JP5402273B2 - 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, it is necessary to improve the light extraction efficiency of the organic EL element.

  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.

  However, when these structures are employed in the above-described laminated organic EL element for illumination, the light exit surface is caused by the fact that the depth from the light exit surface to the light emitting layer differs depending on the light emitting layer of each color. There is a problem that the tint is greatly different between when the image is observed from the front and when observed from an angle inclined from the front.

  Furthermore, when a concavo-convex structure such as a prism is provided on the light exit surface of the light source device, there is a problem that it is difficult to increase the mechanical strength of the device because the top of the concavo-convex structure is easily chipped.

Japanese Patent Application Laid-Open No. 2002-237381 JP 2003-59641 A

  An object of the present invention is to provide a surface light source device, a luminaire, and a backlight device that have high light extraction efficiency, little change in color depending on an observation angle, and high mechanical strength.

  As a result of diligent research to solve the above problems, the present inventors have solved the above problems by providing a light emitting surface of the surface light source device with a specific structure and providing a diffusing member in the surface light source device. Based on this finding, the present invention has been completed.

That is, according to the present invention, the following [1] to [12] are provided.
[1] An organic electroluminescent element including a light emitting layer, and a surface light source device provided with a light-emitting surface structure layer that is provided in contact with one surface of the organic electroluminescent element and defines a concavo-convex structure on the surface of the device light-emitting surface There,
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 enters the 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 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 at a position farther from the light exit surface structure layer than the organic electroluminescence element. Light source device.
[2] The surface light source device, wherein the diffusing member is a member provided as a layer constituting a part or all of the light-emitting surface structure layer, and transmits incident light in a diffused manner. .
[3] The surface light source device, wherein the diffusing member is an adhesive layer interposed between two layers in 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.
[11] A luminaire including the surface light source device according to any one of [1] to [10].
[12] A backlight device including the surface light source device according to any one of [1] to [10].

The surface light source device of the present invention has high light extraction efficiency, little change in color depending on the viewing angle, and high mechanical strength of the light exit surface of the device, so that the light source of the lighting fixture and the display device such as a liquid crystal display device It is useful as a backlight.
Since the lighting fixture and backlight device of the present invention have the surface light source device of the present invention, the lighting fixture and backlight device have high light extraction efficiency, little change in color depending on the observation angle, and high mechanical strength. It can be.

1 is a perspective view schematically showing a surface light source device according to a first embodiment of the present invention. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device shown in FIG. 1 by the surface perpendicular | vertical to an apparatus light emission surface which passes along line 1a-1b in FIG. It is a top view which shows typically the surface light source device which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device shown in FIG. 3 by the surface perpendicular | vertical to an apparatus light emission surface which passes along line 1a-1b in FIG. It is a perspective view which shows typically the surface light source device which concerns on the 3rd Embodiment of this invention. It is a top view which shows typically the surface light source device which concerns on the 4th Embodiment of this invention. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device shown in FIG. 6 by the surface which passes along the line | wire 3a in FIG. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device which concerns on the 5th Embodiment of this invention by the surface perpendicular | vertical to an apparatus light emission surface. It is a top view which shows typically the surface light source device which concerns on the 6th Embodiment of this invention. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device shown in FIG. 9 by the surface perpendicular | vertical to an apparatus light emission surface which passes along the line 4a in FIG. It is a partial top view which expands and shows the structure of the apparatus light emission surface 10U of the surface light source device 10 shown in FIG. It is a fragmentary sectional view which shows the cross section which cut | disconnected the uneven structure layer 111 shown in FIG. 11 by the perpendicular | vertical surface which passes along the line 10a of FIG. It is a fragmentary sectional view which shows the modification of the recessed part shown in FIG. It is a fragmentary sectional view which shows another modification of the recessed part shown in FIG. It is a top view which shows typically the surface light source device which concerns on the 7th Embodiment of this invention. It is sectional drawing which shows the cross section which cut | disconnected the surface light source device shown in FIG. 15 by the surface perpendicular | vertical to an apparatus light emission surface which passes along the lines 11a and 11b in FIG. 10 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. 6 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. It is a graph which shows the relationship between the measurement angle of chromaticity, and chromaticity x and y value by the measurement result of Example 2. 6 is a graph showing a relationship between a flat portion ratio and a load according to a measurement result of Reference Example 1.

