JP5672108B2 - Surface light emitting device and lighting apparatus - Google Patents

Description

  The present invention relates to a surface light-emitting element including an organic electroluminescence element (hereinafter also referred to as “organic EL element”) and a lighting fixture including the surface light-emitting element.

  A light-emitting element including an organic EL element can have a planar shape, and the light color can be white or a color close thereto. For this reason, it is possible to use the surface light emitting element provided with an organic EL element for the use as a light source of the lighting fixture which illuminates spaces, such as living environment, or as a backlight of a display apparatus.

  However, currently known organic EL elements are low in efficiency for use in the above-described illumination applications. Therefore, it is desired 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 uneven structures on the light emitting surface of the organic EL element. For example, it has been proposed to provide a structure layer having an uneven structure on the light emitting surface of an organic EL element (see Patent Document 1). With this concavo-convex structure, good light collection can be achieved, and the light extraction efficiency can be improved.

  Furthermore, a see-through type surface light emitting element in which the other side of the surface light emitting element can be looked over by making the electrode of the organic EL element transparent has been studied (see Patent Document 2). The applicant of the present application has proposed an uneven structure suitable for a see-through type surface light emitting device in Japanese Patent Application No. 2010-147787 in order to improve the light extraction efficiency of such a see-through type surface light emitting device.

International Publication No. 2004/017106 Japanese Patent No. 3560375

  As an example of the shape of the surface of the concavo-convex structure provided on the light emitting surface of the organic EL element, there is a shape in which concave portions or convex portions are discretely arranged on a flat surface. In the concavo-convex structure having such a shape, the surface portion on which the concave portion or the convex portion is not formed may include a belt-like surface portion extending in the in-plane direction (hereinafter, sometimes referred to as “band-shaped surface portion”). When such a band-shaped surface portion is included in the concavo-convex structure, in the see-through type surface light emitting element, the band-shaped surface portion may be visually recognized depending on an observation angle. For example, when the concavo-convex structure is observed at an oblique polar angle with respect to the light emitting surface of the organic EL element, streaks along the direction in which the band-shaped surface portion extends may be visually recognized. In particular, when the band-shaped surface portion has a lattice shape, unevenness of reflected light on the surface of the concavo-convex structure may be observed by visually recognizing the stripe of the band-shaped surface portion in a certain region. Hereinafter, this unevenness may be referred to as “lattice unevenness”. The lattice unevenness is eliminated when the stripes on the belt-like surface portion are not visually recognized because the light irradiated from the outside of the surface light emitting element and reflected on the surface of the concavo-convex structure is observed in an uneven state. it is conceivable that. However, the lattice unevenness which is a problem here does not mean that the intensity of reflected light to be visually recognized is stronger or larger than the surroundings, and the streaks of the band-shaped surface portion are visually recognized. This means that the reflected light is unevenly visible to the extent that the direction in which the belt-like surface portion extends can be recognized.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a see-through type surface light emitting device that has high light extraction efficiency and is less likely to visually recognize stripes on the belt-like surface portion.

As a result of intensive studies to solve the above-mentioned problems, the present inventor has controlled the area ratio between the flat surface portion and the slope portion of the uneven structure layer in the uneven structure layer provided on the light emitting surface of the organic EL element. It was found that light can be extracted with high efficiency while maintaining see-through. In addition, when the flat surface portion of the concavo-convex structure layer includes the band-shaped surface portion, the inventor may make it difficult to see the stripes of the band-shaped surface portion by changing the width of the band-shaped surface portion in the direction in which the band-shaped surface portion extends. I found out that I can do it. The present invention has been completed based on these findings.
That is, the gist of the present invention is the following [1] to [5].

[1] A double-sided light emitting organic electroluminescent device comprising a first transparent electrode layer, a light emitting layer and a second transparent electrode layer in this order, and directly or indirectly provided on at least one surface of the organic electroluminescent device A light emitting surface structure layer, a surface light emitting device comprising:
The light-emitting surface structure layer includes a flat surface portion parallel to the one surface of the organic electroluminescence element, a slope portion inclined with respect to the flat surface portion, on a surface opposite to the organic electroluminescence element. Having a concavo-convex structure including
The flat surface portion includes a band-shaped surface portion extending in one direction,
The width of the band-shaped surface portion is changed in the direction in which the band-shaped surface portion extends,
A projected area formed by projecting the slope portion in a direction perpendicular to the flat surface portion onto a plane parallel to the flat surface portion is 0.1 times or less of the total area of the flat surface portions. There is a surface light emitting device.
[2] The surface light emitting device according to [1], wherein the maximum value of the height difference of the flat surface portion in the concavo-convex structure is 22 μm or less.
[3] The surface light emitting element according to [1] or [2], wherein the inclined surface portion is inclined at an inclination angle of 80 ° or more and less than 90 ° with respect to the flat surface portion.
[4] The surface light-emitting element according to any one of [1] to [3], wherein a maximum height difference of the flat surface portion is 0.1 μm or more.
[5] A lighting fixture comprising the surface light emitting element according to any one of [1] to [4].

  According to the present invention, it is possible to realize a see-through type surface light emitting device that has high light extraction efficiency and is less likely to visually recognize stripes on the belt-like surface portion.

FIG. 1 is a perspective view schematically showing a surface light emitting device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section of the surface light emitting device shown in FIG. 1 cut along a plane passing through the line 1a-1b and perpendicular to the light exit surface. FIG. 3 is a partial plan view schematically showing an enlarged view of a part of the light emitting surface of the surface light emitting element as viewed from the thickness direction of the surface light emitting element. FIG. 4 is a partial cross-sectional view schematically showing a cross section of the concavo-convex structure layer taken along a plane that passes through the line 3a of FIG. 3 and is perpendicular to the light exit surface. FIG. 5 is a partial plan view schematically showing an enlarged view of a part of the light emitting surface of the surface light emitting element as viewed from the thickness direction of the surface light emitting element. FIG. 6 is a partial plan view schematically showing an enlarged view of a part of the light emitting surface of the surface light emitting element as viewed from the thickness direction of the surface light emitting element. FIG. 7 is a projection view schematically showing a state in which the slope portion of the light emitting surface of the surface light emitting element is projected onto a plane parallel to the flat surface portion in a direction perpendicular to the flat surface portion. FIG. 8 is a perspective view schematically showing a surface light emitting device according to the second embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing a cross section of the concavo-convex structure layer according to the third embodiment of the present invention. FIG. 10 is a perspective view schematically showing a surface light emitting element according to the fourth embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing a cross section of a concavo-convex structure layer according to another embodiment of the present invention. FIG. 12 is a cross-sectional view schematically showing a cross section of a concavo-convex structure layer according to another embodiment of the present invention. FIG. 13 is a cross-sectional view schematically showing a cross section of a structural layer according to another embodiment of the present invention. FIG. 14 is a plan view schematically showing a part of the surface of the metal mold to be cut in order to explain the state of manufacturing the metal mold used in Example 1. FIG. 15 is a cross-sectional view schematically showing a cross section of a part of the metal mold used in Example 1 cut along a plane perpendicular to one of the cutting directions. FIG. 16 is a cross-sectional view schematically showing a cross section of a part of the concavo-convex structure layer obtained in Example 1 cut along a plane perpendicular to one of the cutting directions of the metal mold. FIG. 17: is sectional drawing which shows typically the cross section which cut | disconnected the metal mold used in Examples 2-9 and Comparative Examples 2-5 by the plane perpendicular | vertical with respect to one cutting direction in the cutting completion position. is there.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the embodiments and examples described below, and the gist of the present invention and its equivalent scope. Any change can be made without departing from the scope of the invention. In the following description, being along a certain direction means being parallel to a certain direction.

[1. First embodiment]
1 and 2 are views for explaining a surface light emitting device according to a first embodiment of the present invention. FIG. 1 is a perspective view schematically showing the surface light emitting device, and FIG. It is sectional drawing which shows typically the cross section which cut | disconnected the surface emitting element shown by the surface perpendicular | vertical with respect to the light emission surface through line 1a-1b.

  As shown in FIG. 1, the surface light emitting device 10 according to the first embodiment of the present invention is a device having a rectangular flat plate-like structure, a double-sided light emitting organic EL device 140, and the organic EL device 140. A light-emitting surface structure layer 100 provided directly or indirectly on at least one surface. The organic EL element 140 includes at least a first transparent electrode layer 141, a light emitting layer 142, and a second transparent electrode layer 143 in this order, and can emit light from both surfaces 144 and 145 thereof. In the present embodiment, since the first transparent electrode layer 141 and the second transparent electrode layer 143 are transparent electrode layers, the light from the light emitting layer 142 is transmitted through the first electrode layer 141 and the second electrode layer. 143 is transmitted through the surfaces 144 and 145 to the outside of the organic EL element 140. Therefore, in the following description, the surfaces 144 and 145 are referred to as “light emitting surfaces”.

As described above, the light emitting surface structure layer 100 is provided on the light emitting surface 144 of the organic EL element 140. In the present embodiment, it is assumed that the light exit surface structure layer 100 is directly provided so as to be in contact with the light emitting surface 144.
Furthermore, the surface light emitting device 10 of the present embodiment may include components in addition to the members described above. In the present embodiment, it is assumed that the sealing substrate 151 is provided on the light emitting surface 145 of the organic EL element 140.

  Therefore, the surface light emitting element 10 includes the sealing substrate 151, the organic EL element 140, and the light emitting surface structure layer 100 in this order. In such a surface light emitting element 10, light is emitted through the surface 10 </ b> U opposite to the organic EL element 140 in the light emitting surface structure layer 100, and the side opposite to the organic EL element 140 in the sealing substrate 151. Light exits through the surface 10D. The surfaces 10U and 10D are located on the outermost side of the surface light emitting element 10, and light is emitted to the outside of the surface light emitting element 10 through the surfaces 10U and 10D. Therefore, the surfaces 10U and 10D are referred to as “light emitting surfaces”. Call.

[1-1. Organic EL device]
For example, as exemplified by the organic EL element 140, the organic EL element usually includes two or more electrode layers and a light emitting layer that is provided between these electrode layers and emits light when a voltage is applied from the electrodes. Prepare.

  In the organic EL element, layers such as an electrode and a light emitting layer constituting the organic EL element are formed on a substrate, and a sealing member for covering those layers is provided, and the layer such as the light emitting layer is sealed with the substrate and the sealing member. It is common to have a stopped configuration.

  The light emitting layer is not particularly limited, and a known one can be appropriately selected. The light emitting material in the light emitting layer is not limited to one type, and two or more types may be used in combination at any ratio. In addition, the light emitting layer is not limited to one layer, and may be a single layer or a combination of a plurality of types in order to suit the use as a light source. Thereby, the light of the color which is white or it may be emitted.

  In the present invention, the electrode layers constituting the organic EL element are all transparent electrode layers formed of a transparent material. Here, “transparent” means having a light transmittance of a degree suitable for use in an optical member. For example, an electrode having a light transmittance that is high enough to have a desired total light transmittance, which will be described later, as a whole may be used as the transparent electrode layer. By providing the transparent electrode layer having high transparency as described above, it is possible to improve the extraction efficiency of the light generated in the light emitting layer, and to clearly see the other side through the surface light emitting element. In addition, the material of a transparent electrode layer may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios. Further, the transparent electrode layer may be a single-layer structure including only one layer, or may be a multilayer structure including two or more layers.

