JP2016136484A - Surface light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light-emitting device including a structure that extracts light from the peripheral part of a light-emitting member and suppresses occurrence of color shift, thereby to increase a light-emitting area.SOLUTION: A surface light-emitting device includes a light-emitting member 10, a light guide member 30 formed on the light-emitting member 10, and a transparent member 20 formed on the light guide member 30. The refractive index of the light guide member 30 is set larger than the refractive index of the transparent member 20. In a plane view from the side of the transparent member 20, the light guide member 30 and the transparent member 20 have a first region R1 covering the light-emitting member 10, and a second region R2 adjacent to the peripheral edge of the first region R1. In at least the second region R2, a light diffusion member 40 is provided between the light guide member 30 and the transparent member 20, and the second region R2 contains a light diffusion strength region having light diffusion strength stronger than light diffusion strength in the first region R1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a surface light emitting device used for a backlight of a liquid crystal display.

  Organic EL (ELectro-Luminescence) is used, for example, as a backlight of a liquid crystal display, and a large-area organic EL element is required. However, since the organic RL element is very thin and the thickness of the organic layer is about several tens to several hundreds of nanometers, it is difficult to form the organic layer uniformly over a wide area, resulting in poor yield. In order to solve this problem, a technique has been proposed in which a plurality of light emitting members including organic EL elements are arranged to be used as a large area planar light emitting device.

  However, when a plurality of light emitting members are arranged to have a large area, a connection location between adjacent light emitting members becomes a problem. This is because the peripheral part of the light emitting member is provided with terminal electrodes and electrode connection lines for connection to an external drive circuit, etc., so that no light is emitted from the peripheral part, and a light emitting part and a non-light emitting part can be formed. Because it ends up. Techniques for solving this problem are disclosed in Japanese Unexamined Patent Application Publication No. 2005-158665 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2010-40486 (Patent Document 2).

JP 2005-158665 A JP 2010-40486 A

  In the light-emitting element and the light-emitting device disclosed in Patent Document 1, the area of the light emission surface of the transparent substrate provided with the light-emitting portion is formed larger than the area of the light-emitting portion. Thereby, a part of the light incident on the transparent substrate from the light emitting part is guided in a part other than the part corresponding to the light emitting part of the transparent substrate.

  Of the light traveling to a portion other than the portion corresponding to the light emitting portion of the transparent substrate, most of the light traveling in the direction not exiting from the light exit surface of the transparent substrate is emitted from the light exit surface by the action of the deflecting portion. The traveling direction is changed and emitted from the light exit surface. Accordingly, of the light incident on the transparent substrate from the light emitting portion, light that has not been used conventionally is emitted from the light emitting surface of the portion other than the portion corresponding to the light emitting portion of the transparent substrate, thereby increasing the light emitting area of the light emitting portion. Making it possible.

  However, in the technique disclosed in Patent Document 1, since the refractive index of the light emitting part is generally larger than the refractive index of the transparent substrate, light emitted obliquely with respect to the transparent substrate is guided through the light emitting part by total reflection. It will wave. Therefore, when the amount of light guided to the peripheral portion is reduced, the non-light emitting portion becomes darker than the light emitting portion, and the light emitting portion does not appear in a large area. In addition, it is difficult to disperse the diffusing particles as the deflecting portion on the transparent substrate, and it is considered that the element fabrication process becomes complicated.

  In the light-emitting element and the light-emitting device disclosed in Patent Document 2, the periodic structure is provided on the peripheral part and on the transparent member side with respect to the light-emitting part. Thereby, the light guided inside the organic EL element is extracted outside by the periodic structure. Therefore, since light is emitted from the peripheral portion, the light emitting area of the light emitting portion can be increased.

  However, when light including a plurality of wavelengths is emitted from the light emitting unit, it is conceivable that color deviation occurs in the extracted light because the light has different diffraction angles depending on each wavelength. Furthermore, it is difficult to create a periodic structure, and the element creation process may be complicated.

  The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to increase the light emitting area by extracting light from the peripheral portion of the light emitting member and suppressing the occurrence of color misregistration. It is providing a surface light-emitting device provided with.

