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

Abstract

To provide a light-emitting device capable of easily obtaining excellent contrast between light and dark.SOLUTION: A light-emitting device has a light-emitting element, and a light flux control member for controlling light from the light-emitting element. The light flux control member has an incident surface, a total reflection surface, and an emission surface. In a light distribution curve showing far-field light distribution of the light-emitting device, when an integrated value of a luminous intensity in a range of 0° to 180° is A, and an integrated value of a luminous intensity in a range of 83° to 97° is a1, a1 / A is 0.23 to 0.38.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Surface light source devices used in display devices such as liquid crystal displays are known. The surface light source device has a plurality of light-emitting devices, and light from the plurality of light-emitting devices reaches a light diffusion plate and is diffused to obtain planar light. The surface light source device functions as a surface light source in the liquid crystal display device. 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. 2014 / 0226311 Summary of the Invention [Problem to be solved by the invention]

[0004] Fig. 1A shows a cross-sectional view of the above-described surface light source device 10. As shown in Fig. 1A, the surface light source device 10 has a plurality of light-emitting devices 20 and a light diffusion plate 30. Note that in the cross-sectional view of Fig. 1A, the substrate 31 on which the light-emitting devices 20 are arranged and the light diffusion plate 30 are shown in cross section, but the light-emitting devices 20 are shown in side view. Hatching in the cross section has been omitted. Light-emitting device 20 has light-emitting element 21, which is a light source, and light flux control member (lens) 22, which is a refractive lens for controlling light from light-emitting element 21. The light distribution of light from light-emitting element 21 is controlled by light flux control member 22, and the light reaches and is diffused on light diffusion plate 30, and surface light source device 10 functions as a surface light source.

[0005] In order to reduce costs, it may be necessary to reduce the number of light-emitting devices 20 in such a surface light source device 10. For example, suppose that the middle light-emitting device 20 is removed from three lined-up light-emitting devices 20 as shown in Fig. 1B. This results in a dark area in the portion of the light diffusion plate 30 corresponding to the removed light-emitting device 20.

[0006] Therefore, in order to prevent the occurrence of dark areas, it is conceivable to enlarge light flux controlling member 22, which is a refractive lens, so as to further spread the light. However, doing so would increase the amount of material used for light flux controlling member 22, raising costs. Therefore, the present inventors attempted to use light emitting device 40 having light flux controlling member (reflecting lens) 42, which has total reflection surface 41 as shown in FIG. 1C and which easily spreads light, as the light flux controlling member.

[0007] However, when light flux controlling member 42 having total reflection surface 41 is used, as shown in Fig. 1C , light from light emitting device 40 may reach the top of adjacent light emitting device 40. In this case, for example, in surface light source device 10 of Fig. 1C , when it is desired to express a contrast between light and dark in a display device by turning off light emitting device 40 on the left and turning on light emitting device 40 on the right, appropriate contrast between light and dark may not be obtained. In other words, good local dimming performance may not be achieved.

[0008] An object of the present invention is to provide a light-emitting device that can easily achieve good light-dark contrast in which dark areas on the light-emitting device stand out when the device is turned off, a surface light source device having the light-emitting device, and a display device having the surface light source device. [Means for solving the problem]

