Light-emitting device

Abstract

To provide a light-emitting device that can improve the uniformity of the luminous flux distribution on the light-emitting surface. [Solution] The light-emitting device comprises a plurality of light-emitting elements, a plurality of first light-diffusing layers arranged on each of the plurality of light-emitting elements, a translucent member in contact with the sides of the plurality of light-emitting elements and the sides of the plurality of first light-diffusing layers, and a second light-diffusing layer arranged on the plurality of first light-diffusing layers and the translucent member.

Description

[Technical Field]

[0001] The embodiment relates to a light-emitting device. [Background technology]

[0002] Automotive taillights are constructed by connecting multiple light-emitting diodes (LEDs) in series. There is a demand to reduce the number of LEDs to ensure a consistent driving voltage per LED even when the power supply voltage fluctuates, and to lower costs. However, reducing the number of LEDs leads to a problem of uneven luminous flux distribution on the light-emitting surface of the device. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-027128 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The embodiment aims to provide a light-emitting device that can improve the uniformity of the luminous flux distribution on the light-emitting surface. [Means for solving the problem]

[0005] The light-emitting device according to the embodiment comprises a plurality of light-emitting elements, a plurality of first light-diffusing layers disposed on each of the plurality of light-emitting elements, a translucent member in contact with the sides of the plurality of light-emitting elements and the sides of the plurality of first light-diffusing layers, and a second light-diffusing layer disposed on the plurality of first light-diffusing layers and the translucent member. [Effects of the Invention]

[0006] According to this embodiment, a light-emitting device can be realized that can improve the uniformity of the luminous flux distribution on the light-emitting surface. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a top view showing a light-emitting device according to the first embodiment. [Figure 2] Figure 2 is a bottom view showing a light-emitting device according to the first embodiment. [Figure 3] Figure 3 is a bottom view showing the wiring of a wiring board connected to a light-emitting device according to the first embodiment. [Figure 4] Figure 4 is an end view taken along the line IV-IV shown in Figure 1. [Figure 5] Figure 5 is an end view using the VV line shown in Figure 1. [Figure 6] Figure 6 is an end view showing the operation of the light-emitting device according to the first embodiment. [Figure 7] Figure 7 is a top view showing a light-emitting device according to the second embodiment. [Figure 8] Figure 8 is an end view showing a light-emitting device according to a comparative example. [Figure 9A] Figure 9A shows the evaluation method used in the test example. [Figure 9B] Figure 9B shows the evaluation criteria in the example test. [Figure 10A] Figure 10A shows the evaluation results of the light-emitting device related to the comparative example. [Figure 10B] Figure 10B shows the evaluation results of the light-emitting device according to the first embodiment. [Modes for carrying out the invention]

[0008] <First Embodiment> Figure 1 is a top view showing the light-emitting device according to this embodiment. Figure 2 is a bottom view showing the light-emitting device according to this embodiment. Figure 3 is a bottom view showing the wiring of the light-emitting device and the wiring board connected to the light-emitting device according to this embodiment. Figure 4 is an end view taken along the line IV-IV shown in Figure 1. Figure 5 is an end view using the VV line shown in Figure 1. Each figure is schematic and is emphasized and simplified as appropriate. Also, even for the same components, their positions and shapes do not necessarily exactly match between figures. The same applies to other figures described later.

[0009] As shown in FIGS. 1 to 5, the light-emitting device 1 according to this embodiment includes three light-emitting elements 10, three first light-diffusing layers 20, one translucent member 30, one second light-diffusing layer 40, and one light-reflecting member 50.

[0010] The light-reflecting member 50 is made of, for example, a white resin material, and is made of, for example, a material in which a light-scattering substance such as titanium oxide is contained in silicone. The shape of the light-reflecting member 50 is, for example, a rectangular parallelepiped box shape with an upper part opened. Therefore, the surface of the light-reflecting member 50 consists of the inner surface of the opening and the outer surface of the opening. The outer surface of the light-reflecting member 50 excluding the inner surface of the opening has one upper surface 50U, one lower surface 50L, and four side surfaces 50S. The upper surface 50U is a frame-shaped region surrounding the opening. The inner surface of the light-reflecting member 50 has one bottom surface and four inner side surfaces. The three light-emitting elements 10, the three first light-diffusing layers 20, the one translucent member 30, and the one second light-diffusing layer 40 are arranged inside the box-shaped light-reflecting member 50.

