4′-dicarbazolyl-1,1′-biphenyl (CBP)
-Electron transport layer; phenanthroline derivative (BCP)
-Electron injection layer; lithium fluoride (LiF)
-Reflective electrode layer: Al

The transparent electrode layer was formed by a reactive sputtering method using an ITO target, and the surface resistance was 10Ω / □ or less. In addition, the formation from the hole injection layer to the reflective electrode layer is carried out by placing a glass substrate on which a transparent electrode layer has already been formed in a vacuum evaporation apparatus, and successively using the resistance heating method for the materials from the hole transport layer to the reflective electrode layer. This was done by vapor deposition. The system internal pressure was 5 × 10 ⁻³ Pa and the evaporation rate was 0.1 to 0.2 nm / s.

  Furthermore, wiring for energization was attached to the electrode layer, and further, the hole transport layer to the reflective electrode layer were sealed with a sealing member, and a surface light source device (without a multilayer body) was produced. The obtained surface light source device had a rectangular light exit surface capable of emitting white light from the glass substrate side.

(C1-2: Evaluation)
About the surface light source device obtained by (C1-1), the color nonuniformity by the change of an observation angle was measured as follows.
A spectral radiance meter (BM-5 manufactured by Topcon Corporation) is installed in front (normal direction) of the light exit surface (device light exit surface), a constant current of 100 mA / m ² is applied to the surface light source device, and the light exit surface is rotated. The chromaticity (x, y) was measured by changing the observation direction of the spectral radiance meter with respect to the light exit surface. The observation direction was changed in the range of −90 to 90 ° in the direction parallel to the long side of the light exit surface when the front (normal direction) was 0 °. The measurement results are shown in FIG. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.050, 0.058). Note that Δx is a change amount of the coordinate value x, and Δy is a change amount of the coordinate value y.

<Example 1-1>
The multilayer body 110 prepared by the following procedure was attached to the surface light source device obtained in Comparative Example 1-1, and the surface light source device schematically shown in FIGS. 1 and 2 was produced and evaluated. However, in FIG. 1, an organic EL element 140 having only three layers is schematically illustrated. However, the surface light source device manufactured in this example includes an organic EL element including more light emitting layers. ing.

(1-1: Preparation of multilayer body 110)
A UV (ultraviolet) curable resin (urethane acrylate resin, refractive index n = 1.54) is added with a diffusing agent (silicone resin, n = 1.43) which is a spherical particle having an average particle diameter of 2 μm in the total amount of the composition. The mixture was added at 10% (volume ratio) and stirred to disperse the particles to obtain a resin composition.

After applying the resin composition obtained above onto a base film (ZEONOR film, refractive index 1.53 manufactured by Nippon Zeon Co., Ltd.), a metal mold having a predetermined shape is pressed onto the coating film of the resin composition, It is a rectangular film having a layer structure of a base film layer 112-a concave-convex structure layer 111 by irradiating ultraviolet rays from the base film side with an integrated light amount of 1000 mJ / cm ² to form a concave-convex structure layer on the base film. A multilayer body 110 was obtained.

  In the multilayer body 110, the concavo-convex structure on the concavo-convex structure layer 111 was composed of a plurality of regular quadrangular pyramid-shaped recesses 113 and a flat part 114 positioned around the recesses, as shown in FIGS. The angle (11L, 11M, etc.) formed by the inclined surface forming the recess 113 and the flat portion was 60 °. The length of the bottom sides (11E to 11H) of the recess 113 was 16 μm, and the intervals 11J and 11K of the recess 113 were both 4 μm, which was a constant interval. The bottom side of the recess 113 was parallel to the long side or short side direction of the multilayer body 110. The thickness of the uneven structure layer 111 (thickness from the flat portion 114 to the surface in contact with the base film) was 34 μm, and the thickness of the base film layer 112 was 100 μm. The flat portion ratio was 36%.

