Surface light source device, display device, and luminous flux control member

Abstract

To provide a surface light source device which can inhibit deterioration of quality of an image, and to provide a display device and a luminous flux control member.SOLUTION: A surface light source device has a plurality of light emitting devices which are arrayed in an X direction and a Y direction perpendicular to the X direction; and a light diffusion plate that light from the light emitting devices reaches. Each of the light emitting devices has a light emitting element, and a luminous flux control member for controlling light from the light emitting element. When a surface of the light diffusion plate which the light from the light emitting devices reaches is divided, a ratio of the reaching light is set to a predetermined ratio on each divided surface.SELECTED DRAWING: Figure 11

Description

[Technical field]

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

[0002] Transmissive image display devices such as liquid crystal display devices are known. In transmissive image display devices, an image is displayed when light from a surface light source device strikes a display member. For example, Patent Document 1 discloses such a surface light source device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2015 / 0109762 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned display device, the quality of the image obtained may deteriorate. The inventors have investigated the cause of the deterioration of the image quality and found the following. That is, the surface light source device used in the display device has a plurality of light emitting devices, and the plurality of light emitting devices may be arranged in a row in the X direction and in the Y direction perpendicular to the X direction. In this case, in the surface light source device, because the light emitting devices are arranged in a row, bright areas and dark areas may occur along the row. It has been found that this may cause the quality of the image to deteriorate in the display device.

[0005] An object of the present invention is to provide a surface light source device, a display device, and a light flux controlling member that can suppress deterioration in image quality. [Means for solving the problem]

[0006] The present invention relates to the following surface light source device, display device, and light flux controlling member.[1] A surface light source device comprising: a plurality of light emitting devices arranged in a row in an X direction and a Y direction perpendicular to the X direction; and a light diffusion plate through which light from the plurality of light emitting devices reaches; each of the plurality of light emitting devices has a light emitting device and a light flux control member for controlling light from the light emitting device; the light flux control member is an inner surface of a recess arranged on the back side so as to intersect with the optical axis of the light emitting device, the light flux control member being an incident surface through which light emitted from the light emitting device is incident; and the light flux control member is arranged on the front side, and at least a part of the light incident on the incident surface is directed to a light diffusing plate that is substantially perpendicular to the optical axis of the light emitting device and mainly intersects with each other. a light emitting center of a light emitting element of any one of a plurality of light emitting devices arranged in the X direction and a front light emitting portion of a light emitting element of any one of a plurality of light emitting devices arranged in the X direction on a surface of the light diffusion plate that faces the light emitting device when the surface light source device is seen through in a plan view and that receives light from the light emitting device, the front light emitting portion of a light emitting element of any one of the light emitting devices arranged in the X direction and a front light emitting portion of a light emitting element of any one of the light emitting devices arranged in the X direction are disposed .... A line connecting the light emitting device and the light emitting center of a light emitting element of an adjacent light emitting device in the X direction is denoted by Px, a line connecting the light emitting center of the light emitting element of any one of the light emitting devices and the light emitting center of the light emitting device and the light emitting center of the light emitting element of an adjacent light emitting device in the Y direction is denoted by Py, a rectangle having sides of Px and Py is divided into four equal parts in the X direction and into four equal parts in the Y direction to obtain a total of 16 small rectangles of equal area, and the four small rectangles lined up in the X direction at a position closest to Px are denoted by X0Y0, X1Y0, X2Y0, and X3Y0, in order of distance from Py, When the four small rectangles lined up in the X direction at a position second closest to the Px are respectively designated as X0Y1, X1Y1, X2Y1, and X3Y1 in order of distance from the Py, the four small rectangles lined up in the X direction at a position third closest to the Px are respectively designated as X0Y2, X1Y2, X2Y2, and X3Y2 in order of distance from the Py, and the four small rectangles lined up in the X direction at a position fourth closest to the Px are respectively designated as X0Y3, X1Y3, X2Y3, and X3Y3 in order of distance from the Py, among the light rays emitted from the light emission center of the light source, a light ray that is approximately along the optical axis of the light source,a surface light source device in which an angle with respect to the optical axis is α, an angle with respect to Py when a light ray emitted along a conical wall of a virtual cone formed with an apex at an apex angle of 2α with the light emission point of the light-emitting element as the apex is γ, and the angle with respect to Py when the light ray is projected onto a plane including Px and Py, the light ray being emitted along the conical walls of 30 virtual cones formed by changing α by 1° within 1°≦α≦30°, the total of 2731 light rays being light rays with γ=0.001°, light rays obtained by changing γ by 1° within 1°≦γ≦89°, and light rays with γ=89.999°, when the ratio of the number of light rays reaching X0Y1 is set to 100, the ratio of the number of light rays reaching X0Y2, X1Y1, and X1Y2 is 30 or more. [2] The surface light source device according to [1], wherein, when the 2731 light rays are considered, if the ratio of the 2731 light rays is set to 100, the ratio of the number of light rays that reach X0Y1 is 80 or less. [3] Considering the 2731 light rays, the number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1 is equal to or greater than the number of light rays whose α is in the range of 21° to 30° that reach X0Y2 and X1Y1, and the number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1 is smaller than the number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1, and the number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1 is smaller than the number of light rays whose α is approximately along the optical axis and the number of light rays whose angle α is in the range of 1° to 10° that reach X the number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is greater than or equal to the number of light rays whose α is in the range of 11° to 20° that reach X1Y2, and the number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is greater than or equal to the number of light rays that are approximately aligned with the optical axis and the light rays whose angle α is in the range of 1° to 10° that reach X1Y2. [4] The surface light source device according to [1], wherein Py is longer than Px. [5] The surface light source device of claim [1], wherein the light flux control member has a second exit surface that directly emits a portion of the light incident from the entrance surface, and the second exit surface is a surface located at a portion of the connection portion of the two reflecting surfaces. [6] A display device comprising the surface light source device according to any one of [1] to [5]. [7] A light flux controlling member for use in the surface light source device according to any one of [1] to [5]. Effect of the Invention