[0011] Hereinafter, in this specification, for convenience of explanation, an XYZ orthogonal coordinate system is adopted. Two directions in which the outer edge of the upper surface 50U of the light-reflecting member 50 extends are defined as the "first direction X" and the "second direction Y", and the direction from the lower surface 50L to the upper surface 50U of the light-reflecting member 50 is defined as the "third direction Z". The third direction Z is also referred to as "up", and the opposite direction is also referred to as "down", but this expression is also for convenience and is independent of the direction of gravity. Also, looking from the third direction Z is referred to as "plan view". In plan view, components that are hidden by other components may be described as visible.

[0012] The light-emitting element 10 is, for example, a light-emitting diode (LED). The three light-emitting elements 10 are, for example, LEDs of the same specifications. Each light-emitting element 10 has a translucent substrate 11, a semiconductor laminate 12, and two electrodes 13. The light-emitting element 10 also has a bottom surface 10L, a side surface 10S, and a top surface 10U. The top surface 10U is the opposite side of the bottom surface 10L. The side surface 10S is located between the bottom surface 10L and the top surface 10U. The shape of the top surface 10U and the bottom surface 10L is, for example, rectangular or square. In this case, there are four side surfaces 10S. Two electrodes 13 are located on the bottom surface 10L. The top surface 10U is made of the translucent substrate 11.

[0013] The translucent substrate 11 is formed of a translucent material, for example, sapphire or silicon (Si). The semiconductor laminate 12 includes a p-type layer, an emissive layer, and an n-type layer. One of the two electrodes 13 is connected to the p-type layer, and the other is connected to the n-type layer. In this specification, "connection" means an electrical connection. The electrodes 13 of the light-emitting element 10 penetrate the bottom surface of the light-reflecting member 50 and reach the lower surface 50L of the light-reflecting member 50.

[0014] The three light-emitting elements 10 are positioned at the bottom of the light-reflecting member 50 and are in contact with the bottom surface of the light-reflecting member 50. In a plan view, the centers of the three light-emitting elements 10 are positioned at the vertices of a triangle. Of the three light-emitting elements 10, the orientation of two of them is the same as the orientation of the light-reflecting member 50, while the orientation of one of the light-emitting elements 10 is inclined at 45° relative to the light-reflecting member 50.

[0015] Let's explain in more detail. If we call the three light-emitting elements 10 "the first light-emitting element 10A," "the second light-emitting element 10B," and "the third light-emitting element 10C," then a pair of opposing edges of the outer edge of the first light-emitting element 10A and a pair of opposing edges of the outer edge of the second light-emitting element 10B extend in the first direction X, while the other pair of edges of the first light-emitting element 10A and the other pair of edges of the second light-emitting element 10B extend in the second direction Y. On the other hand, a pair of opposing edges of the outer edge of the third light-emitting element 10C extend in a direction inclined 45° clockwise with respect to the first direction X in a plan view, while the other pair of edges extend in a direction inclined 45° counterclockwise with respect to the first direction X in a plan view.

[0016] The three first light-diffusing layers 20 are each positioned on the three light-emitting elements 10 described above. Each first light-diffusing layer 20 has a base material made of resin and a light-scattering material disposed within the base material. The resin is, for example, silicone, and the light-scattering material is, for example, titanium dioxide. Each first light-diffusing layer 20 has a rectangular plate shape and has an upper surface 20U, a lower surface 20L, and four side surfaces 20S. The lower surface 20L of the first light-diffusing layer 20 is in contact with the upper surface 10U of the light-emitting element 10. The three first light-diffusing layers 20 are spaced apart from each other, and in a plan view, the outer edge of each light-emitting element 10 is located inside the outer edge of the first light-diffusing layer 20 positioned directly above the light-emitting element 10. That is, the first light-diffusing layers 20 extend outward from the area directly above the light-emitting element 10.

