JP2023004228A - Light-emitting device, surface light source device and display device - Google Patents

Abstract

To provide a light-emitting device having a plurality of luminous elements and a luminous flux control member, capable of properly emitting light not only in a direction orthogonal to an arrangement direction of the plurality of luminous elements but also in the arrangement direction of the plurality of luminous elements.SOLUTION: A light-emitting device includes a plurality of luminous elements, and a luminous flux control member. The luminous flux control member has an incidence surface, a reflection surface including a first reflection surface and a second reflection surface, and an emission surface. As the luminous flux control member is viewed in plane, a first axis parallel to a first direction is virtually arranged such that the plurality of luminous elements is overlapped with arranged area, and the first reflection surface reflects light to be separated from the first axis. The second reflection surface reflects light incident on the incidence surface so as to be separated from the plurality of luminous. On the first axis through the center of the luminous flux control member, a distance between the center and an intersection point of an end part on the center side of the second reflection surface and the first axis is shorter than a distance between the center and, the intersection point of the optic axis of the luminous element positioned at the farthest among the plurality of luminous elements and the first axis.SELECTED DRAWING: Figure 6

Description

The present invention relates to a light emitting device, a surface light source device and a display device.

2. Description of the Related Art In recent years, in transmissive image display devices such as liquid crystal display devices, a direct type surface light source device having a plurality of light emitting elements is used as a light source. Further, in a direct type surface light source device, a large number of light emitting elements may be arranged in order to irradiate light over a wide range (see, for example, Patent Document 1).

US Pat. No. 6,200,000 discloses a lighting package having a package base, a plurality of light emitters, and an optical element. A plurality of light emitters arranged in a first direction and an optical element arranged to cover the plurality of light emitters are arranged on the package base. The optical element has an entrance surface and a top surface located opposite the entrance surface. The top surface has no curvature in a first direction and has curvature in a second direction orthogonal to the first direction. Light emitted from the light emitter is incident on the incident surface and reflected on the upper surface in a second direction perpendicular to the first direction. The light reflected by the upper surface is emitted to the outside in the second direction.

JP 2006-099117 A

In the lighting package described in Patent Document 1, the light emitted from the light emitter is emitted in a direction (second direction) orthogonal to the arrangement direction (first direction) of the plurality of light emitters. It is difficult to emit light in the body arrangement direction (first direction). Here, in a light emitting device such as the lighting package described in Patent Document 1, there are cases where it is desired to emit light emitted from the light emitter not only in the second direction but also in the first direction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting device having a plurality of light emitting elements and a light flux controlling member, in which light is appropriately emitted not only in a direction orthogonal to the arrangement direction of the plurality of light emitting elements but also in the arrangement direction of the plurality of light emitting elements. Another object of the present invention is to provide a light-emitting device capable of emitting light to the outside. Another object of the present invention is to provide a surface light source device and a display device having the light emitting device.

A light emitting device according to an embodiment of the present invention includes a plurality of light emitting elements arranged in a first direction, and a light flux controlling member for controlling light distribution of light emitted from the plurality of light emitting elements. wherein the light flux controlling member is arranged on the rear surface of the plurality of light emitting elements so as to face the plurality of light emitting elements, and has an incident surface for allowing the light emitted from the plurality of light emitting elements to enter; A reflective surface disposed on the front surface opposite to the back surface for reflecting light incident on the incident surface, and at least part of the light incident on the incident surface and the light reflected on the reflective surface. a first axis parallel to the first direction when the light flux controlling member is viewed from above, and a region where the plurality of light emitting elements are arranged. In the state of being virtually arranged so as to overlap, the reflective surface includes a first reflective surface for reflecting light incident on the incident surface and the first reflective surface of the first reflective surface so as to be separated from the first axis. and two second reflecting surfaces arranged at both ends in one direction for reflecting light incident on the incident surface so as to be separated from the plurality of light emitting elements, and pass through the center of the light flux controlling member. On the first axis, the distance between the center and the intersection of the center-side end of the second reflecting surface and the first axis is the distance between the center and the plurality of light emitting elements. It is shorter than the distance between the intersection point of the optical axis of the light emitting element positioned at the end and the first axis.