<First Embodiment>
In the following, the present invention will be described in more detail with reference to the drawings.
The surface light source device of the present invention includes an organic EL element including a light-emitting layer, and a light-emitting surface structure layer that is provided in contact with one surface of the organic EL element and defines a concavo-convex structure on the device light-emitting surface side.
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 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 present invention, for example, an error of ± 5 ° from a parallel or vertical angle. May be included.

  FIG. 1 is a perspective view schematically showing a surface light source device according to the first embodiment of the present invention. In the first embodiment, the surface light source device 10 is a device having a rectangular flat plate 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.

  The organic EL element 140 includes a first electrode layer 141, a light emitting layer 142, and a second electrode layer 143. In the first embodiment, 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 the concavo-convex structure layer 111 and the base film layer 112, a glass substrate 131 as a substrate, and an adhesive layer 121 that bonds the multilayer body 110 and the glass substrate 131. . In the surface light source device 10, one or more of the concavo-convex structure layer 111, the base film layer 112, the adhesive layer 121, and the glass substrate 131 are made of a material containing a diffusing agent, thereby diffusing incident light. A diffusing member that transmits or reflects.

  The concavo-convex structure layer 111 is located on the upper surface of the surface light source device 10 (that is, the outermost layer on the light output surface side of the surface light source device 10), and includes concavo-convex portions including a plurality of recesses 113 and flat portions 114 positioned around the recesses 113. It has a structure. The light exit surface 10U is defined by the uneven 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 present invention, the organic EL element includes two or more electrode layers, a light emitting layer that is provided between these electrode layers and emits light when a voltage is applied from the electrodes. It can be set as the element provided with these.

  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 present invention may be any of these, and in the case of a bottom emission type, a combination of a substrate for forming a layer and an optional layer as necessary is a light emitting surface structure layer. On the other hand, in the case of the top emission type, a combination including a light emitting surface side structure such as a sealing member and an optional layer as necessary constitutes a light emitting surface structure layer.

  In this invention, it does not specifically limit as a light emitting layer which comprises an organic EL element, A well-known thing can be selected suitably. 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. Like the organic EL element 140 according to the first embodiment, 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; can do. Moreover, by making both electrodes into transparent electrodes and further having a reflecting member on the side opposite to the light-emitting surface structure layer, it is possible to achieve light output to the light-emitting surface structure layer side.

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.
As a material for the red light emitting layer, a europium complex or the like can be used.
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 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 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 output surface structure layer as a whole has a total light transmittance of 80% or more. It can have.
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-emitting surface structure layer includes the concavo-convex structure layer and the substrate film layer as in the light-emitting surface structure layer 100, the refractive index of the concavo-convex structure layer and the substrate film should be as close as possible, preferably the refractive index The difference is 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 components include phenolic / amine-based deterioration inhibitors, surfactant-based / siloxane-based antistatic agents, triazole-based, 2-hydroxybenzophenone-based light-resistant additives, and the like. it can.

  In 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 surface on the substrate side 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 present invention, the light-emitting surface structure layer can further include a substrate such as the glass substrate 131 in the light-emitting surface structure layer 100, thereby giving the surface light source device rigidity to suppress deflection. 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. The refractive index of the substrate is not particularly limited, but can be 1.4 to 2.0. In the present 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 and the transparent resin layer and being 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 present invention is a layer constituting 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 And a diffusing member that diffuses and transmits or reflects the incident light. That is, in the present invention, a part or the whole of the light exit surface structure layer may have a function as a diffusion member, and a separate member as a diffusion member is provided separately from the light exit surface structure layer. May be.

