Light emitting device, light flux controlling member and surface light source device

Abstract

To provide a light emitting device that can further spread light while sealing a light emitting element.SOLUTION: A light emitting device includes: a light emitting element; a light flux controlling member including a recess configured to transmit light emitted from the light emitting element, a first reflecting surface configured to reflect a part of light transmitted through the recess in a direction that is substantially perpendicular to a central axis of the light emitting element and is away from the central axis, an emission surface configured to emit, to the outside, light reflected at the first reflecting surface and another part of the light emitted from the light emitting element; and a light transmissive resin which is filled in the recess to seal the light emitting element, the light transmissive resin bonding the light flux controlling member to a substrate and the light emitting element. In a planar perspective view, an end of the first reflecting surface on the central axis side is located inside an outer edge of the light emitting element, and a distance between the end of the first reflecting surface and the outer edge is 25% or less of a length of a minor axis of the light emitting element passing through a center of the light emitting element.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light emitting device, a light flux controlling member, and a surface light source device. [Background technology]

[0002] A potting technique is known in which resin is injected into components and circuits arranged on a substrate, hardened, and then sealed. Also known is a light-emitting element having a light-reflecting film on its upper surface. In recent years, a light-emitting element arranged on a substrate and having a light-reflecting film on its upper surface sealed with resin has been used as a light-emitting device for use in a high-end direct-type surface light source device. For example, Patent Document 1 discloses such a light-emitting device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-082802 Summary of the Invention [Problem to be solved by the invention]

[0004] In the light emitting device described above, the resin that covers and seals the light emitting element has the effect of spreading the light. Therefore, the light from the light emitting element sealed with resin spreads more than when it is only the light emitting element. If the light spreads more, the center distance (pitch) between multiple light emitting elements in the surface light source device can be increased, and there are advantages such as being able to reduce the number of light emitting elements and reduce costs.

[0005] However, in potting, the resin is dripped onto the light emitting element placed on the substrate to seal the light emitting element, so the resin cannot be shaped as desired, and as a result, the effect of spreading light may be insufficient.

[0006] An object of the present invention is to provide a light emitting device capable of diffusing light while sealing a light emitting element. Another object of the present invention is to provide a surface light source device having the light emitting device. Another object of the present invention is to provide a light flux controlling member for use in the light emitting device. [Means for solving the problem]

[0007] The present invention relates to the following light emitting device, light flux controlling member, and surface light source device. a light-emitting element having a light-reflecting film on an upper surface thereof and disposed on the substrate; a recessed portion disposed on a back side thereof so as to cover the light-emitting element and through which light emitted from the light-emitting element passes; a light flux controlling member disposed on a front side thereof and having a first reflective surface that is approximately perpendicular to a central axis of the light-emitting element and that reflects a portion of the light that has passed through the recessed portion in a direction away from the central axis; and an exit surface that emits to the outside the light reflected by the first reflective surface and another portion of the light emitted from the light-emitting element; and a light-transmitting resin that fills the recessed portion, seals the light-emitting element, and bonds the light flux controlling member to the substrate and the light-emitting element, wherein, when viewed from above, an end of the first reflective surface on the central axis side is located inside an outer edge of the light-emitting element, and the distance between the end of the first reflective surface and the outer edge is 25% or less of a length of a minor axis of the light-emitting element that passes through a center of the light-emitting element. [2] The light emitting device according to [1], wherein the distance between the edge of the first reflecting surface and the outer edge is 23% or less of the length of the minor axis of the light emitting element passing through the center of the light emitting element. [3] The light emitting device according to [1], wherein an area of ​​an inner side of an inner edge formed by an edge of the first reflecting surface is 60% to 80% of an area of ​​an inner side of an outer edge of the light emitting element. [4] The light emitting device according to [1], wherein the light flux controlling member further has a second reflecting surface that is a flat surface approximately perpendicular to the central axis and that is arranged on the outer side of the first reflecting surface. [5] The light emitting device described in [4], wherein a first angle ray is emitted from a position half the height of the light emitting element at an angle of 70° or more and 110° or less when a direction perpendicular to the substrate and toward the front side of the light flux controlling member is defined as 0°, and includes a light ray that is emitted from the light emitting element and then emitted from the exit surface without being reflected by the first reflecting surface and the second reflecting surface. [6] The light emitting device according to [4], wherein a second angle light ray emitted at an angle of 60° or more and less than 70° and a third angle light ray emitted at an angle of more than 110° and less than 120° are emitted from a position half the height of the light emitting element as an emission point, and the direction perpendicular to the substrate and toward the front side of the light flux controlling member is defined as 0°. The second angle light ray and a third angle light ray are emitted at an angle of more than 110° and less than 120°. The second angle light ray and a third angle light ray are reflected by the second reflecting surface and emitted from the emission surface toward the substrate. [7] The light emitting device according to [1], wherein the light flux controlling member and the light transmitting resin each have a refractive index of 1.4 to 1.6. [8] A light flux controlling member for use in the light emitting device according to any one of [1] to [7]. [9] A surface light source device comprising a light diffusion plate and at least one light emitting device according to any one of [1] to [7].