  In the surface light-emitting device based on this invention, the light-emitting member includes a light-emitting member, a light guide member formed on the light-emitting member, and a transparent member formed on the light guide member. The refractive index is provided larger than the refractive index of the transparent member, and when viewed in plan from the transparent member side, the light guide member and the transparent member include a first region that covers the light emitting member, and the above A second region adjacent to the periphery of the first region, and at least in the second region, a light diffusing member is provided between the light guide member and the transparent member, and the light in the second region The diffusion intensity includes a light diffusion intensity region that is stronger than the light diffusion intensity of the first region.

In another embodiment, the light diffusing member is provided only in the second region.
In another form, the refractive index of the said light guide member is larger than the refractive index of the said light emitting member, and the refractive index of the said light emitting member is provided larger than the refractive index of the said transparent member.

In another form, the color of the light emitted from the light emitting member is white.
In another embodiment, the amount of light emitted from the light emitting member is larger in the oblique direction than in the front direction.

  In another embodiment, the light emitting member and the light diffusing member are layers formed by a coating process.

  In another embodiment, the light diffusing member includes scattering particles that scatter light, and the particle number density of the scattering particles in the second region is larger than the particle number density of the scattering particles in the first region. .

  In another embodiment, the thickness of the light diffusing member in the second region is greater than the thickness of the light diffusing member in the first region.

  According to this surface light emitting device, it is possible to provide a surface light emitting device having a structure that allows light to be extracted from the peripheral portion of the light emitting member and suppress the occurrence of color misregistration to increase the light emitting area. To do.

It is a figure which shows the structure of the surface light-emitting device in embodiment, and is the II sectional view taken on the line in FIG. It is a figure which shows the structure of the surface light-emitting device in embodiment, and is a top view at the time of planar view from the transparent member side. It is a figure which shows the thickness of the structural member of the surface emitting device in embodiment. It is a partial expanded sectional view which shows the structure of the surface emitting device in embodiment. It is sectional drawing which modeled the structure of the surface emitting apparatus in related technology. It is the 1st sectional view which modeled the composition of the surface emitting device in an embodiment. It is the 2nd sectional view which modeled the composition of the surface emitting device in an embodiment. It is a cross section corresponding to the II arrow directional cross section in FIG. 2 of the surface emitting device in Example 1. FIG. It is a cross section corresponding to the II cross section of the surface light-emitting device in Example 2 in FIG. It is a partial expanded sectional view of the surface emitting device shown in FIG. It is the 1st figure which graphed the light quantity (light distribution shape) of the light radiate | emitted from the light emission member of the surface emitting device in Example 3. FIG. It is the 2nd figure which graphed the light quantity (light distribution shape) of the light radiate | emitted from the light emission member of the surface emitting device in Example 3. FIG. It is a figure which shows the comparison result of the light emission area of the present Examples 1-3 and a comparative example technique. It is a figure which shows the measurement position of a light emission area. It is a figure which shows the particle number density of the scattering member in the light-diffusion member in Examples 1-3. It is a figure which shows the measurement position of scattering particle number density. It is sectional drawing which shows the structure of the surface emitting device in other embodiment.

  The surface light emitting device in each embodiment based on the present invention will be described below with reference to the drawings. Note that in the embodiment described below, when referring to the number, amount, and the like, the scope of the embodiment is not necessarily limited to the number, amount, or the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. In addition, it is planned from the beginning to use the structures in the embodiments in appropriate combinations.

  With reference to FIGS. 1 to 3, the configuration of surface emitting device 100 in the present embodiment will be described. 1 is a cross-sectional view taken along the line II in FIG. 2, FIG. 2 is a plan view when viewed from the transparent member side, and FIG. 3 is a diagram showing the thickness of the constituent members of the surface light emitting device 100. is there.

  Referring to FIGS. 1 and 2, surface light emitting device 100 in the present embodiment includes light emitting member 10, light guide member 30 formed on light emitting member 10, and light guide member 30. And the formed transparent member 20. The refractive index of the light guide member 30 is set larger than the refractive index of the transparent member 20.

  When viewed in plan from the transparent member 20 side, the light guide member 30 and the transparent member 20 have a first region R1 that covers the light emitting member 10 and a second region R2 that is adjacent to the periphery of the first region R1. doing. A light diffusion member 40 is provided between the light guide member 30 and the transparent member 20, and the light diffusion intensity of the second region R2 includes a region that is stronger than the light diffusion intensity of the first region R1. In the present embodiment, the light emitting member 10, the light guide member 30, the light diffusing member 40, and the transparent member 20 are formed so as to be optically in close contact with each other.

