WO2018109978A1

WO2018109978A1 - Planar light source device and display device

Info

Publication number: WO2018109978A1
Application number: PCT/JP2017/029372
Authority: WO
Inventors: 中村　真人
Original assignee: 株式会社エンプラス
Priority date: 2016-12-15
Filing date: 2017-08-15
Publication date: 2018-06-21

Abstract

A planar light source device has: a plurality of light emitting elements; a luminous flux control member including a first luminous flux control member which is a diffusing lens, a second luminous flux control member having a Fresnel structure, and a third luminous flux control member having a plurality of lens surfaces; and a diffusion member. When the focal distance of the first luminous flux control member is f, and the distance between a first central axis and an optical axis in the light emitting element separated farthest from the first central axis is d, the planar light source device satisfies –0.6 < d/f < 0. Also, when the width in the cross section including the central axis of the lens surface is w, the radius of curvature of the lens surface is R, and the distance between the diffusion member and the intersection point of the center line of the lens surface and the surface at the diffusion member side in the third luminous flux control member is t, the planar light source device satisfies 0 < w²/t < 0.85 and 0.4 < w/R < 1.4.

Description

Surface light source device and display device

The present invention relates to a surface light source device having a light emitting device including a plurality of light emitting elements and a light flux controlling member, and a display device having the surface light source device.

In recent years, a head-up display (hereinafter also simply referred to as “HUD”) capable of directly displaying information such as a speed display on a screen (for example, a windshield of a car) has been used. In some HUDs, light emitted from a light emitting element is projected onto a screen via a liquid crystal panel or the like after light distribution is controlled by a lens (light flux controlling member). In this case, the user can recognize the information projected by the reflected light from the screen.

In HUD, a surface light source device using a plurality of light emitting elements (for example, LEDs) can be adopted as a light source. However, in a surface light source device using a plurality of light emitting elements, luminance unevenness having a high luminance region and a low luminance region may occur on the emission surface of the surface light source device. Therefore, several means for eliminating such luminance unevenness have been proposed (for example, Patent Document 1).

1A is a cross-sectional view illustrating a configuration of a surface light source device 10 described in Patent Document 1, and FIG. 1B is a plan view illustrating an outline of a lens array 14 included in the surface light source device 10 described in Patent Document 1. FIG. 1C is a graph showing the luminance distribution (relative luminance) of light emitted from the lens array 14 described in Patent Document 1, and FIG. 1D does not have an uneven shape on the boundary line between two adjacent lenses. It is a graph which shows the luminance distribution (relative luminance) of the emitted light from a lens array.

The surface light source device 10 described in Patent Document 1 includes a plurality of LEDs 12 arranged on a substrate 11, a lens array 14, and a diffusion member 15. As shown in FIG. 1A, in the surface light source device 10, seven LEDs 12 are arranged in a line. As shown in FIG. 1B, in the lens array 14, seven lenses 13 are arranged in a line corresponding to the seven LEDs 12. An uneven portion 17 is formed on a boundary line 16 between two adjacent lenses 13 of the lens array 14. In the surface light source device 10 described in Patent Document 1, the emitted light from the LED 12 is focused by the lens 13 and the focused light is diffused by the diffusion member 15. At this time, the brightness of the light emitted from the lens array 14 is averaged by the uneven portion 17. As a result, in the surface light source device 10 described in Patent Document 1, the difference in luminance between the high luminance region and the low luminance region is smaller than in the case where the uneven shape is not formed (see FIG. 1D). (See FIG. 1C).

JP 2011-76832 A

However, as shown in FIG. 1C, the surface light source device 10 described in Patent Document 1 has a problem that luminance unevenness cannot be sufficiently reduced.

Therefore, an object of the present invention is to provide a surface light source device including a light emitting device with small luminance unevenness while using a plurality of light emitting elements. Another object of the present invention is to provide a display device having the surface light source device.