[0017] The translucent member 30 is arranged in a plan view to surround the three light-emitting elements 10 and the three first light-diffusing layers 20. The translucent member 30 is in contact with the sides 10S of the three light-emitting elements 10, the sides 20S of the three first light-diffusing layers 20, and the inner surface of the light-reflecting member 50. The translucent member 30 is made of a translucent material, for example, a transparent resin material. The concentration of light-scattering material in the translucent member 30 is lower than the concentration of light-scattering material in the first light-diffusing layers 20. More preferably, the translucent member 30 contains substantially no light-scattering material. Light-scattering material may inevitably diffuse from the first light-diffusing layers 20 into the translucent member 30, but even in that case, the concentration of light-scattering material in the translucent member 30 will be lower than the concentration of light-scattering material in the first light-diffusing layers 20.

[0018] The second light diffusion layer 40 is arranged on the three first light diffusion layers 20 and on the translucent member 30. In a plan view, the shape of the second light diffusion layer 40 is the same as the shape of the opening of the light reflecting member 50, for example, rectangular. For example, in a plan view, the shape of the second light diffusion layer 40 is square. The second light diffusion layer 40 has a bottom surface 40L, a top surface 40U, and four side surfaces 40S. The top surface 40U is the light-emitting surface of the light-emitting device 1. The entire side surfaces 40S are in contact with the inner surface of the light reflecting member 50. The bottom surface 40L is in contact with the top surfaces 20U of the three first light diffusion layers 20 and the top surface of the translucent member 30. Therefore, between the multiple first light diffusion layers 20, the translucent member 30 is in contact with the second light diffusion layer 40. The second light diffusion layer 40 contains wavelength conversion particles. For example, the light-emitting element 10 emits blue light, and the second light-diffusing layer 40 contains phosphor particles that absorb a portion of the blue light emitted from the light-emitting element 10 and emit yellow light. As a result, the color of the light emitted from the light-emitting device 1 becomes white.

[0019] As shown in Figure 2, each pair of electrodes 13 of the three light-emitting elements 10 are exposed on the lower surface 50L of the light-reflecting member 50. As shown in Figure 3, when the light-emitting device 1 is mounted on a wiring board, the wiring 110 of the wiring board connects the three light-emitting elements 10 in series. As a result, the three light-emitting elements 10 light up simultaneously.

[0020] Next, the operation of the light-emitting device 1 according to this embodiment will be described. Figure 6 is an end view showing the operation of the light-emitting device according to this embodiment. Figure 6 corresponds to the end view of Figure 4, and the hatching indicating the cross-section has been omitted for ease of understanding. In Figure 6, some of the light rays are indicated by arrows.

[0021] When power is supplied to the light-emitting device 1 via the wiring 110 of the wiring board, light L1 is emitted from the light-emitting layer of the semiconductor laminate 12 of each light-emitting element 10. Light L1 is, for example, blue light. A portion of the light L1 is incident on the first light-diffusing layer 20 via the translucent substrate 11 and diffused. As a result, the light L1 is incident on the second light-diffusing layer 40 from the first light-diffusing layer 20 over a wide angular range. On the other hand, another portion of the light L1 emitted from the light-emitting element 10 is incident on the translucent member 30 either directly or via the translucent substrate 11, and is incident on the second light-diffusing layer 40 either directly from the translucent member 30 or reflected by the inner surface of the light-reflecting member 50.

[0022] In this manner, light L1 emitted from the light-emitting element 10 directly above it is diffused by the first light-diffusing layer 20 before entering the second light-diffusing layer 40. On the other hand, light emitted to the side from the light-emitting element 10 enters the second light-diffusing layer 40 without passing through the first light-diffusing layer 20. As a result, a portion of the light emitted directly above the light-emitting element 10 is dispersed to the surrounding area, reducing the concentration of light in the region directly above the light-emitting element 10.