A surface light source device according to an embodiment of the present invention includes a plurality of light emitting devices of the present invention, and a light diffusion member that diffuses and transmits light emitted from the plurality of light emitting devices.
Surface light source device

A display device according to an embodiment of the present invention includes the surface light source device of the present invention and a display member irradiated with light emitted from the surface light source device.

According to the present invention, it is possible to provide a light emitting device capable of appropriately emitting light not only in the direction orthogonal to the arrangement direction of the plurality of light emitting elements but also in the arrangement direction of the plurality of light emitting elements. Further, according to the present invention, it is possible to provide a surface light source device and a display device having the light emitting device.

1A and 1B are diagrams showing the configuration of a surface light source device according to one embodiment of the present invention. 2A and 2B are other diagrams showing the configuration of the surface light source device according to one embodiment of the present invention. FIG. 3 is a partially enlarged sectional view enlarging a part of FIG. 2B. 4A and 4B are diagrams showing the configuration of a light flux controlling member according to one embodiment of the present invention. 5A to 5D are other diagrams showing the configuration of the light flux controlling member according to one embodiment of the present invention. FIG. 6 is a diagram for explaining the positional relationship between the second incident surface, the second reflecting surface, and the light emitting element. 7A and 7B are luminance distributions on the light diffusion member. 8A and 8B are luminance distributions on the light diffusion member. 9A and 9B are graphs showing the luminance distribution on the light diffusion member. 10A and 10B are graphs showing the luminance distribution on the light diffusion member. 11A and 11B are graphs showing the luminance distribution on the light diffusion member. 12A and 12B are diagrams showing optical paths in the light emitting device. 13A and 13B are diagrams showing optical paths in the light emitting device.

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, as a representative example of the surface light source device according to the present invention, a surface light source device suitable for a backlight of a liquid crystal display device or the like will be described. These surface light source devices can be used as a display device 100' by combining with a display member 102 (for example, a liquid crystal panel) that is irradiated with light from the surface light source device (see FIG. 1B).

(Configuration of Surface Light Source Device and Light Emitting Device)
1A, B, 2A, B and 3 are diagrams showing the configuration of a surface light source device 100 according to one embodiment of the present invention. FIG. 1A is a plan view of surface light source device 100, and FIG. 1B is a front view. 2A is a cross-sectional view taken along line AA shown in FIG. 1B, and FIG. 2B is a cross-sectional view taken along line BB shown in FIG. 1A. FIG. 3 is a partially enlarged sectional view enlarging a part of FIG. 2B.

In this embodiment, in each of the plurality of light emitting devices 120, the plurality of light emitting elements 121 are arranged in one direction. The arrangement direction of the plurality of light emitting elements 121 in each light emitting device 120 is the same or parallel. Also, the optical axes LA of the plurality of light emitting elements 121 are parallel to each other.

In the following description, the arrangement direction of the plurality of light emitting elements 121 is defined as the first direction (X direction), the direction along the optical axis LA of the plurality of light emitting elements 121 is defined as the Z direction, and the first direction and the optical axis A direction orthogonal to LA is described as a second direction (Y direction) (see FIG. 2A). A cross section along the first direction (X direction) and the direction of the optical axis LA (Z direction) is defined as a first cross section, and a cross section along the second direction (Y direction) and the direction of the optical axis LA (Z direction). is the second cross section.

As shown in FIGS. 1A, B, 2A, B, and 3, the surface light source device 100 according to the present embodiment includes a housing 110, a plurality of substrates 116, a plurality of light emitting devices 120, a light diffusion and a member 130 . A plurality of light emitting devices 120 are arranged on one of a plurality of substrates 116 arranged on the bottom plate 112 of the housing 110 . A reflective sheet may be placed on the surface of the bottom plate 112, and the substrate 116 may be placed on the surface. It may function as a reflective surface, or the surface of the bottom plate 112 or the substrate 116 may function as a diffusely reflective surface. In this embodiment, the surface of bottom plate 112 and the surface of substrate 116 function as diffuse reflection surfaces. Further, the top plate 114 of the housing 110 is provided with an opening. The light diffusing member 130 is arranged so as to block this opening and functions as a light emitting surface. Although the size of the light emitting surface is not particularly limited, it is, for example, about 400 mm×about 700 mm.