  Hereinafter, each component will be described. The light emitting member 10 has a configuration in which two electrodes sandwich an organic EL layer. The electrode on the light emitting surface (transparent member 20) side is formed of a transparent conductive material, and ITO (Tin-doped indium oxide) or the like is used. Moreover, the electrode located on the opposite side across the organic EL layer is formed of a metal such as aluminum or silver and has light reflectivity.

  The organic EL layer is composed of five layers including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer, and light emitted from the light emitting layer is white light including a plurality of wavelengths. . Therefore, the color of the light emitted from the light emitting member 10 is also white.

  The light guide member 30 is made of light-transmitting ink. The light diffusing member 40 is composed of ink containing scattering particles 41 including white scattering particles typified by titanium oxide. The transparent member 20 is preferably a light transmissive material such as a resin such as acrylic or PC, or glass. It may be made of a bendable material such as silicone rubber.

  With reference to FIG. 3, the thickness of a structural member is shown. In order to suppress the absorption rate of light that guides the inside of the light guide member 30, it is desirable that the thickness of the light guide member 30 be about the wavelength of light. Specifically, when the color of light emitted from the light emitting member 10 is white, the emitted light is light having a wavelength of red (620 nm to 750 nm), green (495 nm to 570 nm), and blue (450 nm to 495 nm). Therefore, the thickness of the light guide member 30 is preferably 750 nm to 450 nm.

  The transparent member 20 preferably has a thickness of about 0.2 mm, the light diffusion member 40 has a thickness of about 1 μm or less, the light guide member 30 has a thickness of about 1 μm or less, and the light emitting member has a thickness of about 1 μm or less.

Examples of the material of the scattering particles 41 that can easily form particles include TiO ₂ (refractive index n = 2.5) and SiOx (refractive index n = 1.4 to 3.5). Examples of other materials include diamond, calcium fluoride (CaF), silicon nitride (Si ₃ N 4), and the like.

  A manufacturing process will be described. The light guide member 30 and the light diffusing member 40 are formed by a coating process. The electrode of the light emitting member 10 is formed by a sputtering method, a vapor deposition method, or a coating process, and the organic EL layer is also formed by a sputtering method, a vapor deposition method, or a coating process.

  Next, with reference to FIG. 4, the relationship of the refractive index in each structural member is demonstrated. FIG. 4 is a partial enlarged cross-sectional view of the surface light emitting device 100. In general, the refractive index of the organic EL layer in the light emitting member 10 is about 1.7, the refractive index of the electrode formed of the transparent member on the light emitting surface side is about 1.8, and the transparent member 20 in terms of the materials used. Is about 1.5.

  Therefore, a light guide member 30 having a refractive index (n = 1.9) higher than the refractive index (n = 1.5) of the transparent member 20 is used. Further, the refractive index of the light diffusing member 40 (n = 2.0) so that the light incident on the light diffusing member 40 from the light guide member 30 can be easily taken out in the second region R2 which is the peripheral portion of the first region R1. Is preferably higher than the refractive index of the light guide member 30 (n = 1.9).

  The effects obtained by the configuration of the surface light emitting device 100 will be described with reference to FIGS. FIG. 5 is a cross-sectional view modeling the configuration of the surface light emitting device in the related art, and FIGS. 6 and 7 are first and second cross-sectional views modeling the configuration of the surface light emitting device in the present embodiment.

  With reference to FIG. 5, in the related art configuration, a light guide member having a refractive index higher than that of transparent member 20 is not provided between light emitting member 10 and transparent member 20. Therefore, most of the light L1 emitted obliquely from the light emitting member 10 has a difference in refractive index between the transparent member 20 and the light emitting member 10 (refractive index of the transparent member 20 (n = 1.5) <refraction of the light emitting member 10). It is difficult to extract light from the second region R2 that is guided in the light emitting member 10 at a rate (n = 1.8)) and is a peripheral portion of the first region R1.