(1-2: Surface light source device (with multiple layers))
On the surface of the surface light source device obtained in (C1-1) of Comparative Example 1-1 on the side of the glass substrate 131, the multilayer body 110 obtained in (1-1) is bonded to an adhesive (acrylic resin, refractive index 1). 49, CS9621 manufactured by Nitto Denko Corporation) to obtain a surface light source device including the layer structure of multilayer body 110-adhesive layer 121-glass substrate 131-organic EL element 140. The thickness of the adhesive layer was 25 μm.

(1-3: Evaluation)
About the obtained surface light source device, the color nonuniformity was measured similarly to (C1-2) of Comparative Example 1-1. The results of obtaining the x value and y value at each observation angle are shown in FIG. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.011, 0.013). From this, it can be seen that the color unevenness is significantly reduced as compared with Comparative Example 1-1.

<Comparative Example 1-2>
In preparing the multilayer body 110 of (1-1) above, a multilayer body 110 was prepared in the same manner as in Example 1-1, except that the diffusing agent was not added to the material for the uneven structure layer. Furthermore, a surface light source device was obtained.

<Light extraction amount>
The light extraction amount of the surface light source devices of Comparative Example 1-1, Example 1-1, and Comparative Example 1-2 is obtained from the measurement result of the tristimulus Y value, and the light extraction amount of Comparative Example 1-1 is set to 1. The relative amount was determined. As a result, the light extraction amount in Example 1-1 was 1.43, and the light extraction amount in Comparative Example 1-2 was 1.37.
The surface light source device of Example 1-1 had significantly improved light extraction efficiency as compared with the surface light source device of Comparative Example 1-1 that did not have an uneven structure that increased light extraction efficiency. The surface light source device of Example 1-1 further has a large improvement in light extraction amount compared to the surface light source device of Comparative Example 1-2 that has the same uneven structure as Example 1-1 but does not have a diffusing member. Was recognized.

<Example 1-2>
Except having changed the following point, it carried out similarly to Example 1-1, and prepared the multilayer body 110, and also obtained the surface light source device.
In preparing the multilayer body 110 of (1-1) above, no diffusing agent was added to the material for the concavo-convex structure layer. On the other hand, the same diffusing agent as used in (1-1) above was added to the acid-modified polyolefin resin (refractive index 1.49, Cornova MPO-B130C manufactured by Nippon Cima Co., Ltd.) in 10% (volume ratio) of the total amount of adhesive. In (1-2) above, this was used as an adhesive replacing the acrylic adhesive.
About the obtained surface light source device, the color nonuniformity was measured similarly to (C1-2) of Comparative Example 1-1. FIG. 30 shows the results of obtaining the x value and y value at each observation angle. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.024, 0.034). From this, it can be seen that the color unevenness is significantly reduced as compared with Comparative Example 1-1.

<Comparative Example 1-3>
In preparing the multilayer body 110 of (1-1) above, a multilayer body 110 was prepared in the same manner as in Example 1-2 except that no diffusing agent was added to the adhesive. Got.
About the obtained surface light source device, the color nonuniformity was measured similarly to (C1-2) of Comparative Example 1-1. The x value and y value at each observation angle were determined. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.027, 0.041).

<Comparative Example 1-4>
In the preparation of the multilayer body 110 of (1-1) above, ultraviolet rays are irradiated without pressing the metal mold in forming the concavo-convex structure layer, and as a result, the same material as the concavo-convex structure layer is used instead of the concavo-convex structure layer. A multi-layer body was prepared in the same manner as in Example 1-2 except that a layer (thickness: 100%) layer (thickness: 34 μm) having no concavo-convex structure was formed, and a surface light source device was obtained. .
About the obtained surface light source device, the color nonuniformity was measured similarly to (C1-2) of Comparative Example 1-1. The x value and y value at each observation angle were determined. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.043, 0.053).

<Light extraction amount>
The light extraction amount of the surface light source devices of Example 1-2, Comparative Example 1-3, and Comparative Example 1-4 is obtained from the measurement result of the Y value of the tristimulus value, and the light extraction amount of Comparative Example 1-1 is set to 1. The relative amount was determined. As a result, the light extraction amount in Example 1-2 was 1.38, the light extraction amount in Comparative Example 1-3 was 1.29, and the light extraction amount in Comparative Example 1-4 was 1. 24.
The surface light source device of Example 1-2 had significantly improved light extraction efficiency as compared with the surface light source device of Comparative Example 1-1 that did not have an uneven structure that increased light extraction efficiency. Further, the surface light source device of Example 1-2 has the same uneven structure as that of Example 1-2, but also compared with the surface light source device of Comparative Example 1-3 that does not have a diffusing member. As compared with the surface light source device of Comparative Example 1-4 having the same diffusing member but not having the uneven structure, a large improvement in light extraction amount was recognized.