As shown in FIG. 3, the distance between the front surface of the substrate 116 and the rear surface of the light diffusing member 130 is preferably in the range of 3 to 10 mm. In this embodiment, the distance between the front surface of substrate 116 and the rear surface of light diffusion member 130 is approximately 6 mm.

As shown in FIG. 3, a plurality of light emitting devices 120 are fixed on substrate 116 . The board 116 is fixed at a predetermined position on the bottom plate 112 of the housing 110 . Light emitting device 120 has a plurality of light emitting elements 121 and light flux controlling member 122 . Legs 126 of light flux controlling member 122 form a gap between substrate 116 on which light emitting element 121 is mounted and the back surface of light flux controlling member 122 to release heat emitted from light emitting element 121 to the outside.

The substrate 116 is arranged on the bottom plate 112 of the housing 110 . The substrate 116 extends in a first direction (X direction) or a second direction (Y direction). In this embodiment, the substrate 116 extends in the first direction (X direction). The number of substrates 116 is appropriately set according to the size of the light emitting surface. In this embodiment, two substrates 116 are arranged in the first direction (X direction) and seven rows are arranged in the second direction (Y direction). In a first direction, adjacent substrates 116 are spaced apart. Also, adjacent substrates 116 are spaced apart in the second direction. The number of light emitting devices 120 arranged on substrate 116 is not particularly limited. In this embodiment, seven light emitting devices 120 are arranged on one substrate. Also, the length of the substrate 116 in the second direction (Y direction) when viewed from above is preferably longer than the length of the light emitting device 120 in the second direction (Y direction). By making the substrate 116 bar-shaped in this way, for example, the handling performance at the time of repair is improved. Moreover, the weight of the surface light source device 100 can be reduced.

The light emitting element 121 is the light source of the surface light source device 100 and is mounted on the substrate 116 . The number of light emitting elements 121 for one light flux controlling member 122 is not particularly limited as long as it is plural. In this embodiment, four light emitting elements 121 are arranged for one light flux controlling member 122 . A plurality of light emitting elements 121 may be arranged in one row along the first direction (X direction) with respect to light flux controlling member 122, or may be arranged in two rows along the first direction. They may be arranged in a staggered manner along the first direction. In the present embodiment, the plurality of light emitting elements 121 are arranged in one row along the first direction (X direction). Also, the interval between the plurality of light emitting elements 121 in the first direction (X direction) is not particularly limited. The intervals between the plurality of light emitting elements 121 may or may not be equal. The four light emitting elements 121 in this embodiment are not equidistant. For example, the distance between the light emitting element 121 arranged in the center of the light flux controlling member 122 and the adjacent light emitting element 121 may be longer than the distance between the adjacent light emitting elements 121 at the end of the light flux controlling member 122. good.

The light-emitting element 121 is, for example, a light-emitting diode (LED) such as a blue light-emitting diode, a white light-emitting diode, or an RGB light-emitting diode. The type of light-emitting element 121 is not particularly limited, but light-emitting element 121 that emits light from the top and side surfaces (for example, a COB light-emitting diode) is preferably used in light-emitting device 120 according to the present embodiment. . The size of one side of the light emitting element 121 is not particularly limited, but is preferably in the range of 0.1 to 0.6 mm, more preferably in the range of 0.1 to 0.5 mm. In the present invention, the use of smaller LEDs enables more appropriate light distribution and provides the surface light source device 100 with less luminance unevenness. For example, the size of the light emitting element 121 is 0.5 mm×0.5 mm.

(Structure of light flux controlling member)
4A, B and 5A-D are diagrams showing the configuration of light flux controlling member 122 in one embodiment of the present invention. 4A is a plan view of light flux controlling member 122. FIG. FIG. 4B is a bottom view. 5A is a front view of light flux controlling member 122. FIG. FIG. 5B is a right side view. FIG. 5C is a cross-sectional view taken along line AA shown in FIG. 4A. FIG. 5D is a cross-sectional view taken along line BB shown in FIG. 4A.