[0009] The present invention relates to the following light emitting device, surface light source device, and display device. [1] A light emitting device having a light emitting element and a light flux controlling member for controlling light from the light emitting element, wherein the light flux controlling member has an incident surface, which is arranged opposite to a light emitting surface of the light emitting element, for receiving light from the light emitting element, a total reflection surface for totally reflecting the light incident on the incident surface in a direction away from the optical axis of the light emitting element, and an exit surface for emitting the light reflected by the total reflection surface, wherein in a light distribution curve showing a far-field light distribution of the light emitting device, when an angle along the optical axis is set to 0°, A is the integral of luminous intensity in the range of 0° to 180°, and a1 is the integral of luminous intensity in the range of 83° to 97°, a1 / A is 0.23 to 0.38. [2] The light emitting device according to [1], wherein when the integral of luminous intensity in the range of 0° to 80° is a2 in the light distribution curve, a2 / A is 0.60 or less. [3] The light emitting device according to [1] or [2], wherein when the integral of luminous intensity in the range of 110° to 180° is a3 in the light distribution curve, a3 / A is 0.40 or less. [4] The light emitting device according to any one of [1] to [3], wherein at least a portion of the light emitted from the light emitting center of the light emitting element at an angle of 30° to 50° with respect to the optical axis is reflected by the total reflection surface at an angle of 90° or more with respect to the optical axis. [5] A surface light source device comprising: a substrate; a plurality of light-emitting devices arranged on the substrate; and a light diffusion plate for diffusing light from the light-emitting devices, wherein the plurality of light-emitting devices are the light-emitting devices according to any one of [1] to [4]. [6] The surface light source device according to [5], wherein H is the distance between the substrate and the light diffusion plate, and P is the center-to-center distance between the adjacent light emitting devices, and H>7 mm, and H / P is 0.15 to 0.25. [7] A display device having the surface light source device according to [5] or [6]. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a light-emitting device that is easy to obtain a good contrast between light and dark, in which dark areas on the light-emitting device stand out when the device is turned off, a surface light source device that includes the light-emitting device, and a display device that includes the surface light source device. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1A is a diagram showing a conventional surface light source device, FIG. 1B is a diagram showing a state in which a light emitting device has been removed from the conventional surface light source device, and FIG. 1C is a diagram showing a state in which a light emitting device having a light flux controlling member with a reflective surface is used in the surface light source device in FIG. 1B. [Figure 2] 2A and 2B are diagrams showing a surface light source device according to an embodiment. [Figure 3] 3A and 3B are cross-sectional views of a surface light source device according to an embodiment. [Figure 4] FIG. 4A is a diagram for explaining a simulation of light distribution, and FIG. 4B is a graph showing a light distribution curve of the light emitting device according to the embodiment. [Figure 5] 5A to 5D are diagrams showing a light flux controlling member according to an embodiment. [Figure 6] FIG. 6 is a graph showing the light distribution curves of the example and the comparative example. [Figure 7] FIG. 7A shows the contrast between light and dark of the surface light source device according to the example, and FIGS. 7B and 7C show the contrast between light and dark of the surface light source device according to the comparative example. [Figure 8] FIG. 8A is a graph of the contrast between light and dark in FIGS. 7A to 7C, and FIG. 8B is a graph showing the angles of light reflected by the reflecting surfaces in the light emitting devices of the example and the comparative example. [Figure 9] FIG. 9A shows the optical path in the light emitting device of the example, and FIG. 9B shows the optical path in the light emitting device of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0012] 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 a surface light source device according to the present invention (see FIG. 2A). The surface light source device can be used as a light source for a display device 100' (e.g., a liquid crystal display device) by combining it with a display member 102 (e.g., a liquid crystal panel) that is irradiated with light from the surface light source device (see FIG. 2B).

[0013] [Embodiment Mode] (Configuration of surface light source device) 2A and 2B are diagrams showing a configuration of surface light source device 100 according to an embodiment of the present invention. FIG. 2A is a plan view of surface light source device 100, and FIG. 2B is a front view. FIGS. 3A and 3B are cross-sectional views of surface light source device 100. FIG. 3A is a schematic cross-sectional view taken along line AA shown in FIG. 2B, and FIG. 3B is a partially enlarged cross-sectional view taken along line BB shown in FIG. 2A. Note that in FIG. 3B, hatching of light flux controlling member 300 is omitted, and only the outline shown on the cross section is shown. FIG. 3A shows an outline of the arrangement of multiple light-emitting devices 200 in surface light source device 100, and FIG. 3B shows an outline of the configuration of light-emitting device 200 in a cross-sectional view.