[0023] A portion of the light L1 incident on the second light diffusion layer 40 is absorbed by wavelength conversion particles and emitted as light L2 of a different wavelength. Light L2 is, for example, yellow light. The remaining portion of the light L1 incident on the second light diffusion layer 40 is diffused by the second light diffusion layer 40 and emitted without changing its wavelength. As a result, light L1 and light L2 are mixed and emitted from the second light diffusion layer 40. Consequently, the light-emitting device 1 emits white light.

[0024] Next, the effects of this embodiment will be described. In the light-emitting device 1 according to this embodiment, there are three light-emitting elements 10. This reduces the cost of the light-emitting device 1 compared to the case where four or more light-emitting elements 10 are provided. Furthermore, when the light-emitting device 1 is mounted in an automobile, the drive voltage supplied to each light-emitting element 10 can be secured even if the automobile's power supply voltage fluctuates.

[0025] For example, if four light-emitting elements 10 are used for a rectangular second light-diffusing layer 40 in plan view, one light-emitting element 10 can be placed near each corner of the second light-diffusing layer 40, thus reducing the bias in the placement of the light-emitting elements 10 relative to the second light-diffusing layer 40. For this reason, even without providing a first light-diffusing layer 20, the uniformity of the luminous flux distribution in the second light-diffusing layer 40 is considered to be higher when four light-emitting elements 10 are used compared to when three light-emitting elements 10 are used. However, in this case, it is necessary to connect four light-emitting elements 10 in series, so the voltage supplied to each light-emitting element 10 becomes lower compared to the case where three light-emitting elements 10 are used.

[0026] In contrast, the light-emitting device 1 has a first light-diffusing layer 20 on each light-emitting element 10. This allows the light emitted upward from the light-emitting elements 10 to be diffused by the first light-diffusing layer 20. As a result, even if there is a large bias in the arrangement of the light-emitting elements 10 relative to the second light-diffusing layer 40, the concentration of light in the area directly above the light-emitting elements 10 can be reduced, and the uniformity of the luminous flux distribution of the second light-diffusing layer 40, which is the light-emitting surface of the light-emitting device 1, can be improved.

[0027] Furthermore, the multiple first light diffusion layers 20 are spaced apart from each other. This allows for efficient extraction of light between the first light diffusion layers 20, further improving the uniformity of the luminous flux distribution of the second light diffusion layer 40.

[0028] Furthermore, the translucent member 30 is in contact with the second light diffusion layer 40 between the multiple first light diffusion layers 20. This reduces the loss of light when it enters the second light diffusion layer 40 from the translucent member 30. However, other translucent layers or air layers may be interposed between the translucent member 30 and the second light diffusion layer 40.

[0029] Furthermore, the first light diffusion layer 20 contains a light-scattering material. This allows for efficient scattering of the light L1 emitted from the light-emitting element 10. On the other hand, the translucent member 30 contains substantially no light-scattering material. This allows for efficient transmission of the light L1 emitted laterally from the light-emitting element 10 to the second light diffusion layer 40.

[0030] Furthermore, in a plan view, the outer edge of one light-emitting element 10 is located inside the outer edge of one first light-diffusing layer 20. This ensures that even if a misalignment occurs between the light-emitting element 10 and the first light-diffusing layer 20 during the manufacturing of the light-emitting device 1, the first light-diffusing layer 20 can reliably cover the entire upper surface 10U of the light-emitting element 10. The greater the width of the first light-diffusing layer 20 in the first direction X and the second direction Y relative to the upper surface 10U of the light-emitting element 10, the better the uniformity of the luminous flux distribution on the light-emitting surface. On the other hand, if the width of the first light-diffusing layer 20 is too large, it will not be possible to place it on the light-emitting surface, i.e., within the second light-diffusing layer 40, in a plan view. Thus, considering the balance between the uniformity of the luminous flux distribution and the size of the light-emitting surface, it is preferable that the width of the first light-diffusing layer 20 in the first direction X and the second direction Y is 100% or more and 120% or less of the width of the light-emitting element 10 in the first direction X and the second direction Y, respectively.

