Light-emitting device, surface light source device, and display device

Abstract

To provide a light emitting device capable of suppressing luminance unevenness.SOLUTION: A wave height device includes a light emitting element and a luminous flux control member. The luminous flux control member includes an incident surface which is an inner surface of a recess part, and an emission surface. An opening part of the recess part includes a first long axis and a first short axis. In a plan view, an outer edge of the emission surface includes a second short axis and a second long axis. In a virtual ellipse which passes both ends of the first long axis and both ends of the first short axis, when a long radius is defined as IL, a curvature radius at one end part of the long radius is defined as RL, the length of the light emitting element in the direction along a short radius is defined as b, and a short radius is defined as IS, the following (RL / IL)<0.8 and 0.7≤(a / RL) are satisfied, or (RL / IL)<0.8 and 0.4≤(a / IS)<2.0 are satisfied. In a region excluding both end parts of the first long axis and both end parts of the first short axis of the opening part, a region which is arranged further on an optical axis side than the virtual ellipse exists.SELECTED DRAWING: Figure 10

Description

[[Technical Field]]

[0001] The present invention relates to a light-emitting device, a surface light source device, and a display device. [[Background Art]]

[0002] In transmissive image display devices such as liquid crystal display devices, a direct-type surface light source device is sometimes used as a backlight. In recent years, direct-type surface light source devices having a plurality of light-emitting elements as light sources have come into use.

[0003] For example, a direct-type surface light source device includes a substrate, a plurality of light-emitting elements, a plurality of light flux control members (lenses), and a light diffusion member. The light-emitting elements are, for example, light-emitting diodes (LEDs) such as white light-emitting diodes. The plurality of light-emitting elements are arranged in a matrix on the substrate. Above each light-emitting element, a light flux control member that spreads the light emitted from the light-emitting element in the plane direction of the substrate is arranged. The light emitted from the light flux control member is diffused by the light diffusion member, and illuminates an irradiated member (for example, a liquid crystal panel) in a planar manner (see, for example, Patent Document 1).

[0004] Patent Document 1 describes a surface light source including a light-emitting device including a light source and a lens, and a diffusion plate that radiates the light emitted from the light-emitting device while diffusing the light. The lens has an entrance surface and an exit surface. Both the planar shape of the entrance surface and the planar shape of the exit surface are elliptical. When viewed in plan, the major axis of the entrance surface is arranged to be perpendicular to the major axis of the exit surface. [[Prior Art Documents]] [[Patent Documents]]

[0005] [[Patent Document 1]] International Publication No. 2011 / 114608 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0006] However, the light-emitting device described in Patent Document 1 had a problem in that, when viewed from above, a bright area was created in the region located on the extension of the long axis of the emission surface, and a dark area was created around the bright area, resulting in uneven brightness.

[0007] The objective of the present invention is to provide a light-emitting device that can suppress brightness unevenness.

[0008] Another object of the present invention is to provide a surface light source device and a display device having the light-emitting device. [Means for solving the problem]