[10] The surface light source device according to [9], wherein the at least one light emitting device is a plurality of light emitting devices, the plurality of light emitting devices are arranged in a row at equal intervals in an X direction and a Y direction perpendicular to the X direction, a center-to-center distance between two light emitting devices adjacent to each other in the X direction among the plurality of light emitting devices is Px, a center-to-center distance between two light emitting devices adjacent to each other in the Y direction among the plurality of light emitting devices is Py, Px is equal to or less than Py, and a distance between the substrate and the light diffusion plate is H, where H / Px is 0.2 to 0.3. Effect of the Invention

[0008] According to the present invention, it is possible to provide a light emitting device capable of diffusing light while sealing a light emitting element. Also, according to the present invention, it is possible to provide a surface light source device having the light emitting device. Also, according to the present invention, it is possible to provide a light flux controlling member used in the light emitting device. [Brief description of the drawings]

[0009] [Figure 1] 1A and 1B are diagrams showing the configuration of a surface light source device according to embodiment 1. FIG. [Diagram 2] 2A and 2B are diagrams showing the arrangement of light emitting devices in a surface light source device. [Diagram 3] 3A to 3E are diagrams showing the configuration of a light flux controlling member according to an embodiment. [Figure 4] 4A and 4B are enlarged views of a light flux controlling member according to an embodiment. [Diagram 5] 5A and 5B are diagrams illustrating the light distribution of a light flux controlling member according to embodiment 1. FIG. [Figure 6] 6A to 6D are diagrams illustrating the light distribution of a light flux controlling member according to embodiment 1. In FIG. [Figure 7] FIG. 7 is a diagram showing the luminance distribution of the light emitting device according to the first embodiment. [Figure 8] FIG. 8 is a diagram illustrating the light distribution of light beams by the light flux controlling members according to the first embodiment and the first modification. [Figure 9] FIG. 9 is a diagram illustrating the light distribution of light beams by the light flux controlling members according to the first embodiment and the first modification. [Figure 10] FIG. 10 is a diagram showing the luminance distribution of the light emitting devices according to the first embodiment and the first modification. [Figure 11] FIG. 11 is a diagram illustrating the light distribution of light beams by the light flux controlling members according to the first embodiment and the second modification. In FIG. [Figure 12] FIG. 12 is a diagram illustrating the light distribution of light beams by the light flux controlling members according to the first embodiment and the second modification. [Figure 13] FIG. 13 is a diagram showing the luminance distribution of the light emitting devices according to the first embodiment and the second modification. [Figure 14] 14A and 14B are diagrams showing luminance distributions of the light emitting devices according to the first embodiment, the third modification, and the fourth modification. [Figure 15]15A and 15B are diagrams illustrating the light distribution of a light flux controlling member according to embodiment 1. [Figure 16] 16A to 16F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 2. [Figure 17] FIG. 17 is a diagram showing a method for manufacturing a light emitting device. [Figure 18] FIG. 18 is a diagram showing a method for manufacturing a light emitting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a surface light source device suitable for backlighting of a liquid crystal display device will be described as a representative example of the surface light source device according to the present invention. These surface light source devices can be used as a display device 100' by combining them with a display member 102 (e.g., a liquid crystal panel) that is irradiated with light from the surface light source device (see FIG. 1B).

[0011] [Embodiment Mode] (Configuration of surface light source device and light emitting device) 1A, 1B, and 2A are diagrams showing a configuration of a surface light source device 100 according to an embodiment of the present invention. Fig. 1A is a plan view of the surface light source device 100, and Fig. 1B is a front view. Fig. 2A is a schematic cross-sectional view taken along line AA shown in Fig. 1B, and Fig. 2B is an enlarged cross-sectional view taken along line BB shown in Fig. 1A. Fig. 2A shows a schematic arrangement of a plurality of light-emitting devices 200 in the surface light source device 100, and Fig. 2B shows the arrangement of the light-emitting devices 200 in a cross-sectional view.

[0012] As shown in FIGS. 1A to 2B, a surface light source device 100 according to the present embodiment includes a housing 110, a plurality of light emitting devices 200, and a light diffusion plate 120. As shown in FIG. 2A, the plurality of light emitting devices 200 are arranged on a bottom plate 112 of the housing 110. The inner surface of the bottom plate 112 functions as a diffuse reflection surface. An opening is provided in a top plate 114 of the housing 110. The light diffusion plate 120 is arranged so as to cover the opening, and functions as a light emitting surface. The size of the light emitting surface is not particularly limited, but is, for example, about 400 mm×about 700 mm.

[0013] As shown in Fig. 2A, in the present embodiment, light emitting device 200 is fixed on substrate 210 which is fixed at a predetermined position on bottom plate 112 of housing 110. In the present embodiment, substrate 210 is bar-shaped. Light emitting device 200 has light flux controlling member 300 (lens) for controlling the distribution of light from light emitting element 220. Note that light emitting element 220 is disposed below light flux controlling member 300 and therefore is not actually visible, but light emitting element 220 is shown in Fig. 2A for the sake of explanation.