  In addition to the light emitting layer 142, the organic EL element 140 includes a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and the like between the first transparent electrode layer 141 and the second transparent electrode layer 143. The layer (not shown) may be further included. The organic EL element 140 further includes optional components such as wiring for energizing the first transparent electrode layer 141 and the second transparent electrode layer 143 and a peripheral structure for sealing the light emitting layer 142. It may be.

Although it does not specifically limit as a material which comprises a transparent electrode layer and the layer provided in between, The following can be mentioned as a specific example.
Examples of the material for the transparent electrode layer include ITO (indium tin oxide).
Examples of the material for the hole injection layer include a starburst aromatic diamine compound.
Examples of the material for the hole transport layer include triphenyldiamine derivatives.
Examples of the host material for the yellow light emitting layer include triphenyldiamine derivatives, and examples of the dopant material for the yellow light emitting layer include tetracene derivatives.
Examples of the material for the green light emitting layer include pyrazoline derivatives.
Examples of the host material for the blue light emitting layer include anthracene derivatives, and examples of the dopant material for the blue light emitting layer include perylene derivatives.
Examples of the material for the red light emitting layer include europium complexes.
Examples of the material for the electron transport layer include an aluminum quinoline complex (Alq).

  The above-described or other light-emitting layers may be combined as appropriate to form a light-emitting layer that generates a light emission color having a complementary color relationship, which is called a stacked type or a tandem type. The combination of complementary colors may be, for example, yellow / blue or green / blue / red.

[1-2. (Light emitting surface structure layer)
The light exit surface structure layer 100 includes a light exit surface 10U located on the outermost side of the surface light emitting element 10. The light emitting surface 10U is the surface of the light emitting surface structure layer 100 opposite to the organic EL element 140, and the light emitting surface as the surface light emitting element 10, that is, the light emitted when light is emitted from the surface light emitting element 10 to the outside of the apparatus. Surface.

When viewed macroscopically, the light exit surface 10U is a surface parallel to the light emitting surface 144 of the organic EL element 140 and parallel to the main surface of the surface light emitting element 10. However, since the light exit surface 10U has a concavo-convex structure when viewed microscopically, the surface on the concave portion or the convex portion can form an angle that is not parallel to the light emitting surface 144. Therefore, in the following description, being parallel or perpendicular to the light exit surface means that it is parallel or perpendicular to the light exit surface viewed macroscopically ignoring the recesses or projections unless otherwise specified. Say. Further, unless otherwise specified, the surface light emitting element 10 will be described in a state where the light emitting surface 10U is placed so as to be parallel to the horizontal direction and upward.
Further, the fact that the component is “parallel” or “vertical” may include an error within a range that does not impair the effects of the present invention, for example, ± 5 °.

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 support substrate 131 as a substrate, and an adhesive layer 121 that adheres the multilayer body 110 and the support substrate 131. .
The uneven structure layer 111 is a layer located on one surface of the surface light emitting element 10 (that is, the outermost layer on one light emitting surface side of the surface light emitting element 10, the upper side in the drawing). A concavo-convex structure is formed on the light output surface 10U which is the surface of the concavo-convex structure layer 111. Although the concavo-convex structure will be described in detail later, the concavo-convex structure is composed of flat surface portions 113 and 114 that are parallel to the light emitting surface 144 of the organic EL element 140 and inclined surface portions 115 that are inclined with respect to the flat surface portions 113 and 114. And is configured. Specifically, the light exit surface 10U of the concavo-convex structure layer 111 includes a plurality of concave portions 116 having the flat surface portion 114 as a bottom surface and a slope portion 115 as a side surface, and a flat surface portion 113 corresponding to a gap portion between adjacent concave portions 116. And is configured. Here, that the slope portion is inclined with respect to the flat surface portion means that the slope portion is not parallel to the flat surface portion.

  In the present specification, since the drawings are schematic, only a small number of recesses 116 are shown on the light emitting surface 10U. However, in an actual surface light emitting device, one surface light emission is shown. A much larger number of recesses may be provided on the light exit surface of the element.

(Description of uneven structure)
Hereinafter, the uneven structure of the light exit surface 10U will be described in detail with reference to the drawings.
FIG. 3 is a partial plan view schematically showing an enlarged view of a part of the light emitting surface 10U of the surface light emitting element 10 when viewed from the thickness direction of the surface light emitting element 10. FIG. 4 is a partial cross-sectional view schematically showing a cross section of the concavo-convex structure layer 111 taken along a plane that passes through the line 3a of FIG. 3 and is perpendicular to the light exit surface 10U. The line 3a is a line passing over all the flat surface portions 114 of the recesses 116 in one row. In the following description, the “thickness direction” refers to the thickness direction of the surface light emitting element unless otherwise specified.

  As shown in FIG. 3, the light exit surface 10 </ b> U includes a plurality of concave portions 116 and a flat surface portion 113 that is a gap portion between the concave portions 116. Each recess 116 has a shape (pyramidal trapezoidal shape) obtained by cutting the top of a quadrangular pyramid parallel to the bottom surface. Each recess 116 includes a rectangular flat surface portion 114 corresponding to the bottom portion thereof, and four inclined surface portions 115 respectively extending from four sides of the rectangle. Specifically, the four inclined surfaces 115 constituting the recess 116 are all trapezoidal. In addition, the boundary line 117 between the slope 115 and the flat surface 113 forms a quadrangle. That is, in this embodiment, the recessed part 116 is a quadrangular frustum shape.

  Since the light emitting surface 10U has an uneven structure having the flat surfaces 113 and 114 and the inclined surface 115, the surface light emitting element 10 has a light extraction efficiency through the light emitting surface 10U as compared with the case where the light emitting surface 10U does not have an uneven structure. Can be increased. That is, even if light that could not be extracted due to internal reflection by the flat surface portions 113 and 114 can be extracted through the slope portion 115, the light extraction efficiency can be improved. .

  The recesses 116 are usually provided so that the positions are discrete. Here, the plurality of recesses 116 are arranged along two directions X and Y that are parallel to the light exit surface 10U and orthogonal to each other. Specifically, the recesses 116 are continuously arranged along two orthogonal directions X and Y with a certain interval. In the two directions X and Y, a gap is provided between the adjacent recesses 116, and the gap constitutes the flat surface portion 113. Therefore, on the light exit surface 10U, the slope portion 115 is usually located around the flat surface portion 114, and the flat surface portion 113 is located around the slope portion 115 (and thus around the recess 116).

5 and 6 are partial plan views schematically showing an enlarged view of a part of the light emitting surface 10U of the surface light emitting element 10 as viewed from the thickness direction of the surface light emitting element 10. FIG. In FIG. 5, the band-shaped surface portion 113 </ b> X extending along the direction X is indicated by hatching. In FIG. 6, the belt-like surface portion 113 </ b> Y extending along the Y direction is indicated by hatching.
As shown in FIGS. 5 and 6, the flat surface portion 113 includes a group of strip-shaped surface portions 113 </ b> X extending along one direction X and a group of strip-shaped surface portions 113 </ b> Y extending along another one direction Y. included. Here, since both the band-like surface portions 113X and 113Y are surface portions included in the flat surface portion 113, in the present embodiment, they are located on the outer side in the thickness direction than the surrounding inclined surface portion 115. For this reason, the belt-like surface portions 113X and 113Y are surface portions that protrude from the surrounding slope portion 115.

  The band-shaped surface portions 113X and 113Y are both band-shaped surface portions when viewed from the thickness direction. Since the direction X in which the strip surface portion 113X extends and the direction Y in which the strip surface portion 113Y extends are not parallel, the strip surface portion 113X and the strip surface portion 113Y intersect at a plurality of intersecting portions 113Z. For this reason, when the beltlike surface portion 113X and the beltlike surface portion 113Y are viewed from the thickness direction, they are in a lattice shape as a whole.

Furthermore, the widths of the strip surface portions 113X and 113Y change in the directions X and Y in which the strip surface portions 113X and 113Y extend. Here, “the width changes” means that the widths of the strip surface portions 113X and 113Y are not uniform in the directions X and Y in which the strip surface portions 113X and 113Y extend.
At this time, the change in the width of the band-shaped surface portions 113X and 113Y may be discontinuous, but is preferably continuous because of easy manufacture. Here, the change in the width of the band-shaped surface portions 113X and 113Y is continuous means that the band-shaped surface portions 113X and 113Y extend from one end to the other end in the directions X and Y in which the band-shaped surface portions 113X and 113Y extend. By gradually increasing or decreasing the width, it means that the widths of the band-shaped surface portions 113X and 113Y are not uniform in the directions X and Y.

In this embodiment, the width of the strip-shaped surface portion 113X is altered in direction X, for example, the width L ₂ of the band-like surface portions 113X in the width L ₁ and the other end of the strip surface 113X at one end of the direction X as shown in FIG. 5 Is different. Also, the width of the strip-shaped surface portion 113Y altered in direction Y, for example, different from the width L ₄ of the strip surface 113Y in the width L ₃ and the other end of the strip surface portion 113Y at one end of the direction Y, as shown in FIG. 6 Yes.

  Since the widths of the band-shaped surface portions 113X and 113Y change in the extending directions X and Y, it is possible to prevent the stripes of the band-shaped surface portions 113X and 113Y from being visually recognized when the surface light emitting element 10 is observed. As a result, lattice unevenness can be prevented. The reason why the strip-like surface portions 113X and 113Y can be prevented from being visually recognized in this way is not necessarily clear, but according to the study of the present inventors, the strip-like surface portions 113X and 113Y can be obtained by making the widths of the strip-like surface portions 113X and 113Y non-uniform. This is presumably because the regularity of the shape of the film can be lowered. For example, since the regularity of the surface shape of the light-emitting surface when viewed from the thickness direction becomes high when the width of the band-shaped surface portion is made uniform as in the prior art, the reflected light on the light-emitting surface can be seen according to the high regularity. However, it is considered that a certain regularity occurred, and this regularity was a cause of visible stripes on the belt-like surface portion. In addition, when the regularity of the surface shape of the light exit surface is high as in the prior art, interference and diffraction occur due to the periodic structure of the slope around the belt-like surface portion, and the light is strengthened or weakened by these interference and diffraction. It is thought that this was also one of the reasons why the stripes on the belt-like surface portion were visible. On the other hand, if the widths of the band-shaped surface portions 113X and 113Y are made non-uniform, the regularity of the surface shape of the light-emitting surface is lowered, so that it is presumed that the band-shaped surface portions can be prevented from being visually recognized as stripes.