[0031] Furthermore, the light-emitting device 1 according to this embodiment is provided with a light-reflecting member 50. The light-reflecting member 50 is box-shaped with an open top surface 50U, and the light-emitting element 10, the first light-diffusing layer 20, the light-transmitting member 30, and the second light-diffusing layer 40 are arranged inside the box-shaped light-reflecting member 50. As a result, light emitted from the light-emitting element 10, light diffused by the first light-diffusing layer 20, and light transmitted through the light-transmitting member 30 can be reflected by the light-reflecting member 50 and incident on the second light-diffusing layer 40. In addition, light emitted from the second light-diffusing layer 40 and reaching the light-reflecting member 50 can be reflected back towards the second light-diffusing layer 40. As a result, the light extraction efficiency of the light-emitting device 1 is improved.

[0032] Furthermore, in a plan view, the centers of the three light-emitting elements 10 are positioned at the vertices of a triangle. This allows the three light-emitting elements 10 to illuminate every corner of the square-shaped second light-diffusing layer 40 in a plan view. As a result, the uniformity of the luminous flux distribution in the second light-diffusing layer 40 can be further improved.

[0033] Furthermore, in a plan view, each light-emitting element 10 has a rectangular shape, with a portion of the outer edge of the first light-emitting element 10A and a portion of the outer edge of the second light-emitting element 10B extending in the first direction X, and a portion of the outer edge of the third light-emitting element 10C extending in a direction inclined at 45° with respect to the first direction X. By arranging the third light-emitting element 10C diagonally in this way, a large amount of light can be distributed to the two corners on the side of the light-reflecting member 50 where the third light-emitting element 10C is located. As a result, the light beam distribution in the second light-diffusing layer 40 can be made more uniform.

[0034] Furthermore, the second light diffusion layer 40 contains wavelength conversion particles. This allows for the realization of a variety of light colors through the combination of the light-emitting element 10 and the wavelength conversion particles. However, the second light diffusion layer 40 does not necessarily have to contain wavelength conversion particles. Even in this case, it is preferable that the second light diffusion layer 40 diffuses the light L1 emitted from the light-emitting element 10.

[0035] <Second Embodiment> Figure 7 is a top view showing the light-emitting device according to this embodiment. As shown in Figure 7, in the light-emitting device 2 according to this embodiment, the orientation of the three light-emitting elements 10 is the same. That is, in a plan view, the outer edges of the three light-emitting elements 10 extend in the first direction X and the second direction Y. According to this embodiment, the arrangement of the light-emitting elements 10 becomes easier compared to the first embodiment. The configuration, operation, and effects of this embodiment other than those described above are the same as those of the first embodiment.

[0036] <Variation> The following describes variations of the first and second embodiments described above. In the first and second embodiments described above, examples were shown in which the outer edge of the light-emitting element 10 is located inside the outer edge of the first light-diffusing layer 20 in a plan view, but the invention is not limited to this. In a plan view, the outer edge of the light-emitting element 10 may coincide with the outer edge of the first light-diffusing layer 20, or the outer edge of the light-emitting element 10 may be located outside the outer edge of the first light-diffusing layer 20. In this case, it is preferable that the width of the first light-diffusing layer 20 in the first direction X and the second direction Y is 50% or more of the width of the light-emitting element 10 in the first direction X and the second direction Y, respectively. If the width of the first light-diffusing layer 20 is less than 50% of the width of the light-emitting element 10, it is difficult to obtain the target uniformity.

[0037] The planar shape of the first light diffusion layer 20, i.e., the shape of its top surface 20U, is preferably similar to the planar shape of the light-emitting element 10, i.e., the shape of its top surface 10U, but is not limited to this example. For example, the top surface 20U of the first light diffusion layer 20 does not have to be rectangular; it may be circular or polygonal, for example.

[0038] Furthermore, while the first and second embodiments show examples with three light-emitting elements 10, the invention is not limited to this. There may be two or more light-emitting elements 10, or even just one. In the first and second embodiments, there is an effect of improving the uniformity of the luminous flux distribution on the light-emitting surface when there is a large bias in the arrangement of the light-emitting elements 10 with respect to the second light-diffusing layer 40. As described above, if an even number of light-emitting elements 10 are arranged in a matrix with respect to the rectangular second light-diffusing layer 40, it is thought that there will be less bias in the arrangement of the light-emitting elements 10, and a certain degree of uniformity can be achieved. However, from the viewpoint of reducing the concentration of light in the area directly above the light-emitting elements 10, even if there is little bias in the arrangement of the light-emitting elements 10 in a plan view, the uniformity of the luminous flux distribution on the light-emitting surface can be improved.