A surface light source device according to the present invention includes a plurality of light emitting elements, a first light flux controlling member, a second light flux controlling member, and a third light flux controlling member, and controls light distribution of light emitted from the plurality of light emitting elements. A surface light source device comprising: a light emitting device having a luminous flux control member; and a diffusing member that is disposed through the light emitting device and an air layer and is irradiated with light emitted from the light emitting device. The one-beam control member intersects with the first central axis and a concave first incident surface disposed to face the plurality of light emitting elements so as to intersect with the first central axis of the first light-beam control member. An inner exit surface disposed on the outer surface, and an outer exit surface that is disposed so as to surround the inner exit surface and has a convex shape in a cross section including the first central axis. A first light exit surface disposed, and the second light flux control. The member controls the light emitted from the first light flux controlling member to go in a direction along the first central axis, and the third light flux controlling member takes the light emitted from the second light flux controlling member. And a third exit surface disposed on the opposite side of the third entrance surface, and the third entrance surface or the third exit surface has a third light flux controlling member. A plurality of convex lens surfaces having a convex shape or a plurality of concave concave lens surfaces in a cross section including the third central axis are two-dimensionally arranged, and the focal length of the first light flux controlling member is f, and the first central axis And the distance from the optical axis of the light emitting element farthest from the first central axis, where d is the convex lens surface or concave shape in the cross section including the third central axis, which satisfies the following formula (1): The width of the plurality of concave lens surfaces is w, and the convex lens surface or When the radius of curvature of the concave lens surface is R, and the intersection of the convex lens surface or the center line of the concave lens surface and the surface on the diffusion member side in the third light flux controlling member, and the distance of the diffusion member is t, A surface light source device that satisfies the following expressions (2) and (3).
-0.6 <d / f <0 (1)
0 <w ² /t<0.85 (2)
0.4 <w / R <1.4 (3)

The display device according to the present invention includes the surface light source device according to the present invention and a display member that is irradiated with light emitted from the surface light source device.

According to the present invention, it is possible to provide a surface light source device including a light emitting device with little luminance unevenness while using a plurality of light emitting elements, and a display device having the surface light source device.

1A and 1B are diagrams for explaining the configuration of the surface light source device described in Patent Document 1, and FIGS. 1C and 1D are graphs for explaining the luminance distribution of light emitted from the lens array. 2A is a cross-sectional view of the display device according to Embodiment 1 of the present invention, and FIG. 2B is a diagram showing a display area of the display device shown in FIG. 2A. 3A to 3D are diagrams showing the configuration of the first light flux controlling member. 4A to 4D are diagrams showing the configuration of the second light flux controlling member. 5A to 5D are diagrams showing the configuration of the third light flux controlling member. 6A and 6B are sectional views of other third light flux controlling members. FIG. 7 is a diagram illustrating an optical path of the display device. 8A and 8B are diagrams for explaining the relationship between the light flux controlling member and the light emitting element. 9A and 9B are diagrams for explaining the irradiation region. 10A and 10B are diagrams for explaining the expression (2). 11A and 11B are diagrams for explaining the expression (3). FIG. 12 is a diagram for explaining the equations (4) and (5). FIG. 13 is a diagram for explaining the equation (6). 14A to 14D are diagrams for explaining bfl. 15A to 15C are diagrams for explaining the expression (7). 16A and 16B are diagrams for explaining the expression (8). 17A to 17D are diagrams showing the configuration of the third light flux controlling member according to the second embodiment. 18A and 18B are diagrams illustrating a configuration of a display device according to Embodiment 2. FIG. 19 is a schematic diagram illustrating the configuration of the display device used in the example. FIG. 20 is a graph showing the relationship between w ² / t and the uniformity U0 in the display device. FIG. 21 is a graph showing the relationship between w / R and the uniformity ratio U5 / U0 in the display device. FIG. 22A is a graph showing the relationship between (w × bfl) / t and uniformity U0 in another display device in which a convex lens surface or a concave lens surface is arranged on the third incident surface side, and FIG. It is a graph which shows the relationship between | w / bfl | in a display apparatus, and uniformity ratio U5 / U0. FIG. 23A is a graph showing the relationship between (w × bfl) / t and uniformity U0 in another display device in which a convex lens surface or a concave lens surface is arranged on the third exit surface side, and FIG. It is a graph which shows the relationship between | w / bfl | in an apparatus, and uniformity ratio U5 / U0.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, a display device that can be used to display information on a screen in a HUD will be described. The HUD has a display device, a projection lens for appropriately projecting light from the display device onto the screen, and a screen. Light emitted from the display device is irradiated onto the screen through a projection optical system including a projection lens.