  On the other hand, in the surface light emitting device 100 according to the present embodiment, as shown in FIG. 6, a light guide member 30 is provided between the light emitting member 10 and the transparent member 20, and the light guide member 30 is formed by the transparent member 20. Due to the high refractive index (the refractive index of the transparent member 20 (n = 1.5) <the refractive index of the light guide member 30 (n = 1.7)), the light L11 guided in the light emitting member 10 is reflected. The light can be easily incident on the light guide member 30.

  For example, in the relationship of the refractive index shown in FIG. 5, in the case of the light L1 having an incident angle α, the light L1 cannot be incident on the light guide member 30. However, the refractive index relationship shown in FIG. 6 allows the light L11 to be incident on the light guide member 30. Further, the relationship of the refractive index between the light guide member 30 and the transparent member 20 is the above relationship (refractive index of the transparent member 20 (n = 1.5) <refractive index of the light guide member 30 (n = 1. 7)), the incident light on the light guide member 30 can be totally reflected and guided to a position corresponding to the second region R2.

  Furthermore, as shown in FIG. 7, the refractive index of the light guide member 30 is higher than the refractive index of the light emitting member 10 (refractive index of the light guide member 30 (n = 1.9)> refractive index of the light emitting member 10 (n = 1.8)> The refractive index of the transparent member 20 (n = 1.5)), the light that is totally reflected and guided in the light emitting member 10 is eliminated, and all the light L21 is guided by the light guide member 30. It becomes possible to enter.

  As a result, the first region emits more light than the case where the difference in refractive index is “the refractive index of the light emitting member 10> the refractive index of the light guide member 30> the refractive index of the transparent member 20” (the relationship shown in FIG. 6). The light can be guided to the position of the second region R2 that is the peripheral portion of R1.

  Referring again to FIG. 4, the light guided to the position of the second region R <b> 2 is deflected in the traveling direction by the light diffusion member 40 provided on the light guide member 30, and passes through the transparent member 20. To be taken out. Since the light diffusing member 40 deflects light in a random direction by scattering particles, no color shift occurs even when the light emitting member 10 emits light including a plurality of wavelengths. As a result, it is possible to emit light in the first region R1 and the second region R2 without causing a color shift, and the surface emitting device 100 can increase the light emitting area.

Example 1
Next, with reference to FIG. 8, the surface light-emitting device 100A in Example 1 will be described. FIG. 8 is a cross section corresponding to the cross section taken along line I-I in FIG. 2, and the basic structure is the same as that of the surface light emitting device 100.

  The light emitting member 10, the light guide member 30, and the transparent member 20 have areas of a square shape with a side of 3.5 mm, and the light guide member 30 and the transparent member 20 have a square shape with a side of 7.9 mm. When the planar light emitting device 100A is used as viewed from the transparent member 20 side, the area covering the light emitting member 10 constitutes the first area R1, and the area adjacent to the periphery of the first area R1 is the second area R2. It is composed. Since the light emitting member 10 is located at the center of the light guide member 30 and the transparent member 20, the width of the second region R <b> 2 is 2.2 mm over the entire circumference of the light emitting member 10. The light distribution of the light emitting member 10 is Lambert light distribution.

  Between the light guide member 30 and the transparent member 20, a light diffusion member 40 having the same shape as the light guide member 30 and the transparent member 20 in a plan view is provided so as to cover the light emitting surface of the light emitting member 10. . In the present embodiment, the density of the scattering particles 41 provided in the light diffusing member 40 is formed so as to increase continuously from the first region R1 to the second region R2 facing the light emitting member 10. Yes. The density of the scattering particles 41 may be discretely increased from the central part to the peripheral part of the light emitting member 10 (modified example of Example 1).

  With the above configuration, as shown in FIG. 8, the light emitted from the light emitting member 10 toward the first region R <b> 1 in the front direction has a low probability of hitting the scattering particles 41, and thus most of the light L <b> 51. Goes straight ahead and is taken out. In addition, since a part of the light L53 is deflected in the traveling direction by hitting the scattering particles 41, the light L53 becomes guided light toward the second region R2 which is the peripheral portion.

  On the other hand, the light L53 emitted in an oblique direction from the light emitting member 10 and guided by being totally reflected by the light guide member 30 is likely to hit the scattering particles 41 from the first region R1 toward the second region R2. Therefore, it is gradually extracted to the outside as it goes from the first region R1 to the second region R2.