[0039] Furthermore, while the first and second embodiments show examples in which each light-emitting element 10 has a pair of electrodes 13, the invention is not limited to this. Each light-emitting element 10 may have three or more, or multiple pairs of electrodes 13.

[0040] The structure of the light-emitting layer of the semiconductor laminate 12 of the light-emitting element 10 may be a structure having a single active layer, such as a double heterostructure or a single quantum well structure (SQW), or it may be a structure having a group of active layers, such as a multiple quantum well structure (MQW). As a semiconductor laminate 12 including such a light-emitting layer, for example, In x Al y Ga 1-x-y N(0≦x, 0≦y, x+y≦1) can be included. The semiconductor stack 12 may include at least one light-emitting layer capable of the light emission described above.

[0041] For the base material of the first light diffusion layer 20, for example, a thermoplastic resin such as acrylic, polycarbonate, cyclic polyolefin, polyethylene terephthalate, or polyester, a thermosetting resin such as epoxy or silicone, or glass can be used.

[0042] As the light scattering material contained in the first light diffusion layer 20, for example, particles of titanium oxide, silicon oxide, aluminum oxide, zinc oxide, magnesium oxide, zirconium oxide, yttrium oxide, calcium fluoride, magnesium fluoride, niobium pentoxide, barium titanate, tantalum pentoxide, barium sulfate, or glass can be used.

[0043] The light-transmitting member 30 includes, for example, a light-transmitting resin. As the light-transmitting resin, for example, a silicone resin or an epoxy resin can be used.

[0044] For the base material of the second light diffusion layer 40, for example, a material similar to the base material of the first light diffusion layer 20 can be used. A phosphor can be used as the wavelength conversion particle contained in the second light diffusion layer. As the phosphor, a yttrium aluminum garnet-based phosphor (for example, Y3(Al,Ga)5O) can be used. 12 Ce), lutetium-aluminum-garnet phosphors (e.g., Lu3(Al,Ga)5O 12 Ce), terbium aluminum garnet phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), CCA-based phosphors (e.g., Ca10 (PO4)6C 12 :(Eu), SAE-based phosphors (e.g., Sr4Al 14 O 25 :(Eu), chlorosilicate-based phosphors (e.g., Ca8MgSi4O16Cl2:Eu), β-sialon-based phosphors (e.g., (Si,Al)3(O,N)4:Eu) or α-sialon-based phosphors (e.g., Ca(Si,Al)12(O,N)16:Eu), etc., oxynitride-based phosphors, SLA-based phosphors (e.g., SrLiAl3N4:Eu), CASN-based phosphors (e.g., CaAlSiN3:Eu) or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), etc., nitride-based phosphors, KSF-based phosphors (e.g., K2SiF6:Mn), KSAF-based phosphors (e.g., K2Si 0.99 Al 0.01 F 5.99 :Mn) or MGF-based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn), etc., fluoride-based phosphors, phosphors having a perovskite structure (e.g., CsPb(F,Cl,Br,I)3), or quantum dot phosphors (e.g., CdSe, InP, AgInS2 or AgInSe2), etc. can be used. The second light diffusion layer 40 may contain one type of phosphor or may contain a plurality of types of phosphors.

[0045] <Test Example> In this test example, a light-emitting device according to the first embodiment and a light-emitting device according to a comparative example were actually manufactured, and the uniformity of the luminous flux distribution was measured. FIG. 8 is an end view showing a light-emitting device according to a comparative example. FIG. 9A is a diagram showing an evaluation method in this test example, and FIG. 9B is a diagram showing an evaluation criterion in this test example. FIG. 10A is a diagram showing an evaluation result of a light-emitting device according to a comparative example, and FIG. 10B is a diagram showing an evaluation result of a light-emitting device according to the first embodiment. This test example was carried out in accordance with the European standard "ECE / TRANS / WP.29 / 2023 / 41" (hereinafter referred to as "Standard LW6") for rear lamps of automobiles determined by the United Nations Economic Commission for Europe (UNECE).