[Embodiment 1]
(Configuration of surface light source device and display device)
2A is a cross-sectional view of display device 100 according to Embodiment 1 of the present invention, and FIG. 2B is a diagram showing display area 121 of display device 100 shown in FIG. 2A. In FIG. 2A, the first leg, the second leg, and the third leg are omitted.

2A and 2B, the display device 100 according to Embodiment 1 includes a surface light source device 110 and a display member 120.

The surface light source device 110 is a light source of the display device 100. The surface light source device 110 includes a light emitting device 130 and a diffusing member 140. The light emitting device 130 includes a plurality of light emitting elements 112 and a light flux control member 113 including a first light flux control member 114, a second light flux control member 115, and a third light flux control member 116, and is disposed on the substrate 111. Yes.

The substrate 111 supports the plurality of light emitting elements 112 and the light flux controlling member 113. The type of the substrate 111 is not particularly limited. As the substrate 111, a circuit substrate is preferably used from the viewpoint of supplying electricity to the light emitting element 112. For example, the substrate 111 is a glass composite substrate, a glass epoxy substrate, an Al substrate, or the like.

The plurality of light emitting elements 112 are light sources of the surface light source device 110 and are fixed on the substrate 111. For example, the light emitting element 112 is a light emitting diode (LED). The colors of light emitted from the plurality of light emitting elements 112 may be the same or different from each other. In the present embodiment, the colors of light emitted from the plurality of light emitting elements 112 are all the same. Further, the color of light emitted from the light emitting element 112 is not particularly limited. The types of colors of light emitted from the light emitting element 1122 include white, red, blue, green, and the like. In general, the light emitting element 112 emits light most strongly in the normal direction with respect to the light emitting surface of the light emitting element 112.

The number of the light emitting elements 112 can be appropriately changed according to the size of the display member 120, the distance between the substrate 111 and the display member 120, and the like. In the present embodiment, the number of light emitting elements 112 is three. The arrangement of the plurality of light emitting elements 112 is not particularly limited. The plurality of light emitting elements 112 may be arranged on a straight line, may be arranged at a position corresponding to a vertex of a polygon, or may be arranged in an annular shape. In the present embodiment, the plurality of light emitting elements 112 are arranged on a straight line.

Further, in the present embodiment, the optical axis of the light emitting element 112 disposed in the center and the first central axis CA1 (second central axis CA2 and third central axis CA3) are arranged to coincide. Yes. Here, the “optical axis of the light emitting element 112” refers to the traveling direction of light at the center of the total luminous flux emitted three-dimensionally from the light emitting element 112. The “optical axis of the plurality of light emitting elements 112” refers to the traveling direction of light at the center of the total luminous flux emitted three-dimensionally from the plurality of light emitting elements 112. Further, the interval between the adjacent light emitting elements 112 (the distance between the optical axes of the adjacent light emitting elements 112) is not particularly limited.

The light flux controlling member 113 controls the light distribution of the light emitted from the light emitting element 112. The light flux control member 113 includes a first light flux control member 114, a second light flux control member 115, and a third light flux control member 116. The first central axis CA1 of the first light flux control member 114, the second central axis CA2 of the second light flux control member 115, and the third central axis CA3 of the third light flux control member 116 may coincide with each other. , Do not have to match. In the present embodiment, the first central axis CA1 of the first light flux controlling member 114, the second central axis CA2 of the second light flux controlling member 115, and the third central axis CA3 of the third light flux controlling member coincide with each other. Yes.

The first light flux control member 114, the second light flux control member 115, and the third light flux control member 116 are sequentially arranged from the light emitting element 112 side toward the diffusion member 140 side. The first light flux controlling member 114 is disposed on the light emitting element 112 side, and the second light flux controlling member 115 is disposed at a position (diffusing member 140 side) away from the first light flux controlling member 114 with respect to the light emitting element 112. Yes. Further, the third light flux controlling member 116 is disposed at a position (on the diffusing member 140 side) away from the second light flux controlling member 115 with respect to the light emitting element 112. The first light flux controlling member 114 (the first incident surface 131 and the first light exiting surface 132 (see FIG. 3)) is rotationally symmetric with the first central axis CA1 as the rotation axis, and the second light flux controlling member 115 (second The incident surface 141 and the second exit surface 142 (see FIG. 4) are rotationally symmetric with the second central axis CA2 as the rotation axis.