  Therefore, the density of the scattering particles 41 is formed so as to increase from the first region R1 toward the second region R2, so that the density of the scattering particles 41 decreases as the distance from the first region R1 toward the second region R2. As compared with the case where the density of the scattering particles 41 is uniform in the entire light guide layer, the light emission area can be increased while the light amount difference between the first region R1 and the second region R2 is made constant.

(Example 2)
With reference to FIG. 9 and FIG. 10, the structure of the surface emitting device 200 in Example 2 is demonstrated. FIG. 9 is a cross section corresponding to the cross section taken along line I-I in FIG. 2, and the basic structure is the same as that of the surface light emitting device 100. FIG. 10 is a partially enlarged cross-sectional view of the surface light emitting device 200 shown in FIG.

  The difference from the configuration of the surface light emitting device 100A shown in Example 1 is that the light diffusion member 40 is formed only in the second region R2. Furthermore, it is desirable that the refractive index of the light diffusing member 40 is higher than the refractive index of the light guiding member 30 in order to make it easier for light to enter the light diffusing member 40 from the light guiding member 30. With this configuration, the light emitted from the light emitting member 10 to the first region R1 does not hit the scattering particles 41, and proceeds straight as it is to the outside.

  On the other hand, the light emitted from the light emitting member 10 in the oblique direction and guided to the second region R2 while totally reflecting the light guide member 30 hits the scattering particles 41 of the light diffusion member 40 located in the second region R2, Take out to the outside. Therefore, since the light diffusing member 40 may be provided at least in the second region R2, it is possible to reduce the material used for the light diffusing member 40 and to reduce the manufacturing cost.

Example 3
Example 3 has the same configuration as that of Example 2, but has a different light distribution. FIG. 11 shows a light distribution of the light emitting member 10 of Example 3. The amount of light emitted from the light emitting member 10 is larger in the oblique direction than the front direction, and has a light intensity peak in a direction inclined from the normal direction of the light emitting member 10 (heart-shaped light distribution). As shown in FIG. 12, the light distribution may have a shape (three-way light distribution) having a light intensity peak in the normal direction of the light emitting member 10 and a direction inclined from the normal direction. The shape may have a plurality of peaks in a direction inclined from the line direction. In FIG. 11 and FIG. 12, the radial direction indicates the normalized luminance (the angle with the highest luminance is 1), and the circumferential direction indicates the angle.

  The difference from the surface light emitting devices 100A and 200 in the first and second embodiments is that a light emitting member is used in which the amount of light emitted from the light emitting member 10 is larger in the oblique direction than in the front direction. For example, in FIG. 11, the light distribution shape of the light emitted from the light emitting member 10 is a heart shape, and in FIG. 12, the light distribution shape of the light emitted from the light emitting member 10 is trifurcated.

  By using the light emitting member 10 having the light distribution shape as shown in FIG. 11 and FIG. 12, the amount of light that is totally reflected by the light guide member 30 and guided is increased, so that the first region R1 and the second region It is possible to reduce the light amount difference of R2 and increase the light emitting area of the surface light emitting device.

(Comparison)
With reference to FIG. 13 and FIG. 14, the comparison result of the light emission area in the surface emitting device of this Example 1-3 and the comparative example technique modeled in FIG. 5 is shown. FIG. 13 is a diagram illustrating a comparison result of the light emission areas of Examples 1 to 3 and the comparative example technique, and FIG. 14 is a diagram illustrating a measurement position of the light emission area.

  Referring to FIG. 13, it can be seen that the light source width is increased in Examples 1, 2, and 3 in comparison with the comparative example at the normalized luminance of 0.4 (40%). In particular, Example 3 (heart-shaped light distribution) has the largest light source width. This is because the light emitting member 10 has a light distribution having a larger amount of light in the second region R2 than in the first region R1, so that light is emitted from the second region R2 as compared with the first and second embodiments and the comparative example. This is because it is possible to reduce the luminance difference between the first region R1 and the second region R2 by taking out a large amount. Even in the configuration of the first embodiment, by using a light distribution in which the amount of light is larger in the oblique direction than in the front direction, a large amount of light is extracted from the second region R2, and between the first region R1 and the second region R2. In this case, it is possible to reduce the luminance difference.