[0046] As shown in Figure 8, the light-emitting device 101 according to this test example differs from the light-emitting device 1 according to the first embodiment in that it does not have a first light diffusion layer 20, and the light-emitting element 10 is in contact with the second light diffusion layer 40. The arrangement of the light-emitting elements 10 in a plan view is the same as that of the light-emitting device 1 according to the first embodiment, and it has three light-emitting elements 10.

[0047] As shown in Figure 9A, in this test example, the light-emitting surface of the light-emitting device and its surroundings were equally divided into 36 regions in a 6x6 grid. Twelve regions A were placed in the areas excluding the central corners, four regions B were placed in the central corners, and 20 regions C were placed on the outer periphery. Regions A and B correspond to the light-emitting surface of the light-emitting device, i.e., the upper surface 40U of the second light diffusion layer 40, while region C corresponds to the periphery of the light-emitting surface. Then, as shown in Figure 9B, a standard for the luminous flux that each region must satisfy was set. If this standard is met, the luminous flux distribution of the light-emitting device is judged to conform to standard LW6 and to have high uniformity.

[0048] As shown in Figure 10A, in the comparative example light-emitting device 101, the luminous flux in the two regions B was 2.9%, which did not reach the standard of 3% shown in Figure 9B. Therefore, the luminous flux distribution of the light-emitting device 101 did not conform to standard LW6.

[0049] As shown in Figure 10B, in the light-emitting device 1 according to the first embodiment, the luminous flux was 4.5% or more in all regions B, satisfying the criteria shown in Figure 9B. Furthermore, the light-emitting device 1 also satisfied the other criteria shown in Figure 9B. Therefore, the luminous flux distribution of the light-emitting device 1 conformed to the LW6 standard.

[0050] The embodiments and their modifications described above are examples that embody the present invention, and the present invention is not limited to these embodiments and modifications. For example, the present invention also includes the addition, deletion, or modification of some components or processes in the embodiments and modifications described above. Furthermore, the embodiments and modifications described above can be implemented in combination with each other.

[0051] The present invention includes the following embodiments.

[0052] (Note 1) Multiple light-emitting elements, A plurality of first light-diffusing layers are arranged on each of the plurality of light-emitting elements, A light-transmitting member in contact with the sides of the plurality of light-emitting elements and the sides of the plurality of first light-diffusing layers, A second light-diffusing layer disposed on the plurality of first light-diffusing layers and the light-transmitting member, A light-emitting device.

[0053] (Note 2) The light-emitting device according to Appendix 1, wherein the second light-diffusing layer includes wavelength-converting particles.

[0054] (Note 3) The light-emitting device according to Appendix 1 or 2, wherein the light-transmitting member is in contact with the second light-diffusing layer between the plurality of first light-diffusing layers.

[0055] (Note 4) The first light-diffusing layer comprises a base material made of resin and a light-scattering material disposed within the base material. The light-emitting device according to any one of the appendices 1 to 3, wherein the concentration of the light-scattering material in the light-transmitting member is lower than the concentration of the light-scattering material in the first light-diffusing layer.

[0056] (Note 5) The light-emitting device according to any one of the appendices 1 to 4, wherein the light-transmitting member does not contain a light-scattering substance.

[0057] (Note 6) The aforementioned multiple first light-diffusing layers are separated from each other. In a plan view, the outer edge of one of the light-emitting elements is located inside the outer edge of one of the first light-diffusing layers. The light-emitting device according to any one of the appendices 1 to 5.

[0058] (Note 7) The light-emitting device according to any one of appendices 1 to 6, further comprising the plurality of light-emitting elements, the light-transmitting member, and the light-reflecting member in contact with the second light-diffusing layer.