[0009] [1] A light-emitting device comprising a light-emitting element and a light-beam control member arranged to intersect the optical axis of the light-emitting element and for controlling the distribution of light emitted from the light-emitting element, wherein the light-beam control member has an incident surface on the inner surface of a recess opening on the back side for allowing light emitted from the light-emitting element to be incident, and an exit surface arranged on the front side for emitting light incident on the incident surface to the outside, the opening of the recess includes a first major axis along a first direction perpendicular to the optical axis and a first minor axis along a second direction perpendicular to the optical axis and the first direction, and when viewed from above, the outer edge of the exit surface includes a second minor axis along the first direction and a second major axis along the second direction, and in a virtual ellipse passing through both ends of the first major axis and both ends of the first minor axis, the major axis is IL, the radius of curvature at one end of the major axis is RL, and the length of the light-emitting element in the direction along the minor axis is a When the minor radius is IS, the following equations (1) and (2) are satisfied, or equations (1) and (3) are satisfied, and the opening In the region of the part excluding both ends of the first major axis and both ends of the first minor axis, the virtual ellipse A light-emitting device in which there is also a region located on the optical axis side. (RL / IL) < 0.8 Formula (1) 0.7≦( a / RL) expression (2) 0.4≦( a / IS)<2.0 formula (3) [2] The light-emitting device according to [1], wherein the region of the opening other than both ends of the first major axis and both ends of the first minor axis is positioned on the optical axis side of the virtual ellipse. [3] At the outer edge of the opening, when θA is the angle of the straight line connecting the center of the opening and any point A on the outer edge of the opening with respect to the first major axis, there exists a region within the range of 80° ≤ θA ≤ 90° in which the radius of curvature at point A is 2 / 3 or less of the radius of curvature at the intersection of the straight line and the virtual ellipse. The light-emitting device according to [1] or [2]. [4] At the outer edge of the opening, when θB is the angle of the straight line connecting the center of the opening and any point B on the outer edge of the opening with respect to the first major axis, the radius of curvature at point B within the range of 30° ≤ θB ≤ 60° is greater than the radius of curvature at the intersection of the straight line and the virtual ellipse, as described in any one of [1] to [3]. [5] The light-emitting device according to any one of [1] to [4], wherein the opening of the incident surface is rotationally symmetrical twice, and the outer edge of the exit surface is elliptical. A display device comprising: a plurality of light-emitting devices as described in any one of [6][1] to [5]; a substrate supporting the plurality of light-emitting devices; and a light-diffusing member that diffuses and transmits light emitted from the light-emitting devices, wherein when the distance between the substrate and the light-diffusing plate is H, the distance between two adjacent light-emitting devices in the first direction is Px, and the distance between two adjacent light-emitting devices in the second direction is Py, the distance H between the substrate and the light-diffusing plate is 30 mm or less, and H / Px ≥ 0.1 and Px / Py ≥ 2. [Effects of the Invention]

[0010] The light-emitting device of the present invention can suppress unevenness in the brightness of the emitted light. [Brief explanation of the drawing]

[0011] [Figure 1] Figures 1A and 1B show the configuration of the surface light source device according to Embodiment 1. [Figure 2]FIG. 2 is a diagram illustrating the configuration of the surface light source device according to Embodiment 1. [Figure 3] FIG. 3 is a cross-sectional view of the surface light source device according to Embodiment 1. [Figure 4] FIGS. 4A to 4C are diagrams illustrating the configuration of the light beam control member according to Embodiment 1. [Figure 5] FIG. 5 is a diagram for explaining the relationship between the shape and size of an opening and a light emitting element. [Figure 6] FIGS. 6A to 6F are diagrams for explaining the luminance distribution in a light emitting device. [Figure 7] FIGS. 7A to 7F are diagrams for explaining the luminance distribution in a light emitting device. [Figure 8] FIGS. 8A to 8F are diagrams for explaining the luminance distribution in a light emitting device. [Figure 9] FIGS. 9A to 9C are graphs showing the shape relationship between a virtual ellipse and an opening of a recess. [Figure 10] FIGS. 10A to 10C are graphs showing the shape relationship between a virtual ellipse and an opening of a recess. [Figure 11] FIG. 11 is a diagram for explaining the luminance distribution in a light emitting device. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a light emitting device, a surface light source device, and a display device according to the present embodiment will be described with reference to the drawings. In the following description, as a representative example of the surface light source device according to the present embodiment, a surface light source device suitable for a backlight of a liquid crystal display device or the like will be described.

[0013] (Configuration of Surface Light Source Device and Light Emitting Device) FIGS. 1 to 3 are diagrams illustrating the configuration of the surface light source device 100 according to Embodiment 1. FIG. 1A is a plan view of the surface light source device 100 according to Embodiment 1, and FIG. 1B is a front view. FIG. 2A is a cross-sectional view taken along line A-A shown in FIG. 1B. FIG. 3 is a partially enlarged cross-sectional view of the surface light source device 100.

[0014] In the following explanation, the direction along the first minor axis L1a of the recess 145 of the light beam control member 123 is referred to as the first direction (X direction) D1, the direction along the first major axis L1b of the recess 145 is referred to as the second direction (Y direction) D2, and the third direction (Z direction) D3 is perpendicular to the first direction (X direction) D1 and the second direction (Y direction) D2. The third direction D3 is the direction along the optical axis OA of the light-emitting element 122 and the central axis CA of the light beam control member 123.