[0007] According to the present invention, it is possible to provide a surface light source device, a display device, and a light flux controlling member that can suppress deterioration in image quality. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams showing a configuration of a surface light source device according to an embodiment. [Diagram 2] FIG. 2A shows the arrangement of light emitting devices in a surface light source device, and FIG. 2B is a diagram for explaining the division into small rectangles of a light diffusion plate through which light reaches. [Diagram 3] FIG. 3A is a diagram for explaining a specific light ray, FIG. 3B shows light emission from a surface light source device according to the present embodiment, and FIG. 3C shows light emission from a surface light source device according to a comparative example. [Figure 4] 4A to 4F are diagrams showing the configuration of a light flux controlling member according to embodiment 1. [Diagram 5] 5A to 5F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 2. [Figure 6] 6A to 6F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 3. [Figure 7] 7A to 7F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 4. [Figure 8] 8A to 8F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 5. [Figure 9] 9A to 9F are diagrams illustrating the configuration of a light flux controlling member according to embodiment 6. [Figure 10] 10A to 10F are diagrams showing the configuration of a light flux controlling member according to a comparative example. [Figure 11] 11A to 11G are diagrams showing the proportion of light rays reaching each small rectangle. [Figure 12] 12A to 12G are diagrams showing the proportion of light rays reaching each small rectangle. [Figure 13] 13A to 13F are diagrams showing the number of light rays reaching each small rectangle. [Figure 14] 14A to 14F are diagrams showing the number of light rays reaching each small rectangle. [Figure 15] 15A to 15F are diagrams showing the number of light rays reaching each small rectangle. [Figure 16] 16A to 16C are diagrams showing the number of light rays reaching each small rectangle. [Figure 17] 17A to 17F are diagrams showing the proportion of light rays reaching each small rectangle. [Figure 18] 18A to 18E are diagrams for explaining the light distribution of light rays other than a predetermined light ray. [Figure 19] 19A to 19E are diagrams for explaining the light distribution of light rays other than a predetermined light ray. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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).

[0010] [Embodiment 1] (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 embodiment 1 of the present invention. Fig. 1A is a plan view, and Fig. 1B is a front view. Fig. 2A is a schematic cross-sectional view taken along line AA shown in Fig. 1B, showing an outline of the arrangement of light-emitting devices 200.

[0011] As shown in FIGS. 1A to 2A, 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.

[0012] 2A, in this embodiment, light emitting device 200 is fixed on a substrate which is fixed at a predetermined position on bottom plate 112 of housing 110. In this embodiment, substrate 210 is bar-shaped.

[0013] 2A, in this embodiment, the light emitting devices 200 are arranged in a row in the X direction and in the Y direction perpendicular to the X direction. Specifically, in this embodiment, the light emitting devices 200 are arranged at equal intervals in the X direction and also at equal intervals in the Y direction. In this embodiment, the interval in the Y direction is longer than the interval in the X direction. The light emitting devices 200 arranged along the X direction are arranged on a single bar-shaped substrate 210 extending in the X direction.

[0014] Each of multiple light emitting devices 200 has light emitting element 220 and light flux controlling member 300. 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.

[0015] (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 type of the light emitting element 220 is not particularly limited, but a light emitting element 220 that emits light from the top surface and the side surface (for example, a COB type light emitting diode) is preferably used in the light emitting device 200 according to this embodiment. The size of the light emitting element 220 is not particularly limited, but is preferably 0.1 mm to 1.0 mm, and more preferably 0.2 mm to 0.7 mm. The substrate 210 is a rectangular substrate with the long side in the X direction and the short side shorter than Py, and a plurality of light emitting devices 220 are arranged on the substrate 210 in the X direction. In this way, a plurality of substrates 210 with the long side in the X direction are arranged at a distance in the Y direction. Alternatively, a plurality of substrates 210 with the long side in the Y direction may be arranged at a distance in the X direction.

[0016] (Light flux control member) Light flux controlling member 300 is an optical member that controls the light distribution of light emitted from light emitting element 220, and is fixed on substrate 210. Light flux controlling member 300 has an incident surface, two reflecting surfaces, and two first exit surfaces. Here, the incident surface is the inner surface of a recess arranged on the back side of light flux controlling member 300 so as to intersect with optical axis OA of light emitting element 220. The two reflecting surfaces are arranged on the front side of light flux controlling member 300, and reflect at least a part of the light incident on the incident surface in two directions that are substantially perpendicular to the optical axis of light emitting element 220 and are mainly substantially opposite to each other. The two directions are along the Y direction. The two first exit surfaces are arranged to face each other with the two reflecting surfaces in between, and emit the light reflected by the two reflecting surfaces and another part of the light incident on the incident surface to the outside.

[0017] As will be described later, light flux controlling member 300 has an incident surface, and is disposed on light emitting element 220 such that central axis CA of the incident surface coincides with optical axis LA of each light emitting element 220. Note that "optical axis OA of light emitting element 220" means the central light ray of the three-dimensional emitted light flux from light emitting element 220. Between substrate 210 on which light emitting element 220 is mounted and the back surface of light flux controlling member 300, a gap for releasing heat generated from light emitting element 220 to the outside may or may not be formed.

[0018] Light flux controlling member 300 is formed by integral molding. The material of light flux controlling member 300 is not particularly limited as long as it is a material that can transmit light of a desired wavelength. For example, the material of light flux controlling member 300 is a light-transmitting resin such as polymethylmethacrylate (PMMA), polycarbonate (PC), epoxy resin (EP), polystyrene (PS), styrene-methyl methacrylate copolymer resin (MS), silicone, or glass.

[0019] The specific configuration of light flux controlling member 300 will be described in detail separately.

[0020] The light diffusion plate 120 is a plate-like member having light diffusion properties, and transmits the light emitted from the light emitting device 200 while diffusing it. Usually, the light diffusion plate 120 is approximately the same size as a display member such as a liquid crystal panel. For example, the light diffusion plate 120 is formed of a light-transmitting resin such as polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), or styrene-methyl methacrylate copolymer resin (MS). To impart light diffusion properties, fine irregularities are formed on the surface of the light diffusion plate 120, or light diffusers such as beads are dispersed inside the light diffusion plate 120.

[0021] In surface light source device 100 according to the present embodiment, light emitted from each light emitting element 220 is spread by light flux controlling member 300 so as to illuminate a wide range of light diffusion plate 120. The light emitted from each light flux controlling member 300 is further diffused by light diffusion plate 120. Most of the light reaching light diffusion plate 120 is transmitted through light diffusion plate 120, but a part of the light is reflected by light diffusion plate 120. Most of the light reflected by light diffusion plate 120 is reflected by the inner surface of bottom plate 112 or substrate 210, which functions as a diffuse reflection surface, and directed again toward light diffusion plate 120. A part of the light reflected by light diffusion plate 120 is reflected by the front surface or rear surface of light flux controlling member 300 and directed again toward light diffusion plate 120. As a result, surface light source device 100 according to the present embodiment can uniformly illuminate a planar display member (for example, a liquid crystal panel). It is preferable that a reflective member (reflective sheet) is disposed on bottom plate 112 of surface light source device 100.