[0014] 2A to 3B, surface light source device 100 according to the present embodiment includes housing 110 in which multiple light emitting devices 200 are arranged, multiple light emitting devices 200 arranged in housing 110, and light diffusion plate 120 that diffuses light from light emitting devices 200. As shown in FIG. 3A, multiple light emitting devices 200 are arranged on bottom plate 112 of housing 110. The inner surface of bottom plate 112 functions as a diffuse reflection surface and reflects light from light emitting devices 200. An opening is provided in top plate 114 of housing 110. Light diffusion plate 120 is arranged to cover this opening and functions as a light emitting surface. The size of the light emitting surface is not particularly limited, but is, for example, approximately 400 mm × approximately 700 mm.

[0015] As shown in Fig. 3A, in the present embodiment, light emitting device 200 is fixed on substrate 210, which is fixed at a predetermined position on bottom plate 112 of housing 110. In the present embodiment, substrate 210 is bar-shaped. Light emitting device 200 has light flux controlling member 300 (lens) for controlling the distribution of light from light emitting element 220. Note that light emitting element 220 is arranged below light flux controlling member 300 and therefore is not actually visible, but light emitting element 220 is shown in Fig. 3A for the sake of explanation.

[0016] 3A, in this embodiment, the plurality of light emitting devices 200 are arranged in rows at equal intervals in the X direction, and also in rows at equal intervals in the Y direction perpendicular to the X direction. In this embodiment, the interval (center-to-center distance) between adjacent light emitting devices arranged in the X direction is the same as the interval (center-to-center distance P) between adjacent light emitting devices arranged in the Y direction.

[0017] Fig. 3B is a cross-sectional view of light emitting device 200 shown in Fig. 3A. As shown in Fig. 3B, in light emitting device 200, light flux controlling member 300 (lens) is arranged above light emitting element 220.

[0018] As shown in FIG. 3A, the center-to-center distance between adjacent light-emitting devices 200 is P, and as shown in FIG. 3B, the distance between the surface (substrate 210) on which the light-emitting devices 200 are arranged and the rear surface of the light diffuser plate 120 is H. From the viewpoint of obtaining good contrast between light and dark and suppressing uneven brightness even when H changes due to bending of the light diffuser plate, it is preferable that H>7 and H / P be 0.15 to 0.25. By satisfying the above condition for H / P, good contrast between light and dark can be easily obtained even with a large center-to-center distance P in the surface light source device. Furthermore, by satisfying the above condition for H, it is possible to suppress a large change in uneven brightness on the light diffuser plate 120, which would adversely affect the quality of the light-emitting surface, even when H changes slightly due to bending of the light diffuser plate 120, for example.

[0019] Light flux controlling member 300 has incident surface 310 for receiving light emitted from light emitting element 220, total reflection surface 320 for totally reflecting the light incident from incident surface 310, and exit surface 330 for exiting the light reflected by total reflection surface 320. The configuration of light flux controlling member 300 will be described in detail later.

[0020] Fig. 4A is a diagram for explaining a simulation of light distribution obtained by control using the above-described light flux controlling member 300. Fig. 4B is a graph showing a light distribution curve obtained by the simulation.

[0021] As shown in Fig. 4A, in the simulation, the angle in the direction along optical axis OA of light emitting element 220 is set to 0°. Then, in a hemisphere arranged in the far field centered on the light emitting center of light emitting surface 221 of light emitting element 220 as shown in Fig. 4A, light emitted from light emitting element 220 and controlled by light flux controlling member 300 is received, and a light distribution curve as shown in Fig. 4B showing the relationship between angle and luminous intensity is obtained. The integral value of the luminous intensity is A, and the integral value of the luminous intensity in the range of 83° to 97° is a1. In this case, a good contrast between light and dark can be obtained if a1 / A is 0.23 to 0.38. Hereinafter, this will also be referred to as condition 1 where appropriate.