[0015] As shown in Figures 1A, B, 2, and 3, the surface light source device 100 comprises a housing 110, a plurality of light-emitting devices 120, and a light-diffusing member 130. The surface light source device 100 according to this embodiment can be applied to the backlight of a liquid crystal display device, etc. Furthermore, as shown in Figure 1B, the surface light source device 100 can also be used as a display device 100' by combining it with a display member (illuminated member) 107 (shown by a dotted line in Figure 1B) such as a liquid crystal panel.

[0016] Multiple light-emitting devices 120 are arranged in a matrix or in a single row on the bottom plate 111 of the housing 110. The inner surface of the bottom plate 111 functions as a diffuse reflecting surface. An opening is provided in the top plate 112 of the housing 110. The light-diffusing member 130 is positioned to cover this opening and functions as a light-emitting surface. The size of the light-emitting surface is not particularly limited, but can be, for example, approximately 400 mm x approximately 700 mm.

[0017] When multiple light-emitting devices 120 are arranged in a matrix, the distance between the centers of the light-emitting devices 120 (pitch) Px in the first direction D1 and the distance between the centers of the light-emitting devices 120 (pitch) Py in the second direction D2, which is orthogonal to the first direction D1, may be the same or different. In this embodiment, the pitch of the light-emitting devices 120 in the first direction D1 and the pitch of the light-emitting devices 120 in the second direction D2 are different. The distance between the centers of the light-emitting devices 120 (pitch) Px in the first direction D1 is preferably 10 mm or more. The distance between the centers of the light-emitting devices 120 (pitch) Py in the second direction D2 is preferably 20 mm or more. In this embodiment, the pitch of the light-emitting devices 120 in the first direction D1 is shorter than the pitch of the light-emitting devices 120 in the second direction D2. When the pitch in the first direction D1 and the pitch in the second direction D2 are different in this way, the shape of the light-diffusing member 130 illuminated by the light-emitting devices 120 is preferably substantially elliptical. In this embodiment, the major axis of the ellipse of the irradiated area is aligned with the first direction D1.

[0018] Each of the multiple light-emitting devices 120 is fixed to a predetermined position on the bottom plate 111 of the housing 110. As shown in Figure 3, each of the multiple light-emitting devices 120 has a light-emitting element 122 and a light-flux control member 123. In this embodiment, the multiple light-emitting devices 120 are arranged on a substrate 121.

[0019] The substrate 121 is a plate-shaped member that supports a plurality of light-emitting devices 120 (light-emitting elements 122 and light-flux control members 123), and supplies power to each light-emitting device 120 via electrical wiring or the like. In this embodiment, the plurality of light-emitting devices 120 on the substrate 121 are in the shape of a long rectangle along the second direction D2. Furthermore, the plurality of light-emitting devices 120 are arranged so that their first major axis L1b is aligned along the second direction D2.

[0020] The light-emitting element 122 is the light source of the surface light source device 100 and is arranged on the substrate 121. The light-emitting element 122 is a light-emitting diode (LED), such as a white light-emitting diode. The shape of the light-emitting surface of the light-emitting element 122 is preferably square or rectangular. In this embodiment, the shape of the light-emitting surface of the light-emitting element 122 is square. The size of the light-emitting surface of the light-emitting element 122 is appropriately set according to the size and curvature of the opening 148 of the recess 145 of the light-fuel control member 123. The length of one side of the light-emitting surface of the light-emitting element 122 is in the range of 0.1 to 2.0 mm. In this embodiment, the length of one side of the light-emitting element 122 and the length of one side of the light-emitting surface are approximately the same. The optical axis OA of the light-emitting element 122 coincides with the central axis CA of the light-fuel control member 123. "Optical axis OA of the light-emitting element" refers to the light ray at the center of the three-dimensional emitted light beam from the light-emitting element 122. In this embodiment, the optical axis OA of the light-emitting element 122 passes through the center of the light-emitting surface.

[0021] The light beam control member 123 is a lens and is fixed on the substrate 121. The light beam control member 123 controls the distribution of light emitted from the light-emitting element 122 and expands the direction of light propagation in the plane direction of the substrate 121. The light beam control member 123 is positioned on the light-emitting element 122 such that its central axis CA coincides with the optical axis OA of the light-emitting element 122 (see Figure 3). Note that "the central axis CA of the light beam control member 123" means a straight line passing through the rotation center of the emission surface 142. In the light beam control member 123 according to this embodiment, since it is rotationally symmetric (twice symmetric), the central axis CA of the light beam control member 123 coincides with the midpoint of the light beam control member 123 in the first direction D1 and also coincides with the midpoint of the light beam control member 123 in the second direction D2.