  When the strip-shaped surface portions having different extending directions intersect with each other, the widths of the strip-shaped surface portions can be easily specified if the intersecting strip-shaped surface portions have different positions in the thickness direction. However, when the thickness direction positions of the intersecting strip surface portions 113X and 113Y are the same as in this embodiment, the width of the strip surface portions 113X and 113Y at the intersecting portion 113Z may not be clearly specified. In this case, if the widths of the band-shaped surface portions 113X and 113Y other than the intersecting portion 113Z are changed, the band-shaped surface portions 113X and 113Y can be prevented from being visually recognized. This is because the band-shaped surface portions 113X and 113Y are considered to be visually recognized when light that has been reflected, diffracted, or interfered by the band-shaped surface portions 113X and 113Y other than the intersecting portion 113Z is seen.

When the band-like surface portions 113X and 113Y have a shape that gradually increases in width from one end portion to the other end portion, the direction in which the width increases becomes the same or different. For example, in FIG. 5, the width of the band-shaped surface portion 113X increases from the left end in the drawing to the right end in the drawing (the first band-shaped surface portion 113X from the top in FIG. 5) and from the right end in the drawing to the left end in the drawing. Although an example in which the belt-like surface portion (second belt-like surface portion 113X from the top in FIG. 5) is mixed on the same light exit surface 10U has been shown, these may be arranged in either one.
Moreover, the dimension of each strip | belt-shaped surface part 113X and 113Y may be the same, and may differ.

  Specific dimensions of the band-shaped surface portions 113X and 113Y are arbitrary as long as the effects of the present invention are not impaired. For example, the width of the band-shaped surface portions 113X and 113Y is usually 5.0 μm or more, preferably 7.5 μm or more, more preferably 10.0 μm or more, and usually 500 μm or less, preferably 400 μm or less, more preferably 300 μm. It is as follows. If the width of the band-shaped surface portions 113X and 113Y is set to be equal to or greater than the lower limit value of the above range, the light extraction efficiency can be effectively increased, and if the width is equal to or less than the upper limit value, the opposite side can be easily viewed with the naked eye through the surface light emitting element 10.

  Furthermore, although the extent to which the width of each strip-shaped surface portion 113X and 113Y changes depends on the width and length of the strip-shaped surface portions 113X and 113Y, from the viewpoint of achieving the effect of the present invention, the strip-shaped surface portion 113X And the ratio of the maximum value and the minimum value of the width of 113Y (maximum value / minimum value), usually 1.1 or more, preferably 1.2 or more, more preferably 1.5 or more, usually 3 or less, preferably Is 2.9 or less, more preferably 2.8 or less.

  FIG. 7 schematically illustrates a state in which the inclined surface portion 115 of the light emitting surface 10U of the surface light emitting element 10 is projected onto a plane 900 parallel to the flat surface portions 113 and 114 in a direction perpendicular to the flat surface portions 113 and 114. FIG. In the present embodiment, the direction perpendicular to the flat surface portions 113 and 114 coincides with the direction perpendicular to the light exit surface 10U and the direction parallel to the thickness direction of the surface light emitting element 10. Further, the plane 900 parallel to the flat surface portions 113 and 114 is a plane parallel to the light exit surface 10U. However, the plane 900 parallel to the flat surface portions 113 and 114 is not a plane that the surface light emitting element 10 has, but a projection plane that is set to measure the projection area of the slope portion 115. In FIG. 7, the slope 115 of the light emitting surface 10U of the surface light emitting element 10 is projected onto a plane 900 parallel to the flat surface portions 113 and 114 in a direction perpendicular to the flat surface portions 113 and 114. The image 901 is shown with hatching.

  As shown in FIG. 7, in the surface light emitting device 10 of the present embodiment, the slope 115 is projected onto a plane 900 parallel to the flat surfaces 113 and 114 in a direction perpendicular to the flat surfaces 113 and 114. The projected area formed in this manner is usually 0.1 times or less, preferably 0.05 times or less, more preferably 0.01 times or less the total area of the flat surface portions 113 and 114. Further, the lower limit of the ratio of the projected area of the slope 115 to the total area of the flat surface portions 113 and 114 is usually 0.0001 times or more, preferably 0.0005 times or more, more preferably 0.001 times or more.

  Thereby, the other side of the surface light emitting element 10 can be seen through. When the concavo-convex structure provided in the conventional single-sided surface light-emitting element is applied to a double-sided light-emitting surface light-emitting element, the haze is usually increased by increasing the ratio of the sloped portion, and the other side of the surface light-emitting element is I can't see through. On the other hand, when the ratio of the projected area of the slope 115 to the total area of the flat surfaces 113 and 114 falls within the above range, the haze is improved by the concavo-convex structure when viewed from the direction perpendicular to the light exit surface 10U. Can be suppressed. Therefore, according to the surface light emitting device 10 of the present embodiment, the increase in haze can be suppressed while having a concavo-convex structure, so that see-through is not impaired.

  Furthermore, according to the surface light emitting element 10 of the present embodiment, it is possible to prevent the concavo-convex structure from being lost due to an external impact and to improve the mechanical strength of the light exit surface 10U. In general, when a surface has a concavo-convex structure, when an impact is applied to the surface, the force concentrates on a part of the concavo-convex structure and tends to cause breakage. However, in the surface light emitting device 10 according to the present embodiment, the flat surface portion 113 is aligned in the thickness direction so as to be a uniform and flat surface, and therefore, the surface of the concavo-convex structure layer 111 is affected by a force or impact applied to the light exit surface 10U from the outside. It is possible to suppress the concentration of force on the part. For this reason, damage to the concavo-convex structure layer 111 can be prevented, and both good light extraction efficiency and high mechanical strength of the light emitting surface 10U of the surface light emitting element 10 can be achieved at the same time.

  Furthermore, as shown in FIG. 4, the maximum value of the height difference H between the flat surface portion 113 and the flat surface portion 114 in the light exit surface 10U is preferably 22 μm or less, and may be 21.5 μm or less or 21.0 μm or less. The lower limit is usually 0.1 μm or more, and may be 0.15 μm or more or 0.2 μm or more. Here, the height difference means a distance in the thickness direction. Therefore, the height difference H between the flat surface portion 113 and the flat surface portion 114 in the present embodiment means the depth of the concave portion 116.

  By keeping the maximum value of the height difference H between the flat surface portion 113 and the flat surface portion 114 within such a range, surface light emission is possible even when viewed from a direction (oblique direction) inclined with respect to the normal direction of the light exit surface 10U. The other side of the element 10 can be seen through. When the area ratio of the slope 115 is large, the haze tends to increase when the light exit surface 10U is viewed from an oblique direction. On the other hand, the ratio of the projected area of the slope 115 to the total area (total area) of the flat surfaces 113 and 114 is within the above range, and the maximum value of the height difference H between the flat surface 113 and the flat surface 114 is By staying within the above range, improvement in haze when viewed from an oblique direction can be suppressed, so that see-through can be maintained even when the surface light emitting element 10 is viewed from an oblique direction.

  As shown in FIG. 4, the slope 115 is generally 80 ° or more, preferably 81 ° or more, more preferably 82 ° or more, and usually less than 90 °, preferably 89 ° with respect to the flat surface portions 113 and 114. In the following, it is preferable to incline at an inclination angle θ of 88 ° or less. That is, the slope 115 is a surface that is not parallel to the flat surfaces 113 and 114, but the angle θ formed by the slope 115 and the flat surfaces 113 and 114 is preferably within the above range. As described above, since the inclination angle θ of the slope 115 is large, the light extraction efficiency can be stably increased. In addition, when the inclination angle θ is large, the projected area per inclined surface 115 can be reduced when the inclination angle θ is small. Therefore, when viewed from a direction perpendicular to the light emitting surface 10U, the surface light emitting element 10 The other side is clearer and easier to see. The direction perpendicular to the light emitting surface 10U corresponds to the front direction of the surface light emitting element 10, and it is usually assumed that the frequency of looking through the front side of the surface light emitting element 10 from this front direction is high. Above is useful.

  Moreover, in this embodiment, although the inclination | tilt angle (theta) of all the slope parts 115 is set to the same magnitude | size, it does not specifically limit and may differ.

  The thickness T of the concavo-convex structure layer 111 is preferably in an appropriate range in relation to the maximum value of the height difference H between the flat surface portion 113 and the flat surface portion 114. For example, when a hard material advantageous for maintaining the durability of the concavo-convex structure layer 111 is used as the material of the concavo-convex structure layer 111, the thickness of the concavo-convex structure layer 111 is made thinner so that the flexibility of the surface light emitting element 10 is improved. It is possible to increase the height, and the uneven structure layer 111 can be easily handled in the manufacturing process of the surface light emitting element 10, which is preferable. Specifically, the difference between the maximum value of the height difference H between the flat surface portion 113 and the flat surface portion 114 and the thickness T of the uneven structure layer 111 is preferably 0 to 30 μm.

  In the directions X and Y in which the recesses 116 are arranged, the pitch P of the recesses 116 is usually 0.1 μm or more, preferably 0.15 μm or more, more preferably 0.2 μm or more, and usually 500 μm or less, preferably 450 μm or less, more Preferably it is 400 micrometers or less. The light extraction efficiency can be improved when the pitch P is equal to or higher than the lower limit value of the above range, and the transparency can be increased when the pitch P is equal to or lower than the upper limit value.

The thickness T of the uneven structure layer 111 is not particularly limited, but is preferably 1 μm to 70 μm. In the present embodiment, the thickness T of the concavo-convex structure layer 111 is a distance between the surface on the base film layer 112 side where the concavo-convex structure is not formed and the flat surface portion 113.
Moreover, it is preferable that the thickness of the base film layer 112 is 20 micrometers-300 micrometers.

(Description of the material of the multilayer)
The light exit surface structure layer 100 may be composed of a plurality of layers, but may be composed of a single layer. From the viewpoint of easily obtaining the light-emitting surface structure layer 100 having desired characteristics, it is preferable that the light-emitting surface structure layer 100 includes a plurality of layers. In the present embodiment, as shown in FIG. 1, the light exit surface structure layer 100 includes a multilayer body 110 in which an uneven structure layer 111 and a base film layer 112 are combined. Thereby, the light emission surface structure layer 100 with high performance can be obtained easily.

  The uneven structure layer 111 and the base film layer 112 are usually formed of a transparent resin. In the present embodiment, each layer constituting the light exit surface structure layer 100 may have a light transmittance suitable for use in an optical member. For example, the light exit surface structure layer 100 as a whole has a total light transmittance of 80% or more.

  The transparent resin is not particularly limited, and various resins that can form a transparent layer may 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 the uneven structure layer 111 can be efficiently formed.

  Examples of the thermoplastic resin include polyester-based, polyacrylate-based, and cycloolefin polymer-based resins. In addition, examples of the ultraviolet curable resin include epoxy resins, acrylic resins, urethane resins, ene / thiol resins, isocyanate resins, and the like. As these resins, those having a plurality of polymerizable functional groups can be preferably used. In addition, the said resin may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Among them, as the material of the concavo-convex structure layer 111 constituting the multilayer body 110, a material having a high hardness at the time of curing from the viewpoint of easily forming the concavo-convex structure of the light exit surface 10U and easily obtaining the scratch resistance of the concavo-convex structure. Is preferred. 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, as the material of the base film layer 112, in order to facilitate the handling when forming the concavo-convex structure layer 111 and the handling of the multilayer body 110 after forming the multilayer body 110, a certain degree of flexibility is provided. There are preferred. By combining such materials, the multilayer body 110 that is easy to handle and excellent in durability can be obtained, and as a result, the high-performance surface light emitting device 10 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 111, while the transparent resin constituting the material of the base film layer 112 is made of an alicyclic olefin polymer. It is preferable to use a film (such as a ZEONOR film described later) or a polyester film.