[0022] Furthermore, from the viewpoint of spreading the light (preventing the generation of bright areas directly above the lit light emitting device 200 (light emitting element 220)), the following is preferable. That is, as shown in Figure 4B, when the integral value of luminous intensity simulated in 0.1° increments in the range of 0° to 80° in the light distribution curve is a2, it is preferable that a2 / A is 0.60 or less. Also, to prevent the area directly above the lit light-emitting element from becoming dark, it is preferable that a2 / A is 0.15 or more. Hereinafter, this will be referred to as condition 2 where appropriate. 4B, when the integral of the luminous intensity in the range of 110° to 180° on the light distribution curve is a3, it is preferable that a3 / A is 0.40 or less. Hereinafter, this is also referred to as condition 3 where appropriate. These details will be described later with reference to simulations.

[0023] Each component of the light emitting device 200 will be described below.

[0024] (light-emitting element) The light emitting element 220 is a light source of the surface light source device 100, and is mounted on the substrate 210. The light emitting element 220 is, for example, a light emitting diode (LED) such as a white light emitting diode. The light emitting element 220 has a light emitting surface 221 on its upper surface. This allows the light emitting element 220 to emit light from the upper surface. In this embodiment, the light emitting surface is circular.

[0025] The light emitting element 220 has an optical axis OA. The optical axis OA is the center of the entire radially emitted light. In this embodiment, the optical axis OA of the light emitting element 220 is a straight line that passes through the center of the light emitting surface and is perpendicular to the light emitting surface.

[0026] Light emitting element 220 is arranged within incident surface 310 so that light emitted from light emitting element 220 is incident on incident surface 310 of light flux controlling member 300. In the present embodiment, air exists between light emitting element 220 and incident surface 310.

[0027] (Light flux control member) Fig. 5A is a plan view of light flux controlling member 300, Fig. 5B is a bottom view, Fig. 5C is a side view, and Fig. 5D is a cross-sectional view taken along line DD in Fig. 5A and including optical axis OA. Note that in Fig. 5D, hatching is omitted and only the outline of the cross-sectional view is shown.

[0028] Light flux controlling member 300 is an optical member that controls the distribution of light emitted from light emitting element 220, and is disposed on substrate 210. Light flux controlling member 300 is, for example, bonded to substrate 210. Light flux controlling member 300 has a shape that is rotationally symmetric (circularly symmetric) about optical axis OA. The outer shape of light flux controlling member 300 is approximately disc-shaped, and is circular when viewed from above and from the bottom. The refractive index of light flux controlling member 300 may be, for example, 1.4 to 1.6. In the present embodiment, light flux controlling member 300 has incident surface 310, total reflection surface 320, exit surface 330, and flange 340. Each of these components also has a shape that is rotationally symmetric (circularly symmetric) with respect to optical axis OA. Each component will be described below.

[0029] <Incidence surface> Incident surface 310 is arranged on the back side of light flux controlling member 300. More specifically, incident surface 310 is arranged to face light-emitting surface 221 of light-emitting element 220. Incident surface 310 is also arranged on the back side of light flux controlling member 300 so as to intersect with optical axis OA of light-emitting element 220. Incident surface 310 is the inner surface of a recess in which light-emitting element 220 is arranged.

[0030] In this embodiment, the incident surface 310 has a first incident surface 311 and a second incident surface 312 .

[0031] The first incident surface 311 intersects with the optical axis OA, is closer to the optical axis OA than the second incident surface 312, and is located at a higher position (farther from the substrate 210) than the second incident surface 312. The first incident surface 311 is a surface that forms a larger angle with respect to the optical axis OA than the second incident surface 312, and has a portion that is approximately perpendicular to the optical axis OA. Specifically, in this embodiment, the first incident surface 311 is a curved surface whose tangent changes from being nearly parallel to the optical axis OA to approaching perpendicular as it moves away from the optical axis OA. The first incident surface 311 is a surface onto which light emitted from the light-emitting element 220 that forms a small angle with respect to the optical axis OA is incident. The first incident surface 311 is a convex surface with respect to this light.

[0032] The second incident surface 312 is a surface disposed outside the first incident surface 311. The first incident surface 311 and the second incident surface 312 are continuous. The second incident surface 312 is a surface that is approximately parallel to the optical axis OA. The second incident surface 312 is a surface onto which light rays that form a large angle with respect to the optical axis OA are incident. The second incident surface 312 is a convex surface for such light rays.