[0022] The luminous flux control member 123 can be formed by integral molding. The material of the luminous flux control member 123 can be any material that can transmit light of a desired wavelength. For example, the material of the luminous flux control member 123 may be a light-transmitting resin such as polymethyl methacrylate (PMMA), polycarbonate (PC), epoxy resin (EP), or silicone resin, or glass. The detailed structure of the luminous flux control member 123 and the relationship between the light-emitting element 122 and the luminous flux control member 123 will be described later.

[0023] The light-diffusing member 130 is a plate-shaped member with light-diffusing properties, which diffuses and transmits the light emitted from the light-emitting device 120. The light-diffusing member 130 is arranged on a plurality of light-emitting devices 120, approximately parallel to the substrate 121, with an air layer in between. Typically, the light-diffusing member 130 is approximately the same size as the irradiated material, such as a liquid crystal panel. For example, the light-diffusing member 130 is formed from a light-transmitting resin such as polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), or styrene-methyl methacrylate copolymer resin (MS). To impart light-diffusing properties, the light-diffusing member 130 has fine irregularities formed on its surface, or light diffusers such as beads are dispersed inside it. The distance between the substrate 121 and the light-diffusing member 130, and the distance between the light-emitting device 120 (light flux control member 123) and the light-diffusing member 130 are not particularly limited. The distance between the substrate 121 and the light diffusion member 130 is preferably 30 mm or less, and more preferably within the range of 5 to 30 mm. The distance between the light-emitting device 120 (light flux control member 123) and the light diffusion member 130 is preferably within the range of 1 to 26 mm.

[0024] In the surface light source device 100 according to this embodiment, the light emitted from each light-emitting element 122 is spread by the light-flux control member 123 to illuminate a wide area of ​​the light-diffusing member 130. The light emitted from each light-flux control member 123 is further diffused by the light-diffusing member 130. As a result, the surface light source device 100 according to this embodiment can uniformly illuminate a planar illuminating member (for example, a liquid crystal panel).

[0025] (Configuration of the light beam control component) Figures 4A to 4C show the configuration of the luminous flux control member 123 according to the embodiment. Figure 4A is a plan view of the luminous flux control member 123, Figure 4B is a front view, and Figure 4C is a bottom view.

[0026] As shown in Figures 4A to 4C, the light beam control member 123 has an incident surface 141, an exit surface 142, a flange portion 143, and a leg portion 144.

[0027] The incident surface 141 is the inner surface of a recess 145 located in the center of the back side so as to intersect with the central axis CA of the light beam control member 123. The incident surface 141 controls the direction of propagation of most of the light emitted from the light-emitting element 122 and directs it into the interior of the light beam control member 123. The opening 148 of the recess 145 includes a first minor axis L1a along a first direction D1 perpendicular to the central axis CA (optical axis OA) and a first major axis L1b along a second direction D2 perpendicular to the central axis CA (optical axis OA) and the first direction D1 (see Figure 5). In the opening 148 of the recess 145, the longest straight line passing through the center is the first major axis L1b, and the shortest is the first minor axis Lia. In the luminous flux control member 123 of this embodiment, the first major axis L1b and the first minor axis Lia are always perpendicular to each other. In the region of the opening 148 excluding both ends of the first major axis L1b and both ends of the first minor axis L1a, there exists a region that is located on the optical axis OA side of the virtual ellipse passing through both ends of the first minor axis L1a and both ends of the first major axis L1b. In this embodiment, the region of the opening 148 other than both ends of the first major axis L1b and both ends of the first minor axis L1a is located on the optical axis OA side of the virtual ellipse. In Figure 5, the line representing the opening 148 of the recess 145 and the virtual ellipse overlap and are not visible, but in reality, the opening 148 of the recess 145 has a shape that is slightly closer to a rhombus than an ellipse, and the four corners of this rhombus overlap with the virtual ellipse, but the other regions are located inward from the virtual ellipse. Furthermore, the shape of the horizontal cross-section of the recess 145 at any height, not just its opening 148, is similar to the shape of the opening 148 of the recess 145. In particular, the angle of the opening 148 of the recess 145 with respect to the central axis CA is preferably 30° or less, and more preferably within the range of 7 to 23°. Within this range, it is preferable that there exists a region located on the optical axis OA side of the ellipse corresponding to the virtual ellipse. Also, in a cross-section perpendicular to the central axis CA, the recess 145 (incident surface 141) is composed of a curve. The incident surface 141 is formed of a curve such that, in a cross-section including the central axis CA, it approaches the back surface 146 as it moves away from the central axis CA. In a cross-section including the central axis CA, the recess 145 (incident surface 141) is composed of a curve. The incident surface 141 is rotationally symmetric (2-fold symmetry) with respect to the central axis CA as the axis of rotation.In the following explanation, the "cross-section perpendicular to the central axis CA" will also simply be referred to as the "horizontal cross-section." The relationship between the opening 148 of the recess 145 and the light-emitting element 122 will be described later. In this embodiment, since the shape of the opening 148 is roughly rhombic, light traveling in the first direction D1 is spread toward the second direction D2. Therefore, it is possible to suppress the occurrence of bright areas in regions located on the extension of the second major axis.