[0014] As shown in FIG. 2A, in this embodiment, the light emitting devices 200 are arranged in a row at equal intervals in the X direction, and further arranged in a row at equal intervals in the Y direction perpendicular to the X direction. As shown in FIG. 2A, when the center distance between two light emitting devices 200 adjacent to each other in the X direction is Px and the center distance between two light emitting devices 200 adjacent to each other in the Y direction is Py, the X direction and the Y direction are defined so that Px is equal to or smaller than Py. In this embodiment, Px and Py are equal as shown in FIG. 2A. In this specification, the center distance between two light emitting devices 200 means the center distance between two light emitting elements 220 that each of the two light emitting devices 200 has.

[0015] FIG. 2B is a cross-sectional view of light emitting device 200 shown in FIG. 2A. As shown in FIG. 2B, in light emitting device 200, recess 310 of light flux controlling member 300 (lens) is disposed on light emitting element 220. In addition, light transmissive resin 230 is filled between light emitting element 220 and recess 310 (in recess 310) for sealing light emitting element 220 and adhering light flux controlling member 300 to a substrate. Light emitting device 200 in surface light source device 100 according to the embodiment of the present invention can further spread the light from light emitting element 220 by light flux controlling member 300. Therefore, the distance (pitch) between a plurality of light emitting devices 200 can be spread, the number of light emitting devices 200 can be reduced, and costs can be reduced. The configuration of such light flux controlling member 300 will be described in detail later.

[0016] Furthermore, in the surface light source device of the present embodiment, the relationship between the distance between the substrate 210 and the light diffusion plate 120 and the pitch of the light emitting devices 200 can be as follows: That is, when the center-to-center distance of the light emitting elements 220 of two light emitting devices 200 adjacent in the X direction is Px, and the center-to-center distance of the light emitting elements 220 of two light emitting devices 200 adjacent in the Y direction is Py (as described above, the X direction and the Y direction are defined so that Px is equal to or smaller than Py), and the distance between the substrate 210 and the light diffusion plate 120 is H, H / Px can be 0.2 to 0.3.

[0017] (Light emitting element) The light emitting element 220 is a light source of the surface light source device 100, and is mounted on the substrate 210. The light emitting element 220 is, for example, a light emitting diode (LED) such as a white light emitting diode. The light emitting element 220 is also a light emitting element having a light reflecting film on its upper surface. As a result, the light emitting element 220 emits almost no light from the upper surface, and mainly emits light from the side surfaces. The light reflecting film is, for example, a DBR (Distributed Bragg Reflector) film. The size of the light emitting element 220 is not particularly limited, but is preferably rectangular in plan view with a side length of 0.1 mm to 1.0 mm, and more preferably 0.2 mm to 0.7 mm. In this embodiment, the light emitting element 220 is rectangular (square) in plan view.

[0018] (translucent resin) As shown in FIG. 2B, light-transmitting resin 230 is filled between light-emitting element 220 and recess 310 on the back side of light flux controlling member 300 (inside recess 310), and adheres light flux controlling member 300 to substrate 210 while sealing light-emitting element 220. There are no particular limitations on light-transmitting resin 230 as long as it has this function. From the viewpoint of suppressing refraction of light emitted from light-emitting element 220, light-transmitting resin 230 preferably has a refractive index close to that of the material of light flux controlling member 300. Specifically, it is preferable that the absolute value of the difference between the refractive index of light flux controlling member 300 and the refractive index of light-transmitting resin 230 is 0.1 or less. The refractive index of light-transmitting resin 230 may be, for example, 1.4 to 1.6. Examples of such a light-transmitting resin 230 include epoxy resin, silicone resin, and a mixture of these resins.

[0019] (Light flux control member) Fig. 3A is a perspective view of light flux controlling member 300, Fig. 3B is a plan view, Fig. 3C is a bottom view, Fig. 3D is a side view, and Fig. 3E is a cross-sectional view taken along line EE in Fig. 3B. Note that Figs. 3C and E show a state in which light emitting element 220 is sealed in recess 310 of light flux controlling member 300 by light-transmitting resin 230.

[0020] Light flux controlling member 300 is an optical member that controls the distribution of light emitted from light emitting element 220, and is adhered to substrate 210 by light transmissive resin 230 filled in recess 310 on the back side of light flux controlling member 300. The outer shape of light flux controlling member 300 is approximately disk-shaped, and is circular when viewed from above and from the bottom. The refractive index of light flux controlling member 300 may be, for example, 1.4 to 1.6. Light flux controlling member 300 has recess 310, first reflecting surface 320, second reflecting surface 330, and exit surface 340. Each will be described below.

[0021] <Recess> Recess 310 is arranged on the back side of light flux controlling member 300 so as to intersect with central axis CA (see FIG. 2B) of light emitting element 220. The inner surface of recess 310 is a surface through which light from light emitting element 220 passes into light flux controlling member 300. Recess 310 is filled with light transmissive resin 230 to seal light emitting element 220. In the present embodiment, recess 310 is disc-shaped, and is circular when light flux controlling member 300 is viewed from the bottom.

[0022] Recess 310 formed in light flux controlling member 300 is recess 310 capable of containing light emitting element 220, and it is sufficient that light flux controlling member 300 and light emitting element 220 are adhered via translucent resin 230 in recess 310, and the shape of recess 310 is not limited to the shape shown in the figure.