[0033] <Total reflection surface> Total reflection surface 320 is arranged on the front side of light flux controlling member 300, and is a surface for totally reflecting the light incident on incident surface 310 in a direction away from optical axis OA.

[0034] 5D , total reflection surface 320 has a curved surface such that the slope of its tangent approaches parallel to substrate 210 the further away from optical axis OA. Total reflection surface 320 is a curved surface configured to move away from substrate 210 the further away from optical axis OA it is. Total reflection surface 320 is formed so as to totally reflect incident light in a direction away from optical axis OA. Total reflection surface 320 is the inner surface of a recess formed on the front side of light flux controlling member 300, and part of the incident light reaches total reflection surface 320 and is reflected, and travels inside light flux controlling member 300.

[0035] As shown in FIG. 5A, total reflection surface 320 has a circular shape when light flux controlling member 300 is viewed in plan, and is located at the innermost side.

[0036] <Exit surface> Exit surface 330 is a surface that emits light reflected by total reflection surface 320 to the outside of light flux controlling member 300. Furthermore, exit surface 330 is a surface that emits light that is incident on incident surface 310 (second incident surface 312) and does not pass through total reflection surface 320. Exit surface 330 is arranged at a position corresponding to a side surface of light flux controlling member 300. Exit surface 330 has first exit surface 331 and second exit surface 332. Exit surface 330 (first exit surface 331) is continuous with total reflection surface 320. Furthermore, when light flux controlling member 300 is seen in a plan view, exit surface 330 is arranged outside total reflection surface 320, as shown in FIG. 5A .

[0037] First exit surface 331 is a surface that is closer to optical axis OA and located at a higher position than second exit surface 332. First exit surface 331 is continuous with total reflection surface 320. First exit surface 331 is a surface that is approximately parallel to optical axis OA. First exit surface 331 is a more gently concave surface with respect to the outgoing light than second exit surface.

[0038] Second exit surface 332 is a surface that is located farther from optical axis OA and at a lower position than first exit surface 331. First exit surface 331 and second exit surface 332 are continuous. Second exit surface 332 is a curved surface whose tangent becomes closer to being parallel to optical axis OA as it moves away from optical axis OA. Second exit surface 332 is a concave surface with respect to the outgoing light.

[0039] <Flange> Flange 340 has a structure that protrudes outward most from the lowermost part of light flux controlling member 300. Flange 340 is continuous with emission surface 330 (second emission surface 332). Furthermore, flange 340 is arranged outward from emission surface 330 (second emission surface 332) when light flux controlling member 300 is viewed in plan. In the present embodiment, flange 340 has a surface that is parallel to optical axis OA.

[0040] [simulation] FIG. 6 shows the light distribution curves obtained by the above simulation for the light emitting devices of the example and comparative examples 1 and 2. Table 1 also shows the ratios of the integral values ​​obtained from these light distribution curves. The light emitting devices of comparative examples 1 and 2 have light flux controlling members that simulate conventional light flux controlling members. As can be seen from Table 1, in the light emitting device of the example, the incident surface, total reflection surface, and exit surface of the light flux controlling member are configured to satisfy condition 1, but the light emitting devices of comparative examples 1 and 2 do not satisfy condition 1.

[0041] The light emitting device of the example is light emitting device 200 having the above-described light flux controlling member 300. Comparative Examples 1 and 2 are also light emitting devices having a reflecting lens with a total reflection surface as a light flux controlling member, but do not satisfy condition 1.

[0042] [Table 1]

[0043] 7A to 7C show the contrast between light and dark in the surface light source devices having the light emitting devices of Example and Comparative Examples 1 and 2, which produce the light distribution curves described above. Specifically, in FIGS. 7A to 7C, a total of 49 light emitting devices are arranged, 7 horizontally and 7 vertically. The contrast between light and dark is shown when only the central light emitting device is turned off and all the other light emitting devices are turned on. The center-to-center distance (P) between adjacent light emitting devices was 135 mm, and the distance (H) between the surface (substrate) on which the light emitting devices were arranged and the back surface of the light diffusion plate was 15 mm.