[0028] The back surface 146 is located on the back side of the light beam control member 123 and is a plane that extends radially from the opening edge of the recess 145. In addition to the recess 145, a mark 147 is located on the back surface 146.

[0029] Mark 147 is used to locate the center (center of gravity) of the opening 148 of the recess 145. The shape of Mark 147 is not particularly limited as long as it performs the above function. In this embodiment, Mark 147 has a pair of protrusions 147a. Each protrusion 147a has an arc-shaped outer surface 147b. In this embodiment, the outer surface 147b of one protrusion 147a and the outer surface 147b of the other protrusion 147a are arranged on a virtual circle. The center of the virtual circle coincides with the first central axis O1. By determining the center of the virtual circle, the center (center of gravity) of the opening 148 can be determined.

[0030] The emission surface 142 is located on the front side (light diffusion member 130 side) of the light beam control member 123. In this embodiment, the emission surface 142 is positioned to protrude from the flange portion 143. The emission surface 142 causes light incident on the light beam control member 123 to be emitted to the outside while controlling its direction of travel. The emission surface 142 is positioned so that its central axis coincides with the optical axis OA of the light-emitting element 122 (the central axis CA of the light beam control member 123). The outer shape (horizontal cross-section) of the emission surface 142 is elliptical and has a second major axis L2a and a second minor axis L2b.

[0031] The second minor axis L2b of the ejection surface 142 is positioned to coincide with the first major axis L1b of the opening of the recess 145, and the second major axis L2a of the ejection surface 142 is positioned to coincide with the first minor axis L1a of the opening of the recess 145.

[0032] The ejection surface 142 has a first ejection surface 142a located within a predetermined range centered on the central axis CA, and a second ejection surface 142b formed continuously around the first ejection surface 142a (see Figure 4B). In this embodiment, the first ejection surface 142a is a flat plane. The second ejection surface 142b is a smooth curved surface located around the first ejection surface 142a, with a convex shape on the front side. The shape of the second ejection surface 142b is an elliptical annular convex shape. In this embodiment, the waterline cross-section of the second ejection surface 142b is elliptical.

[0033] The flange portion 143 connects the back surface 146 and the emission surface 142. The flange portion 143 facilitates the handling of the light beam control member 123. In this embodiment, a gate mark 143a is provided on a part of the flange portion 143. In this embodiment, although the light beam control member 123 has a flange portion 143, the outer edge of the emission surface 142 is not the outer edge of the flange portion 143.

[0034] The legs 144 form a gap to allow heat emitted from the light-emitting element 122 to escape to the outside, and also position and fix the light beam control member 123 to the substrate 121. The legs 144 are formed to protrude in a columnar shape from the back surface 146. The number of legs 144 is not particularly limited as long as they perform the above functions. In this embodiment, there are four legs 144.

[0035] (Positional relationship between the recessed opening and the light-emitting element) Here, the relationship between the shape and size of the opening 148 of the recess 145 and the light-emitting element 122 is explained. Here, a simulation was conducted to determine what kind of light-emitting element 122 and what kind of light-flux control member 123 would result in bright areas (luminance unevenness). Figure 5 is a diagram illustrating the shape and size of the opening 148 and the light-emitting element 122. For explanatory purposes, the same reference numerals as in the light-emitting device of this embodiment are used here.