[0022] In the above-described surface light source device 100, from the viewpoint of suppressing deterioration in the quality of the image of the display device 100', when the surface of the light diffusion plate 120 that faces the light emitting device 200 when the surface light source device 100 is seen through a plane is divided into small rectangles as shown below, it is preferable that a predetermined light ray from the light emitting element 220 reaches each small rectangle as follows. Below, first, the division into small rectangles will be described, then the predetermined light ray will be described, and finally the arrival of the predetermined light ray at the small rectangle will be described. Note that the planar perspective refers to the appearance when the surface light source device 100 is seen through a plane, assuming that it is transparent.

[0023] (Dividing into smaller rectangles) The division into small rectangles will be described with reference to Figs. 2A and 2B. As shown in Fig. 2A, first, a line connecting the light emitting center of the light emitting element 220 of any one of the light emitting devices 200 arranged in the X direction to the light emitting center of the light emitting element 220 of the light emitting device 200 adjacent to the light emitting device 200 in the X direction is defined as Px, and a line connecting the light emitting center of the light emitting element 220 of the light emitting device 200 to the light emitting center of the light emitting element 220 of the light emitting device 200 adjacent to the light emitting device 200 in the Y direction is defined as Py, and a rectangle with Px and Py as sides is assumed. Note that Py is preferably longer than Px. Specifically, for example, Py is 40 mm and Px is 14 mm. Next, as shown in FIG. 2B, the rectangle is divided into four equal parts in the X direction and four equal parts in the Y direction, resulting in a total of 16 small rectangles of equal area. Next, of the 16 small rectangles, the four small rectangles closest to Px and lined up in the X direction are named X0Y0, X1Y0, X2Y0, and X3Y0 in order of distance from Py, the four small rectangles second closest to Px and lined up in the X direction are named X0Y1, X1Y1, X2Y1, and X3Y1 in order of distance from Py, the four small rectangles third closest to Px and lined up in the X direction are named X0Y2, X1Y2, X2Y2, and X3Y2 in order of distance from Py, and the four small rectangles fourth closest to Px and lined up in the X direction are named X0Y3, X1Y3, X2Y3, and X3Y3 in order of distance from Py. As shown in Figures 2A and 2B, there are four rectangles with sides Px and Py, and the upper right rectangle is the first quadrant rectangle, the upper left rectangle is the second quadrant rectangle, the lower left rectangle is the third quadrant rectangle, and the lower right rectangle is the fourth quadrant rectangle.

[0024] (Specified light beam) Fig. 3A is a diagram for explaining the predetermined light ray. The predetermined light ray is, among the light emitted from the light emitting center O of the light emitting element 220, a light ray approximately along the optical axis OA of the light emitting element 220 as shown in Fig. 3A, and a light ray emitted from the light emitting element 220 at the following angle. That is, as shown in Fig. 3A, the angle with respect to the optical axis OA is α, and the angle with respect to Py when the light ray emitted along the conical wall of the virtual cone formed with the apex angle 2α with the emission point of the light of the light emitting element 220 as the apex is projected onto a plane including Px and Py is γ, the light ray is emitted along the conical wall of 30 virtual cones formed by changing α by 1° within 1°≦α≦30°, and there are a total of 2731 light rays including the light ray of γ=0.001°, the light ray obtained by changing γ by 1° within 1°≦γ≦89°, and the light ray of γ=89.999°. It should be noted that the light ray approximately along the optical axis OA of the light emitting element 220 is a light ray with α of 0.0005° and γ of 0.001°. Moreover, the light beam of γ=0° and the light beam of γ=90° are not included in the predetermined light beam. The reason for this will be explained. The light flux controlling member that can be used in the present invention may have a pair of optical surfaces that include the above Px or Py and are symmetrical with respect to a plane perpendicular to the above rectangle. Here, if the light beam of γ=0° and the light beam of γ=90° are included in the predetermined light beam, these light beams may reach between the pair of optical surfaces or between the entrance surface and the back surface. In this way, the light that reaches between a certain surface and another surface may be separated in the simulation, resulting in inappropriate light. Therefore, the light beam of γ=0° and the light beam of γ=90° are not included in the predetermined light beam.

[0025] (A given ray reaches each small rectangle) In this embodiment, the arrival of a predetermined light ray at the small rectangles divided as described above satisfies the following condition 1. It is also preferable that conditions 2 to 4 are satisfied. <Condition 1> When the proportion of the number of light rays that reach X0Y1 is 100, the proportion of light rays that reach X0Y2, X1Y1, and X1Y2 is 30 or more. <Condition 2> If the ratio of the 2731 rays above is 100, then the ratio of the number of rays that reach X0Y1 is 80 or less. <Condition 3> The number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1 is greater than or equal to the number of light rays whose α is in the range of 21° to 30° that reach X0Y2 and X1Y1, the number of light rays whose α is in the range of 11° to 20° that reach X0Y2 and X1Y1 is greater than or equal to the number of light rays whose α is in the range of 1° to 10° that reach X0Y2 and X1Y1, the number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is greater than or equal to the number of light rays whose α is in the range of 11° to 20° that reach X1Y2, and the number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is greater than or equal to the number of light rays whose α is in the range of 1° to 10° that reach X1Y2. By allowing the light rays to reach the display device so as to satisfy the above conditions 1 to 3, degradation in image quality can be suppressed. <Condition 4> It is preferable that the number of light rays that are approximately along the optical axis and whose α is in the range of 1° to 10° that reach X0Y1 is greater than or equal to the number of light rays that reach X0Y1 whose α is in the range of 11° to 20°, and the number of light rays that are approximately along the optical axis and whose α is in the range of 1° to 10° that reach X0Y1 is greater than or equal to the number of light rays that reach X0Y1 whose α is in the range of 21° to 30°. It is preferable to satisfy the above condition 4.

[0026] It is preferable that the above conditions are satisfied for all of the rectangles in the first quadrant, the second quadrant, the third quadrant, and the fourth quadrant.