  Further, the particle number density of the scattering particles 41 in the light diffusing member 40 will be examined with reference to FIGS. 15 and 16. FIG. 15 is a diagram illustrating the particle number density of the scattering particles 41 in the light diffusing member 40 in Examples 1 to 3, and FIG. 16 is a diagram illustrating measurement positions of the scattering particle number density.

  In FIG. 15, the central portion of the light emitting member 10 is set to 0 mm, and the width of the light emitting member 10 is set to 3.5 mm from the end portion-1.75 mm to the end portion 1.75 mm. In Example 1, the particle number density of the scattering particles 41 is provided so as to increase continuously from the central part to the peripheral part of the light emitting member 10. The particle number density of the scattering particles 41 is highest at the light source end portions of 1.75 mm and −1.75 mm, and the density is the maximum from the end portion of the light emitting member 10 (end portion of the first region R1) to the second region R2. It becomes constant.

  In the surface light emitting device of Example 1, the particle number density of the scattering particles 41 may be discretely increased from the central part of the light emitting member 10 toward the second region R2 (Modified Example 1). In Examples 2 and 3, the scattering particles 41 are present in the second region R2 from the end of the first region R1, and are not present in “−1.75 mm to 1.75 mm” of the first region R1.

  As described above, in the surface light emitting device according to the present embodiment, the light guide member 30 extends to the second region R2, and the refractive index of the light guide member 30 is higher than that of the transparent member 20, thereby Light incident on the light guide member 30 in an oblique direction is guided through the light guide member 30 by total reflection, and is extracted to the outside by the light diffusion member 40 from the position of the second region R2. Accordingly, since more light can be guided to the position of the second region R2, the light emitting area of the surface light emitting device 100 can be increased.

  In the surface emitting devices in Examples 1 to 3, in order to make the light diffusion intensity of the second region R2 larger than the light diffusion intensity of the first region R1, the scattering particles 41 of the second region in the light diffusion member 40 Although the particle number density is larger than the particle number density in the first region, even if the particle number density of the scattering particles 41 is the same in the first region and the second region, the thickness of the light diffusion member 40 is reduced. By changing the number, the number of scattering particles 41 acting on the light in the oblique direction can be increased. For example, when the light diffusion intensity is increased from the first region to the second region, the thickness of the light diffusion member 40 may be increased from the central portion to the peripheral portion of the light emitting member 10 as shown in FIG. .

  Although the embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and includes meanings equivalent to the terms of the claims and all modifications within the scope.

  DESCRIPTION OF SYMBOLS 10 Light emitting member, 20 Transparent member, 30 Light guide member, 40 Light-diffusion member, 41 Scattering particle | grains, 100,100A, 200 Surface light-emitting device, R1 1st area | region, R2 2nd area | region.

Claims (8)

A light emitting member;
A light guide member formed on the light emitting member;
A transparent member formed on the light guide member,
The refractive index of the light guide member is provided larger than the refractive index of the transparent member,
In a plan view from the transparent member side, the light guide member and the transparent member have a first region covering the light emitting member, and a second region adjacent to the periphery of the first region,
At least in the second region, a light diffusion member is provided between the light guide member and the transparent member,
The surface light-emitting device includes a light diffusion intensity region in which the light diffusion intensity of the second region is stronger than the light diffusion intensity of the first region.   The surface light-emitting device according to claim 1, wherein the light diffusion member is provided only in the second region. The refractive index of the light guide member is larger than the refractive index of the light emitting member,
The surface light-emitting device according to claim 1, wherein a refractive index of the light-emitting member is set larger than a refractive index of the transparent member.   The surface light-emitting device of any one of Claim 1 to 3 whose color of the light radiate | emitted from the said light emitting member is white.   The surface emitting device according to any one of claims 1 to 4, wherein the amount of light emitted from the light emitting member is larger in an oblique direction than in a front direction.   The surface light emitting device according to claim 1, wherein the light emitting member and the light diffusing member are layers formed by a coating process.   The said light-diffusion member contains the scattering particle which scatters light, The particle number density of the said scattering particle in the said 2nd area | region is larger than the particle number density of the said scattering particle in the said 1st area | region. Item 7. The surface light-emitting device according to any one of Items6.   The surface emitting device according to claim 1, wherein a thickness of the light diffusing member in the second region is thicker than a thickness of the light diffusing member in the first region.