[0036] As shown in Figure 5, consider a virtual ellipse passing through both ends of the first minor axis L1a and both ends of the first major axis L1b. This virtual ellipse mimics the shape of the opening 148 of the recess 145. Let a be the length of the light-emitting element 122 in the first direction D1, and let b be the length of the light-emitting element 122 in the second direction D2. In this simulation, the length a of the light-emitting element 122 in the first direction D1 and the length b of the light-emitting element 122 in the second direction D2 do not necessarily coincide. Let IL be the semi-major axis of the virtual ellipse (the distance between the center O (centroid) of the opening 148 and one end of the first major axis L1b), and let IS be the semi-minor axis (the distance between the center O (centroid) of the opening and one end of the first minor axis L1a). Let RL be the radius of curvature at one end of the first major axis L1b, and let RS be the radius of curvature at one end of the first minor axis L1a.

[0037] Table 1 shows the size of the light-emitting element 122 used in each light-emitting device, the size of the virtual ellipse that mimics the shape of the opening 148 of the recess 145, and the radius of curvature of the virtual ellipse.

[0038] [Table 1]

[0039] Table 2 shows the light-emitting element / recess shape, light-emitting element / radius of curvature, and radius of curvature / recess shape for each light-emitting device.

[0040] [Table 2]

[0041] Next, the luminance distribution in the light diffusion member 130 of the light emitted from light-emitting devices A to J was investigated. The distance between the substrate 121 and the light diffusion member 130 was 20 mm, and the distance between the light beam control member 123 and the light diffusion member 130 was 16 mm. In an actual surface light source device, the distance between the substrate 121 and the light diffusion member 130 is approximately 25 mm, and the distance between the light beam control member 123 and the light diffusion member 130 is approximately 21 mm. Figures 6A to F, 7A to D, and 8A to F show the relationship between light-emitting devices B to J and the opening of the recess, and the amount of change in the luminance distribution of each light-emitting device B to G relative to the luminance distribution of light-emitting device A.

[0042] Figure 6A schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device B, Figure 6B shows the luminance distribution of light-emitting device B, Figure 6C schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device C, Figure 6D shows the luminance distribution of light-emitting device C, Figure 6E schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device D, and Figure 6F shows the luminance distribution of light-emitting device D. Figure 7A schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device E, Figure 7B shows the luminance distribution of light-emitting device E, Figure 7C schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device F, Figure 7D shows the luminance distribution of light-emitting device F, Figure 7E schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device G, and Figure 7F shows the luminance distribution of light-emitting device G. Figure 8A schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device H, Figure 8B shows the luminance distribution of light-emitting device H, Figure 8C schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device I, Figure 8D shows the luminance distribution of light-emitting device I, Figure 8E schematically shows the arrangement of the light-emitting element 122 and the luminous flux control member in light-emitting device J, and Figure 8F shows the luminance distribution of light-emitting device J. In Figures 6C-F, 7A-F, and 8A-F, the white areas indicate areas that are bright relative to the luminance of light-emitting device A, and the black areas indicate areas that are dark relative to the luminance of light-emitting device A.

[0043] As shown in Figures 6B, 6F, 7B, 7D, and 8D, the light-emitting devices C, E, F, G, and J produced bright areas on the outside in the direction of the second major axis L2a (first minor axis L1a).

[0044] As can be deduced from Table 1, Table 2, Figures 6A-F, Figures 7A-D, and Figures 8A-F, it was found that if the light-emitting device 120 satisfies the following equations (1) and (2), or if it satisfies equations (1) and (3), then a bright area will be generated on the outside in the direction of the second major axis L2a (first minor axis L1a). Equation (1) (RL / IL) < 0.8 Equation (2)0.7≦( a / RL) Equation (3)0.4≦( a / IS)<2.0

[0045] Next, we will describe the shape of the opening of the recess 145 that the light-emitting device should have, which produces a bright area on the outside in the direction of the second major axis L2a (first minor axis L1a). In this embodiment, the shape of the opening 148 of the recess 145 is symmetrical with respect to the first major axis L1b and also symmetrical with respect to the first minor axis L1a, so here we will only describe the upper right region in Figure 5.