[0027] Figure 3B shows the state of light emission from a surface light source device that satisfies condition 1, and Figure 3C shows the state of light emission from a surface light source device that does not satisfy condition 1. The black dots in Figures 3B and 3C indicate the positions of the light-emitting elements. It can be seen that there is little unevenness in brightness in Figure 3B, which satisfies condition 1. On the other hand, in Figure 3C, which does not satisfy condition 1, light and dark areas occur along the rows due to the light-emitting elements (light-emitting devices) being lined up in rows.

[0028] <Configuration of Light Flux Control Member> 4A to 4F show light flux controlling member 400 (one specific example of light flux controlling member 300) according to embodiment 1 that can be used to cause predetermined light rays to reach each small rectangle as described above. The configuration of light flux controlling member 400 will be described below.

[0029] Fig. 4A is a perspective view of light flux controlling member 400 according to embodiment 1 as seen from the front side, Fig. 4B is a perspective view as seen from the back side, Fig. 4C is a plan view, Fig. 4D is a bottom view, Fig. 4E is a front view, and Fig. 4F is a side view. The configuration of light flux controlling member 400 will be described assuming that light flux controlling member 400 is placed in a coordinate system having an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. Specifically, light flux controlling member 400 has an axis of rotational symmetry (axis of two-fold symmetry), but the explanation will be given assuming that the axis of rotational symmetry (axis of two-fold symmetry) coincides with the Z-axis, the back side of light flux controlling member 400 is placed on the XY plane, and first emission surface 430, which will be described later, is disposed perpendicular to the Y-axis. When arranging light flux controlling member 400 in surface light source device 100, it is preferable that the X axis coincides with the above-mentioned X direction, and the Y axis coincides with the above-mentioned Y direction. Here, "coincidence" does not necessarily mean perfect coincidence, but also includes approximate coincidence within the range of installation accuracy of light flux controlling member 400.

[0030] 4A to 4F, light flux controlling member 400 has incident surface 410, reflecting surface 420, and first emission surface 430. Incident surface 410 is the inner surface of a recess arranged on the back side so as to intersect with the optical axis of light emitting element 220, and allows light emitted from light emitting element 220 to enter. There are two reflective surfaces 420 in light flux controlling member 400. The two reflective surfaces are arranged on the front side of light flux controlling member 400, and reflect at least a portion of the light incident on incident surface 410, respectively, in two directions that are approximately perpendicular to optical axis OA of light emitting element 220 and that are mainly approximately opposite to each other. These two directions are along the Y direction (Y axis). There are two first emission surfaces 430 in light flux controlling member 400. First emission surfaces 430 are arranged to face each other with two reflecting surfaces 420 in between, and emit to the outside the light reflected by the two reflecting surfaces 420 and another part of the light incident on incident surface 410. Each of these will be explained in more detail below.

[0031] <Incidence surface> In this embodiment, the incident surface 410 has a shape corresponding to the inner surface of a substantially semi-cylinder shape, as shown in Figs. 4B and 4D. The axis of the semi-cylinder extends in the direction of the Y axis. As shown in Fig. 4D, the incident surface 410 has two first incident surfaces 411 and two second incident surfaces 412 corresponding to the side surfaces of the substantially semi-cylinder, and two third incident surfaces 413 corresponding to the top and bottom surfaces of the semi-cylinder. In the incident surface 410, the first incident surface 411 is disposed at a position closer to the XZ plane than the second incident surface 412. On the other hand, the second incident surface 412 is disposed at a position farther from the XZ plane than the first incident surface 411. In this embodiment, the first incident surface 411 and the second incident surface 412 are continuous. The first incident surface 411 has a tapered shape such that the diameter of the semicylinder becomes smaller as it moves away from the XZ plane. That is, the first incident surface 411 has an inclined surface that inclines toward the Y axis as it moves away from the XZ plane. On the other hand, the diameter of the semicylinder of the second incident surface 412 is constant even when it moves away from the XZ plane. That is, the second incident surface 412 has a surface parallel to the Y axis. The third incident surface 413 has a semicircular shape arranged approximately perpendicular to the Y axis. The first incident surfaces 411 are arranged in a pair, one on each side of the XZ plane. Similarly, the second incident surfaces 412 are arranged in a pair, one on each side of the XZ plane. Similarly, the third incident surfaces 413 are arranged in a pair, one on each side of the XZ plane.

[0032] <Reflective surface> It is preferable that the reflecting surface 420 is configured to reflect at least a part of the light emitted from the light emitting center of the light emitting element and incident on the incident surface 410. As shown in Fig. 4C and F, the reflecting surface 420 has a curved surface like a series of semicircles whose diameters gradually increase with increasing distance from the XZ plane. That is, in this embodiment, the reflecting surface 420 is a curved surface whose tangent is inclined so that the inclination approaches parallel to the Y axis as the tangent moves away from the XZ plane. The reflecting surfaces 420 are arranged in a pair, with one on either side of the XZ plane.

[0033] <First exit surface> As shown in Fig. 4E, first emission surface 430 has a semicircular shape. First emission surface 430 has vertical emission surface 431 perpendicular to the Y axis, and inclined emission surface 432 inclined with respect to the Y axis. In this embodiment, inclined emission surface 432 is inclined so as to be recessed from vertical virtual plane V (see Fig. 4C) perpendicular to the Y axis and including vertical emission surface 431, and is a flat surface.

[0034] Specifically, as shown in FIG. 4C, the inclined emission surface 432 is inclined so as to approach the vertical virtual plane V as it advances in the X direction, and is inclined so as to move away from the vertical virtual plane V as it advances in the Z direction. By inclining the inclined emission surface 432 so as to approach the vertical virtual plane V as it advances in the X direction, it is possible to refract the light beam so as to move away from the Y axis to the X axis direction and emit the light beam. In addition, by inclining the inclined emission surface 432 so as to move away from the vertical virtual plane V as it advances in the Z direction, it is possible to refract the light beam so as to move away from the Y axis to the Z axis direction and emit the light beam. Note that the inclined emission surfaces 432 are present on either side of the YZ plane, and the two inclined emission surfaces 432 are continuous. In addition, the inclined emission surfaces 432 are present on either side of the XZ plane, forming a pair. The inclined emission surfaces 432 contribute to reducing the number of light beams directed toward X0Y1 and increasing the number of light beams directed toward X1Y1, etc.