  When the light-emitting surface structure layer 100 includes the concavo-convex structure layer 111 and the base film layer 112 as in the present embodiment, the refractive index of the concavo-convex structure layer 111 and the base film layer 112 may be as close as possible. . In this case, the refractive index difference between the uneven structure layer 111 and the base film layer 112 is preferably within 0.1, and more preferably within 0.05.

  As a material of a layer that is a constituent element of the light exit surface structure layer 100 such as the uneven structure layer 111 and the base film layer 112, a material having light diffusibility may be used as long as the see-through property is not hindered. Thereby, the light which permeate | transmits the light emission surface structure layer 100 can be diffused, maintaining see-through property, and troubles, such as a color change by an observation angle, can further be reduced.

  Examples of the light diffusing material include a material containing particles, and an alloy resin that diffuses light by mixing two or more kinds of resins. Among these, from the viewpoint that light diffusibility can be easily adjusted, a material including particles is preferable, and a resin including particles is particularly preferable.

  The particles may be transparent or opaque. Examples of the material of the particles include metals and metal compounds, and resins. 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; metal compounds such as silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, tin-added indium oxide, and titanium oxide. be able to. On the other hand, examples of the resin include methacrylic resin, polyurethane resin, and silicone resin. In addition, the particle | grain material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  The shape of the particles may be, for example, 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.

  Furthermore, the resin composition may contain arbitrary components as necessary. Examples of the optional component include additives such as phenol-based and amine-based degradation inhibitors; surfactant-based, siloxane-based antistatic agents; triazole-based, 2-hydroxybenzophenone-based light-resistant agents; Can be mentioned.

(Support substrate)
As shown in FIG. 1, the surface light emitting device 10 of this embodiment includes a support substrate 131 between the organic EL device 140 and the multilayer body 110. By providing the support substrate 131, the surface light emitting element 10 can be given rigidity for suppressing deflection. Further, the supporting substrate 131 is provided with a substrate that is excellent in the performance of sealing the organic EL element 140 and that can easily form the layers constituting the organic EL element 140 on the manufacturing process in order. As a result, the durability of the surface light emitting element 10 can be improved and the manufacture can be facilitated.

  As an example of the material constituting the support substrate 131, a transparent material is usually used. Examples of the material include glass and resin. In addition, the material of the support substrate 131 may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The refractive index of the material constituting the support substrate 131 is not particularly limited, but is preferably 1.4 to 2.0.
The thickness of the support substrate 131 is not particularly limited, but is preferably 0.1 mm to 5 mm.

(Adhesive layer)
The surface light emitting device 10 of this embodiment includes an adhesive layer 121 between the multilayer body 110 and the support substrate 131. The adhesive layer 121 is a layer that is interposed between the base film layer 112 of the multilayer body 110 and the support substrate 131 and adheres these two layers.
The adhesive that is the material of the adhesive layer 121 is not only a narrowly defined adhesive (a so-called hot melt type adhesive having a shear storage modulus of 1 to 500 MPa at 23 ° C. and not exhibiting tackiness at room temperature), A pressure-sensitive adhesive having a shear storage modulus at 23 ° C. of less than 1 MPa is also included. Specifically, a transparent material having a refractive index close to that of the support substrate 131 or the base film layer 112 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 μm to 100 μm.

[1-3. Sealing substrate)
The surface light emitting device 10 of the present embodiment includes a sealing substrate 151 on the light emitting surface 145. The sealing substrate 151 may be provided so as to be in direct contact with the light emitting surface 145. Further, an arbitrary substance such as a filler or an adhesive may be present between the light emitting surface 145 and the sealing substrate 151, or a gap may be present. As long as there is no inconvenience such as greatly impairing the durability of the light emitting layer 142, air or other gas may be present in the space, or the space may be evacuated.

  As the sealing substrate 151, any member that can seal the organic EL element 140 and transmits light emitted from the light emitting surface 145 can be used. For example, a member similar to the support base 131 can be used.

[1-4. Production method〕
The manufacturing method of the surface light emitting element 10 is not particularly limited. For example, a step of laminating each layer constituting the organic EL element 140 on one surface of the support substrate 131, a step of preparing a multilayer body 110 having the concavo-convex structure layer 111 and the base film layer 112, and a prepared multilayer By performing the step of attaching the body 110 to the other surface of the support substrate 131 via the adhesive layer 121 and the step of providing the sealing substrate 151 on the surface opposite to the support substrate 131 of the organic EL element 140 It may be manufactured. In addition, there is no restriction | limiting in order of each said process as long as the desired surface emitting element 10 is obtained.

For manufacturing the multilayer body 110 having the concavo-convex structure layer 111 and the base film layer 112, for example, a mold such as a mold having a desired shape is prepared, and this mold is used as a layer of a material for forming the concavo-convex structure layer 111 This can be done by transferring. As a more specific method,
(Method 1) An unprocessed multilayer having a layer of the resin composition A constituting the base film layer 112 and a layer of the resin composition B constituting the concavo-convex structure layer 111 (the concavo-convex structure is not yet formed) A method for preparing and forming a concavo-convex structure on the surface of the raw multilayer body on the resin composition B side; and (Method 2) applying the resin composition B in a liquid state on the base film layer 112 Then, a method may be mentioned in which a mold is applied to the applied layer of the resin composition B, the resin composition B is cured in that state, and the concavo-convex structure layer 111 is formed.

In Method 1, a raw multilayer body can be obtained by extrusion molding in which resin A and resin B are coextruded, for example. An uneven structure can be formed by pressing a mold having a desired surface shape on the surface of the raw multilayer body on the resin 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.) when the glass transition temperature of the resin B is Tg. 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, it is preferable to use a resin that can be cured by energy rays such as ultraviolet rays as the resin B constituting the concavo-convex structure layer 111. The resin B is applied on the base film layer 112, and in a state where the mold is applied, from a light source located on the back side of the application surface (the side opposite to the surface on which the resin B is applied). By irradiating energy rays such as ultraviolet rays, curing the resin B, and then releasing the mold, the coating film of the resin B is used as the concavo-convex structure layer 111, and the multilayer body 110 can be obtained.

[1-5. (Description of main advantages)
Since the surface light emitting device 10 of the present embodiment is configured as described above, light emitted from the light emitting surface 144 of the organic EL device 140 passes through the light emitting surface structure layer 100 and exits through the light emitting surface 10U. The light emitted from the light emitting surface 145 passes through the sealing substrate 151 and exits through the light emitting surface 10D.

  At this time, since the light exit surface 10U has a concavo-convex structure including the flat surface portions 113 and 114 and the slope portion 115, light can be extracted through the light exit surface 10U with high efficiency.

  Further, since the widths of the band-shaped surface portions 113X and 113Y are changed in the extending directions X and Y, the band-shaped surface portions 113X and 113Y can be prevented from being visually recognized, and furthermore, the occurrence of lattice unevenness can also be prevented.

  Furthermore, since all the layers included in the surface light emitting element 10 are transparent, in the surface light emitting element 10, light incident on one light emitting surface 10U passes through the surface light emitting element 10 and exits through the other light emitting surface 10D. Further, the light incident on the other light exit surface 10D can also be transmitted through the surface light emitting element 10 and emitted through one light exit surface 10U. Furthermore, in this embodiment, since the ratio of the projected area of the slope 115 to the total area of the flat surfaces 113 and 114 is within a predetermined range, haze can be suppressed. Accordingly, the opposite side can be clearly seen through the surface light emitting element 10 with the naked eye, and a see-through type surface light emitting element can be realized.

  Specifically, the surface light emitting element 10 as a whole has a total light transmittance of 60% or more, preferably 70% or more, more preferably 80% or more as a whole. The upper limit is ideally 100%, but is usually 90% or less.

  Furthermore, since the surface light emitting device 10 has an appropriately concavo-convex shape, the haze of the surface light emitting device 10 is generally 10% or less, preferably 8% or less, more preferably 6 as the surface light emitting device 10 as a whole. % Or less. The lower limit value is ideally zero, but is usually 0.1% or more.

[2. Second embodiment]
In the first embodiment, the concavo-convex structure is disposed on one of the two light-emitting surfaces of the organic EL element, but the concavo-convex structure may be disposed on both light-emitting surfaces. Hereinafter, the example is demonstrated using drawing.

  FIG. 8 is a perspective view schematically showing a surface light emitting device according to the second embodiment of the present invention. As shown in FIG. 8, the surface light emitting device 20 according to the second embodiment of the present invention includes the light emitting surface structure layer 100 instead of the sealing substrate 151, and the surface light emitting device according to the first embodiment. 10 is the same. Accordingly, the surface light emitting element 20 includes the light emitting surface structure layer 100 on both of the two light emitting surfaces 144 and 145 of the organic EL element 140. Therefore, the surface light emitting element 20 has a concavo-convex structure on both of the two light exit surfaces 10U and 10D. In the present embodiment, the two light exit surfaces are provided with the uneven structure layer having the same shape. However, the present invention is not necessarily limited to such a form, and the shape of the uneven structure on one light output surface and the other The shape of the concavo-convex structure on the light exit surface may be different.

  Since the surface light emitting element 20 of the present embodiment is configured as described above, light emitted from the light emitting surface 144 of the organic EL element 140 is emitted through the light emitting surface 10U, and light emitted from the light emitting surface 145 is emitted. Light exits through the surface 10D. At this time, light can be extracted with high efficiency while maintaining see-through. Further, it is possible to prevent the band-shaped surface portions 113X and 113Y (see FIG. 3) from being visually recognized on both the light exit surface 10U and the light exit surface 10D. Furthermore, the same effect as the first embodiment can be obtained.

[3. Third Embodiment]
In the first and second embodiments, the height difference H between the flat surface portion 113 and the flat surface portion 114 in the same light exit surface 10U is made constant. However, the height difference H may be made uneven to provide a dimensional difference. . In particular, when a dimensional difference exceeding the difference that causes interference between one or both of the outgoing light that exits through the light exit surface 10U and the reflected light that is reflected by the light exit surface 10U is provided, one or both of the outgoing light and the reflected light. This is preferable because rainbow unevenness due to interference can be suppressed. Here, the emitted light emitted through the light emitting surface includes not only light emitted from the organic EL element but also transmitted light that has entered the surface light emitting element from the opposite side of the light emitting surface and transmitted through the surface light emitting element. Hereinafter, examples of such an uneven structure will be described with reference to the drawings.

  FIG. 9 is a cross-sectional view schematically showing a cross section of the concavo-convex structure layer according to the third embodiment of the present invention. As shown in FIG. 9, the light exit surface 30U that is the surface of the concavo-convex structure layer 311 according to the third embodiment of the present invention includes a concave portion 316 having a flat surface portion 314 as a bottom surface and a slope portion 315 as a side surface, and a flat surface portion 317. A plurality of recesses 319 having a bottom surface as a bottom surface and a slope portion 318 as a side surface are provided. Further, a gap is provided between the recesses 316 and 319, and this gap constitutes a flat surface portion 313.