[0023] <First reflective surface> First reflecting surface 320 is disposed on the front side of light flux controlling member 300, and reflects at least a part of light incident at recess 310 in a direction substantially perpendicular to central axis CA of light emitting element 220 and away from central axis CA. As shown in FIG. 3B, first reflecting surface 320 is disposed in a ring shape surrounding the center of light flux controlling member 300 when light flux controlling member 300 is viewed in a plan view. Furthermore, as can be seen from the cross-sectional view of FIG. 3E, first reflecting surface 320 is a curved surface, and a tangent to this curved surface gradually approaches parallel to the rear surface of light flux controlling member 300 from the center toward the outside of light flux controlling member 300. As first reflecting surface 320 has such a shape, light that transmits through the recess and reaches first reflecting surface 320 is reflected in a direction away from the central axis of light emitting element 220, and is mainly emitted from emission surface 340.

[0024] Fig. 4A is an enlarged view of Fig. 3B. Fig. 4A shows light emitting element 220 arranged below light flux controlling member 300. With reference to Fig. 4A, the positional relationship between light emitting element 220 and the inner edge which is the end on the center side of first reflecting surface 320 will be described. Light emitting element 220 arranged below light flux controlling member 300 is not actually visible, but is shown by a dashed line in Fig. 4A for the sake of explanation.

[0025] 4A, when the first reflecting surface 320 is viewed in plan, an inner edge 321 formed by an end of the first reflecting surface 320 on the central axis CA side of the light-emitting element 220 is a circle. When viewed in a plan view, the inner edge 321 is inside the outer edge 221 of the light-emitting element 220. The distance between the inner edge 321 and the outer edge 221 may be 25% or less of the length of the minor axis of the light-emitting element 220 passing through the center of the light-emitting element 220, and is preferably 23% or less.

[0026] Since the inner edge of the first reflecting surface 320 and the outer edge of the light-emitting element 220 are in the positional relationship described above, the light emitted from the side of the light-emitting element 220 having a reflective film on its upper surface is more easily reflected by the first reflecting surface 320, resulting in a good brightness distribution.

[0027] When viewed from above, the area inside inner edge 321 formed by the edge of first reflecting surface 320 is preferably 60% to 80% of the area inside outer edge 221 of light emitting element 220.

[0028] 3E in the present embodiment, the region inside inner edge 321 is a plane, and is parallel to the back side of light flux controlling member 300. Note that this region does not have to be a plane.

[0029] <Second reflective surface> Second reflecting surface 330 is arranged on the front side of light flux controlling member 300, and outside first reflecting surface 320. Second reflecting surface 330 mainly reflects light that has reached second reflecting surface 330, toward substrate 210. Second reflecting surface 330 is a flat surface that is approximately perpendicular to central axis CA of light emitting element 220. When light flux controlling member 300 is viewed in a plan view, second reflecting surface 330 is arranged in a ring shape.

[0030] <Exit surface> Emission surface 340 is a surface arranged on a side surface of light flux controlling member 300, and emits the light reflected by first reflecting surface 320 and another portion of the light emitted from light emitting element 220 to the outside of light flux controlling member 300. Emission surface 340 is approximately parallel to central axis CA of light emitting element 220.

[0031] Fig. 4B is a partial enlarged view of Fig. 3D, showing details of emission surface 340. As shown in Fig. 4B, in this embodiment, emission surface 340 has first emission surface 341, second emission surface 342, and third emission surface 343, in that order from the back side to the front side.

[0032] First emission surface 341 and third emission surface 343 are perpendicular to central axis CA of light emitting element 220. Second emission surface 342 is slightly inclined so as to approach the back side of light flux controlling member 300 with increasing distance from central axis CA of light emitting element 220. Second emission surface 342 and third emission surface 343 may be roughened.

[0033] (Light distribution simulation) 5A and B show the results of a light distribution simulation for light emitting device 200 according to the present embodiment. In Figs. 5A and B, light emitting element (light emitting diode) 220 having a height of 0.08 mm and a reflective film on its upper surface is used, and a point at a height of 0.04 mm, which is half the height, is set as the light emitting point, and the light distribution of a light ray from the emitting point is shown in a cross section. Light emitting element 220 is sealed with light transmissive resin 230 filled in recess 310 of light flux controlling member 300. The refractive index of light flux controlling member 300 is 1.41, and the refractive index of light transmissive resin 230 is 1.41.

[0034] FIG. 5A shows the light distribution of light rays emitted from the exit point at angles of 0° to 90°, with the direction from the exit point perpendicular to substrate 210 and toward the front side of light flux controlling member 300 being 0°, and FIG. 5B shows the light distribution of light rays emitted from the exit point at angles of 91° to 180°.

[0035] 5A, light rays between 0° and 90° are mainly reflected by first reflecting surface 320 or second reflecting surface 330 and emitted from exit surface 340, or are not reflected by first reflecting surface 320 and directly emitted from exit surface 340. On the other hand, light rays at angles between 91° and 180° are mainly reflected by substrate 210 and then reflected by first reflecting surface 320 or second reflecting surface 320 and emitted from exit surface 340, or are reflected by substrate 210 and then directly emitted from exit surface 340. In the light emitting device of the present embodiment, since translucent resin 230 having a small refractive index difference from light flux controlling member 300 is filled between the back surface of light flux controlling member 300 and substrate 210, light rays are not reflected by the back surface but are transmitted through the back surface and reflected by substrate 210.