[0035] Two inclined emission surfaces 432 that are continuous with each other across the YZ plane are fan-shaped when viewed from the direction along the Y axis as shown in Fig. 4E. The two inclined emission surfaces 432 are disposed from the highest position of first emission surface 430 in the Z direction to a position that is about half the height from the highest position of first emission surface 430. The length of the fan-shaped curved portion of the two inclined emission surfaces 432 is about one-fourth the length of the curved portion of first emission surface 430.

[0036] [Embodiment 2] The surface light source device, display device, and light flux controlling member according to embodiment 2 differ from those of embodiment 1 mainly in the configuration of the light flux controlling member. Therefore, the following description of the configuration of light flux controlling member 500 according to embodiment 2 will focus on the differences from light flux controlling member 400 according to embodiment 1, and similar configurations will be denoted by similar reference numerals and descriptions thereof will be omitted.

[0037] FIG. 5A is a perspective view of light flux controlling member 500 according to embodiment 2 seen from the front side, FIG. 5B is a perspective view seen from the back side, FIG. 5C is a plan view, FIG. 5D is a bottom view, FIG. 5E is a front view, and FIG. 5F is a side view.

[0038] Light flux controlling member 500 differs from light flux controlling member 400 of embodiment 1 mainly in the configuration of first emission surface 530. Specifically, of first emission surface 530, the configuration of vertical emission surface 531 differs from the configuration of vertical emission surface 431 of light flux controlling member 400. Accordingly, in light flux controlling member 500, the configuration of reflecting surface 520 connected to first emission surface 530 differs from the configuration of reflecting surface 420 of light flux controlling member 400. These differences will be described below.

[0039] As shown in FIG. 5E, vertical exit surface 531 differs from vertical exit surface 431 in that, when viewed from the Y-axis direction, it has a shape that is longer in the X-axis direction (a substantially semi-elliptical shape that is longer in the X-axis direction) (see FIG. 4E). 5C and 5D, the reflecting surface 520 has a shape of successive semicircles whose diameter gradually increases as it moves away from the XZ plane, similar to the reflecting surface 420, but the diameter gradually increases in the X direction rather than in the Y direction (see comparison of FIGS. 4C and 4D). Therefore, the cross section of the reflecting surface 520 perpendicular to the Y axis is an approximately semi-elliptical shape that becomes longer in the X axis direction as it moves away from the XZ plane. Such a perpendicular exit surface 531 and reflecting surface 520 contribute to reducing the number of rays heading toward X0Y1 and increasing the number of rays heading toward X1Y1, etc.

[0040] [Embodiment 3] The surface light source device, display device, and light flux controlling member according to embodiment 3 differ from those of embodiment 2 mainly in the configuration of the light flux controlling member. Therefore, the following description of the configuration of light flux controlling member 600 according to embodiment 3 will focus on the differences from light flux controlling member 500 according to embodiment 2, and similar configurations will be denoted by similar reference numerals and descriptions thereof will be omitted.

[0041] FIG. 6A is a perspective view of light flux controlling member 600 in accordance with embodiment 3 as seen from the front side, FIG. 6B is a perspective view as seen from the back side, FIG. 6C is a plan view, FIG. 6D is a bottom view, FIG. 6E is a front view, and FIG. 6F is a side view.

[0042] Light flux controlling member 600 differs from incident surface 410 of embodiment 2 mainly in the configuration of incident surface 610. Specifically, as shown in Fig. 6D, incident surface 610 has first incident surface 411 like incident surface 410, but does not have second incident surface 412 and third incident surface 413, and instead has fourth incident surface 614. Fourth incident surface 614 will be described below.

[0043] As shown in FIGS. 6B and 6D, fourth incidence surface 614 is disposed at a position farther from the XZ plane than first incidence surface 411. Fourth incidence surface 614 has inclined incidence surface 614a that is inclined so as to approach the Y axis as it moves away from the XZ plane. In the present embodiment, inclined incidence surface 614a is parallel to the Z axis. Since light flux controlling member 600 has such inclined incidence surface 614a, light that has entered inclined incidence surface 614a along the Y axis can be refracted in the direction of the X axis and entered. Inclined incidence surfaces 614a are present on either side of the YZ plane, and two inclined incidence surfaces 614a are continuous. In addition, a pair of inclined incidence surfaces 614a are present on either side of the XZ plane. Inclined incidence surface 614a contributes to reducing the number of light rays heading toward X0Y1 and increasing the number of light rays heading toward X1Y1 and the like.

[0044] [Embodiment 4] The surface light source device, display device, and light flux controlling member according to embodiment 4 differ from those of embodiments 2 and 3 mainly in the configuration of the light flux controlling member. Therefore, the following description of the configuration of light flux controlling member 700 according to embodiment 4 will focus on the differences from light flux controlling member 500 according to embodiment 2, and similar configurations will be denoted by similar reference numerals and descriptions thereof will be omitted.

[0045] FIG. 7A is a perspective view of light flux controlling member 700 according to embodiment 4 seen from the front side, FIG. 7B is a perspective view seen from the back side, FIG. 7C is a plan view, FIG. 7D is a bottom view, FIG. 7E is a front view, and FIG. 7F is a side view.

[0046] Light flux controlling member 700 differs from embodiments 2 and 3 mainly in that it has second exit surface 740 that directly emits a portion of light incident from the entrance surface. Second exit surface 740 is a surface disposed at a portion of the connection portion of two reflecting surfaces 520. Specifically, in the present embodiment, when viewed along the X-axis as shown in FIG. 7F, second exit surface 740 extends from the lowest portion of the connection portion of two reflecting surfaces 520 to a height that is approximately half the height of the highest position of light flux controlling member 700. The presence of second exit surface 740 can reduce the light reflected by reflecting surface 520 and also reduce the light emitted from first exit surface 730. The light emitted from second exit surface 740 is mainly emitted in the direction of the X-axis. Second exit surface 740 exists on either side of the YZ plane.

[0047] Furthermore, similarly to the second and third embodiments, light flux controlling member 700 has inclined emission surfaces 732 that are inclined so as to approach vertical imaginary plane V as they proceed in the X direction and are inclined so as to move away from vertical imaginary plane V as they proceed in the Z direction. In addition, inclined emission surfaces 732 are present in a pair, one on each side of the YZ plane. In addition, the two inclined emission surfaces 732 are continuous. However, the two continuous inclined emission surfaces 732 are disposed from a position slightly below the highest position in the Z direction of first emission surface 730 to a position approximately half the height from the highest position of first emission surface 730, as shown in FIG.