The materials of the first light flux control member 114, the second light flux control member 115, and the third light flux control member 116 may be the same or different. Examples of the material of the first light flux control member 114, the second light flux control member 115, and the third light flux control member 116 include light transmissivity such as polymethyl methacrylate (PMMA), polycarbonate (PC), and epoxy resin (EP). Resins and light-transmitting glass are included. Moreover, the 1st light beam control member 114, the 2nd light beam control member 115, and the 3rd light beam control member 116 are manufactured by injection molding, for example. The configurations of the first light flux control member 114, the second light flux control member 115, and the third light flux control member 116 will be described later.

The diffusing member 140 diffuses and transmits the light emitted from the surface light source device 110. Examples of the diffusing member 140 include a transparent plate-like member that has been subjected to light diffusion treatment (for example, roughening treatment) and a transparent plate-like member that is mixed with scatterers such as beads.

The display member 120 is, for example, a liquid crystal panel. The display member 120 has a display area 121 in which an image to be projected on the screen is displayed. The display area 121 is uniformly irradiated with light controlled by the surface light source device 110. In the present embodiment, when the long side of the display member 120 is represented by X and the short side is represented by Y, the region represented by 0.8X × 0.8Y is defined as the display region 121 (see FIG. 2B).

The light distribution of the light emitted from the light emitting element 112 is controlled by the first light flux control member 114, the second light flux control member 115, and the third light flux control member 116. The light emitted from the third light flux controlling member 116 is transmitted while being diffused by the diffusing member 140 and illuminates the display member 120 uniformly.

(Configuration of luminous flux control member)
As described above, the light flux control member 113 includes the first light flux control member 114, the second light flux control member 115, and the third light flux control member 116. FIG. 3 is a diagram illustrating a configuration of the first light flux controlling member 114. 3A is a plan view of the first light flux controlling member 114, FIG. 3B is a bottom view, FIG. 3C is a side view, and FIG. 3D is a sectional view taken along line AA shown in FIG. 3A. It is.

The first light flux controlling member 114 controls the light distribution of the light emitted from the light emitting element 112. As shown in FIGS. 3A to 3D, the first light flux controlling member 114 has a first incident surface 131 and a first emission surface 132. The first light flux controlling member 114 may be provided with a first flange 133. A first leg (not shown) for fixing the first light flux controlling member 114 to the substrate 111 may be provided on the back side of the first flange 133. The first light flux controlling member 114 is disposed to face the light emitting element 112. The method for fixing the first light flux controlling member 114 to the substrate 111 is not particularly limited, and adhesive fixing, screwing, fixing with a holder, or the like may be employed. For example, the first light flux controlling member 114 and the substrate 111 can be fixed to each other by bonding the first leg to the substrate 111 with an adhesive.

The first incident surface 131 causes the light emitted from the light emitting element 112 to enter the first light flux controlling member 114 and refracts the incident light toward the first outgoing surface 132. The first incident surface 131 is disposed so as to face the light emitting surface of the light emitting element 112 and intersect the first central axis CA1. The shape of the 1st entrance plane 131 will not be specifically limited if the above-mentioned function can be exhibited. In the present embodiment, the first incident surface 131 is the inner surface of the first recess 134 that is disposed to face the light emitting surface of the light emitting element 112. The first incident surface 131 may be a spherical surface or an aspherical surface. In the present embodiment, the first incident surface 131 has a negative power with respect to a part of the light emitted from the light emitting element 112. That is, the shape of the first incident surface 131 is a concave lens shape, and the first incident surface 131 is an aspherical surface.

The first emission surface 132 causes the light traveling inside the first light flux controlling member 114 to be emitted to the outside. The first exit surface 132 is disposed on the opposite side of the first entrance surface 131 (on the second light flux controlling member 115 side). The first emission surface 132 has an inner first emission surface 132a and an outer first emission surface 132b.