[0036] 6A to 6D show the results of a simulation of light distribution when the angle of the light rays is divided more finely.

[0037] FIG. 6A shows the light distribution of light rays emitted from the exit point at an angle of 50° to 70°, FIG. 6B shows the light distribution of light rays emitted from the exit point at an angle of 70° to 90°, FIG. 6C shows the light distribution of light rays emitted from the exit point at an angle of 90° to 110°, and FIG. 6D shows the light distribution of light rays emitted from the exit point at an angle of 110° to 130°.

[0038] As can be seen from FIG. 6A, light rays with an angle between 50° and 70° are mainly reflected by first reflecting surface 320 or second reflecting surface 330 and emitted from exit surface 340. As can be seen from FIG. 6B, light rays at angles between 70° and 90° mainly exit from exit surface 340 directly without being reflected by first reflecting surface 320. As can be seen from FIG. 6C, light rays between 90° and 110° are mainly reflected by substrate 210 first, and then directly exit from exit surface 340. As can be seen from FIG. 6D, light rays between 110° and 130° are mainly reflected by substrate 210 first, then reflected by first reflecting surface 320 or second reflecting surface 330, and emitted from exit surface 340. As shown in FIG.

[0039] FIG. 7 shows the luminance distribution of the light emitting device according to the embodiment and the luminance distribution of the light emitting devices of Comparative Examples 1 and 2. The luminance distribution in FIG. 7 shows the luminance distribution of light reaching the light diffusion plate. The horizontal axis of FIG. 7 indicates the intersection point between the central axis of the light emitting element and the light diffusion plate as 0 mm. The vertical axis of FIG. 7 indicates normalized luminance. Here, in order to compare the light spreading ability of each light emitting device, the maximum luminance value of each light emitting device is set to 1.

[0040] The light emitting device according to the embodiment has light flux controlling member 300 as described above, and has the light distribution characteristics as shown in FIGS. On the other hand, the light emitting device of Comparative Example 1 is a potted light emitting element having a reflective film on its upper surface, and the light emitting device of Comparative Example 2 is a potted light emitting element that does not have a reflective film on its upper surface.

[0041] As can be seen from FIG. 7, the light emitting device according to the embodiment spreads light more widely than the comparative examples 1 and 2.

[0042] 6A to 6D and 7, from the viewpoint of spreading the light, it is considered preferable that the light flux controlling member of the light emitting device distributes the light rays as follows.

[0043] That is, a light ray emitted from a position half the height of light emitting element 220 as an emission point, and emitted at an angle of 70° or more and 110° or less, with a direction perpendicular to substrate 210 and toward the front side of light flux controlling member 300 being taken as 0°, is taken as a first angle light ray. In this case, it is considered preferable that the first angle light ray includes a light ray that is emitted from light emitting element 220 and then emitted from emission surface 340 without being reflected by first reflecting surface 320 and second reflecting surface 330 (see FIGS. 6B and 6C).

[0044] How much of the first angle light rays are emitted from the light emitting element 220 and then emitted from the exit surface 340 without being reflected by the first reflecting surface 320 and the second reflecting surface 330 may be appropriately adjusted according to the desired light distribution characteristics. For example, 80% or more, 85% or more, 90% or more, or 95% or more of the first angle light rays may be emitted from the exit surface 340 without being reflected by the first reflecting surface 320 and the second reflecting surface 330. The upper limit of this numerical value may be, for example, 100% or less, 95% or less, or 90% or less.

[0045] Similarly, a light ray emitted from a position half the height of light emitting element 220 as an emission point, a direction perpendicular to the substrate and toward the front side of light flux controlling member 300 as 0°, and emitted at an angle of 60° or more and less than 70° as a second angle ray, and an angle greater than 110° and less than 120° as a third angle ray. In this case, it is considered preferable that the second angle ray and the third angle ray include a light ray that is emitted from light emitting element 220, reflected by second reflecting surface 330, and emitted from emission surface 340 toward substrate 210 (see FIGS. 6A and 6D).

[0046] How much of the second angle light rays are emitted from the light emitting element 220, reflected by the second reflecting surface 330, and emitted from the exit surface 340 toward the substrate 210 may be appropriately adjusted according to the desired light distribution characteristics. For example, 80% or more, 85% or more, 90% or more, or 95% or more of the second angle light rays may be reflected by the second reflecting surface 330, and emitted from the exit surface 340 toward the substrate 210 after being emitted from the light emitting element 220. The upper limit of this numerical value may be, for example, 100% or less, 95% or less, or 90% or less.

[0047] How much of the third angle light rays are emitted from the light emitting element 220, reflected by the second reflecting surface 330, and emitted from the exit surface 340 toward the substrate 210 may be appropriately adjusted according to the desired light distribution characteristics. For example, 80% or more, 85% or more, 90% or more, or 95% or more of the third angle light rays may be reflected by the second reflecting surface 330, and emitted from the exit surface 340 toward the substrate 210 after being emitted from the light emitting element 220. The upper limit of this numerical value may be, for example, 100% or less, 95% or less, or 90% or less.