  In the light exit surface 30U of the present embodiment, the flat surface portion 313 is formed of two groups of strip-shaped surface portions extending along two directions that are parallel to the light exit surface 30U and orthogonal to each other, like the flat surface portion 113 of the first embodiment. The width of the belt-like surface portion changes in the direction in which each belt-like surface portion extends. Further, the projected areas of the slope portions 315 and 318 are usually 0.1 times or less the total area of the flat surface portions 313, 314 and 317, as in the first embodiment.

Here, the depth of the concave portion 316 (that is, the height difference between the flat surface portion 313 and the flat surface portion 314) H ₃₁₆ is the depth of the concave portion 319 (that is, the height difference between the flat surface portion 313 and the flat surface portion 317) H ₃₁₉ . Is also getting smaller. In this case, if there is a dimensional difference H ₃₁₉ -H ₃₁₆ that exceeds the difference between the depth H ₃₁₆ of the recess ₃₁₆ and the depth H ₃₁₉ of the recess 319 that causes interference of one or both of the emitted light and reflected light, Rainbow irregularities due to interference can be suppressed. At this time, the dimensional difference H ₃₁₉ -H ₃₁₆ may be a dimensional difference exceeding the difference that causes interference of the emitted light, but the reflected light tends to have a greater influence on the rainbow unevenness than the emitted light. Therefore, a dimensional difference that exceeds the difference that causes interference of reflected light is preferable, and a dimensional difference that exceeds the difference that causes interference of both outgoing light and reflected light is more preferable. More specifically, when there is no dimensional difference as described above, interference occurs between the reflected light from the flat surface portions 313, 314, and 317 on the upper surface of the uneven structure layer 311 and the reflected light from the lower surface of the uneven structure layer 311. And rainbow unevenness occurred. However, by providing the surface concavo-convex structure with the predetermined dimensional difference, interference between reflected lights can be suppressed, and rainbow unevenness on the light exit surface 30U can be suppressed.

  The dimensional difference exceeding the difference causing the interference is, for example, interference of outgoing light emitted from the organic EL element, for example, usually 0.62 times or more, preferably 1. The dimensional difference is 5 times or more. By providing this dimensional difference, the occurrence of rainbow unevenness can be suppressed. The upper limit of the dimensional difference is not particularly limited, but is preferably 60 times or less of the center wavelength of the emitted light.

  The above numerical range is confirmed from the knowledge shown below. In other words, in a structural layer designed in such a manner that all the depths of the recesses are made uniform, if an error of 170 nm or more occurs in the depth of the recesses, interference occurs and rainbow unevenness appears. It has been found that the generation of rainbow unevenness can be suppressed by daringly providing a dimensional difference that is twice or more the minimum value. Further, in the structure layer designed in such a manner that all the depths of the recesses are made uniform, if a variation of σ1 nm (≈60 nm) with a standard deviation occurs in the depth of the recesses, interference occurs and rainbow unevenness appears. = 360 nm) It is known that the generation of rainbow unevenness can be suppressed by intentionally providing a dimensional difference of not less than 360 nm. Based on the above two findings, it can be shown that the dimensional difference exceeding the difference that causes interference of the emitted light is 0.62 or more times the center wavelength of the light emitted from the surface light emitting element.

  For the same reason, in the interference between transmitted light and reflected light, the dimensional difference exceeding the difference that causes interference is usually 0.62 times or more, preferably 1.5 times or more the center wavelength of transmitted light and reflected light. And a dimensional difference of usually 60 times or less. However, normally, since transmitted light and reflected light are natural light and include light having an arbitrary wavelength, it is difficult to determine the center wavelength of the reflected light. Therefore, in view of the fact that the light that causes rainbow unevenness is visible light, the dimensional difference is usually set as the center wavelength of light that reflects 550 nm, which is the center wavelength of visible light.

  Furthermore, even when the concavo-convex structure has a dimensional difference as in this embodiment, light can be extracted with high efficiency while maintaining see-through. Further, it is possible to prevent the band-shaped surface portion from being visually recognized on the light exit surface 30U. Furthermore, the same effect as the first embodiment can be obtained.

  Moreover, the same effect can be obtained even when the dimensional difference is provided in the elements other than the height difference between the flat surface portions. For example, if there is the dimensional difference in one or more elements among the element groups such as the height difference between the flat surface portions, the maximum width of the belt-shaped surface portion, the pitch of the repeating structure such as the concave portion or the convex portion, the rainbow unevenness similarly. Can be suppressed.

[4. Fourth Embodiment]
The light-emitting surface structure layer according to the present invention is applicable to any surface light-emitting element including an organic EL element. Therefore, the above-described light emitting surface structure layer may be provided for a surface light emitting device having a symmetric layer structure with respect to the organic EL device, and for a surface light emitting device having an asymmetric layer structure with respect to the organic EL device. A light exit surface structure layer may be provided. For example, the light emitting surface structure layer may be applied to a surface light emitting device having a layer structure asymmetric with respect to the organic EL device. Hereinafter, the example is demonstrated using drawing.

  FIG. 10 is a perspective view schematically showing a surface light emitting device according to the fourth embodiment of the present invention. As shown in FIG. 10, the surface light emitting device 40 according to the fourth embodiment of the present invention includes an inert gas layer 461 between the second transparent electrode layer 143 of the organic EL device 140 and the sealing substrate 151. It is the same as that of the surface emitting element 10 which concerns on 1st embodiment except having.

  The inert gas layer 461 protects the organic EL element 140 from being deteriorated by oxygen and moisture entering from the outside, and is a layer filled with an inert gas such as nitrogen gas. In addition, since the side surface of the surface light emitting element 40 is normally sealed with a sealing member (not shown), the gas in the inert gas layer 461 does not leak to the outside.

  The surface light emitting element 40 has an asymmetric layer structure with respect to the organic EL element 140 in that it has an inert gas layer 461 only on one light emitting surface 145 side of the organic EL element 140. Even such a surface light emitting device 40 can extract light with high efficiency while maintaining see-through. Further, it is possible to prevent the band-shaped surface portion from being visually recognized on the light exit surface 30U. Furthermore, the same effect as the first embodiment can be obtained.

[5. Others]
Although the surface light emitting device of the present invention has been described with reference to the embodiment, the present invention may be further modified.
For example, in the above-described embodiment, the width of all the band-shaped surface portions is changed in the extending direction. However, some of the band-shaped surface portions have a uniform width in the extending direction. It may be.

  Further, for example, in the above-described embodiment, a concave portion is provided on the light exit surface, and the concave / convex structure having the flat surface portion and the slope portion is configured by the concave portion, but a convex portion may be provided instead of the concave portion. In the case where a convex portion is provided instead of the concave portion, the flat surface portion is usually located at an inner position in the thickness direction than the surrounding slope portion (that is, a position close to the light emitting surface 144). For this reason, the belt-like surface portion included in the flat surface portion is also a surface portion that is recessed from the surrounding slope portion. Even in such a case, it is possible to prevent the band-shaped surface portion from being visually recognized by changing the width of the band-shaped surface portion in the direction in which the band-shaped surface portion extends. As a specific example, the light-emitting surface having a concavo-convex structure in which the concavo-convex structure of the light-exiting surface 10U described in the first embodiment is inverted has discretely formed quadrangular pyramid-shaped convex portions in which the concave portions 116 are inverted. It becomes the light exit surface. When this light exit surface is viewed from the thickness direction, it has the same shape as shown in FIGS. 3, 5 and 6, and the same advantages as in the first embodiment can be obtained. Furthermore, for example, a concave portion and a convex portion may be mixed on the same light exit surface.

  Further, for example, the shape of the concave portion and the convex portion formed on the light exit surface may be a shape other than the quadrangular pyramid shape. Specific examples include a truncated pyramid shape having a bottom surface other than a quadrangle such as a triangle, a pentagon, and a hexagon. Further, it may be a pyramid shape, a prism shape, or the like.

  In the above-described embodiment, the concave or convex portions distributed over the entire surface of the light exit surface are shown as having only the same type of shape (specifically, the shape of a truncated pyramid) distributed. The light exit surface may include a concave portion or a convex portion having different shapes. For example, there may be a mix of recesses or projections of different sizes, a mix of recesses or projections with triangular and truncated pyramid shapes, or slopes with different inclination angles. Good.

Further, for example, the positions, orientations, shapes, numbers, and combinations of the flat surface portion and the slope portion are not limited to those of the embodiment, and may be changed within a range that does not significantly impair the effects of the present invention.
As a specific example, the flat surface portion may be provided in one step as shown in FIG. 11 in addition to providing the height position in two steps as in the embodiment described above. FIG. 11 is a cross-sectional view schematically showing a cross section of a concavo-convex structure layer according to another embodiment of the present invention. In the concavo-convex structure layer 511 shown in FIG. 11, a slope portion 515 is provided as a side surface of the conical recess 516, and a flat surface portion 513 is provided with the height position aligned in the gap between the adjacent recesses 516. Thus, even when the height position of the flat surface portion is aligned in one step, light can be extracted with high efficiency while maintaining the see-through state, and the band-shaped surface portion can be prevented from being visually recognized on the light exit surface 50U. Note that when the height positions of the flat surface portions are aligned in one step, the height difference between the flat surface portions is zero, but even in this case, if a dimensional difference is provided in the height H of the concave or convex portions, the emitted light and the reflected light Rainbow unevenness due to one or both of the interferences can be suppressed.

Further, for example, as shown in FIG. 12, the height position of the flat surface portion may be arranged in three or more stages. FIG. 12 is a cross-sectional view schematically showing a cross section of a concavo-convex structure layer according to another embodiment of the present invention. In the concavo-convex structure layer 611 shown in FIG. 12, the concave portion 616 has flat surface portions 614 and 617 and inclined surface portions 615 and 618. In addition, as a bottom surface, a slope portion 615 is provided around the flat surface portion 614, a flat surface portion 617 is provided around the slope portion 615, a slope portion 618 is provided around the flat surface portion 617, and a gap between adjacent recesses 616. Is provided with a flat surface portion 613. In this way, even when the height position of the flat surface portion is arranged in three or more steps, light can be extracted with high efficiency while maintaining the see-through, and the band-shaped surface portion can be visually recognized on the light exit surface 60U. Can be prevented. In addition, when aligning the height position of a flat surface part in multiple steps | paragraphs of 3 steps or more, the maximum value of the height difference of the flat surface part of a thickness direction becomes a dimension shown by code _| symbol _HMAX in FIG.

  In addition to making the sloped portion flat as in the above-described embodiment, it may be curved as shown in FIG. FIG. 13 is a cross-sectional view schematically showing a cross section of a structural layer according to another embodiment of the present invention. In the concavo-convex structure layer 711 shown in FIG. 13, a flat surface portion 714 is provided as a bottom surface of the concave portion 716, and a curved surface shape in which the inclination angle gradually increases or decreases as the distance from the flat surface portion 714 increases around the flat surface portion 714. A slope portion 715 is provided, and a flat surface portion 713 is provided around the slope portion 715. As described above, even when the slope portion 715 is a curved surface, light can be extracted with high efficiency while maintaining the see-through state, and the belt-like surface portion can be prevented from being visually recognized on the light exit surface 70U.