<Reference Example 1-1: Scratch resistance>
Except for changing the shape of the metal mold, the same procedure as in (1-1) of Example 1-1 was performed to obtain several multilayer bodies having different concavo-convex structure shapes. In the obtained multilayer body, the shape of the concave portions was the same, but the flat portion ratio was changed variously by changing the distances 11J and 11K between the concave portions.
Several obtained multilayered bodies were placed horizontally, and the sapphire needle having a diameter of 2 mm was pressed against the sapphire needle vertically while being loaded, and moved in the horizontal direction. It was visually determined whether or not the needle was damaged as a result of the movement. The load was gradually lowered to determine the load (g) at which scratches were not generated. The relationship between the load at which scratches do not occur and the flat portion ratio is plotted in FIG. From the results of FIG. 31, it can be seen that the greater the flat portion ratio, the better the scratch resistance.

<Reference Example 1-2: Light extraction efficiency pyramid>
The light extraction efficiency was calculated by simulation assuming a surface light source device composed of the following organic EL element and light-emitting surface structure layer.
The organic EL element had a light emitting layer, a transparent electrode, and a reflective electrode. The reflection electrode reflectance was 85%, and the light emission characteristics of the light emitting layer were in accordance with Lambert distribution.
The light-emitting surface structure layer is a plate-like body having a thickness of 20 μm, and is made of a transparent material having a refractive index of 1.53, or a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43 is added to the entire material. It consisted of what was added in the ratio of 7.5%. The concavo-convex structure on the light-emitting surface structure layer was formed by arranging concave portions having a regular quadrangular pyramid shape (vertical angle 60 °, base 20 μm) similarly to the concavo-convex structure layer in FIG. The flat portion ratio was variously changed by changing the distances 11J and 11K between the concave portions.
This light-emitting surface structure layer was placed on the surface of the organic EL element on the transparent electrode side to form a surface light source device.

  The relative light extraction efficiency was determined with 1.00 as the case where there was no diffusing agent and the flat portion ratio was 100%. The results are shown in Table 1.

<Reference Example 1-3: Light extraction efficiency hemisphere>
The light extraction efficiency was calculated by simulation assuming a surface light source device composed of the following organic EL element and light-emitting surface structure layer.
The organic EL element had a light emitting layer, a transparent electrode, and a reflective electrode. The reflection electrode reflectance was 85%, and the light emission characteristics of the light emitting layer were in accordance with Lambert distribution.
The light-emitting surface structure layer is a plate-like body having a thickness of 20 μm, and is made of a transparent material having a refractive index of 1.53, or a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43 is added to the entire material. It shall consist of what was added in the ratio of 10.0%. The concavo-convex structure on the light-emitting surface structure layer has hemispherical (diameter 20 μm) recesses arranged in the same manner as the concavo-convex structure layer in FIG. The interval between the concave portions was changed, and the flat portion ratio was changed variously.
This light-emitting surface structure layer was placed on the surface of the organic EL element on the transparent electrode side to form a surface light source device.

  The relative light extraction efficiency was determined with 1.00 as the case where there was no diffusing agent and the flat portion ratio was 100%. The results are shown in Table 2.

  From the results of Table 1 and Table 2, when the light exit surface structure layer does not contain a diffusing agent, the light extraction efficiency decreases significantly when the flat portion ratio increases, whereas when the light exit surface structure layer contains a diffuser, It can be seen that such a significant decrease in light extraction efficiency is alleviated, and as a result, both high light extraction efficiency and high scratch resistance can be achieved.