[0048] (effect) In the light flux controlling member according to the embodiment of the present invention, the recess of the light flux controlling member covers the light emitting element, and the light emitting element is sealed with a light transmissive resin filled in the recess, thereby making it possible to further spread light by the light flux controlling member while sealing the light emitting element.

[0049] [Variation 1] The light emitting device according to the first modification will be described below.

[0050] 8 and 9 show a comparison between light distribution by light flux controlling member 300 of light emitting device 200 according to the embodiment and light distribution by light flux controlling member 300a of a light emitting device according to Modification 1. In FIG.

[0051] 8 and 9, as indicated by the dashed lines on the left, the positions of light emitting elements 220 are aligned in the embodiment and Modification 1. Then, as indicated by the dashed lines on the right, second reflecting surface 320a of light flux controlling member 300a according to the modification is smaller in the radial direction by 0.4 mm than second reflecting surface 320 of light flux controlling member 300 according to the embodiment. Figures 8 and 9 compare the light distribution in such a light emitting device according to Modification 1 with the light distribution in the light emitting device according to the embodiment. Specifically, the upper diagram in Figure 8 shows the light distribution of light rays from 60° to 80° in a light emitting device of the embodiment, and the lower diagram shows the light distribution of light rays from 60° to 80° in a light emitting device of variant example 1. Similarly, the upper diagram in FIG. 9 shows the light distribution from 100° to 120° in the light emitting device according to the embodiment, and the lower diagram shows the light distribution from 100° to 120° in the light emitting device according to the first modification.

[0052] As can be seen from FIGS. 8 and 9, in light flux controlling member 300a of the light emitting device of Variation 1, second reflecting surface 320a is short, and therefore less light is reflected by second reflecting surface 320a and directed toward the substrate side.

[0053] FIG. 10 shows the luminance distribution of the light emitting device according to the embodiment and the light emitting device according to the first modification. In FIG. 10, the maximum luminance is set to 1, as in FIG. 7, to facilitate a comparison of the spread of light between the two. As can be seen from FIG. 10, the luminance distribution is almost the same in the light emitting device according to the embodiment and the light emitting device according to the first modification, but the light emitting device according to the first modification has a location with higher luminance at about 8 mm compared to the light emitting device according to the embodiment. This corresponds to the fact that, as shown in FIGS. 8 and 9, in the light emitting device according to the first modification, light emitted at a specific angle reaches the light diffusion plate without being reflected by the second reflection surface 320a.

[0054] (effect) The light emitting device according to the first modification has the same effects as the light emitting device according to the embodiment.

[0055] [Variation 2] The light emitting device according to the second modification will be described below.

[0056] 11 and 12 show a comparison between light distribution by light flux controlling member 300 included in light emitting device 200 according to the embodiment and light distribution by light flux controlling member 300b included in a light emitting device according to Modification 2. In FIG.

[0057] 11 and 12, as indicated by the dashed lines on the left side, the positions of light emitting elements 220 are aligned in the embodiment and in Modification 2. Furthermore, as indicated by the dashed lines on the right side, the positions of the outer edges of second reflecting surfaces 320a are also aligned. However, in light flux controlling member 300b of Modification 2, the height of light flux controlling member (second reflecting surface 330) is lower than that of light flux controlling member 300 of the embodiment. 11 and 12 compare the light distribution in the light emitting device according to the second modification with the light distribution in the embodiment. Specifically, the upper diagram in Figure 11 shows the light distribution of light rays from 60° to 80° in a light emitting device of the embodiment, and the lower diagram shows the light distribution of light rays from 60° to 80° in a light emitting device of variant example 2. Similarly, the upper diagram in FIG. 12 shows the light distribution from 100° to 120° in the light emitting device according to the embodiment, and the lower diagram shows the light distribution from 100° to 120° in the light emitting device according to the second modification.

[0058] 11 and 12, in light flux controlling member 300b of the light emitting device according to modification 2, second reflecting surface 320b is located at a low position, and therefore the amount of light that reaches second reflecting surface 320b and is reflected towards the substrate side is greater than in the embodiment. The light headed towards the substrate is reflected and hits a light diffuser plate located close to light emitting element 220.

[0059] Fig. 13 shows the luminance distribution of the light emitting device according to the embodiment and the light emitting device according to Modification 2. As can be seen from Fig. 13, the light emitting device according to Modification 2 has higher luminance in the vicinity directly above the light emitting element than the light emitting device according to the embodiment. This corresponds to the fact that, as shown in Figs. 11 and 12, in Modification 2, the light reflected by second reflection surface 320b toward the substrate is reflected by the substrate and strikes the light diffusion plate located close to light emitting element 220.

[0060] (effect) The light emitting device according to the second modification has the same effects as the light emitting device according to the embodiment.

[0061] [Variations 3 and 4] The light emitting devices according to the third and fourth modifications will be described below.

[0062] 14A and 14B show the luminance distributions of the light emitting devices according to the embodiment and the third and fourth modifications.