[0046] Figures 9A-C and 10A-C are graphs showing the relationship between the shape of a virtual ellipse and the shape of the opening 148 of the recess 145. Figure 9A shows the relationship between the distance from the center of the opening 148 in the direction of the first minor axis L1a and the distance from the center of the opening 148 in the direction of the first major axis L1b. The horizontal and vertical axes of Figure 9A represent the distance from the center of the opening 148. The horizontal axis is the first minor axis L1a, and the vertical axis is the first major axis L1b. Figure 9B shows the relationship between the distance from the center of the opening 148 in the direction of the first minor axis L1a and the angle θ. Here, the angle θ refers to the angle of the straight line connecting the center of the opening 148 and any point on the outer edge of the opening 148 with respect to the first major axis L1b. The horizontal axis of Figure 9B represents the distance from the center of the opening 148 in the direction of the first minor axis L1a, and the vertical axis represents the angle θ. Figure 9C shows the relationship between the distance from the center of the opening 148 in the direction of the first minor axis L1a and the radius of curvature. The horizontal axis of Figure 9C shows the distance from the center of the opening 148 in the direction of the first minor axis L1a, and the vertical axis shows the radius of curvature. Figure 10A shows the relationship between the angle θ and the distance from the center of the opening 148 in the direction of the first major axis L1b. The horizontal axis of Figure 10A shows the angle θ, and the vertical axis shows the distance from the center of the opening 148 in the direction of the first major axis L1b. Figure 10B shows the relationship between the angle θ and the inclination angle of the tangent at the outer edge of the opening of the recess 145 corresponding to that angle θ. The horizontal axis of Figure 10B shows the angle θ, and the vertical axis shows the inclination angle of the tangent at the outer edge of the opening of the recess 145 corresponding to the angle θ. Figure 10C shows the relationship between the angle θ and the radius of curvature. The horizontal axis of Figure 10C shows the angle θ, and the vertical axis shows the radius of curvature. The solid lines in Figures 9A-C and 10A-C show the results based on the opening 148 of the recess 145 in this embodiment, while the dashed lines in Figures 9A-C and 10A-C show the results based on a perfect ellipse having a first major axis L1b and a first minor axis L1a similar to the recess 145 in this embodiment.

[0047] As shown in Figures 9A-C and 10A-C, there is a region in the aperture 148, excluding both ends of the first major axis L1b and both ends of the first minor axis L1a, that is located on the optical axis OA side of the virtual ellipse. More specifically, as shown in Figure 9A, in the aperture 148 of the recess 145 in this embodiment, all regions other than both ends of the first minor axis L1a and the second major axis L1b are located on the central side of the virtual ellipse.

[0048] Furthermore, as shown in Figure 10C, the light-emitting device 120 sets the angle θ of the straight line connecting the center of the opening 148 and any point A on the outer edge of the opening 148 with respect to the first major axis L1b. A When this is the case, 80°≦θ A It is preferable that within the range of ≤90°, there exists a region where the radius of curvature at point A is less than or equal to 2 / 3 of the radius of curvature at the intersection of the straight line and the virtual ellipse. This condition means that both ends of the first minor axis L1a of the opening of the recess 145 are pointed.

[0049] Furthermore, as shown in Figure 10C, at the outer edge of the opening 148, the angle of the line connecting the center of the opening 148 and an arbitrary point B on the outer edge of the opening 148 with respect to the first major axis L1b is θ B When this is the case, 30°≦θ B The radius of curvature at point B within the range ≤60° is preferably greater than the radius of curvature at the intersection of the line and the virtual ellipse. This condition is met when the outer edge of the opening 148 is 30° ≤ θ B Within the range of ≤60°, this means that it is located closer to the center of the opening 148 than the perfect ellipse.

[0050] Thus, in this embodiment, since the shape of the opening 148 of the recess 145 is approximately rhombic, light traveling in the first direction D1 is refracted so as to spread in the second direction D2 and enters the interior of the light beam control member 123. Then, it is refracted again so as to spread in the second direction D2 and exits from the light beam control member 123. Therefore, brightness unevenness occurring in the region located on the extension of the long axis of the exit surface 142 can be suppressed.