[0048] Also, light flux controlling member 700 has first entrance surface 711 having a tapered shape such that the diameter of the semicylinder decreases with increasing distance from the XZ plane, as in the second embodiment. Also, light flux controlling member 700 has second entrance surface 712 having a shape in which the diameter of the semicylinder is constant even with increasing distance from the XZ plane. However, as shown in FIG. 7D, first entrance surface 711 and second entrance surface 712 are smoothly connected (compare FIG. 5D).

[0049] [Embodiment 5] The surface light source device, display device, and light flux controlling member according to embodiment 5 differ from those of embodiment 4 mainly in the configuration of the light flux controlling member. Therefore, the following description of the configuration of light flux controlling member 800 according to embodiment 5 will focus on the differences from light flux controlling member 700 of embodiment 4, and similar configurations will be denoted by similar reference numerals and descriptions thereof will be omitted.

[0050] FIG. 8A is a perspective view of light flux controlling member 800 according to embodiment 5 as seen from the front side, FIG. 8B is a perspective view as seen from the back side, FIG. 8C is a plan view, FIG. 8D is a bottom view, FIG. 8E is a front view, and FIG. 8F is a side view.

[0051] As shown in Fig. 8D, light flux controlling member 800 differs from embodiment 4 in that it has fourth incident surface 814 having inclined incident surface 614a similar to embodiment 3, instead of second incident surface 712 and third incident surface 413 (compare Fig. 7D). Also, as shown in Fig. 8F, light flux controlling member 800 has second exit surface 840 whose shape differs from second exit surface 740 of embodiment 4 (compare Fig. 7F). Like second exit surface 740, second exit surface 840 extends from the bottom of the connection portion between the two reflecting surfaces to a height that is approximately half the height of the highest position of light flux controlling member 800.

[0052] [Embodiment 6] The surface light source device, display device, and light flux controlling member according to embodiment 6 differ from those of embodiment 5 mainly in the configuration of the light flux controlling member. Therefore, the following description of the configuration of light flux controlling member 900 according to embodiment 6 will focus on the differences from light flux controlling member 800 of embodiment 5, and similar configurations will be denoted by similar reference numerals and descriptions thereof will be omitted.

[0053] FIG. 9A is a perspective view of light flux controlling member 900 according to embodiment 6 seen from the front side, FIG. 9B is a perspective view seen from the back side, FIG. 9C is a plan view, FIG. 9D is a bottom view, FIG. 9E is a front view, and FIG. 9F is a side view.

[0054] Light flux controlling member 900 differs from embodiment 1 in that it has fourth entrance surface 814 having inclined entrance surface 614a, similar to embodiment 5. Also, light flux controlling member 900 has reflecting surface 920, which has a curved surface like a continuous semi-ellipse whose diameter gradually increases with increasing distance from the XZ plane, similar to the second embodiment. Furthermore, light flux controlling member 900 has a shape of first emission surface 930 which differs from first emission surface 730 of embodiment 5. Specifically, first emission surface 930 has vertical emission surface 931 perpendicular to the Y axis, two first inclined emission surfaces 932, and second inclined emission surface 933 sandwiched between the two first inclined emission surfaces 932.

[0055] 9C, first inclined emission surface 932 is inclined so as to approach vertical imaginary plane V as it progresses in the X-axis direction, and is inclined so as to move away from vertical imaginary plane V as it progresses in the Z direction. On the other hand, second inclined emission surface 933 is parallel to the X-axis, but is inclined so as to move away from vertical imaginary plane V as it progresses in the Z direction. The first inclined emission surface 932 can refract the light beam in the X and Z directions, while the second inclined emission surface 933 can refract the light beam in the Z direction.

[0056] Light flux controlling member 900 differs from embodiment 5 in that it has third inclined emission surface 934 as shown in Fig. 9E. As shown in Fig. 9E, third inclined emission surface 934 is an inclined surface arranged at each end in the X direction when light flux controlling member 900 is viewed from the direction along the Y axis. Third inclined emission surface 934 inclines so as to approach the Y axis as it moves away from the XZ plane. Third inclined emission surface 934 refracts a light ray so as to approach the Y axis.

[0057] [simulation] A simulation was performed on the distribution of light rays using light flux controlling members according to the above-mentioned embodiments 1 to 6 and a comparative example. As the light flux controlling member of the comparative example, light flux controlling member 1000 shown in Figures 10A to 10F was used. Figure 10A is a perspective view of light flux controlling member 1000 seen from the front side, Figure 10B is a perspective view seen from the back side, Figure 10C is a plan view, Figure 10D is a bottom view, Figure 10E is a front view, and Figure 10F is a side view.

[0058] Light flux controlling member 1000 differs from light flux controlling member 400 of embodiment 1 in that first emission surface 1030 has only vertical emission surface 1031 perpendicular to the Y axis, and does not have an inclined emission surface. Furthermore, in light flux controlling member 1000, configurations similar to those of light flux controlling member 400 are given similar reference numerals and descriptions thereof will be omitted.

[0059] Specifically, the simulation was carried out by using the light flux controlling members of the above-mentioned embodiments 1 to 6 and the comparative example to investigate whether each of the above-mentioned conditions 1 to 4 was satisfied. In the simulation, it was assumed that the light flux controlling member was disposed above the light emitting element so that the optical axis of the light emitting element and the two-fold symmetry axis of the light flux controlling member coincided. It was also assumed that the light flux controlling member was disposed so that the perpendicular emission surface of the first emission surface was perpendicular to Py.

[0060] (Simulation for condition 1) Figures 11A to 11G correspond to light distributions when light flux controlling members according to Embodiments 1 to 6 and the comparative example are used, and show simulation results of whether or not Condition 1 is satisfied. In Figures 11A to 11G, the numbers shown under the names of the small rectangles indicate the proportion of light rays that reach each small rectangle, when the proportion of light rays that reach X0Y1 is taken as 100.

[0061] 11A-F, when the ratio of the number of light rays reaching X0Y1 is taken as 100, when the light flux controlling members according to embodiments 1-6 were used, the ratios of the number of light rays reaching X0Y2, X1Y1, and X1Y2 were 30 or more, satisfying condition 1. In contrast, when the light flux controlling member according to the comparative example was used, as shown in FIG.