[0063] The light flux controlling member of the light emitting device of modification 3 is a reduced version of light flux controlling member 300 of the light emitting device of the embodiment. The reduction is effected so that the radial length, height, etc. of light flux controlling member 300 are at the same ratio. Therefore, the shape of light flux controlling member 300 and the shape of the light flux controlling member of modification 3 are similar. The reduction is effected so that the size of light flux controlling member 300 is 90% of that of light flux controlling member 300, which is 100%.

[0064] On the other hand, the light flux controlling member of the light emitting device of modification 4 is enlarged to 116% when the size of light flux controlling member 300 is taken as 100%. Note that the enlargement is performed so that the shape of light flux controlling member 300 and the shape of the light flux controlling member of modification 4 are similar to each other.

[0065] Fig. 14A shows the luminance distribution of the embodiment, modified example 3, and comparative example, and Fig. 14B shows the maximum luminance shown in Fig. 14A, which is set to 1. From Fig. 14B, modified example 4 was not preferable because the light spread laterally.

[0066] (effect) The light emitting devices according to the third and fourth modifications have the same effects as the light emitting device according to the embodiment.

[0067] Refractive Index 15A and 15B show the light distribution when the refractive index of the material constituting light flux controlling member 300 of the light emitting device according to the embodiment is set to 1.41 and 1.51, respectively. As shown in FIGS. 15A and 15B, even if the refractive index of the material constituting light flux controlling member 300 changes, the light distribution of the light does not change much. This is because light emitting element 220 is sealed by light transmissive resin 230 filled in the recess of light flux controlling member 300, and therefore the light emitted from light emitting element 220 does not travel through the air before entering the inside of light flux controlling member 300 from the recess of light flux controlling member. Therefore, refraction of the light is suppressed, and therefore the light distribution of the light does not change much even if the refractive index of the material constituting light flux controlling member 300 changes.

[0068] [Embodiment 2] Fig. 16A is a plan view of light flux controlling member 400 according to embodiment 2, Fig. 16B is a bottom view, Fig. 16C is a cross-sectional view taken along line CC in Fig. 16A, and Fig. 16D is a cross-sectional view taken along line DD in Fig. 16A. Also, Figs. 16E and F are side views of light flux controlling member 400. Note that Figs. 16B, C, and D show a state in which light emitting element 220 is sealed in recess 410 of light flux controlling member 400 by light-transmitting resin 230.

[0069] Light flux controlling member 400 pertaining to embodiment 2 differs from light flux controlling member 300 pertaining to embodiment 1 mainly in that its shape in plan view is elliptical, as shown in Fig. 16A. Like light flux controlling member 300, light flux controlling member 400 has recess 410, first reflecting surface 420, second reflecting surface 430, and exit surface 440. Each of these will be described below.

[0070] <Recess> Recess 410 is disposed on the back side of light flux controlling member 400 so as to intersect with the central axis of light emitting element 220. The inner surface of recess 410 is a surface through which light from the light emitting element passes into light flux controlling member 400. Recess 410 is filled with light transmissive resin 230 to seal light emitting element 220. In the present embodiment, recess 410 is hemispherical in shape, and is circular when light flux controlling member 400 is viewed from the bottom.

[0071] Recess 410 formed in light flux controlling member 400 is recess 410 capable of containing light emitting element 220, and it is sufficient that light flux controlling member 400 and light emitting element 220 are bonded via translucent resin 230 in recess 410, and the shape of recess 410 is not limited to the shape shown in the figure.

[0072] <First reflective surface> First reflecting surface 420 is disposed on the front side of light flux controlling member 400, and reflects at least a part of light incident at recess 410 in a direction substantially perpendicular to the central axis of light emitting element 220 and away from the central axis. As shown in FIG. 16A, when light flux controlling member 400 is viewed in plan, first reflecting surface 420 surrounds the center of light flux controlling member 300, has an inner edge and an outer edge that are elliptical, and is disposed in a ring shape. As can be seen from the cross-sectional views of FIGS. 16C and 16D, first reflecting surface 420 is a curved surface, and this curved surface has a shape such that a tangent to the curved surface gradually approaches parallel to the rear surface of light flux controlling member 400 from the center of light flux controlling member 400 toward the outside. As first reflecting surface 420 has such a shape, light that passes through the recess and reaches first reflecting surface 420 is reflected in a direction away from the central axis of light emitting element 220.

[0073] <Second reflective surface> Second reflecting surface 430 is disposed on the front side of light flux controlling member 400, and outside first reflecting surface 420. Second reflecting surface 430 is a flat surface that is approximately perpendicular to the central axis of light emitting element 220. When light flux controlling member 400 is viewed in a plan view, second reflecting surface 430 surrounds first reflecting surface 420, has an elliptical inner edge and an elliptical outer edge, and is disposed in a ring shape.

[0074] <Exit surface> Emission surface 440 is a surface arranged on a side surface of light flux controlling member 400, and emits the light reflected by first reflecting surface 420 and another portion of the light emitted from light emitting element 220 to the outside of light flux controlling member 300. Emission surface 440 is approximately parallel to the central axis of light emitting element 220.

[0075] (effect) According to the second embodiment, it is possible to provide a light emitting device that can further diffuse light while sealing the light source.