  Further, for example, in the above-described embodiment, two groups of the group along the direction X and the group along the direction Y are provided as the band-shaped surface portion, but only one group of the band-shaped surface portions along one direction may be provided. You may make it provide 3 or more groups of strip | belt-shaped surface parts along the direction or more. Further, when a plurality of groups of band-shaped surface portions are provided along different directions, the angle at which these band-shaped surface portions intersect is not limited to 90 °, and may be an arbitrary angle such as 60 ° or may be random. .

  In addition, for example, in the above-described embodiment, the light emitting surface structure layer is provided so as to be in direct contact with the light emitting surface, but the light emitting surface structure layer may be provided on the light emitting surface via another layer. Examples of the other layer include a gas barrier layer that protects the organic EL element from the outside air and moisture, and an ultraviolet cut layer that blocks ultraviolet rays.

  Furthermore, for example, in the above-described embodiment, the light emitting surface structure layer is composed of a concavo-convex structure layer, a base film layer, an adhesive layer, and a support 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 surface of the concavo-convex structure layer, and this may define the concavo-convex structure on the light exit surface.

[6. (Use)
The surface light-emitting device of the present invention may be used for applications such as lighting fixtures, backlight devices, and display devices.
The luminaire includes the surface light-emitting element of the present invention as a light source, and further includes optional components such as a member for holding the light source and a circuit for supplying electric power as necessary.
Further, the backlight device has the surface light emitting device of the present invention as a light source, and further, as necessary, a casing, a circuit for supplying power, a diffusion plate for making light emitted more uniform, and a diffusion sheet And optional components such as a prism sheet. Applications of the backlight device include a display device such as a liquid crystal display device that displays an image by controlling pixels, and a backlight of a display device that displays a fixed image such as a signboard.
Furthermore, examples of the display device include an organic EL display device. In addition, a liquid crystal display device including the above-described backlight device is also included in the display device.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below, and may be arbitrarily changed without departing from the gist of the present invention and its equivalent scope. May be implemented.
In the following description, “parts” and “%” indicating amounts are based on weight unless otherwise specified. In addition, the operations described below were performed under normal temperature and normal pressure conditions unless otherwise specified.

[Example 1]
(Manufacture of multilayers)
A roll-shaped base film (trade name “ZEONOR FILM”, manufactured by Nippon Zeon Co., Ltd., alicyclic structure-containing polymer resin film, thickness 100 μm, refractive index 1.53) is mainly composed of urethane acrylate. A UV curable resin (refractive index of 1.54) was applied to form a coating film, and a metal mold was pressed onto the coating film. In this state, ultraviolet rays were irradiated at 1.5 mJ / cm ² to cure the coating film, thereby forming an uneven structure layer (25 μm) having an uneven structure.

FIG. 14 is a plan view schematically showing a part of the surface of the metal mold to be cut in order to explain the state of manufacturing the metal mold used in Example 1. As shown in FIG. 14, the metal mold for producing the concavo-convex structure was produced by cutting according to the following procedure using a cutting tool having an apex angle of 5 ° and a tip width of 50 μm.
(1) On one surface of the metal plate used as a mold, cutting is performed at a certain cutting pitch P along a certain direction in the surface. A cutting mark 801 formed by the first cutting is indicated by a one-dot chain line in FIG.
(2) The cutting start position 802 and the cutting pitch P are set to be the same as the first cutting, and cutting is performed again. As for the cutting direction in this cutting, the already formed cutting trace 801 and the cutting trace 803 formed by the current cutting overlap, and the total of the cutting surface width at the cutting end position 804 is the tip width of the cutting bite. In a direction that is about twice the number of times of cutting (for example, twice in the case of the second cutting) or less. As an example, a cutting mark 803 formed by the second cutting is shown by a solid line in FIG.
(3) Further, the cutting described in the above (2) is performed as many times as the total cutting surface width at the cutting end position 804 becomes a desired cutting surface width. Usually, the cutting surface width at the cutting end position 804 is the maximum cutting surface width of a groove formed by cutting. The maximum cutting surface width can be arbitrarily changed by adjusting the angle in the cutting direction as long as it is within three times the tip width of the cutting tool. Thereby, the first group of grooves whose groove widths continuously change in the extending direction are formed in the metal mold.
(4) Cutting is performed by the cutting methods (1) to (3) above along the direction intersecting at a predetermined crossing angle with respect to the direction cut first time to form the first group of grooves. The second group of grooves intersecting the first group of grooves is formed in the metal mold.

FIG. 15 is a cross-sectional view schematically showing a cross section of a part of the metal mold used in Example 1 cut along a plane perpendicular to one of the cutting directions. As shown in FIG. 15, in Example 1, the cutting pitch P was 200 μm, the maximum cutting surface width was 150 μm, and the intersecting angle in the cutting direction between the first group of grooves and the second group of grooves was 90 °. The groove 806 formed in the produced metal mold 805 had an in-plane cutting surface width W continuously changing from 50 μm to 150 μm in the extending direction. Further, the depth of the groove 806 formed by cutting was changed in five steps in the order of H _{1 to} H ₅ , and repeated cutting was performed using the five grooves 806 thus formed as a repeating unit. In the present embodiment, the depths H _{1 to} H ₅ of the grooves 806 included in the repeating unit are as follows: H ₁ is 19.4 μm, H ₂ is 19.7 μm, H ₃ is 20.0 μm, and H ₄ is 20.3 μm. , And H ₅ were set to 20.6 μm.

  FIG. 16 is a cross-sectional view schematically showing a cross section of a part of the concavo-convex structure layer obtained in Example 1 cut along a plane perpendicular to one of the cutting directions of the metal mold. As shown in FIG. 16, the surface of the obtained concavo-convex structure layer 807 is formed with a concavo-convex structure having a number of quadrangular pyramid-shaped concave portions 808 corresponding to the grooves formed in the metal mold. A flat surface portion 809 is formed, and a plurality of flat surface portions 810 are formed between the recesses 808. Among these, the flat surface portion 810 is a belt-like surface portion extending in parallel with the cutting direction of the metal mold.

  Further, in this concavo-convex structure layer 807, the average inclination angle with respect to the flat surface portions 809 and 810 of the inclined surface portion 811 of the recessed portion 808 was 87.5 °. Further, the ratio of the projected area of the inclined surface portion 811 to the total area of the flat surface portions 809 and 810 was 0.03. Furthermore, the maximum height difference between the flat surface portion 809 and the flat surface portion 810 was 20.6 μm.

(Manufacture of transparent organic EL elements)
A hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, a charge generation layer, a metal oxide layer, and a cathode were formed in this order on a glass substrate having a transparent electrode layer formed on the main surface. The material and film thickness for forming each layer are as follows.

-Transparent electrode layer: ITO 300nm
Hole injection layer: Molybdenum trioxide (MoO ₃ ) 5 nm
-Hole transport layer: NS-21 [manufactured by Nippon Steel Chemical Co., Ltd.] and MoO ₃ 20 nm, NS-21 5 nm, total 25 nm
-Light emitting layer: NS-21 and EY52 (manufactured by e-Ray Optoelectronics Technology (hereinafter referred to as e-Ray)) 20 nm, EB43 and EB52 (both manufactured by e-Ray) 30 nm, total 50 nm
Hole blocking layer: bis (2-methyl-8-quinolinolato) (p-phenylphenolate) aluminum (BAlq) 5 nm
Charge generation layer: Liq and DPB 35 nm, further aluminum 1.5 nm, further NS-21 and MoO ₃ 10 nm, total 37.5 nm
Metal oxide layer: MoO ₃ 5 nm
-Cathode: ITO 100nm

For the formation from the hole injection layer to the metal oxide layer, a glass substrate on which a transparent electrode layer has already been formed is placed in a vacuum evaporation apparatus, and the materials from the hole transport layer to the metal oxide layer are sequentially applied by resistance heating. 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. Thereafter, ITO of the cathode layer was formed by facing target sputtering. This was sealed with another glass plate using a UV curable resin to obtain a transparent organic EL element 1. When the obtained transparent organic EL element 1 was energized and driven, good white light emission was obtained, and both the front direction and the oblique direction were excellent in transparency. Here, the front direction refers to a direction parallel to the normal direction of the light emitting surface, and the oblique direction refers to a direction inclined by 45 ° with respect to the light emitting surface.

(Manufacture of surface light emitting device 1)
A substrate film on which a concavo-convex structure layer is formed is bonded to the obtained transparent organic EL element 1 via an adhesive layer (acrylic resin, refractive index 1.49, manufactured by Nitto Denko Corporation, CS9621), and the transparent organic EL element A surface light emitting device 1 having a layer configuration of 1-adhesive layer-base film-uneven structure layer was obtained. When the obtained surface light-emitting device 1 was energized to emit light and the transparency of the surface light-emitting device 1 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