Light flux controlling member 122 is an optical member that controls the light distribution of light emitted from light emitting element 121, and is fixed on substrate 116 (see FIG. 3). Light flux controlling member 122 is formed by integral molding. The material of light flux controlling member 122 is, for example, a light transmissive resin or glass that allows light of a desired wavelength to pass therethrough. Examples of light-transmitting resins include polymethyl methacrylate (PMMA), polycarbonate (PC), and epoxy resin (EP).

As shown in FIGS. 4A, B and 5A-D, light flux controlling member 122 has entrance surface 123, reflective surface 124, exit surface 125, and legs 126. As shown in FIG.

Incidence surface 123 is the inner surface of a recess formed at a position opposite to light flux controlling member 122 and opposite light emitting elements 121 . Incidence surface 123 causes most of the light emitted from light emitting elements 121 to enter inside light flux controlling member 122 while controlling the traveling direction of the light. The incident surface 123 has a first incident surface 123a, two second incident surfaces 123b, and two third incident surfaces 123c.

The first incident surface 123a is arranged to extend in the first direction (X direction). The first incident surface 123a mainly receives light emitted from the light emitting element 121 facing the first incident surface 123a.

A plan view shape of the first incident surface 123a is not particularly limited. In the present embodiment, the planar shape of the first incident surface 123a is a rectangle elongated in the first direction (X direction). The first incidence surface 123a is the inner surface of a recess disposed on the back side. In this embodiment, the first incidence surface 123a in the first direction (X direction) has no curvature, and the first incidence surface 123a has curvature in the second direction (Y direction). there is The first incident surface 123a in the first direction (X direction) preferably has no curvature, but may have curvature. In the present embodiment, first incident surface 123a has a translationally symmetrical shape in which a curve of a specific shape extends in the first direction. The first incident surface 123a has a substantially triangular prism shape with an isosceles triangle as a bottom surface. Two inclined surfaces forming the first incident surface 123a face each other corresponding to the two equilateral sides of the isosceles triangle. Each of these two equilateral sides is a back-convex curve, and each of these two inclined surfaces is a back-convex curve. Therefore, the light incident on the first incident surface 123a is condensed toward the first reflecting surface 124a.

The second incident surface 123b is arranged at both ends of the first incident surface 123a in the first direction (X direction). In the first direction (X direction), the second incident surface 123b allows light emitted mainly from the light emitting elements 121 arranged at both ends among the plurality of light emitting elements 121 to enter. A plan view shape of the second incident surface 123b is not particularly limited. In the present embodiment, the planar view shape of the second incident surface 123b is a semicircular shape. The second incident surface 123b is the inner surface of the recess located on the back side. The second incident surface 123b is part of a rotationally symmetrical surface with respect to the second rotation axis RA2.

In the cross section including the second rotation axis RA2, the second incident surface 123b is arranged so as to face the back side, then the front side, and finally the back side in the second direction from the second rotation axis RA2. there is The second incident surface 123b has a shape obtained by rotating a curve that goes to the back side, then to the front side, and finally to the back side by 180°. The generatrix on the second incident surface 123b and the generatrix on the first incident surface 123a have the same shape. Therefore, the light incident on the second incident surface 123b is condensed toward the second reflecting surface 124b.

The third incident surface 123c is arranged at both ends of the first incident surface 123a in the second direction (Y direction). The third incident surface 123c mainly receives light having a large output angle among the lights emitted from the light emitting elements 121 facing the first incident surface 123a. A plan view shape of the third incident surface 123c is not particularly limited. In the present embodiment, the planar view shape of the third incident surface 123c is a rectangular shape elongated in the first direction (X direction). Third entrance surface 123c is arranged to face the back side in the second direction (Y direction) from the center of light flux controlling member 122 in the second cross section along the second direction (Y direction). .