[0076] [Manufacturing method] A method for manufacturing a light emitting device will be described using an example in which light flux controlling member 300 is used. The method for manufacturing a light emitting device includes the steps of preparing substrate 210 on which light emitting element 220 is arranged, and filling recess 310 of light flux controlling member 300 with translucent resin 230 to seal light emitting element 220 and adhere the light flux controlling member to substrate 210, as shown in the upper diagram of Fig. 17 .

[0077] As another manufacturing method, as shown in FIG. 18 , there is a method including the steps of dripping light-transmitting resin 230 onto light-emitting element 220 mounted on substrate 210, aligning recess 310 of light flux controlling member 300 onto light-transmitting resin 230 and placing light flux controlling member 300 on substrate 210, and hardening light-transmitting resin 230, for example, by heat, to mount light flux controlling member 300 on substrate 210.

[0078] These manufacturing methods can be applied to other embodiments, and in order to avoid air bubbles remaining in the recesses of the light flux controlling member, it is preferable to appropriately adjust and modify the design of the amount of translucent resin used and the shape of the recesses, etc., so as to prevent air bubbles from remaining that would affect the light flux controlling function. [Industrial Applicability]

[0079] The light emitting device, light flux controlling member, and surface light source device of the present invention can be applied to, for example, backlights for liquid crystal display devices, general lighting, and the like. [Explanation of symbols]

[0080] 100 surface light source device 100' display unit 102 Display material 110 Cabinet 112 Bottom plate 114 Tabletop 120 Light Diffuser 200 Light emitting device 210 Substrate 220 Light emitting element 221 Outer edge 230 Translucent resin 300, 300a, 300b, 400 Light flux control member 310, 410 Recess 320, 420 1st reflective surface 321 Common-law marriage 330, 330a, 430 2nd reflective surface 340, 440 exit surface 341 First exit surface 342 Second exit surface 343 Third exit surface

Claims

1. A substrate; A light emitting element having a light reflecting film on an upper surface thereof, the light emitting element being disposed on the substrate; a light flux controlling member having: a recess disposed on a back side so as to cover the light emitting element, through which light emitted from the light emitting element passes; a first reflecting surface disposed on a front side, which reflects a portion of the light transmitted through the recess in a direction substantially perpendicular to a central axis of the light emitting element and away from the central axis; and an exit surface which emits to the outside the light reflected by the first reflecting surface and another portion of the light emitted from the light emitting element; a light-transmitting resin that fills the recess, seals the light-emitting element, and bonds the light flux controlling member to the substrate and the light-emitting element; having When viewed from above, an end of the first reflecting surface on the central axis side is located inside an outer edge of the light-emitting element, and a distance between the end of the first reflecting surface and the outer edge is 25% or less of a length of a minor axis of the light-emitting element passing through a center of the light-emitting element. Light emitting device.

2. The light emitting device according to claim 1 , wherein the distance between the edge of the first reflecting surface and the outer edge is 23% or less of a length of a minor axis of the light emitting element passing through a center of the light emitting element.

3. 2. The light emitting device according to claim 1, wherein an area inside an inner edge formed by an edge of the first reflecting surface is 60% to 80% of an area inside an outer edge of the light emitting element.

4. The light emitting device according to claim 1 , wherein the light flux controlling member further includes a second reflecting surface that is a flat surface substantially perpendicular to the central axis and that is disposed outside the first reflecting surface on the front side.

5. When light is emitted from a position half the height of the light emitting element as an emission point, and a direction perpendicular to the substrate and toward the front side of the light flux controlling member is defined as 0°, 5. The light emitting device of claim 4, wherein the first angle light ray emitted at an angle of 70° or more and 110° or less includes a light ray that is emitted from the light emitting element and then emitted from the exit surface without being reflected by the first reflecting surface and the second reflecting surface.

6. When light is emitted from a position half the height of the light emitting element as an emission point, and a direction perpendicular to the substrate and toward the front side of the light flux controlling member is defined as 0°, The light emitting device of claim 4, wherein the second angle light ray emitted at an angle of 60° or more and less than 70°, and the third angle light ray emitted at an angle of more than 110° and less than 120°, include light rays that are emitted from the light emitting element, reflected by the second reflecting surface, and emitted from the exit surface toward the substrate.

7. 2. The light emitting device according to claim 1, wherein the light flux controlling member and the light transmissive resin each have a refractive index of 1.4 to 1.

6.

8. A light flux controlling member for use in the light emitting device according to any one of claims 1 to 7.

9. A surface light source device comprising a light diffusing plate and at least one light emitting device according to any one of claims 1 to 7.

10. the at least one light emitting device is a plurality of light emitting devices; The plurality of light emitting devices are arranged in a row at equal intervals in an X direction and a Y direction perpendicular to the X direction, A center-to-center distance between two adjacent light-emitting devices in the X direction among the plurality of light-emitting devices is defined as Px, A center-to-center distance between two adjacent light-emitting devices in the Y direction among the plurality of light-emitting devices is defined as Py, The Px is equal to or less than the Py, When the distance between the substrate and the light diffusion plate is H, H / Px is 0.2 to 0.3; The surface light source device according to claim 9 .

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