  As in the case of the surface light source device 10 in the first embodiment, when one of the electrode layers of the organic EL element is a reflective electrode and the other is transparent, 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, 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 are layers that diffuse light. Thus, part or all of these layers can be used as a diffusion 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 the diffusibility can be easily adjusted, a material containing particles, particularly a resin composition containing particles, is particularly preferable.

  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% in volume ratio in the total amount of the material constituting the diffusing member, and more preferably 5 to 50%. By doing so, it is possible to obtain a desired effect such as a reduction in change in color depending on the observation angle. 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, It is more preferable that it is 0.07-0.5. 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 exit surface structure layer is used as a diffusing member, which of the layers constituting the light exit surface structure layer is used as a diffusing member is not particularly limited, and from various viewpoints. You can choose. 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 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 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. 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 a part or all of the light exit surface structure layer, the degree of diffusion is not particularly limited, but as an example, the diffusing member may be part or all between the concavo-convex structure layer and the adhesive layer. In some cases, the total light transmittance from the concavo-convex structure layer to the adhesive layer portion in a state where the surface of the concavo-convex structure layer is not uneven is preferably 70 to 95%, more preferably 75 to 90%. preferable.

(Uneven structure)
In the present invention, the concavo-convex structure on the light-emitting surface structure layer includes a plurality of concave portions including inclined surfaces and a flat portion positioned around the concave portion. 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. 11 and 12. FIG. 11 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 concavo-convex structure layer 111. As shown in FIG. FIG. 12 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 of 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 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. 12 respectively) are set to 60 °, for example. The apex angle of the regular quadrangular pyramid, that is, the angle formed by the opposed slopes at the apex 11P (the angle 11N shown in FIG. 12 for the angles formed by the slopes 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 present invention has the above-described configuration, so that the displacement of at least one of the x-coordinate and y-coordinate of the chromaticity coordinate in all hemispherical directions on the light-emitting surface is not compared with the case where the above configuration is not used. 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 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. 12, the top portion 11P of the quadrangular pyramid has a pointed shape, but this may have a rounded shape like the top portion 61P of the concave portion 613 shown in FIG. Further, a flat portion 71P may be provided at the top of the pyramid, as in the concave portion 713 shown in FIG.

  As shown in FIG. 13, when the apex of the pyramid has a rounded shape, the height difference 61R between the apex 61P and the apex 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. 14, 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 advantageous for maintaining the durability of the concavo-convex structure layer is used as the material of the concavo-convex structure layer, reducing the thickness of the concavo-convex structure layer increases the flexibility of the multilayer body. Handling of the multilayer body in the manufacturing process of the light source device is facilitated. Specifically, the thickness 16E of the uneven structure layer 111 with respect to the depth 16D of the recess shown in FIG. 12 is preferably 0 to 30 μm.

  In the present invention, the angle formed by the inclined surface of the recess and the light exit surface 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, 11 and 12, the apex angle (corner 11P in FIG. 12) 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. 13 and 14, the surfaces 613a, 613b, 713a, and 713b are inclined pyramids. 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 recesses can be arranged along two or more directions 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. 11, gaps with intervals 11J and 11K are provided in two orthogonal directions, respectively, and the flat part 114 is configured by such 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 present invention is not particularly limited, when manufacturing the 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, Each layer constituting the organic EL element is laminated on one surface of the glass substrate, and thereafter or before that, a multilayer body having a concavo-convex structure layer and a base film on the other surface of the glass substrate is interposed via an adhesive layer. It can be manufactured by sticking.

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) 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 is not yet formed) is prepared, 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) A resin composition B in a liquid state was applied on the base film and applied. A method may be mentioned in which a mold is applied to the layer of the resin composition B, the resin composition B is cured in that state, and a concavo-convex structure layer is formed.