In the present embodiment, the first incident surface 123a and the second incident surface 123b are directly connected, but a connecting surface (not shown) is arranged between the first incident surface 123a and the second incident surface 123b. may have been

Reflective surface 124 is the inner surface of a recess provided on the front side of light flux controlling member 122 . Reflective surface 124 is disposed on the front surface opposite incident surface 123 and reflects light incident on the incident surface away from the first axis. The reflecting surface 124 has a first reflecting surface 124a and a second reflecting surface 124b. Here, the first axis means an axis parallel to the first direction (X direction), and is virtually arranged so as to overlap the region where the plurality of light emitting elements 121 are arranged.

The first reflecting surface 124a extends in the first direction (X direction) and is perpendicular to the straight line along the first direction (X direction) and the optical axis LA of some of the optical axes of the plurality of light emitting elements 121. The light incident on the first incident surface 123a is reflected in the second direction (Y direction). More specifically, the first reflecting surface 124a mainly reflects the light incident on the first incident surface 123a in the second direction (Y direction).

The first reflecting surface 124a is arranged to face the first incident surface 123a. The planar view shape of the first reflecting surface 124a is not particularly limited. In the present embodiment, the planar shape of the first reflecting surface 124a is a rectangle elongated in the first direction (X direction). The first reflective surface 124a is the inner surface of a recess arranged on the surface. In this embodiment, the first reflecting surface 124a in the first direction (X direction) has no curvature. The first reflecting surface 124a in the first direction (X direction) preferably has no curvature, but may have curvature. In the second cross section, first reflecting surface 124a is arranged so as to face the front side in the second direction (Y direction) from the center of light flux controlling member 122 . The first reflecting surface 124a has a shape of translational symmetry in which the curve as described above extends in the first direction.

The second reflecting surfaces 124b are arranged at both ends of the first reflecting surface 124a in the first direction (X direction). The second reflective surface 124 b mainly reflects the light incident on the second incident surface 123 b away from the plurality of light emitting elements 121 . The second reflecting surface 124b is arranged to face the second incident surface 123b. The plan view shape of the second reflecting surface 124b is not particularly limited. In the present embodiment, the planar view shape of the second reflecting surface 124b is a semicircular shape. The second reflecting surface 124b is the inner surface of the recess arranged on the back surface. The second reflecting surface 124b is arranged so as to face the front side with increasing distance from the first rotation axis RA1 in a cross section along the optical axis LA and including the first rotation axis RA1 (see FIG. 6). The second reflecting surface 124b is curved toward the front side with increasing distance from the first rotation axis RA1 in a cross section including the first rotation axis RA1. The second reflecting surface 124b is part of a rotationally symmetric surface with respect to the first rotation axis RA1.

In this embodiment, the first reflecting surface 124a and the second reflecting surface 124b are directly connected, but a connecting surface (not shown) is arranged between the first reflecting surface 124a and the second reflecting surface 124b. may have been

Emission surface 125 is arranged on the side surface of light flux controlling member 122 . Outgoing surface 125 emits at least a portion of the light incident on incident surface 123 and the light reflected on reflecting surface 124 sideways.

Leg portion 126 is arranged on the back surface of light flux controlling member 122 . Leg portion 126 forms a gap between substrate 116 and the back surface of light flux controlling member 122 to allow heat emitted from light emitting element 121 to escape to the outside. The number of legs 126 is not particularly limited. In this embodiment, the number of legs 126 is four.

Here, the positional relationship between the second incident surface 123b, the second reflecting surface 124b, and the light emitting elements 121 arranged at both ends among the plurality of light emitting elements 121 will be described. FIG. 6 is a diagram for explaining the positional relationship among the second incident surface 123b, the second reflecting surface 124b, and the light emitting elements 121 arranged at both ends among the plurality of light emitting elements 121. FIG.

In the present embodiment, on the first axis passing through the center of light flux controlling member 122, the distance between the center of light flux controlling member 122, the center-side end of second reflecting surface 124b, and the intersection of the first axis is shorter than the distance L1 between the center and the intersection of the first axis and the optical axis LA of the light emitting element 121 positioned at the end (see FIG. 6). That is, the light-emitting element 121 is arranged so that at least a portion of the light-emitting element 121 faces the second reflecting surface 124b with the second incident surface 123b interposed therebetween. As a result, most of the light emitted from the light emitting elements 121 positioned at the ends reaches the second reflecting surface 124b. Therefore, most of the light emitted from the light emitting elements 121 positioned at the ends can be emitted in the first direction (X direction) (see FIG. 13A).