[0059] (Note 8) The light-emitting device described in Appendix 7, wherein the light-reflecting member has the shape of a box with an open top, and the plurality of light-emitting elements, the plurality of first light-diffusing layers, the light-transmitting member, and the second light-diffusing layer are arranged inside the light-reflecting member.

[0060] (Note 9) In a plan view, the shape of the second light-diffusing layer is square. The light-emitting device according to Appendix 8, wherein the entire side surface of the second light-diffusing layer is in contact with the inner surface of the light-reflecting member.

[0061] (Note 10) The aforementioned light-emitting elements consist of three, In a plan view, the light-emitting device according to any one of the appendices 1 to 9, wherein the centers of each of the three light-emitting elements are positioned to form the vertices of a triangle.

[0062] (Note 11) In a plan view, The shape of the light-emitting element is rectangular. A portion of the outer edge of the first light-emitting element and a portion of the outer edge of the second light-emitting element extend in the first direction. The light-emitting device according to Appendix 10, wherein a portion of the outer edge of the third light-emitting element extends in a direction inclined at 45° with respect to the first direction. [Industrial applicability]

[0063] The present invention can be used, for example, in the taillights of automobiles. [Explanation of Symbols]

[0064] 1, 2 Light-emitting devices 10 light-emitting elements 10A First light-emitting element 10B Second light-emitting element 10C Third light-emitting element 10L bottom 10S side 10U top 11 Translucent substrate 12 Semiconductor stack 13 electrodes 20 First light diffusion layer Below 20L 20S Side View 20U on top 30 Translucent Components 40 Second light diffusion layer 50 light reflective materials Below 50L 50s side view 50U on top 101 Lighting device 110 wiring Domains A, B, and C L1, L2 light X, first direction Y 2nd direction Z, direction 3

Claims

1. Multiple light-emitting elements, A plurality of first light-diffusing layers are arranged on each of the plurality of light-emitting elements, A light-transmitting member in contact with the sides of the plurality of light-emitting elements and the sides of the plurality of first light-diffusing layers, A second light-diffusing layer disposed on the plurality of first light-diffusing layers and the light-transmitting member, A light-emitting device.

2. The light-emitting apparatus according to claim 1, wherein the second light-diffusing layer includes wavelength-converting particles.

3. The light-emitting device according to claim 1, wherein the light-transmitting member is in contact with the second light-diffusing layer between the plurality of first light-diffusing layers.

4. The first light-diffusing layer comprises a base material made of resin and a light-scattering material disposed within the base material. The light-emitting device according to claim 1, wherein the concentration of the light-scattering material in the light-transmitting member is lower than the concentration of the light-scattering material in the first light-diffusing layer.

5. The light-emitting device according to claim 1, wherein the light-transmitting member does not contain a light-scattering substance.

6. The plurality of first light-diffusing layers are separated from each other. The light-emitting device according to claim 1, wherein, in a plan view, the outer edge of one of the light-emitting elements is located inside the outer edge of one of the first light-diffusing layers.

7. The light-emitting device according to claim 1, further comprising the plurality of light-emitting elements, the light-transmitting member, and the light-reflecting member in contact with the second light-diffusing layer.

8. The light-emitting device according to claim 7, wherein the shape of the light-reflecting member is a box shape with an open top, and the plurality of light-emitting elements, the plurality of first light-diffusing layers, the light-transmitting member, and the second light-diffusing layer are arranged inside the light-reflecting member.

9. In a plan view, the shape of the second light-diffusing layer is square. The light-emitting device according to claim 8, wherein the entire side surface of the second light-diffusing layer is in contact with the inner surface of the light-reflecting member.

10. The aforementioned light-emitting element consists of three elements. In a plan view, the centers of each of the three light-emitting elements are positioned at the vertices of a triangle, as described in any one of claims 1 to 9.

11. In a plan view, The shape of the light-emitting element is rectangular. A portion of the outer edge of the first light-emitting element and a portion of the outer edge of the second light-emitting element extend in the first direction. The light-emitting device according to claim 10, wherein a portion of the outer edge of the third light-emitting element extends in a direction inclined at 45° with respect to the first direction.

Images