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 5 seconds or more and 600 seconds or less.

  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.

<Second Embodiment>
In the surface light source device 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 first embodiment, and for example, as in the second embodiment shown below, The shape of the part may be sufficient.
FIG. 3 is a top view schematically showing a surface light source device according to the second embodiment of the present invention, and FIG. 4 shows the surface light source device shown in FIG. 3 along line 1a-1b in FIG. FIG. 3 is a cross-sectional view showing a cross section cut along a plane perpendicular to the device light exit surface. As shown in FIGS. 3 and 4, the surface light source device 20 according to the second embodiment has the shape of the device light exit surface, that is, the surface of the concavo-convex structure layer 211 in the multilayer body 210 constituting the light exit surface structure layer 200. Except for the difference in shape, it has the same configuration as the first embodiment.

  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 in the same manner as the pyramid-shaped concave portion in the first embodiment. 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.

<Third Embodiment>
In the surface light source device of the present invention, the shape of the recess constituting the device light exit surface may also be a groove shape as in a third embodiment described below.
FIG. 5 is a perspective view schematically showing a surface light source device according to the third embodiment of the present invention. As shown in FIG. 5, the surface light source device 30 according to the third embodiment is different in the shape of the device light exit surface, that is, the shape of the surface 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 first embodiment.

  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. A cross section cut by a plane perpendicular to the cross section 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 structure having a groove-shaped recess and a flat portion that is a gap between them, light is emitted in the same manner as the pyramid-shaped recess in the first embodiment. 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, as described above in connection with the first embodiment, the top of the pyramid or cone is shaped like a rounded shape or a flat chamfered shape. The shape may be transformed into a shape with rounded vertices or a flat chamfered shape.

<Fourth Embodiment>
In the surface light source device of the present invention, when the shape of the recess constituting the device light-emitting surface is a pyramid shape, the pyramid shape is not limited to the simple pyramid shape exemplified as the first embodiment, and for example, As in the fourth embodiment shown, each recess may have a shape in which a plurality of pyramids are combined.

  FIG. 6 is a top view schematically showing a surface light source device according to the fourth embodiment of the present invention, and FIG. 7 is a device passing the surface light source device shown in FIG. 6 along the line 3a in FIG. It is sectional drawing which shows the cross section cut | disconnected by the surface perpendicular | vertical to the light emission surface. As shown in FIGS. 6 and 7, the surface light source device 40 according to the fourth embodiment includes the shape of the device light-emitting surface 40 </ b> U, that is, in the concavo-convex structure layer 411 in the multilayer body 410 constituting the light-emitting surface structure layer 400. The configuration of the concave portion 413 is the same as that of the first embodiment except that the shape of the concave portion 413 is different from the concave portion 113 in the first embodiment.

  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 1st Embodiment.

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

<Fifth Embodiment>
In the first to fourth embodiments 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. However, the diffusing member in the surface light source device of the present invention is not limited to this, and is incident at a position farther from the light emitting surface structure layer than the organic EL element, as exemplified in the fifth embodiment shown below. It may be a member that diffuses and reflects light.

  FIG. 8: is sectional drawing which shows the cross section which cut | disconnected the surface light source device which concerns on the 5th Embodiment of this invention by the surface perpendicular | vertical to an apparatus light emission surface. As shown in FIG. 8, the surface light source device 50 according to the fifth embodiment includes, as a second electrode layer, an electrode layer 144 that is a second transparent electrode instead of the reflective electrode 143, and a sealing substrate. Instead of 151, it differs from the first embodiment in that it has a reflecting member 551 and a reflecting member substrate 552, and is otherwise the same as the first embodiment.