[0044] Condition 1 is a condition for suppressing light from a light-emitting device that is lit adjacent to the turned-off light-emitting device from reaching the light diffusion plate above the turned-off light-emitting device, thereby improving the contrast between light and dark. Here, if the light from the lit light-emitting device is controlled to satisfy condition 1, the light is prevented from reaching the light diffusion plate above the adjacent turned-off light-emitting device, but the light is instead redirected to other areas. If this redirected light reaches the light diffusion plate unevenly, a bright area is likely to occur on the light diffusion plate above the turned-on light-emitting device. To suppress the occurrence of such a bright area, it is preferable to satisfy condition 2 and / or condition 3. This makes it possible to obtain a surface light source device that achieves good contrast between light and dark and has high uniformity in the lighting area of ​​the turned-on light-emitting device.

[0045] That is, the occurrence of bright areas is suppressed when a2 / A is 0.60 or less, which is condition 2, and the occurrence of bright areas is suppressed when a3 / A is 0.40 or less, which is condition 3. Here, if a2 / A is too small, dark areas may occur. Therefore, in order to suppress the occurrence of dark areas, it is preferable that a2 / A is 0.15 or more.

[0046] Fig. 8A is a graph of the light-dark contrast in the surface light source devices of Fig. 7A to C. Specifically, Fig. 8A shows the magnitude of luminance in a cross section including the optical axis of the light-emitting device in the middle of Fig. 7A to C that is turned off and the optical axes of the two light-emitting devices on either side of it that are turned on.

[0047] More specifically, the horizontal axis of the graph in Fig. 8A represents the distance in the horizontal direction (toward the surface of the light diffuser plate), and the vertical axis represents the relative luminance intensity of the surface of the light diffuser plate of the surface light source device. That is, the 0 mm position on the horizontal axis of Fig. 8 corresponds to the position on the surface of the light diffuser plate that intersects with the optical axis of the central light-emitting device (light-emitting element) that is turned off, and -135 mm and 135 mm correspond to the positions on the surface of the light diffuser plate that intersect with the optical axis OA of the light-emitting devices (light-emitting elements) on either side that are turned on. For comparison, the luminance on the surface of the light diffuser plate at -135 mm and 135 mm is set to 1, and the relative luminance is shown.

[0048] As can be seen from FIGS. 7A-C and 8A, in the example, the luminance directly above the unlit light-emitting device was low, while the luminance directly above the adjacent lit light-emitting device was high, resulting in good contrast between light and dark. That is, good local dimming performance was achieved. On the other hand, in comparative examples 1 and 2, the difference between the two was small, and good contrast between light and dark was not achieved. That is, good local dimming performance was not achieved. This is because example 1 satisfies condition 1, but comparative examples 1 and 2 do not. Specifically, by satisfying condition 1, light from the lit light-emitting device in example 1 is prevented from reaching the light directly above the unlit light-emitting device.

[0049] Fig. 8B is a graph showing the relationship between the angle of light emitted from the light-emitting center of the light-emitting element of the light-emitting devices of Example and Comparative Examples 1 and 2 relative to the optical axis OA and the angle of light reflected by the reflecting surface relative to the optical axis OA (total reflection angle of the reflecting surface). Fig. 9A shows the optical path in the light-emitting device of Example, and Fig. 9B shows the optical path in the light-emitting device of Comparative Example 1.

[0050] 8B, in the embodiment, at least a part of the light emitted from the light-emitting center of the light-emitting element at an angle of 30° to 50° with respect to the optical axis OA is reflected by the total reflection surface at an angle of 90° or more with respect to the optical axis OA (toward the bottom side of the light-emitting device). As a result, in the embodiment, as shown in FIG. 9A, more light is directed toward the bottom side of the light-emitting device, and light reaching the light diffusion plate located above the adjacent light-emitting device can be suppressed. On the other hand, in Comparative Examples 1 and 2, the light emitted from the light-emitting center of the light-emitting element at an angle of 30° to 50° with respect to the optical axis OA is reflected so that the total reflection angle on the surface is less than 90° (toward the upper part of the light-emitting device). As a result, in Comparative Example 1, more light reaches the light diffusion plate located above the adjacent light-emitting device, as shown in FIG. 9B.