[Example 2]
FIG. 17 is a cross section of the metal mold used in Example 2 (and Examples 3 to 9 and Comparative Examples 2 to 5 described later) cut at a plane perpendicular to one of the cutting directions at the cutting end position. It is sectional drawing which shows this typically.
The cutting tool was changed to one having an apex angle of 30.0 ° and a tip width of 100.0 μm.
Further, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 20.0 μm, the cutting pitches P _{1 to} P ₅ are set to 400 μm, and the cutting surface width at the cutting end position of the grooves. W _{1 to} W ₅ are repeatedly cut with W ₁ being 100 μm, W ₂ being 150 μm, W ₃ being 200 μm, W ₄ being 250 μm, and W ₅ being 300 μm. Went.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, a concavo-convex structure layer (thickness 25 μm) was manufactured, and a surface light emitting device 2 was manufactured.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 75.0 °. Further, the ratio of the projected area of the slope portion to the total area of the flat surface portion was 0.09, and the maximum height difference of the flat surface portion was 20.1 μm. When the obtained surface light emitting element 2 was made to emit light by being energized and the transparency of the surface light emitting element 2 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 3
The cutting tool was changed to one having an apex angle of 20.0 ° and a tip width of 100 μm.
As shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are 30.0 μm, the cutting pitches P _{1 to} P ₅ are P ₁ of 450 μm, P ₂ of 475 μm, P ₃ is 500 [mu] m, _{P 4} is 525 [mu] m, so _{P 5} is 550 .mu.m, further cutting plane width _W 1 to _W-5 at the cutting end position of the groove and 200 [mu] m, as five repeating units grooves thus formed, Cutting was repeated.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, and a concavo-convex structure layer (thickness: 35 μm) was manufactured to manufacture the surface light emitting device 3.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 80.0 °. The ratio of the projected area of the slope portion to the total area of the flat surface portion was 0.05, and the maximum height difference of the flat surface portion was 30.1 μm. When the obtained surface light emitting device 3 was energized to emit light and the transparency of the surface light emitting device 3 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 4
The cutting tool was changed to one having an apex angle of 30.0 ° and a tip width of 150 μm.
As shown in FIG. 17, the groove depths H _{1 to} H ₅ are set such that H ₁ is 24.4 μm, H ₂ is 24.7 μm, H ₃ is 25.0 μm, H ₄ is 25.3 μm, and H ₅ is 25.6 μm, the cutting pitches P _{1 to} P ₅ are set so that P ₁ is 360 μm, P ₂ is 380 μm, P ₃ is 400 μm, P ₄ is 420 μm, P ₅ is 440 μm, and grooves The cutting surface widths W _{1 to} W ₅ at the cutting end positions were set to 300 μm, and the five grooves thus formed were used as repeating units for repeated cutting.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, and a concavo-convex structure layer (thickness 30 μm) was manufactured to manufacture the surface light emitting device 4.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 75.0 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.09, and the maximum height difference of the flat surface portion was 25.6 μm. When the obtained surface light emitting element 4 was made to emit light by being energized and the transparency of the surface light emitting element 4 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 5
The cutting tool was changed to an apex angle of 8.0 ° and a tip width of 50.0 μm.
Further, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 20.0 μm, the cutting pitches P _{1 to} P ₅ are set to 180 μm for P ₁ , 190 μm for P ₂ , and P _3. Is 200 μm, P ₄ is 210 μm, and P ₅ is 220 μm. Further, the cutting surface widths W _{1 to} W ₅ at the cutting end position of the groove are W ₁ is 50 μm, W ₂ is 75 μm, W ₃ is 100 μm, W ₄ was 125 μm, W ₅ was 150 μm, and the _five grooves thus formed were used as repeating units, and repeated cutting was performed.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, and a concavo-convex structure layer (thickness 25 μm) was manufactured to manufacture the surface light emitting element 5.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the inclined portion with respect to the flat surface portion was 86.0 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.04, and the maximum height difference of the flat surface portion was 20.1 μm. When the obtained surface light emitting device 5 was energized to emit light and the transparency of the surface light emitting device 5 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 6
The cutting tool was changed to one having an apex angle of 25.0 ° and a tip width of 50.0 μm. Also, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold were changed to H _1. There 19.4μm, _{H 2} is 19.7μm, _{H 3} is 20.0 .mu.m, _{H 4} is 20.3Myuemu, so _{H 5} is 20.6Myuemu, so that the cutting pitch _P 1 to P ₅ becomes 400μm Further, the cut surface widths W _{1 to} W ₅ at the groove end positions are set so that W ₁ is 50 μm, W ₂ is 62.5 μm, W ₃ is 75 μm, W ₄ is 87.5 μm, and W ₅ is 100 μm. Then, the five grooves thus formed were repeatedly used as a repeating unit, and cutting was performed repeatedly.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, and a concavo-convex structure layer (thickness 25 μm) was manufactured to manufacture the surface light emitting element 6.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 77.5 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.09, and the maximum height difference of the flat surface portion was 20.6 μm. When the obtained surface light emitting element 6 was made to emit electricity and light was emitted, and the transparency of the surface light emitting element 6 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 7
The cutting tool was changed to one having an apex angle of 5.0 ° and a tip width of 50.0 μm.
As shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 19.4 μm, H ₂ is 19.7 μm, H ₃ is 20.0 μm, and H ₄ is 20 .3 μm and H ₅ are set to 20.6 μm, and the cutting pitches P _{1 to} P ₅ are set such that P ₁ is 180 μm, P ₂ is 190 μm, P ₃ is 200 μm, P ₄ is 210 μm, and P ₅ is 220 μm. And the cut surface widths W _{1 to} W ₅ at the groove cutting end positions are set such that W ₁ is 50 μm, W ₂ is 75 μm, W ₃ is 100 μm, W ₄ is 125 μm, and W ₅ is 150 μm. Cutting was repeated using the five grooves as a repeating unit.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, a concavo-convex structure layer (thickness 25 μm) was manufactured, and the surface light emitting device 7 was manufactured.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the inclined portion with respect to the flat surface portion was 87.5 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.03, and the maximum height difference of the flat surface portion was 20.6 μm. When the obtained surface light emitting device 7 was energized to emit light and the transparency of the surface light emitting device 7 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 8
The cutting tool was changed to one having an apex angle of 5.0 ° and a tip width of 25.0 μm.
As shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 19.4 μm, H ₂ is 19.7 μm, H ₃ is 20.0 μm, and H ₄ is 20 .3 μm and H ₅ are set to 20.6 μm, and the cutting pitches P _{1 to} P ₅ are set such that P ₁ is 180 μm, P ₂ is 190 μm, P ₃ is 200 μm, P ₄ is 210 μm, and P ₅ is 220 μm. The cut surface widths W _{1 to} W ₅ at the groove cutting end positions are set such that W ₁ is 25.0 μm, W ₂ is 37.5 μm, W ₃ is 50.0 μm, W ₄ is 62.5 μm, and W ₅ is 75. The crossing angle between the first group of grooves and the second group of grooves was set to 60 °.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, and a concavo-convex structure layer (thickness: 25 μm) was manufactured to manufacture the surface light emitting device 8.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the inclined portion with respect to the flat surface portion was 87.5 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.03, and the maximum height difference of the flat surface portion was 20.6 μm. When the obtained surface light emitting device 8 was made to emit light by being energized and the transparency of the surface light emitting device 8 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 9
The cutting tool was changed to one having an apex angle of 10.0 ° and a tip width of 60.0 μm.
As shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 14.4 μm, H ₂ is 14.7 μm, H ₃ is 15.0 μm, and H ₄ is 15 .3 μm and H ₅ are 15.6 μm, and the cutting pitches P _{1 to} P ₅ are set such that P ₁ is 180 μm, P ₂ is 190 μm, P ₃ is 200 μm, P ₄ is 210 μm, and P ₅ is 220 μm. Then, the cut surface widths W _{1 to} W ₅ at the groove cutting end position are set such that W ₁ is 60.0 μm, W ₂ is 90.0 μm, W ₃ is 120.0 μm, W ₄ is 150.0 μm, and W ₅ is 180. A metal mold was manufactured in the same manner as in Example 1 except that the crossing angle between the first group of grooves and the second group of grooves was 60 °. A die having an inverted shape from this metal mold was manufactured by Ni electroforming (thickness: about 300 μm). A surface light emitting device 9 was manufactured by manufacturing a concavo-convex structure layer (thickness 20 μm) in the same manner as in Example 1 except that the mold thus obtained was a transfer mold for forming the concavo-convex structure layer.

  On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 85.0 °. The ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.04, and the maximum height difference of the flat surface portion was 15.6 μm. When the obtained surface light emitting device 9 was energized to emit light and the transparency of the surface light emitting device 9 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

[Comparative Example 2]
The cutting tool was changed to one having an apex angle of 20.0 ° and a tip width of 10.0 μm.
As shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 19.4 μm, H ₂ is 19.7 μm, H ₃ is 20.0 μm, and H ₄ is 20 0.3 μm and H ₅ were set to 20.6 μm, and the cutting pitches P _{1 to} P ₅ were set to 100.0 μm.
Further, the cutting in each direction was performed only once, so that the cutting surface width was uniform in the direction in which the groove extends.
Except for the above, a metal mold was produced in the same manner as in Example 1, and a concavo-convex structure layer (thickness 25 μm) was produced to produce the surface light emitting device 10.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.32, and the maximum height difference of the flat surface portion was 20.6 μm. .
When the obtained surface light emitting device 10 was energized to emit light and the transparency of the surface light emitting device 10 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Comparative Example 3]
The cutting tool was changed to one having an apex angle of 40.0 ° and a tip width of 10.0 μm.
In addition, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 5.0 μm, the cutting pitches P _{1 to} P ₅ are set to P ₁ of 31.5 μm, and P _2. Was 33.3 μm, P ₃ was 35.0 μm, P ₄ was 36.8 μm, and P ₅ was 38.5 μm.
Further, the cutting in each direction was performed only once, so that the cutting surface width was uniform in the direction in which the groove extends.
Except for the above, a metal mold was manufactured in the same manner as in Example 1, a concavo-convex structure layer (thickness 10 μm) was manufactured, and the surface light emitting element 11 was manufactured.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.40, and the maximum height difference of the flat surface portion was 5.1 μm. .
When the obtained surface light emitting element 11 was made to emit light by being energized and the transparency of the surface light emitting element 11 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Comparative Example 4]
The cutting tool was changed to one having an apex angle of 20.0 ° and a tip width of 30.0 μm.
Further, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 24.4 μm, H ₂ is 24.7 μm, H ₃ is 25.0 μm, and H ₄ is 25. .3Myuemu, so _{H 5} is 25.6Myuemu, the cutting pitch _{P 1} ~P _{5, P} 1 is 90.0μm, _{P 2} is 95.0μm, _{P 3} is 100.0, _{P 4} is 105.0μm , was set to _{P 5} is 110.0μm.
Further, the cutting in each direction was performed only once, so that the cutting surface width was uniform in the direction in which the groove extends.
Except for the above, a metal mold was produced in the same manner as in Example 1, a concavo-convex structure layer (thickness 30 μm) was produced, and a surface light emitting device 12 was produced.

In the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.28, and the maximum height difference of the flat surface portion was 25.6 μm. .
When the obtained surface light emitting device 12 was energized to emit light and the transparency of the surface light emitting device 12 was visually evaluated, the transparency from the front direction and the oblique direction was poor.

[Comparative Example 5]
The cutting tool was changed to one having an apex angle of 30.0 ° and a tip width of 50.0 μm.
Further, as shown in FIG. 17, the heights H _{1 to} H ₅ of the grooves formed in the metal mold are as follows: H ₁ is 24.4 μm, H ₂ is 24.7 μm, H ₃ is 25.0 μm, and H ₄ is 25. .3Myuemu, so _{H 5} is 25.6Myuemu, the cutting pitch _{P 1} ~P _{5, P} 1 is 90.0μm, _{P 2} is 95.0μm, _{P 3} is 100.0, _{P 4} is 105.0μm , was set to _{P 5} is 110.0μm.
Further, the cutting in each direction was performed only once, so that the cutting surface width was uniform in the direction in which the groove extends.
Except for the above, a metal mold was produced in the same manner as in Example 1, a concavo-convex structure layer (thickness 30 μm) was produced, and a surface light emitting device 13 was produced.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.26, and the maximum height difference of the flat surface portion was 25.6 μm. .
When the obtained surface light emitting device 13 was energized to emit light and the transparency of the surface light emitting device 13 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Evaluation]
(Light extraction amount)
About the transparent organic EL element 1 obtained in Example 1, and the surface light-emitting elements 1 to 13 obtained in Examples 1 to 9 and Comparative Examples 2 to 5, the program (program name “ASAP”, manufactured by Breath Research) In the optical simulation using, the luminous intensity of the light emitting layer was set to 1 lm, and the luminous intensity emitted from both sides was calculated. The obtained values are shown in Tables 1-3. In Tables 1 to 3, the numerical value in the “bonding surface” column represents the amount of light extracted from the light exit surface having the uneven structure provided with the uneven structure layer, and the numerical value in the “back surface” column represents the uneven structure layer. Represents the amount of light extracted from the glass surface. Further, the transparent organic EL element 1 is handled as Comparative Example 1. In Comparative Example 1, the numerical value in the “bonding surface” column and the numerical value in the “back surface” column both represent the amount of light extracted from the glass surface without the uneven structure layer.