  In the surface 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). Thus, 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 the first embodiment, a layer constituting a 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 the fifth embodiment, a reflecting member is used. The same effect as that of the diffusing member in the light-emitting surface structure layer can be obtained by the reflection of the light diffused by 551. Therefore, the effect of the present invention can be obtained without providing the diffusing member in the light-emitting surface structure layer. be able to. 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 the first embodiment may 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 144 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 scattering plate made of an arbitrary material having a white surface may be used to reflect incident light in a diffused manner.

<Sixth Embodiment>
In the first embodiment and the other embodiments described above, when the quadrangular pyramids are arranged along the two directions of the device light exit surface, the flat portion has a gap between the quadrangular pyramids adjacent in both of the two directions. However, the present invention is not limited to this. For example, a gap may be provided in only one of two directions as in a sixth embodiment described below.

  FIG. 9 is a top view schematically showing a surface light source device according to a sixth embodiment of the present invention, and FIG. 10 is a device that passes the surface light source device shown in FIG. 9 along a line 4a in FIG. It is sectional drawing which shows the cross section cut | disconnected by the surface perpendicular | vertical to the light emission surface. As shown in FIGS. 9 and 10, the surface light source device 80 according to the sixth embodiment has the shape of the device light exit surface, that is, the surface of the concavo-convex structure layer 811 in the multilayer body 810 constituting the light exit surface structure layer 800. Except for the difference in shape, it has the same configuration as the first embodiment.

  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 first embodiment, 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 first embodiment, 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.

<Seventh Embodiment>
In the first to seventh embodiments, the flat portion on the concavo-convex structure layer has no difference in height (that is, the height when the device light-emitting surface is placed so as to be parallel to the horizontal direction and upward) Although all have a uniform height, the present invention is not limited to this, and for example, there may be a difference in height of the flat portion as in a seventh embodiment described below.

  FIG. 15 is a top view schematically showing a surface light source device according to a seventh embodiment of the present invention. FIG. 16 shows the surface light source device shown in FIG. 15 through lines 11a and 11b in FIG. FIG. 3 is a cross-sectional view showing a cross section cut along a plane perpendicular to the device light exit surface. As shown in FIGS. 15 and 16, the surface light source device 90 according to the seventh embodiment includes the shape of the device light exit surface, that is, the surface of the concavo-convex structure layer 911 in the multilayer body 910 constituting the light exit surface structure layer 900. Except for the difference in shape, it has the same configuration as the first embodiment.

  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 the first embodiment, but a flat portion 914 having a low height and a height between the recesses 913 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 911 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. 11, 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. There is a possibility that interference occurs in the light from the light exit surface of the apparatus and rainbow unevenness occurs. Here, by setting the dimensional difference between the heights of the two types of flat portions 914 and 915 to be a dimensional difference that exceeds the difference that causes interference of the emitted light, the occurrence of interference is prevented and rainbow unevenness is suppressed. be able to. The dimensional difference exceeding the difference causing interference can 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.

  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. From the above two findings, it can be shown that the dimensional difference exceeding the difference that causes interference is 0.62 times or more the center wavelength of the light emitted from the surface light source device.

<Lighting equipment and backlight device>
The lighting fixture of the present invention and the backlight device of the present invention both include the surface light source device of the present invention.
The lighting fixture of the present invention has the surface light source device of the present invention as a light source, and can further include arbitrary components such as a member for holding the light source and a circuit for supplying power. The backlight device of the present invention has the surface light source device of the present invention as a light source, and further includes a housing, a circuit for supplying electric power, a diffusion plate for making light emitted more uniform, a diffusion sheet, a prism sheet, etc. Optional components. The backlight device of the present invention can be 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.

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 its equivalent scope.
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, rainbow unevenness due to interference is suppressed by adopting an aspect in which one or more elements of the height, width, and interval of the flat portion are provided with a dimensional difference exceeding the difference that causes interference of emitted light. can do.
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.

  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.