[0062] (Simulation for condition 2) Figures 12A to 12G correspond to light distributions when light flux controlling members according to Embodiments 1 to 6 and the comparative example are used, and show simulation results as to whether or not Condition 2 is satisfied. In Figures 12A to 12G, the numbers shown under the names of the small rectangles indicate the proportion of light rays that reach each small rectangle, assuming that the proportion of the above 2731 light rays is 100.

[0063] 12A-F, when the light flux controlling members according to embodiments 1-6 were used, the proportion of the number of light rays that reach X0Y1 was 80 or less, satisfying condition 2. In contrast, when the light flux controlling member according to the comparative example was used, as shown in FIG. 12G, condition 2 was not satisfied.

[0064] (Simulation for conditions 3 and 4) 13A-C, 13D-F, 14A-C, 14D-F, 15A-C, 15D-F, and 16A-C correspond to light distributions when the light flux controlling members of embodiments 1-6 and the comparative example are used, and show simulation results of whether or not condition 3 is satisfied. In Figures 13A, 13D, 14A, 14D, 15A, 15D, and 16A, the numbers shown under the names of the small rectangles indicate the number of light rays that are approximately along the optical axis and light rays with α in the range of 1° to 10° that reach each small rectangle. In Figures 13B, 13E, 14B, 14E, 15B, 15E, and 16B, the numbers shown under the names of the small rectangles indicate the number of light rays with α in the range of 11° to 20° that reach each small rectangle. In Figures 13C, 13F, 14C, 14F, 15C, 15F, and 16C, the numbers shown under the names of the small rectangles indicate the number of light rays with α in the range of 21° to 30° that reach each small rectangle.

[0065] As shown in FIGS. 13A-C, 13D-F, 14A-C, 14D-F, 15A-C, and 15D-F, when the light flux controlling members according to embodiments 1-6 were used, the number of light rays where α is in the range of 11° to 20° that reach X0Y2 and X1Y1 was greater than the number of light rays where α is in the range of 21° to 30° that reach X0Y2 and X1Y1. In addition, the number of light rays with α in the range of 11° to 20° that reach X0Y2 and X1Y1 was greater than the number of light rays approximately along the optical axis and light rays with α in the range of 1° to 10° that reach X0Y2 and X1Y1. Furthermore, the number of light rays with α in the range of 21° to 30° that reach X1Y2 was greater than or equal to the number of light rays with α in the range of 11° to 20° that reach X1Y2. Furthermore, the number of light rays with α in the range of 21° to 30° that reach X1Y2 was greater than the number of light rays approximately along the optical axis and light rays with α in the range of 1° to 10° that reach X1Y2. That is, when the light flux controlling members according to any one of embodiments 1 to 6 were used, condition 3 was satisfied. In contrast, it was clear from Figures 16A to 16C that when the light flux controlling member of the comparative example was used, condition 3 was not satisfied.

[0066] 13A-C, 13D-F, 14A-C, 14D-F, 15A-C, and 15D-F, when the light flux controlling members according to embodiments 1 to 6 were used, the number of light rays substantially along the optical axis and light rays whose α is in the range of 1° to 10° that reach X0Y1 was equal to or greater than the number of light rays whose α is in the range of 11° to 20° that reach X0Y1, and the number of light rays substantially along the optical axis and light rays whose α is in the range of 1° to 10° that reach X0Y1 was equal to or greater than the number of light rays whose α is in the range of 21° to 30° that reach X0Y1, thereby satisfying condition 4. Moreover, as can be seen from FIGS. 16A-C, when the light flux controlling members of the comparative example were used, condition 4 was also satisfied.

[0067] [Regarding light rays other than those specified] As described above, the present invention only considers the distribution of light rays approximately along the optical axis and light rays with α between 1° and 30°, and does not consider the distribution of light rays with α between 31° and 90°. Also, only the light emitted from the light-emitting center of the light-emitting element is considered, and light emitted from other than the light-emitting center is not considered. However, in the present invention, if a specific light ray satisfies the above conditions, there is no need to consider light rays other than the specific light ray, and deterioration of image quality can be suppressed. This will be explained below.

[0068] 17A to 17C and 17D to 17F show the proportions of the above-mentioned specified light rays (the above-mentioned 2731 light rays) and light rays other than the specified light rays that reach the 16 small rectangles, using the light flux controlling members of the comparative example and embodiment 2, respectively, where α is the angle with respect to the optical axis, γ is the angle with respect to Py when the light rays emitted along the conical walls of 90 virtual cones formed by changing α by 1° within 1°≦α≦90°, and γ is the angle with respect to Py when the light rays emitted along the conical walls of 90 virtual cones formed by changing α by 1° within 1°≦α≦90°, and γ=89.999° is the proportion of a total of 8191 light rays, which is the sum of the light rays of γ=0.001°, the light rays obtained by changing γ by 1° within 1°≦γ≦89°, and the light rays of γ=89.999°. Specifically, FIG. 17A shows the proportion of light rays that reach the target when a comparative example light flux controlling member is used, FIG. 17B shows the proportion of light rays that reach the target when α is in the range of 31° to 60°, and FIG. 17C shows the proportion of light rays that reach the target when α is in the range of 61° to 90°. Similarly, FIG. 17D shows the proportion of light rays that reach the light beam when a light flux controlling member of embodiment 2 is used, FIG. 17E shows the proportion of light rays that reach the light beam when α is in the range of 31° to 60°, and FIG. 17F shows the proportion of light rays that reach the light beam when α is in the range of 61° to 90°.

[0069] Here, it is believed that the degradation of image quality is mainly due to the concentration of light rays at X0Y1. As can be seen from FIGS. 17A to 17C of the comparative example, the majority of the light emitted from the light emitting element that reaches X0Y1 is a predetermined light ray. Also, as can be seen from FIGS. 17D to 17F of the embodiment, in the embodiment, the predetermined light that reaches X0Y1 is reduced, and degradation of image quality can be suppressed. For this reason, it can be seen that degradation of image quality can be sufficiently suppressed by considering only the predetermined light ray.

[0070] Figures 18A to 18E show the light distribution from a region including the light emitting center of a light emitting element and the light distribution from other regions when using a light flux controlling member of a comparative example. Specifically, in each of Figures 18A to 18E, the square on the left side indicates, by hatching, the region of the light emitting surface of the light emitting element from which light is emitted. That is, Figure 18A shows the light distribution when light is emitted from the entire light emitting surface of the light emitting element, Figure 18B shows the light distribution when light is emitted from a central region including the light emitting center of the light emitting surface, and Figures 18C to 18E show the light distribution when light is emitted from each peripheral region surrounding that region.