<Example 1-3>
In preparing the multilayer body 110 of (1-1) above, the multilayer body 110 was prepared in the same manner as in Example 1-1 except that the shape of the metal mold was changed, and a surface light source device was obtained. . In the obtained multilayer body, the shape of the concave portion was substantially the same as that in Example 1-1. However, the flat portion has two kinds of high portions, such as flat portions 914 and 915 shown in FIG. It consisted of a flat part having a thickness. The difference in height between the two types of flat portions was 2 μm.
When the reflection image of the surface of the obtained surface light source device was observed without being turned on, it was observed that rainbow unevenness was reduced.

[Example of refractive index of adhesive layer]
In the embodiment according to the first aspect of the present invention, the light-emitting surface structure layer includes a multilayer body including an uneven structure layer and a base film layer, a glass substrate, and an adhesive layer that bonds the multilayer body and the glass substrate. Configured. In this case, when the adhesive layer is a layer having light diffusibility, the refractive index of the matrix material constituting the adhesive layer is a matrix constituting the adhesive surface of the multilayer body (in this case, the base film layer). It is preferably greater than the refractive index of the material. “Large” means that the difference is at least 0.01 or more, the difference is preferably 0.05 or more, and more preferably 0.15 or more. In this case, the difference between the refractive index of the glass substrate and the refractive index of the adhesive layer is preferably small. “Small” means that the difference is at least 0.15, preferably the difference is 0.1 or less, and more preferably 0.05 or less. The advantage of such a configuration was calculated by the following simulation.

  Such a configuration is not limited to the first aspect of the present invention, and is the same in the second aspect of the present invention. That is, in the embodiment according to the second aspect of the present invention, the concavo-convex structure is, for example, a glass substrate provided on the surface of the second electrode layer, the concavo-convex structure body, and an adhesive layer that bonds the substrate and the concavo-convex structure body. And configured. At this time, when the adhesive layer is a layer having light diffusibility, the refractive index of the matrix material constituting the adhesive layer is preferably larger than the refractive index of the matrix material constituting the adhesive surface of the concavo-convex structure body. . “Large” means that the difference is at least 0.01 or more, the difference is preferably 0.05 or more, and more preferably 0.15 or more. In this case, the difference between the refractive index of the glass substrate and the refractive index of the adhesive layer is preferably small. “Small” means that the difference is at least 0.15, preferably the difference is 0.1 or less, and more preferably 0.05 or less.

<Example 1-4>
Corresponding to FIG. 2, the light extraction efficiency was calculated by simulation assuming a surface light source device composed of the following organic EL element and light output surface structure layer.

The organic EL element had a light-emitting layer with a refractive index of 1.9, a transparent electrode with a refractive index of 1.9, and a reflective electrode. The reflection electrode reflectance was 100%, and the light emission characteristics of the light emitting layer were in accordance with Lambert distribution.
The concavo-convex structure layer is a plate-like body having a thickness of 20 μm, made of a transparent material having a refractive index of 1.53, and concave portions having a regular quadrangular pyramid shape (vertical angle 60 °, base 20 μm) at a pitch of 25 μm, as shown in FIG. It was arranged in the same manner as the uneven structure layer.
The base film layer was a plate having a thickness of 100 μm and had a refractive index of 1.53.
The glass substrate was a material having a thickness of 500 μm and a refractive index of 1.7.

The following aspects 1 and 2 were set for the adhesive layer.
(Aspect 1)
A plate-like body having a thickness of 15 μm, and a transparent material as a matrix material having a refractive index of 1.7, containing a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43 in a ratio of 30% in the total volume. Aspect used (Aspect 1).
(Aspect 2)
A plate-like body having a thickness of 15 μm and containing a transparent material as a matrix material having a refractive index of 1.53 and containing a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43 at a ratio of 30% in the total volume. Aspect used (Aspect 2).

In aspect 1, the refractive index difference between the refractive index of the matrix material constituting the adhesive layer and the material constituting the base film layer is 0.17 (= 1.7−1.53), and constitutes the adhesive layer. The refractive index difference between the refractive index of the matrix material and the material constituting the glass substrate was 0 (= 1.7 to 1.7).
Moreover, in aspect 2, the refractive index difference between the refractive index of the matrix material constituting the adhesive layer and the material constituting the base film layer is 0 (= 1.53 to 1.53), and constitutes the adhesive layer. The refractive index difference between the refractive index of the matrix material and the material constituting the glass substrate was 0.17 (= 1.7−1.53).