[0051] Figure 11 shows the luminance distribution in the light-emitting device 120 according to this embodiment. Here, we show the case when one light-emitting element is lit. As shown in Figure 11, it can be seen that luminance unevenness is suppressed in the light-emitting device 120 that satisfies the above conditions. More specifically, when one light-emitting element 122 is lit, the light is controlled so that the luminance distribution on the light-diffusing plate 130 forms an X shape. By controlling it in this way, when multiple light-emitting elements 122 are lit, the luminance on the light-diffusing plate 130 can be made uniform.

[0052] (effect) As described above, the light-emitting device 120 according to this embodiment can suppress brightness unevenness because there is a region in which the outer edge of the opening 148 of the recess 145 is positioned on the optical axis OA side than the virtual ellipse. [Industrial applicability]

[0053] The light-emitting device of the present invention can be applied, for example, to the backlight of a liquid crystal display device or to general lighting. [Explanation of Symbols]

[0054] 100 surface light source device 100' display unit 107 Display component (irradiated component) 110 cabinets 111 Bottom plate 112 Top plate 120 Light-emitting devices 121 circuit boards 122 Light-emitting element 123 Light beam control member 130 Light Diffusing Member 141 Entrance plane 142 Ejection surface 142a 1st exit surface 142b Second launch surface 143 Tsuba (guard) 143a Gate remains 144 Legs 145 Opening 145 recess 146 Back side 147 Mark 147a Convex part 147b External surface 148 Opening

Claims

1. A light-emitting device comprising a light-emitting element and a light-beam control member arranged to intersect the optical axis of the light-emitting element and for controlling the light distribution of the light emitted from the light-emitting element, The aforementioned light beam control member is The inner surface of the recess opening on the back side, which includes an incident surface for allowing light emitted from the light-emitting element to enter, It has an exit surface positioned on the front side for emitting light incident on the incident surface to the outside, The opening of the recess includes a first minor axis along a first direction perpendicular to the optical axis and a first major axis along a second direction perpendicular to the optical axis and the first direction. When viewed from above, the outer edge of the ejection surface includes a second major axis along the first direction and a second minor axis along the second direction. In a virtual ellipse passing through both ends of the first major axis and both ends of the first minor axis, Let the semi-major axis be IL. Let RL be the radius of curvature at one end of the aforementioned semi-major axis. Let a be the length of the light-emitting element in the direction along the minor radius. When the aforementioned minor radius is IS, The following equations (1) and (2) are satisfied, or equations (1) and (3) are satisfied. In the region of the opening excluding both ends of the first major axis and both ends of the first minor axis, there exists a region that is positioned closer to the optical axis than the virtual ellipse. Light-emitting device. (RL / IL)<0.8 Formula (1) 0.7≦(a / RL) Formula (2) 0.4≦(a / IS)<2.0 Formula (3)

2. The light-emitting device according to claim 1, wherein the region of the opening other than both ends of the first major axis and both ends of the first minor axis is located on the optical axis side of the virtual ellipse.

3. The light-emitting device according to claim 1, wherein, at the outer edge of the opening, when θA is the angle of the straight line connecting the center of the opening and any point A on the outer edge of the opening with respect to the first major axis, there exists a region within the range of 80° ≤ θA ≤ 90° in which the radius of curvature at point A is 2 / 3 or less of the radius of curvature at the intersection of the straight line and the virtual ellipse.

4. The light-emitting device according to claim 1, wherein, at the outer edge of the opening, when θB is the angle of the straight line connecting the center of the opening and any point B on the outer edge of the opening with respect to the first major axis, the radius of curvature at point B within the range of 30° ≤ θB ≤ 60° is greater than the radius of curvature at the intersection of the straight line and the virtual ellipse.

5. The aforementioned opening is rotationally symmetrical twice, The outer edge of the aforementioned ejection surface is elliptical in shape. The light-emitting device according to claim 1.

6. A plurality of light-emitting devices according to any one of claims 1 to 5, A substrate supporting multiple light-emitting devices, A light-diffusing member that diffuses and transmits the light emitted from the light-emitting device, It has, When the distance between the substrate and the light-diffusing member is H, the distance between two adjacent light-emitting devices in the first direction is Px, and the distance between two adjacent light-emitting devices in the second direction is Py, The distance H between the substrate and the light-diffusing member is 30 mm or less. Satisfying H / Px ≥ 0.1 and Px / Py ≥ 2, Surface light source device.

7. A surface light source device according to claim 6, A display member that is illuminated by light emitted from the aforementioned surface light source device, Display device.

Images