The inner first emission surface 132a is disposed so as to intersect with the first central axis CA1. The shape of the inner first emission surface 132a is not particularly limited as long as light is emitted so as to be expanded with respect to the first central axis CA1. That is, the shape of the inner first exit surface 132a is formed in a concave shape when the light beam reaching the inner first exit surface 132a is further expanded with respect to the first central axis CA. In this case, the inner first emission surface 132a has a negative power with respect to the light reaching the inner first emission surface 132a. On the other hand, in order to prevent the light beam reaching the inner first emission surface 132a from spreading too much with respect to the first central axis CA, it is formed into a shallow ridge. In this case, the inner first emission surface 132a has a positive power with respect to the light reaching the inner first emission surface 132a. In any case, the light emitted from the inner first emission surface 132a is controlled so as to be expanded with respect to the first central axis CA1.

The outer first emission surface 132b is disposed at a position away from the inner first emission surface 132a with respect to the first central axis CA1 so as to surround the inner first emission surface 132a. The outer first exit surface 132b refracts (condenses) part of the light incident on the first incident surface 131 toward the first central axis CA1. In other words, the outer first emission surface 132b has a positive power with respect to light emitted from the light emitting element 112 and having a large emission angle with respect to the first central axis CA1. The shape of the outer first emission surface 132b is a convex lens shape, and the outer first emission surface 132b is an aspherical surface.

FIG. 4 is a diagram showing a configuration of the second light flux controlling member 115. 4A is a plan view of the second light flux controlling member 115, FIG. 4B is a bottom view, FIG. 4C is a side view, and FIG. 4D is a sectional view taken along line AA shown in FIG. 4A. It is.

The second light flux controlling member 115 controls the light emitted from the first light flux controlling member 114 to be substantially parallel light. As shown in FIGS. 4A to 4D, the second light flux controlling member 115 has a second incident surface 141 and a second emitting surface 142. The shape of the second light flux controlling member 115 is not particularly limited as long as the above function can be exhibited. The second light flux controlling member 115 may have a convex lens surface on the second incident surface 141, and may have a convex lens surface on the second outgoing surface 142. From the viewpoint of miniaturization, the second light flux controlling member 115 may have a refractive Fresnel lens part or a reflective Fresnel lens part. In the present embodiment, the second light flux controlling member 115 has a refractive Fresnel lens portion 145 on the second exit surface 142. The second light flux controlling member 115 having the refractive Fresnel lens portion 145 can absorb an assembly error as compared with the second light flux controlling member 115 having the reflective Fresnel lens portion. The second light flux controlling member 115 may be provided with a second flange 143. Further, on the back side of the second flange 143, a second leg (not shown) for fixing the second light flux controlling member 115 to the substrate 111 may be provided. The method for fixing the second light flux controlling member 115 to the substrate 111 is not particularly limited, and adhesive fixing, screwing, fixing with a holder, or the like may be employed. For example, the second light flux controlling member 115 and the substrate 111 can be fixed to each other by bonding the second leg portion to the substrate 111 with an adhesive.

The second incident surface 141 causes the light emitted from the first light flux controlling member 114 to enter the second light flux controlling member 115 and refract it toward the Fresnel lens portion 145. The shape of the 2nd entrance plane 141 will not be specifically limited if the above-mentioned function can be exhibited. In the present embodiment, second incident surface 141 is a flat surface.

The second emission surface 142 emits the light traveling inside the second light flux controlling member 115 to the outside and refracts the light so as to be substantially parallel to the second central axis CA2. The second exit surface 142 has a Fresnel lens portion 145. The Fresnel lens portion 145 has a plurality of convex portions 146 arranged concentrically and having a circular shape in plan view.

Each of the plurality of convex portions 146 has a refracting surface 147 that refracts incident light and a connection surface 148 that connects adjacent refracting surfaces 147. In the convex portion 146, the refracting surface 147 is disposed on the outer side, and the connecting surface 148 is disposed on the inner side (second central axis CA2 side). The plurality of refracting surfaces 147 are arranged so that the first central axis CA1 (second central axis CA2) of the first light flux controlling member 114 (second light flux controlling member 115) and the optical axis OA coincide with each other. It is designed so that the light emitted from 112 becomes parallel light.