<Comparative Example 1>
(C1-1: Formation of organic EL element, production of surface light source device (no multilayer))
On one main surface of a glass substrate having a thickness of 0.7 mm, 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, and a reflective electrode layer 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 of the device exit surface (normal direction), a constant current of the surface light source device 100 mA / m ² is applied, the exit surface is rotated, The viewing direction of the spectral radiance meter was changed, and chromaticity (x, y) was measured. 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).

<Example 1>
The multilayer body 110 prepared by the following procedure was attached to the surface light source device obtained in Comparative Example 1, and a 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 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 amount of 1000 mJ / cm ² to form a concavo-convex structure layer on the base film, and a multilayer body 110 which was a rectangular film having a layer structure of the base film 112-the concavo-convex structure layer 111 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))
The multilayer body 110 obtained in (1-1) is bonded to the surface on the glass substrate 131 side of the surface light source device obtained in (C1-1) of Comparative Example 1 with an adhesive (acrylic resin, refractive index 1.49). A surface light source device including a multilayer structure 110-adhesive layer 121-glass substrate 131-organic EL element 140 layer structure was obtained through CS9621 manufactured by Nitto Denko Corporation. 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 the comparative example 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 color unevenness is significantly reduced as compared with Comparative Example 1.

<Comparative example 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 except that no diffusing agent was added to the material for the uneven structure layer. A light source device was obtained.

<Light extraction amount>
The light extraction amount of the surface light source devices of Comparative Example 1, Example 1 and Comparative Example 2 is obtained from the measurement result of the tristimulus Y value, and the relative amount when the light extraction amount of Comparative Example 1 is 1 is obtained. It was. As a result, the light extraction amount in Example 1 was 1.43, and the light extraction amount in Comparative Example 2 was 1.37.
The surface light source device of Example 1 had significantly improved light extraction efficiency compared to the surface light source device of Comparative Example 1 that did not have an uneven structure that increased light extraction efficiency. The surface light source device of Example 1 was further improved in light extraction amount as compared with the surface light source device of Comparative Example 2 having the same uneven structure as that of the example but having no diffusion member.

<Example 2>
A multilayer body 110 was prepared in the same manner as in Example 1 except that the following points were changed, and a surface light source device was obtained.
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 the comparative example 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) = (0.024, 0.034). From this, it can be seen that color unevenness is significantly reduced as compared with Comparative Example 1.

<Comparative Example 3>
In preparing the multilayer body 110 of (1-1) above, a multilayer body 110 was prepared in the same manner as in Example 2 except that no diffusing agent was added to the adhesive, and a surface light source device was obtained. It was.
About the obtained surface light source device, the color nonuniformity was measured similarly to (C1-2) of the comparative example 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 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 multilayer body was prepared in the same manner as in Example 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 the comparative example 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 2, Comparative Example 3 and Comparative Example 4 is obtained from the measurement result of the Y value of the tristimulus value, and the relative amount when the light extraction amount of Comparative Example 1 is 1 is obtained. It was. As a result, the light extraction amount in Example 2 was 1.38, the light extraction amount in Comparative Example 3 was 1.29, and the light extraction amount in Comparative Example 4 was 1.24.
The surface light source device of Example 2 had significantly improved light extraction efficiency as compared with the surface light source device of Comparative Example 1 that did not have a concavo-convex structure that increased light extraction efficiency. The surface light source device of Example 2 further has the same diffusing member as that of Example 2 compared to the surface light source device of Comparative Example 3 which has the same uneven structure as Example 2 but does not have a diffusing member. Even when compared with the surface light source device of Comparative Example 4 that does not have a concavo-convex structure, a significant improvement in the amount of light extraction was observed.

<Reference Example 1: Scratch resistance>
Except for changing the shape of the metal mold, the same procedure as in (1-1) of Example 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. 20, it can be seen that the greater the flat portion ratio, the better the scratch resistance.