Further, in the present embodiment, in the first direction (X direction), the distance L2 between the center of light flux controlling member 122 and the intersection of the center-side end of second incident surface 123b and the first axis may be the same distance as the distance L3 between the center and the center-side end of the second reflecting surface 124b and the intersection of the first axis, or the center and the center-side end of the second reflecting surface 124b and the intersection of the first axis is preferably shorter than the distance L3. In the present embodiment, in the first direction (X direction), the distance L2 between the center and the intersection of the center-side end of the second incident surface 123b and the first axis is equal to the distance L2 between the center and the second axis. It is shorter than the distance L3 between the center-side end of the reflecting surface 124b and the intersection of the first axis (see FIG. 6). In addition, in the first direction (X direction), the distance L2 between the center and the center-side end of the second incident surface 123b and the intersection of the first axis is It is shorter than the distance L1 between the optical axis LA of 121 and the intersection of the first axis (see FIG. 6). As a result, most of the light emitted from the light emitting element 121 positioned at the end and incident on the second incident surface 123b can travel to the second reflecting surface 124b.

(simulation)
Next, the distance L1 between the center and the intersection of the optical axis LA of the light emitting element 121 located at the end and the first axis, The distance L2 between the intersection point and the center, the distance L3 between the center-side edge of the second reflecting surface 124b and the intersection point of the first axis correspond to the luminance distribution and the optical path on the surface of the light diffusing member 130. We investigated the influence of

In this simulation, luminance distribution on light diffusion member 130 in surface light source device 100 using light emitting device 120 having four light emitting elements 121 and one light flux controlling member 122 was investigated. In this simulation, only four light emitting elements 121 of one light emitting device 120 were lit. The distance between substrate 116 and light diffusion member 130 was set to 6 mm. In this simulation, the brightness distribution by the light-emitting device 120 in which the distance L1, the distance L2, and the distance L3 are 12.9 mm (match) was used as a reference. Then, the light emitting device 120 with the distance L3 changed to 12.5 mm (-0.4 mm), 12.6 mm (-0.3 mm), 12.7 (-0.2 mm), and 13.1 mm (+0.2 mm). We investigated the luminance distribution of Further, the distance L3 is changed as described above, and the distance L2 is changed to 12.5 mm (-0.4 mm), 12.6 mm (-0.3 mm), 12.7 (-0.2 mm), 13.1 mm ( +0.2 mm). That is, the luminance distribution on the light diffusing member 130 was examined for 25 types of light emitting devices 120 with different distances L2 and L3.

In the following description, the light emitting device 120 (hereinafter also referred to as “light emitting device A”) having the same distances L1, L2, and L3 and the light emitting device having the distances L2 and L3 set to −0.4 mm, respectively. A device 120 (hereinafter also referred to as “light emitting device B”), a light emitting device 120 (hereinafter also referred to as “light emitting device C”) having a distance L2 of −0.3 mm and a distance L3 of −0.2 mm, and a distance L2 and the distance L3 of +0.2 mm (hereinafter also referred to as “light emitting device D”), and the results of using light emitting devices 120 other than these are omitted.

7A, B and 8A, B show the luminance distribution on the light diffusion member 130. FIG. FIG. 7A shows the results when the light emitting device 120 (light emitting device A) with the same distance L1, L2 and L3 is used. FIG. 7B shows the results when using the light-emitting device 120 (light-emitting device B) with the distances L2 and L3 set to −0.4 mm. FIG. 8A shows the results when using the light emitting device 120 (light emitting device C) with the distance L2 set to −0.3 mm and the distance L3 set to −0.2 mm. FIG. 8B shows the results when using the light-emitting device 120 (light-emitting device D) with the distance L2 and the distance L3 each set to +0.2 mm. The vertical axes in FIGS. 7A, B and 8A, B indicate the distance from the center of the light emitting device 120 in the second direction (Y direction). The horizontal axes in FIGS. 7A, B and 8A, B indicate the distance from the center of the light emitting device 120 in the first direction (X direction).