FIG. 5 is a diagram showing a configuration of the third light flux controlling member 116. 5A is a plan view of the third light flux controlling member 116, FIG. 5B is a bottom view, FIG. 5C is a side view, and FIG. 5D is a sectional view taken along line AA shown in FIG. 5A. It is. 6A and 6B are sectional views showing another third light flux controlling member 116. FIG.

The third light flux controlling member 116 emits the light emitted from the second light flux controlling member 116 toward the diffusing member 140 while controlling so that luminance unevenness does not occur. As shown in FIGS. 5A to 5D, the third light flux controlling member 116 has a third entrance surface 151 and a third exit surface 152. Note that the third light flux controlling member 116 may have a third flange 154. The third incident surface 151 allows the light emitted from the second light flux controlling member 115 to enter. In the example shown in FIG. 5, the shape of the third entrance surface 151 is a plane.

The third exit surface 152 is disposed on the opposite side of the third entrance surface 151 and emits the light traveling inside the third light flux controlling member 116 toward the diffusing member 140. The third emission surface 152 includes a plurality of convex lens surfaces 153 or a plurality of concave lens surfaces having a convex cross-sectional shape including the third central axis CA3. Here, the “third central axis CA3” means a central portion of the third emission surface 152 when the third light flux controlling member 116 is viewed in plan. In addition, “a cross section including the third central axis CA3” means a cross section cut along a plane including the third central axis CA3 and a second direction described later. In the example shown in FIG. 5, the third light flux controlling member 116 has a convex lens surface 153 on the third exit surface 152, but is not limited thereto, and has a convex lens surface 153 on the third incident surface 151. Also good. Further, as shown in FIG. 6A, the third entrance surface 151 may have a concave lens surface 155, and as shown in FIG. 6B, the third exit surface 152 has a concave lens surface 155. Also good. In addition, when the convex lens surface 153 is arrange | positioned at the 3rd entrance surface 151 and the 3rd output surface 152, the condensing effect of the light which passed through the convex lens of both surfaces has an effect equivalent to the case where the convex lens surface is formed in one side. The third light flux controlling member is highly accurate compared to the case where it is formed on one side, for example, adjustment is necessary to obtain it, or it is necessary to align the convex lens on one surface and the convex lens on the other surface. Difficulty in creating 116.

The convex lens surface 153 includes a ridge line extending linearly in a first direction perpendicular to the thickness direction of the third light flux controlling member 116, and in a second direction perpendicular to the thickness direction and the first direction. Only curved surface with curvature. That is, the convex lens surface 153 according to the present embodiment has a cylindrical structure. A plurality of convex lens surfaces 153 are arranged in the second direction without any gap. The cross-sectional shape of the convex lens surface 153 including the third central axis CA3 may be an arc, a curve having a radius of curvature that increases with distance from the top, or a portion that intersects the third central axis CA3 is an arc. Thus, the curve may have a radius of curvature that increases with distance from the arc. The thickness direction of the third light flux controlling member 116 is a direction along the third central axis CA3.

Further, on the back side of the third flange 154, a third leg (not shown) for fixing the third light flux controlling member 116 to the substrate 111 may be provided. A method for fixing the third light flux controlling member 116 to the substrate 111 is not particularly limited, and adhesive fixing, screwing, fixing with a holder, or the like may be employed. For example, the third light flux controlling member 116 and the substrate 111 can be fixed to each other by bonding the third leg portion to the substrate 111 with an adhesive.

As described above, as shown in FIGS. 6A and 6B, the third light flux controlling member 116 may have a plurality of concave lens surfaces 155 on the third incident surface 151 or the third emitting surface 152. The concave lens surface 155 includes a ridge line extending linearly in a first direction perpendicular to the thickness direction of the third light flux controlling member 116, and in a second direction perpendicular to the thickness direction and the first direction. Only curved surface with curvature. A plurality of concave lens surfaces 155 are arranged in the second direction without a gap. The cross-sectional shape of the concave lens surface 155 including the third central axis CA3 may be an arc, a curve having a radius of curvature that increases with distance from the top, or a portion that intersects the third central axis CA3 is an arc. Thus, the curve may have a radius of curvature that increases with distance from the arc. The thickness direction of the third light flux controlling member 116 is a direction along the third central axis CA3.