[0071] 19A to 19E similarly show the light distribution in a region including the light emitting center of a light emitting element and the light distribution from other regions, using a light flux controlling member according to the second embodiment.

[0072] As can be seen from FIGS. 18A to 18E, the light distribution from the region including the light emitting center is similar to the light distribution from the other regions. Similarly, as can be seen from Figures 19A to 19E, the light distribution from the region including the light-emitting center is similar to the light distribution from the other regions. That is, the light from the central region including the light-emitting center in Figure 19B is distributed so as to be spread in the left-right direction (X direction) (see comparison with Figure 18B). Similarly, the light from the other regions in Figures 19C to 19E is distributed so as to be spread in the left-right direction (see comparison with Figures 18C to 18E). For this reason, it can be seen that the deterioration of image quality can be sufficiently suppressed by considering only the light rays from the light-emitting center.

[0073] (effect) According to the embodiments of the present invention, it is possible to provide a surface light source device, a display device, and a light flux controlling member that are capable of suppressing degradation in image quality. [Industrial Applicability]

[0074] The surface light source device of the present invention can be used, for example, as a backlight for a liquid crystal display device or as general lighting. [Explanation of symbols]

[0075] 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 300, 400, 500, 600, 700, 800, 900, 1000 Light flux control member 410, 610, 710, 810, entrance plane 411, 711 1st entrance plane 412, 712 2nd entrance plane 413 3rd entrance plane 420, 520, 920 reflective surface 430, 530, 730, 1030 First exit surface 431, 531, 931, 1031 Vertical exit surface 432, 732 Inclined exit surface 614, 814 4th entrance plane 614a Inclined entrance surface 740, 840 Second exit surface 932 1st inclined exit surface 933 Second inclined exit surface 934 Third inclined exit surface

Claims

1. A surface light source device comprising: a plurality of light emitting devices arranged in a row in an X direction and a Y direction perpendicular to the X direction; and a light diffusion plate through which light from the plurality of light emitting devices reaches; each of the plurality of light emitting devices has a light emitting element and a light flux control member for controlling light from the light emitting element, The light flux controlling member is an inner surface of a recess disposed on the back side so as to intersect with an optical axis of the light-emitting element, the inner surface being an incident surface through which light emitted from the light-emitting element is incident; two reflecting surfaces arranged on a front side and reflecting at least a part of the light incident on the incident surface in two directions that are substantially perpendicular to an optical axis of the light emitting element and are mainly substantially opposite to each other, the two directions being along the Y direction; two first exit surfaces arranged to face each other with the two reflecting surfaces therebetween, and configured to emit to the outside the light reflected by the two reflecting surfaces and another part of the light incident on the incident surface, having On a surface of the light diffusion plate that faces the light emitting device when the surface light source device is seen through a plane, and through which light from the light emitting device reaches, A line connecting a light emitting center of a light emitting element of any one of the plurality of light emitting devices arranged in the X direction and a light emitting center of a light emitting element of a light emitting device adjacent to the light emitting device in the X direction is defined as Px, a line connecting the light emitting center of the light emitting element of the arbitrary one light emitting device and the light emitting center of the light emitting element of the light emitting device adjacent to the light emitting device in the Y direction is defined as Py; Divide the rectangle having sides Px and Py into four equal parts in the X direction and into four equal parts in the Y direction to divide it into a total of 16 small rectangles having equal areas; The four small rectangles arranged in the X direction at the positions closest to Px are designated as X0Y0, X1Y0, X2Y0, and X3Y0 in order of distance from Py, The four small rectangles arranged in the X direction at the second closest position to Px are designated as X0Y1, X1Y1, X2Y1, and X3Y1 in order of distance from Py, The four small rectangles arranged in the X direction at the third closest position to Px are designated as X0Y2, X1Y2, X2Y2, and X3Y2 in order of distance from Py, When the four small rectangles arranged in the X direction at the position fourth closest to Px are denoted as X0Y3, X1Y3, X2Y3, and X3Y3 in order of distance from Py, Among the light rays emitted from the light emitting center of the light emitting element, A light ray substantially along an optical axis of the light emitting element; The angle with respect to the optical axis is defined as α, and the angle with respect to Py when a light ray emitted along a cone wall of a virtual cone formed with an apex angle of 2α with the emission point of the light from the light emitting element as the apex is projected onto a plane including Px and Py is defined as γ, A total of 2731 light rays are emitted along the cone walls of the 30 virtual cones formed by changing α by 1° in the range of 1°≦α≦30°, the light rays being a light ray of γ=0.001°, a light ray obtained by changing γ by 1° in the range of 1°≦γ≦89°, and a light ray of γ=89.999°; When I thought about When the ratio of the number of light rays reaching the X0Y1 is 100, the ratio of the number of light rays reaching the X0Y2, the X1Y1, and the X1Y2 is 30 or more. Surface light source device.

2. Considering the 2731 rays, 2 . The surface light source device according to claim 1 , wherein a ratio of the number of light rays reaching X0Y1 is 80 or less when a ratio of the 2731 light rays is taken as 100.

3. Considering the 2731 rays, the number of light rays whose α is in the range of 11° to 20° that reach the X0Y2 and X1Y1 is equal to or greater than the number of light rays whose α is in the range of 21° to 30° that reach the X0Y2 and X1Y1, the number of light rays whose α is in the range of 11° to 20° that reach the X0Y2 and X1Y1 is equal to or greater than the number of light rays that are approximately along the optical axis and the number of light rays whose angle α is in the range of 1° to 10° that reach the X0Y2 and X1Y1, The number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is equal to or greater than the number of light rays whose α is in the range of 11° to 20° that reach X1Y2, The number of light rays whose α is in the range of 21° to 30° that reach X1Y2 is equal to or greater than the number of light rays that are approximately along the optical axis and the number of light rays whose angle α is in the range of 1° to 10° that reach X1Y2. The surface light source device according to claim 1 .

4. The surface light source device according to claim 1 , wherein the Py is longer than the Px.

5. 2. The surface light source device of claim 1, wherein the light flux control member has a second exit surface that directly emits a portion of the light incident from the entrance surface, and the second exit surface is a surface located at a portion of the connection portion of the two reflecting surfaces.

6. A display device comprising the surface light source device according to any one of claims 1 to 5.

7. A light flux controlling member for use in the surface light source device according to any one of claims 1 to 5.

Images