[0051] In the examples, a light distribution that satisfies condition 1 is achieved, in part, because the total reflection surface reflects light as described above (see Table 1). Note that light emitting devices (light flux controlling members) configured to achieve condition 1 are not limited to those in the examples. The light distribution that satisfies condition 1 may be achieved by appropriately adjusting the shapes of the incident surface, reflecting surface, and exit surface of the light flux controlling member, and the present invention also includes light emitting devices having light flux controlling members configured to achieve condition 1 by appropriately combining incident surfaces, reflecting surfaces, and exit surfaces with shapes different from those in the above examples.

[0052] Furthermore, in the embodiment, satisfying conditions 2 and 3 spreads light over a wide range, suppressing the occurrence of bright areas. That is, satisfying condition 2 in addition to condition 1 spreads light over a wider range than light-emitting device 20 having light flux controlling member (refractive lens) 22 as shown in FIG. 1A, and emphasizes dark areas on the light-emitting device when it is turned off, thereby achieving good contrast between light and dark. Furthermore, satisfying condition 3 prevents light from bouncing off a member such as a reflective sheet and returning to the area directly above the light flux controlling member, thereby suppressing excessive brightness in the area directly above. [Industrial Applicability]

[0053] The light emitting device of the present invention can be applied to, for example, a surface light source device used for backlighting of a liquid crystal display device or general lighting. [Explanation of symbols]

[0054] 10, 100 surface light source device 30, 120 Light diffuser 20, 40, 200 Light-emitting device 21, 220 Light-emitting element 22, 42, 300 Light flux control member 41, 320 total reflection surface 100' display unit 102 Display components 110 Case 112 Bottom plate 114 Top plate 210 Substrate 221 Light-emitting surface 310 Incidence plane 311 1st entrance plane 312 2nd entrance plane 330 Exit surface 331 First exit surface 332 Second exit surface 340 flange

Claims

1. A light emitting device having a light emitting element and a light flux controlling member for controlling light from the light emitting element, The light flux controlling member is an incident surface for allowing light from the light-emitting element to be incident thereon, the incident surface being arranged to face the light-emitting surface of the light-emitting element; a total reflection surface for totally reflecting the light incident on the incident surface in a direction away from the optical axis of the light emitting element; an exit surface for emitting light reflected by the total reflection surface; and In a light distribution curve showing a far-field light distribution of the light emitting device, The angle in the direction along the optical axis is set to 0°, The integral value of the luminous intensity in the range of 0° to 180° is A, When the integral value of the luminous intensity in the range of 83° to 97° is a1, a1 / A is 0.23 to 0.38; Light-emitting device.

2. 2. The light emitting device according to claim 1, wherein, in the light distribution curve, when an integral value of luminous intensity in a range of 0° to 80° is a2, a2 / A is 0.60 or less.

3. 2. The light emitting device according to claim 1, wherein, in the light distribution curve, when an integral value of luminous intensity in a range of 110° to 180° is a3, a3 / A is 0.40 or less.

4. 2. The light emitting device according to claim 1, wherein at least a portion of the light emitted from the light emitting center of the light emitting element at an angle of 30° to 50° with respect to the optical axis is reflected by the total reflection surface so that the angle with respect to the optical axis is 90° or more.

5. A substrate; a plurality of light emitting devices disposed on the substrate; a light diffusion plate for diffusing light from the light emitting device; and The plurality of light emitting devices are light emitting devices according to any one of claims 1 to 4. Surface light source device.

6. 6. The surface light source device according to claim 5, wherein when a distance between the substrate and the light diffusion plate is H and a center-to-center distance between the adjacent light emitting devices is P, H>7 mm and H / P is 0.15 to 0.

25.

7. A display device comprising the surface light source device according to claim 5.

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