9A, B, 10A, B, and 11A, B show the luminance distribution on a certain line on the light diffusion member 130. FIG. FIG. 9A shows the luminance distribution on line A in FIG. 7A and line A in FIG. 7B. FIG. 9B shows the luminance distribution on line B in FIG. 7A and line B in FIG. 7B. FIG. 10A shows the luminance distribution on line A in FIG. 7A and line A in FIG. 8A. FIG. 10B shows the luminance distribution on line B in FIG. 7A and line B in FIG. 8A. FIG. 11A shows the luminance distribution on line A in FIG. 7A and line A in FIG. 8B. FIG. 11B shows the luminance distribution on line B in FIG. 7A and line B in FIG. 8B. The solid lines in FIGS. 9A, B, 10A, B, and 11A, B show the luminance distribution when using the light emitting device 120 with the same distance L1, L2, and L3. The vertical axes in FIGS. 9A, 9B, 10A, 10B, and 11A, 11B are values normalized with the maximum luminance being "1".

As shown in FIGS. 7A,B, 8A, 9A,B and 10A,B, the distance L3 between the center and the intersection of the center-side end of the second reflecting surface 124b and the first axis However, in the light-emitting device B and the light-emitting device C, which is shorter than the distance L1 between the center and the intersection of the optical axis LA of the light-emitting element 121 located at the end and the first axis, on the light diffusion member 130, the second It can be seen that much light is emitted not only in the direction (Y direction) but also in the first direction (X direction). It is considered that this is because a large amount of light reaches the second reflecting surface 124b and is reflected. On the other hand, as shown in FIGS. 7A, 8B and 11A, B, the distance L3 between the center and the intersection of the center-side end of the second reflecting surface 124b and the first axis is In the light-emitting device A and the light-emitting device D having a length equal to or longer than the distance L1 between the optical axis LA of the light-emitting element 121 positioned at the end and the intersection of the first axis, a large amount of light is emitted in the second direction (Y direction). is emitted, but not much light is emitted in the first direction (X direction). It is considered that this is because sufficient light did not reach the second reflecting surface 124b. Also, from a comparison of light emitting device B and light emitting device C, it can be seen that the distance L3 between the center of light flux controlling member 122 and the center-side end of second reflecting surface 124b has a preferable distance range.

Further, from a comparison between the light emitting device A and the light emitting device C, the distance L2 between the center and the edge of the second incident surface 123b on the center side and the intersection of the first axis is is preferably shorter than the distance L3 between the center-side ends of the .

(Optical path diagram)
12A, B and 13A, B are diagrams showing optical paths in the light emitting device 120. FIG. FIG. 12A shows optical paths in the light emitting device A where the distances L1, L2 and L3 are the same. FIG. 12B shows the optical path in the light-emitting device B where the distance L2 and the distance L3 are each -0.4 mm. FIG. 13A shows the optical path in the light-emitting device C where the distance L2 is -0.3 mm and the distance L3 is -0.2 mm. FIG. 13B shows the optical path in the light-emitting device D with the distance L2 and the distance L3 of +0.2 mm, respectively. 12A and 12B and FIGS. 13A and 13B show only the optical paths of light emitted from the light emitting elements 121 positioned at the ends among the plurality of light emitting elements 121. FIG.

As shown in FIGS. 9A, 9B, 12A and 12B, the distance L3 between the center and the center-side edge of the second reflecting surface 124b and the intersection of the first axis is the distance between the center and the edge. If the distance L1 between the intersection point of the first axis and the optical axis LA of the light emitting element 121 positioned at the side is significantly shorter than the distance L1, the luminance distribution on the light diffusing member 130 may not form a smooth curve. This is probably because part of the light emitted from the light emitting element 121 and incident on the second incident surface 123b is emitted from the second reflecting surface 124b.

In addition, as shown in FIGS. 12B and 13A, the distance L3 between the center and the center-side end of the second reflecting surface 124b and the intersection of the first axis is located at the center and the end. If the distance L1 between the optical axes LA of 121 is shorter than the distance L1, most of the light emitted from the light emitting element 121 reaches the second reflecting surface 124b, so that the light is also emitted in the first direction. be.