FIG. 7 is a diagram showing an optical path of the display device 100. In FIG. 7, hatching is omitted to show the optical path. As shown in FIG. 7, the light emitted from each light emitting element 112 is controlled by the first light flux control member 114 so as to be mixed when it reaches the second light flux control member 115, and from the first emission surface 132. Emitted. The light emitted from the first light flux control member 114 reaches the second light flux control member 115. At this time, the light density of the light reaching the second light flux controlling member 115 is controlled to be low in the central part and high in the peripheral part. In other words, the second incident surface 141 of the second light flux controlling member 115 has a low luminous intensity near the optical axis and a high luminous intensity at a large angle with respect to the optical axis. As a result, the illuminance at the second light flux controlling member 115 is uniform from the vicinity of the optical axis to the peripheral portion. The light reaching the second light flux controlling member 115 is controlled by the second light flux controlling member 115 so as to be substantially parallel light, and is emitted from the second light exit surface 142. The light emitted from the second light flux control member 115 reaches the third light flux control member 116. The light reaching the third light flux controlling member 116 is controlled by the third light flux controlling member 116 so that the luminance is uniform even when the display device 100 is viewed obliquely, and is emitted from the third light exit surface 152. The light emitted from the third emission surface 152 illuminates the display member 120 so that the luminance is uniform even when the display device 100 is viewed obliquely.

The light emitted from the light emitting element 112 is controlled by the first light flux control member 114 and the second light flux control member 115 so as to be substantially parallel to the optical axis. The light controlled by the first light flux control member 114 and the second light flux control member 115 is incident on the third light flux control member 116. From the viewpoint of improving the utilization efficiency of the light emitted from the light emitting element 112, it is preferable that most of the light emitted from the first light flux controlling member 114 is incident on the second light flux controlling member 115. Therefore, the distance between the first light flux control member 114 and the second light flux control member 115 so that most of the light emitted from the first light flux control member 114 enters the second light flux control member 115. Is set.

In the display device 100 described above, the light emitting element 112 and the light flux controlling member 113 are arranged so as to satisfy the following expression (1).
-0.6 <d / f <0 (1)
Here, d is a distance between the first central axis CA1 of the first light flux controlling member 114 and the optical axis OA in the light emitting element 112 farthest from the central axis CA1 of the first light flux controlling member 114 (hereinafter simply referred to as “distance”. d ”). Further, f is a focal length of the first light flux controlling member 114 (hereinafter also simply referred to as “focal length f”).

The relationship between the light emitting element 112 and the light flux controlling member 113 will be described with reference to FIGS. FIG. 8A is a diagram for explaining the focal length f of the first light flux controlling member 114, and FIG. 8B is a diagram for explaining the relationship between the focal length f and the distance d. 9A and 9B are diagrams for explaining the irradiation region S. FIG. FIG. 9A is a diagram for explaining an irradiation region when the distance d is large, and FIG. 9B is a diagram for explaining the irradiation region when the distance d is small.

Since the first light flux controlling member 114 functions in the direction of expanding the light emitted from the light emitting element 112 as a whole lens, the focal length f is defined as follows. As shown in FIG. 8A, for the focal length f of the first light flux controlling member 114, first, virtual incident light L1 parallel to the first central axis CA1 of the first light flux controlling member 114 is transmitted from the first incident surface 131 side. Assume that it is incident. Next, a virtual outgoing light L <b> 1 ′ from which the virtual incident light L <b> 1 is emitted from the first outgoing surface 132 is assumed. Next, the intersection point when the virtual incident light L1 extends in the incident direction and the virtual emitted light L1 'extends in the direction opposite to the emission direction is defined as a principal point A. Next, an intersection point between a virtual line obtained by further extending the virtual outgoing light L1 ′ emitted from the first outgoing surface 132 opposite to the outgoing direction and the first central axis CA1 of the first light flux controlling member 114 is defined as a focal point F. To do. At this time, the distance along the first central axis CA1 between the principal point A and the focal point F is the focal length f. In the present embodiment, the focal length f is a negative value.