(Transparency of uneven structure layer)
For the concavo-convex structure layers obtained in Examples 1 to 9 and Comparative Examples 2 to 5, the parallel light transmittance and the diffuse light transmittance were determined by optical simulation using a program (program name “ASAP”, manufactured by Breath Research). As a numerical value representing the transparency of the uneven structure layer, (diffuse light transmittance) / (parallel light transmittance + diffuse light transmittance) × 100 was calculated. It represents that it is excellent in the transparency seen from the thickness direction, so that this figure is low. The obtained values are shown in Tables 1-3.

(Lattice unevenness)
The surface light emitting devices 1 to 13 obtained in Examples 1 to 9 and Comparative Examples 2 to 5 were visually observed to confirm the presence or absence of lattice unevenness. In Examples 1 to 9, since the width of the flat surface portion included in the concavo-convex structure layer was changed, the lattice unevenness was hardly observed and was excellent.

(Visibility)
The transparent organic EL element 1 and the surface light emitting elements 1 to 13 are arranged in a non-lighting state 50 cm before the display surface on which characters of 5 mm × 5 mm size are arranged, and through the transparent organic EL element 1 and the surface light emitting elements 1 to 13, The characters were observed from the front and diagonal directions. Characters that are clearly visible with no blurring or distortion are classified as “excellent”, while those with blurring or distortion are “good”, while those that can read characters are “good”, and those that have many blurring or distortion and are not clearly readable are “bad”. The results are shown in Tables 1-3.

(Rainbow unevenness)
The surface light emitting devices obtained in Examples 1 to 9 and Comparative Examples 2 to 5 were visually observed to confirm the presence or absence of rainbow unevenness. In each of Examples 1 to 4 and Comparative Examples 2 to 5, since the unevenness of the uneven structure is uneven within a predetermined range, rainbow unevenness based on interference in the reflected light on the front and back surfaces of the uneven structure layer Was not observed and was excellent.

Example 10
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 5.0 ° and a tip width of 50.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 20.0 μm. The metal mold was manufactured in the same manner as in Example 1 except that the cutting surface width W at the groove cutting end position was 100.0 μm and the cutting pitch P was 200.0 μm, Furthermore, the uneven | corrugated structure layer (25 micrometers in thickness) was manufactured, and the surface emitting element 14 was manufactured.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the inclined portion with respect to the flat surface portion was 87.5 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.03, and the maximum height difference of the flat surface portion was 20.1 μm.
When the obtained surface light emitting device 14 was energized to emit light and the transparency of the surface light emitting device 14 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 11
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 40.0 ° and a tip width of 100.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 10.0 μm. The metal mold was manufactured in the same manner as in Example 1 except that the cutting surface width W at the groove cutting end position was 200.0 μm and the cutting pitch P was 300.0 μm, Furthermore, the uneven | corrugated structure layer (thickness 15 micrometers) was manufactured, and the surface emitting element 15 was manufactured.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 70.0 °. Further, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.08, and the maximum height difference of the flat surface portion was 10.1 μm.
When the obtained surface light emitting device 15 was energized to emit light, and the transparency of the surface light emitting device 15 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 12
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 15.0 ° and a tip width of 100.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 27.0 μm. A metal mold was manufactured in the same manner as in Example 1 except that the cutting surface width W at the cutting end position was 300.0 μm and the cutting pitch P was 400.0 μm. A structural layer (thickness 32.0 μm) was manufactured to manufacture the surface light emitting device 16.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 82.5 °. The ratio of the projected area of the slope portion to the total area of the flat surface portion was 0.04, and the maximum height difference of the flat surface portion was 27.1 μm.
When the obtained surface light emitting element 16 was energized to emit light and the transparency of the surface light emitting element 16 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

Example 13
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 30.0 ° and a tip width of 200.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 25.0 μm. A metal mold was manufactured in the same manner as in Example 1 except that the cutting surface width W at the cutting end position was 400.0 μm and the cutting pitch P was 500.0 μm. A structural layer (thickness 30.0 μm) was manufactured to manufacture a surface light emitting device 17.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the average inclination angle of the slope portion with respect to the flat surface portion was 75.0 °. The ratio of the projected area of the slope portion to the total area of the flat surface portion was 0.07, and the maximum height difference of the flat surface portion was 25.1 μm.
When the obtained surface light emitting device 17 was energized to emit light and the transparency of the surface light emitting device 17 was visually evaluated, the transparency from the front direction and the oblique direction was excellent.

[Comparative Example 6]
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 20.0 ° and a tip width of 10.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 20.0 μm. The cutting pitch P was set to 100.0 μm, and the cutting in each direction was performed only once so that the cutting surface width was uniform in the direction in which the grooves extend, In the same manner as in Example 1, a metal mold was manufactured, a concavo-convex structure layer (thickness 25 μm) was manufactured, and a surface light emitting element 18 was manufactured.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the total area of the flat surface portion was 0.32, and the maximum height difference of the flat surface portion was 20.1 μm. .
When the obtained surface light emitting device 18 was energized to emit light and the transparency of the surface light emitting device 18 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Comparative Example 7]
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 40.0 ° and a tip width of 10.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 5.0 μm. Except that the cutting pitch P is 35.0 μm, and the cutting surface width is uniform in the direction in which the grooves extend by cutting each direction only once. In the same manner as in Example 1, a metal mold was manufactured, a concavo-convex structure layer (thickness 10 μm) was manufactured, and a surface light emitting device 19 was manufactured.

On the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the area of the flat surface portion was 0.40, and the maximum height difference of the flat surface portion was 5.1 μm.
When the obtained surface light emitting element 19 was made to emit electricity and light was emitted and the transparency of the surface light emitting element 19 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Comparative Example 8]
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 20.0 ° and a tip width of 30.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 25.0 μm. The cutting pitch P was set to 100.0 μm, and the cutting in each direction was performed only once so that the cutting surface width was uniform in the direction in which the grooves extend, In the same manner as in Example 1, a metal mold was manufactured, a concavo-convex structure layer (thickness 30 μm) was manufactured, and the surface light emitting element 20 was manufactured.

In the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the area of the flat surface portion was 0.28, and the maximum height difference of the flat surface portion was 25.1 μm.
When the obtained surface light emitting element 20 was made to energize and light-emit and the transparency of the surface light emitting element 20 was evaluated visually, the transparency from the front direction and the diagonal direction was inferior.

[Comparative Example 9]
As shown in FIG. 15, the cutting tool is changed to one having an apex angle of 30.0 ° and a tip width of 50.0 μm, and the heights H _{1 to} H ₅ of the grooves formed in the metal mold are set to 25.0 μm. The cutting pitch P was set to 100.0 μm, and the cutting in each direction was performed only once so that the cutting surface width was uniform in the direction in which the grooves extend, In the same manner as in Example 1, a metal mold was manufactured, a concavo-convex structure layer (thickness 30 μm) was manufactured, and a surface light emitting device 21 was manufactured.

In the surface of the manufactured concavo-convex structure layer on which the concavo-convex structure was formed, the ratio of the projected area of the inclined surface portion to the area of the flat surface portion was 0.26, and the maximum height difference of the flat surface portion was 25.1 μm.
When the obtained surface light emitting element 21 was energized to emit light and the transparency of the surface light emitting element 21 was visually evaluated, the transparency from the front direction and the oblique direction was inferior.

[Evaluation]
About the surface light emitting elements 14-21 obtained in Examples 10-13 and Comparative Examples 6-9, the amount of light extraction and transparency were evaluated in the way mentioned above. The results are shown in Tables 4 and 5.

  Further, when the surface light-emitting elements 14 to 21 obtained in Examples 10 to 13 and Comparative Examples 6 to 9 were visually observed, some rainbow unevenness was present, but this was not regarded as a problem depending on the use mode. It was about.

DESCRIPTION OF SYMBOLS 10 Surface light emitting element 10U, 10D Light emission surface 20 Surface light emitting element 30U Light emission surface 40 Surface light emitting element 50U Light emission surface 60U Light emission surface 70U Light emission surface 100 Light emission surface structure layer 110 Multi-layer body 111 Uneven structure layer 112 Base film layer 113 Flat surface part 113X Strip surface portion 113Y Strip surface portion 113Z Intersection portion of strip surface portion 114 Flat surface portion 115 Slope portion 116 Recessed portion 117 Boundary line between slope portion 115 and flat surface portion 121 Adhesive layer 131 Support substrate 140 Organic EL element 141 First transparent electrode layer 142 Light emitting layer 143 Second transparent electrode layer 144,145 Light emitting surface 151 Sealing substrate 311 Concavity and convexity structure layer 313 Flat surface portion 314 Flat surface portion 315 Slope portion 316 Concavity 317 Flat surface portion 318 Slope portion 319 Concavity 461 Inert gas layer 511 Concavity and convexity Layer 513 Flat surface part 5 DESCRIPTION OF SYMBOLS 5 Slope part 516 Concave part 611 Uneven structure layer 613 Flat surface part 614 Flat surface part 615 Slope part 616 Concave part 617 Flat surface part 618 Slope part 711 Concavity and convexity structure layer 713 Flat surface part 714 Flat surface part 715 Slope part 716 Concave part 801 Cutting mark 802 Cutting mark 802 Trace 804 Cutting end position 805 Metal mold 806 Groove 807 Concavity and convexity structure layer 808 Concavity 809 Flat surface portion 810 Flat surface portion 811 Slope portion 900 Flat surface parallel to the flat surface portion 901 Slope projection image

Claims (5)

A double-sided light emitting organic electroluminescent device comprising a first transparent electrode layer, a light emitting layer, and a second transparent electrode layer in this order, and light emission provided directly or indirectly on at least one surface of the organic electroluminescent device A surface light emitting device comprising a surface structure layer,
The light-emitting surface structure layer includes a flat surface portion parallel to the one surface of the organic electroluminescence element, a slope portion inclined with respect to the flat surface portion, on a surface opposite to the organic electroluminescence element. Having a concavo-convex structure including
The flat surface portion includes a band-shaped surface portion extending in one direction,
The width of the band-shaped surface portion is changed in the direction in which the band-shaped surface portion extends,
A projected area formed by projecting the slope portion in a direction perpendicular to the flat surface portion onto a plane parallel to the flat surface portion is 0.1 times or less of the total area of the flat surface portions. There is a surface light emitting device.   The surface light emitting element of Claim 1 whose maximum value of the height difference of the said flat surface part in the said uneven structure is 22 micrometers or less.   The surface light emitting element according to claim 1, wherein the slope portion is inclined at an inclination angle of 80 ° or more and less than 90 ° with respect to the flat surface portion.   The surface emitting element according to claim 1, wherein a maximum value of the height difference of the flat surface portion is 0.1 μm or more.   A lighting fixture provided with the surface emitting element as described in any one of Claims 1-4.

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