  In the above, when the relative light extraction efficiency was obtained for the case of aspect 1 and the case of aspect 2, the light extraction efficiency in case of aspect 1 was 1.3 times the light extraction efficiency in case of aspect 2. Met. For this reason, it turned out that light extraction efficiency can be improved further by setting it as the above-mentioned composition.

[Description of Examples and Comparative Examples Related to Second Invention]
<Comparative Example 2-1>
(C1-1: Production of organic EL element, production of surface light source device)
A surface light source device was produced in the same manner as Comparative Example 1-1. The obtained surface light source device is referred to as a surface light source device A. The surface light source device A had a rectangular light exit surface capable of emitting white light from the glass substrate side.

(C1-2: Evaluation)
About the obtained surface light source device A, the color nonuniformity by the change of an observation angle was measured like comparative example 1-1.
Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.050, 0.058).

  In the second aspect of the present invention, the color unevenness evaluation of the surface light source device is evaluated based on the chromaticity difference. However, as a criterion for determining the chromaticity difference, from the viewpoint that there is no practical problem, (Δx, Δy) = (0.025, 0.025) or less is adopted.

<Example 2-1>
The uneven structure main body 2044 prepared by the following procedure was attached to the surface light source device A obtained in Comparative Example 2-1, and a surface light source device schematically shown in FIG. 19 was produced and evaluated. However, although FIG. 19 schematically shows an organic EL element composed of only three layers, the surface light source device manufactured in this example includes an organic EL element including more light emitting layers. Yes.

(1-1: Fabrication of concavo-convex structure body 2044)
A UV (ultraviolet) curable resin (urethane acrylate resin, refractive index n = 1.54) is added with a diffusing agent (silicone resin, n = 1.43) which is a spherical particle having an average particle diameter of 2 μm in the total amount of the composition. The mixture was added at 10% (volume ratio) and stirred to disperse the particles to obtain a resin composition.

After applying the resin composition obtained above onto a base film (ZEONOR film manufactured by Nippon Zeon Co., Ltd.), a metal mold having a predetermined shape is pressed onto the coating film of the resin composition, and ultraviolet rays are applied from the base film side. Was irradiated with an integrated light quantity of 1000 mJ / cm ² to form a concavo-convex structure layer on the base film, and a concavo-convex structure main body 2044 which was a rectangular film having a base film / concave structure layer structure was obtained.

  In the concavo-convex structure body 2044, the concavo-convex structure 2041 on the concavo-convex structure layer 2047 includes a plurality of regular quadrangular pyramid-shaped concave portions and flat portions located around the concave portions. The angle formed by the inclined surface constituting the recess and the flat portion was 60 °. The length of the bottom side of the recess was 16 μm, and the interval between the recesses was 4 μm, which was a constant interval. The bottom side of the concave portion was parallel to the long side or short side direction of the concavo-convex structure main body 2044. The thickness of the concavo-convex structure layer 2047 (corresponding to the thickness of the diffusion portion) was 34 μm, and the thickness of the base film 2045 was 100 μm. Moreover, the ratio of the flat part was 36%.

(1-2: Production of surface light source device)
The concavo-convex structure main body 2044 is attached to the glass substrate of the surface light source device obtained in Comparative Example 2-1, via an adhesive (acrylic resin, refractive index 1.49, Nitto Denko Corporation CS9621), A surface light source device B was obtained. The thickness of the adhesive layer 2046 was 25 μm.

(1-3: Evaluation)
About the obtained surface light source device B, the color nonuniformity was measured similarly to Comparative Example 2-1. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.011, 0.013). From this, it can be seen that the color unevenness is significantly reduced as compared with Comparative Example 2-1.