<Reference Example 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 total volume of a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43. It consisted of what was added at a 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) in the same manner as 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 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 total volume of a diffusing agent having a particle diameter of 2 μm and a refractive index of 1.43. It consisted of what was added at a ratio of 7.5%. In the concavo-convex structure on the light-emitting surface structure layer, hemispherical concave portions (diameter 20 μm) were 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 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 except that the shape of the metal mold was changed, and a surface light source device was obtained. In the obtained multilayered body, the shape of the concave portion was substantially the same as that in Example 1, but the flat portion had two kinds of heights like the flat portions 914 and 915 shown in FIG. It consisted of a flat part. 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.

DESCRIPTION OF SYMBOLS 10 Surface light source device 10U Device light emission surface 100 Light emission surface structure layer 110 Multilayer body 111 Concavity and convexity structure layer 112 Base film 113 Recession 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 151 Sealing substrate 20 Surface light source device 20U Device light exit surface 200 Light exit surface structure layer 210 Multi-layer body 211 Concavity and convexity structure layer 213 Concave portion 214 Flat portion 30 Surface light source device 30U Device light exit surface 300 Light exit surface Structure layer 310 Multi-layer body 311 Concavity and convexity structure layer 313 Concavity 314 Flat portion 40 Surface light source device 40U Device light exit surface 400 Light exit surface structure layer 410 Multilayer body 411 Concavity and convexity structure layer 413 Concavity 41T, 41U, 41V Slope 414 Flat portion 50 Device 551 Reflective member 55 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 Recess 814 Flat portion 90 Surface light source device 90U Device light exit surface 900 Light exit surface structure layer 910 Multi-layer body 911 Concavity and convexity Structural layer 913 Recess 914, 915 Flat part

Claims (11)

An organic electroluminescent element including a light emitting layer, and a surface light source device provided with a light emitting surface structure layer that is provided in contact with one surface of the organic electroluminescent element and defines a concavo-convex structure on a surface on the device light emitting surface side,
The light exit surface structure layer has a concavo-convex structure layer made of an ultraviolet curable resin and a base film layer, and the ultraviolet curable resin is formed on the base film layer with a thickness of 7 μm without the concavo-convex structure. If the pencil hardness is HB or higher,
The concavo-convex structure has a plurality of concave portions including slopes, and a flat portion located around each concave portion,
When the concavo-convex structure is observed from a direction perpendicular to the device light exit surface, 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 concave portion is 10 to 75%. Yes,
The surface light source device includes a diffusing member that enters the 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 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 at a position farther from the light exit surface structure layer than the organic electroluminescence element. Light source device. The surface light source device according to claim 1,
The surface light source device, wherein the diffusing member is a member provided as a layer constituting a part or all of the light emitting surface structure layer, and is a member that transmits incident light in a diffused manner. The surface light source device according to claim 2,
The surface light source device, wherein the diffusing member is an adhesive layer interposed between two layers in the light exit surface structure layer. The surface light source device according to claim 3,
The light exit surface structure layer is
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 diffusing member. The surface light source device according to any one of claims 1 to 4,
The diffusing member is a surface light source device made of a material containing particles that impart light diffusibility. The surface light source device according to claim 1,
The surface light source device, wherein the diffusing member is a member provided at a position farther from the light-emitting surface structure layer than the organic electroluminescence element, and is a member that reflects incident light in a diffused manner. The surface light source device according to any one of claims 1 to 6 ,
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 clearance gap comprises the said flat part, The surface light source device. The surface light source device according to any one of claims 1 to 6 ,
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, a clearance gap is provided only in one direction of the said 2 or more directions, The said clearance gap comprises the said flat part, The surface light source device. The surface light source device according to any one of claims 1 to 6 ,
The recess has a groove shape;
The plurality of recesses are arranged in parallel on the device light exit surface,
A surface light source device in which a gap is provided between the adjacent concave portions, and the gap constitutes the flat portion. A lighting fixture comprising the surface light source device according to any one of claims 1 to 9 . Backlight apparatus including the surface light source device according to any one of claims 1-9.

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