(effect)
As described above, in the surface light source device 100 according to the present embodiment, the distance L3 between the center and the edge of the second reflecting surface 124b on the center side and the intersection of the first axis is equal to the center and the edge. Since it is shorter than the distance L1 between the optical axis LA of the light emitting element 121 positioned at the edge and the intersection of the first axis, most of the light emitted from the light emitting element 121 positioned at both ends reaches the second reflecting surface. 124b and is reflected in the first direction (X direction). Therefore, in the surface light source device 100 according to the present embodiment, light is emitted from each of the plurality of light emitting devices 120 not only in the second direction (Y direction) but also in the first direction (X direction). . Therefore, unevenness in brightness can be prevented even when the elongated substrate 116 is used. Moreover, the cost of the surface light source device 100 can be reduced. Furthermore, the surface light source device 100 according to the present embodiment can also cope with local dimming.

INDUSTRIAL APPLICABILITY The light emitting device and the surface light source device according to the present invention can be applied, for example, to backlights of liquid crystal display devices and general illumination.

REFERENCE SIGNS LIST 100 surface light source device 100' display device 102 display member 110 housing 112 bottom plate 114 top plate 116 substrate 120 light emitting device 121 light emitting element 122 light flux controlling member 123 incident surface 123a first incident surface 123b second incident surface 124 reflecting surface 124a first reflecting surface Reflecting surface 124b Second reflecting surface 125 Output surface 126 Leg 130 Light diffusion member LA Optical axis RA1 First rotation axis RA2 Second rotation axis

Claims (6)

A light emitting device comprising: a plurality of light emitting elements arranged in a first direction; and a light flux controlling member for controlling light distribution of light emitted from the plurality of light emitting elements,
The light flux controlling member
an incident surface disposed on the rear surface of the plurality of light emitting elements so as to face the plurality of light emitting elements and for allowing the light emitted from the plurality of light emitting elements to enter;
a reflecting surface disposed on the front surface opposite to the back surface for reflecting light incident on the incident surface;
an exit surface for exiting at least part of the light incident on the incident surface and the light reflected by the reflective surface,
When the light flux controlling member is viewed from above,
in a state in which a first axis parallel to the first direction is virtually arranged so as to overlap the region in which the plurality of light emitting elements are arranged,
The reflective surface is
a first reflective surface for reflecting light incident on the incident surface away from the first axis;
two second reflecting surfaces arranged at both ends of the first reflecting surface in the first direction for reflecting light incident on the incident surface away from the plurality of light emitting elements;
On the first axis passing through the center of the light flux controlling member, the distance between the center and the intersection of the center-side end of the second reflecting surface and the first axis is , shorter than the distance between the intersection of the first axis and the optical axis of the light emitting element positioned at the end among the plurality of light emitting elements;
Luminescent device. The incident surface is
a first incident surface extending in the first direction;
and two second incidence surfaces arranged at opposite ends of the first incidence surface in the first direction,
On the first axis passing through the center of the light flux controlling member, the distance between the center and the intersection of the center-side end of the second incident surface and the first axis is , shorter than the distance between the center-side end of the second reflecting surface and the intersection of the first axis;
A light-emitting device according to claim 1 . The first reflecting surface has no curvature in the first direction and has a shape that separates from the back surface as it separates from the first axis,
The second reflecting surface is a rotationally symmetrical surface about the first rotation axis, and has a shape that separates from the back surface as the distance from the first rotation axis increases.
The light-emitting device according to claim 1 or 2. The first incident surface has no curvature in the first direction and has a shape that approaches the back surface as it separates from the first axis,
The second incident surface is a rotationally symmetrical surface about the second rotation axis, and has a shape that approaches the back surface as the distance from the second rotation axis increases.
The light emitting device according to claim 2. a plurality of light emitting devices according to any one of claims 1 to 4;
a light diffusing member that diffuses and transmits light emitted from the plurality of light emitting devices;
A surface light source device having a surface light source device according to claim 5;
a display member irradiated with light emitted from the surface light source device;
A display device.

Images