<Comparative Example 2-2>
In producing the concavo-convex structure main body 2044, except that no diffusing agent was added to the material for the concavo-convex structure layer (corresponding to no diffusion part), the concavo-convex structure main body 2044 was produced in the same manner as in Example 2-1, A surface light source device C was obtained and measured in the same manner as described above. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.028, 0.040). From this, it can be seen that the color unevenness is slightly reduced as compared with Comparative Example 2-1.

<Light extraction amount>
The light extraction amounts of the surface light source devices A to C of Comparative Example 2-1, Example 2-1 and Comparative Example 2-2 are obtained from the Y values of the tristimulus values calculated based on the measurement results, and Comparative Example 2 The relative amount when the light extraction amount of -1 was 1 was determined. As a result, the light extraction amount in Example 2-1 was 1.43, and the light extraction amount in Comparative Example 2-2 was 1.37. The surface light source device B of Example 2-1 had significantly improved light extraction efficiency compared to the surface light source device A of Comparative Example 2-1 that did not have an uneven structure that increased light extraction efficiency. The surface light source device B of Example 2-1 further has the same concavo-convex structure 2041 as that of Example 2-1, but compared with the surface light source device C of Comparative Example 2-2 that does not have a layer imparting light diffusibility. Also, a great improvement in the amount of light extraction was observed.

<Example 2-2>
(2-1: Production of transparent resin base film)
Both surfaces of a film made of an alicyclic olefin polymer (manufactured by Nippon Zeon Co., Ltd., ZEONOR film) were subjected to corona discharge treatment. An aqueous solution of 5% polyvinyl alcohol was applied to one side of the film using a # 2 wire bar, and the coating film was dried to form an alignment film having a thickness of 0.1 μm. Next, the alignment film was rubbed to prepare a transparent resin substrate film having the alignment film.

(2-2: Formation of cured liquid crystal layer)
A cholesteric liquid crystal composition for constituting a cured liquid crystal layer was prepared with the following composition.
Solid content 40% by weight
Liquid crystalline compound (Δn (ne-no) = 0.13 rod-like liquid crystal compound 95.70 parts by weight Photopolymerization initiator (trade name IRG907 manufactured by Ciba Specialty Chemicals) 3.1 parts by weight Surfactant (Seimi Chemical Co., Ltd., trade name KH-40) 0.11 parts by weight Chiral agent (BASF Corp., trade name LC756) 4.03 parts by weight Solvent Methyl ethyl ketone 154.82 parts by weight

This cholesteric liquid crystal composition was applied to the surface having the alignment film of the transparent resin substrate film having the alignment film prepared in (2-1) above using a # 4 wire bar. The coating film was dried at 100 ° C. for 5 minutes and subjected to orientation aging. The coating film was further irradiated with ultraviolet rays of 1.0 mJ / cm ² (UV-A: 365 nm ± 5 nm), held at 100 ° C. for 1 minute, and then irradiated with ultraviolet rays of 500 mJ / cm ² to cure the coating film, A circularly polarized light separating sheet in which a selective reflection layer having a dry film thickness of 2 μm was provided on a base film through an alignment film was produced. When the reflection spectrum of the obtained circularly polarized light separating sheet was measured using a spectrophotometer (JASCO V-550 manufactured by JASCO Corporation), it had selective reflection characteristics as shown in FIG.

(2-3: Preparation of organic EL element)
An organic EL element including a second electrode layer, a light emitting layer, and a first electrode layer was provided on one surface of a glass substrate having a thickness of 1.1 mm to obtain a surface light source device E. At this stage, a current was applied to the organic EL element of the surface light source device E, and the light distribution of blue light having a wavelength of 480 nm and yellow light having a wavelength of 575 nm emitted from the glass substrate was measured. The result shown in FIG. Obtained. When the obtained surface light source device E was measured for color unevenness in the same manner as in Comparative Example 2-1, within the range of the observation angle ± 80 °, (Δx, Δy) = (0.129, 0.128). there were.

(2-4: Preparation of diffusion layer)
20% (volume by volume) of the same diffusing agent used in (1-1) of Example 2-1 for acid-modified polyolefin resin (refractive index: 1.49, Nippon Cima Corp., MPO-B130C) The adhesive (diffusion layer) was prepared by adding at a ratio.

(2-5: Production of surface light source device)
Further, after applying the adhesive prepared in (2-4) with a thickness of 30 μm on the other surface of the glass substrate (the adhesive layer corresponds to the diffusion part), the circularly polarized light separating sheet is The surface light source device D having the configuration shown in FIG. 20 was manufactured by pasting the selective reflection layer so as to face the adhesive. When current was passed through the obtained surface light source device D and the light distribution was measured for blue light having a wavelength of 480 nm and yellow light having a wavelength of 575 nm emitted from the light exit surface 2040A, the results shown in FIG. 25 were obtained.

(2-6: Evaluation)
About the obtained surface light source device D, the color nonuniformity was measured similarly to the comparative example 2-1. Within the range of the observation angle ± 80 °, (Δx, Δy) = (0.017, 0.017). From this, it can be seen that the color unevenness is significantly reduced as compared with the surface light source device E.

<Comparative Example 2-3>
A surface light source device F was obtained in the same manner as in Example 2-2, except that no diffusing agent was added to the adhesive of (2-4), and measured in the same manner as described above. (Δx, Δy) = (0.092, 0.091). Therefore, although the color unevenness is slightly improved as compared with the surface light source device E, the effect of eliminating the color unevenness is not necessarily sufficient as that of the surface light source device D. Further, when a current was passed through the obtained surface light source device F and the light distribution was measured for blue light having a wavelength of 480 nm and yellow light having a wavelength of 575 nm emitted from the light exit surface, the results shown in FIG. 24 were obtained.

  As is clear from the comparison of the results of FIGS. 23 to 25, the surface light source device of the present invention including the diffusion layer (adhesive layer) and the circularly polarized light separating sheet in addition to the light emitting element includes the circularly polarized light separating sheet and the diffused layer. It can be seen that the difference in light distribution between blue light and yellow light is smaller than that of a light-emitting element that is not provided, and the change in color depending on the observation angle is small.

<Reference Example 2-1>
Here, the color unevenness evaluation in the case where the diffusion layer is provided on the light output side of the organic EL element and the addition amount of the diffusing agent is changed without providing the uneven structure and the selective reflection layer as in the present invention will be described.
A UV (ultraviolet) curable resin (urethane acrylate resin, refractive index n = 1.54) is added with a diffusing agent (silicone resin, n = 1.43) which is a spherical particle having an average particle diameter of 2 μm in the total amount of the composition. The mixture was added at 10% (volume ratio) and stirred to disperse the particles to obtain a resin composition. This resin composition is applied on the glass substrate of the surface light source device used in Example 2-1, and cured by irradiating with ultraviolet rays to obtain a diffusion layer having a predetermined thickness on the surface of the organic EL element. It was. Specifically, the application amount of the resin composition was changed, and three types having a thickness of 30 μm, a thickness of 50 μm, and a thickness of 100 μm were produced. The chromaticity difference was calculated | required about each of the surface light source device provided with these diffusion layers. Moreover, the total light transmittance was measured about what formed the diffused layer so that thickness might be separately 30 micrometers, 50 micrometers, and 100 micrometers on the said glass-made board | substrates. The results are shown in Table 3.

  As shown in Reference Example 2-1, in order to improve the chromaticity difference (acceptance standard) to the same level as in Examples 2-1 and 2-2, the thickness of the diffusion layer is increased to about 100 μm. I understand that I have to. On the other hand, in Examples 2-1 and 2-2, the thicknesses of the layers constituting the diffusion part are about 30 μm, so the thickness of the diffusion part is set so as not to impair the productivity and thinning. Can be suppressed.

DESCRIPTION OF SYMBOLS 10 Surface light source device 10U Device light emission surface 100 Light emission surface structure layer 110 Multi-layer body 111 Uneven structure layer 112 Base film layer 113 Recess 114 Flat part 11A-11D Slope 11E-11H Bottom 11P Vertex 121 Adhesive layer 131 Glass substrate 140 Organic EL Element 141 Electrode layer 142 Light emitting layer 143 Electrode layer 146 Electrode layer 151 Sealing substrate 20 Surface light source device 20U Device light exit surface 200 Light exit surface structure layer 210 Multi-layered body 211 Concavity and convexity structure layer 213 Concavity 214 Flat portion 30 Surface light source device 30U Device light exit Surface 300 Light-emitting surface structure layer 310 Multi-layer body 311 Concavity and convexity structure layer 313 Recessed portion 314 Flat portion 40 Surface light source device 40U Device light-emitting surface 400 Light-emitting surface structure layer 410 Multi-layer body 411 Concavity and convexity structure layer 413 Concavity 41T, 41U, 41V Slope 414 Flat Part 50 Surface light source device 55 Reflective member 552 Reflective member substrate 553 Gap 80 Surface light source device 80U Device light exit surface 800 Light exit surface structure layer 810 Multi-layer body 811 Concavity and convexity structure layer 813 Concavity portion 814 Flat portion 815 Boundary portion between adjacent concave portions 816 Concavity portion 821 Concavity and convexity structure layer 90 surface Light source device 90U Device light exit surface 900 Light exit surface structure layer 910 Multi-layer body 911 Concavity and convexity structure layer 913 Recess 914, 915 Flat portion 1000 Surface light source device 2001, 2002, 2003, 3004 Surface light source device 2020 Organic EL element 2022 First electrode layer 2024 Light emitting layer 2026 2nd electrode layer 2028 1st electrode layer 2040 Irregular structure 2040A Light emission surface 2041 Irregular structure 2042 Substrate 2044 Irregular structure body 2045 Base material 2046 Adhesive layer 2047 Irregular structure layer 2048 Concave 2048A Slope 2049 Flat part 2060 Light emission side member 2062 Selective reflection member 2064 Base film 2066 Selective reflection layer 2070 Diffusion layer

Claims (9)

A first electrode layer, a light emitting layer, and a second electrode layer are provided in this order, and the organic electroluminescent element whose light emitter is planar is disposed in contact with at least one surface of the organic electroluminescent element, A light output side member having a light output surface for emitting light to the outside, and a surface light source device comprising:
The light emission side member is:
The light distribution of the light emitted from the organic electroluminescence element is changed from chromaticity of light emitted from the light emitting surface along the normal direction of the light emitting surface, along the oblique direction intersecting with the normal direction. A light distribution distribution converter for converting the light distribution distribution unit so as to reduce the difference between the chromaticity of the light emitted from the light exit surface;
A diffusion part for diffusing the light emitted from the organic electroluminescence element ,
The light distribution distribution conversion unit includes an uneven structure layer having an uneven structure formed on the surface,
The concave-convex structure layer, a surface light source device that is configured with a composition comprising particles for imparting light diffusing properties. The surface light source device according to claim 1,
The surface light source device, which is a layer formed of a composition including particles that are disposed between the light distribution distribution conversion unit and the organic electroluminescence element and that impart light diffusibility. The surface light source device according to claim 1,
The surface light source device, wherein the diffusion unit is a layer formed of a composition including particles that are provided on the light output side of the light distribution distribution conversion unit and impart light diffusibility. In the surface light source device according to any one of claims 1 to 3,
The light distribution distribution conversion unit includes a base material ,
The concave-convex structure layer, the provided on the surface of the substrate, opposite to a surface light source device uneven structure is formed on the surface of said substrate. The surface light source device according to claim 4 ,
The said base material is a surface light source device comprised by the composition containing the particle | grains which provide light diffusibility. In the surface light source device according to any one of claims 1 to 5,
A surface light source device, wherein the light output side member includes an adhesive layer, a glass substrate, and a second diffusing portion provided on a surface of the glass substrate on a light emitting layer side. In the surface light source device according to any one of claims 1 to 6,
The concavo-convex structure of the concavo-convex structure layer includes a plurality of concave portions and a flat portion separating the adjacent concave portions,
When the concavo-convex structure layer is observed from the direction perpendicular to the light exit surface, the ratio of the area occupied by the flat portion to the total of the area occupied by the flat portion and the area occupied by the concave portion is 10 to 75%. A surface light source device. Lighting instrument comprising a surface light source device according to any one of claims 1-7. Backlight apparatus including the surface light source device according to any one of claims 1-7.

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