Next, the relationship between the focal length f and the distance d will be described. As shown in FIG. 8B, here, three

light emitting elements

112a, 112b, and 112c in which the distance between the centers of the optical axes is arranged in a line at a distance d and one first light flux controlling member 114 are arranged. Assuming that Further, it is assumed that the optical axis OAb of the light emitting element 112b disposed at the center coincides with the first central axis CA1 of the first light flux controlling member 114. That is, the light emitting element 112 farthest from the first central axis CA1 of the first light flux controlling member 114 is the light emitting element 112a (light emitting element 112c). Furthermore, the arrival points on the virtual irradiated surface Q (corresponding to the diffusing member 140 of the present embodiment) of the virtual emitted light emitted from each of the

light emitting elements

112a, 112b, and 112c are defined as Pa, Pb, and Pc, respectively.

As shown in FIG. 8B, the distance between the first central axis CA1 of the first light flux controlling member 114 and the optical axis OA in the light emitting element 112a (112c) farthest from the first central axis CA1 (adjacent light emitting elements 112). It can be seen that the distance D between the arrival points in the virtual plane of the light beams emitted from the

light emitting elements

112a, 112b, and 112c becomes longer as the distance d between the centers of the light sources becomes longer. Here, since the light emitted from the

light emitting elements

112a, 112b, and 112c illuminates a predetermined area (irradiation area S) on the virtual plane, the irradiation areas S irradiated by the

light emitting elements

112a, 112b, and 112c overlap each other. The area becomes smaller (see FIG. 9A). Conversely, when the distance d is shortened, the area where the irradiation regions S irradiated by the

light emitting elements

112a, 112b, and 112c overlap each other increases (see FIG. 9B). Thus, by adjusting the distance d, the area where the regions irradiated by the

light emitting elements

112a, 112b, and 112c overlap can be adjusted.

On the other hand, as shown in FIG. 8B, when the focal length f of the first light flux controlling member 114 is shortened, the distance D between the reaching points in the virtual plane of the light beams emitted from the respective

light emitting elements

112a, 112b, and 112c is lengthened. I understand that. Here, since the light emitted from the

light emitting elements

112a, 112b, and 112c overlap each other. The area becomes smaller (see FIG. 9A). Conversely, as the focal length f increases, the area where the irradiation regions S irradiated by the

light emitting elements

112a, 112b, and 112c overlap each other increases (see FIG. 9B). Thus, by adjusting the focal length f, the area where the regions irradiated by the

light emitting elements

112a, 112b, and 112c overlap each other can be adjusted.

As described above, the distance d between the focal length f and the optical axis of the light emitting element 112 farthest from the first central axis CA1 of the first light flux controlling member 114 greatly affects the uniformity in the display member 120 described later. . More specifically, when d / f becomes −0.6 or less due to an increase in d, the overlap between the irradiation regions S of the light emitted from the light emitting elements 112 is reduced. In particular, in the case of a rectangular screen, there is less overlap in the long (long side) direction than in the short (short side) direction, so that sufficient luminance cannot be secured at the end in the long direction. On the other hand, when attempting to make f brighter and brighten the periphery, the absolute value of d / f becomes even smaller, and the overlap between the irradiation areas S becomes smaller.

When d / f is greater than 0, the positive power of the first light flux controlling member 114 becomes too strong, the light density at the center becomes higher than the light density at the periphery, and the brightness at the center increases. .

On the other hand, when d / f satisfies −0.6 <d / f <0, the irradiation areas of the light emitted from the light emitting elements 112 are appropriately overlapped, and thus uneven luminance is suppressed.

In the display device 100 described above, the light flux controlling member 113 and the diffusing member 140 are further arranged so as to satisfy the following expressions (2) and (3).
0 <w ² /t<0.85 (2)
0.4 <w / R <1.4 (3)
Here, w is the width of the convex lens surface 153 or the concave lens surface 155 in the cross section including the third central axis CA3. R is the radius of curvature of the convex lens surface or concave lens surface 155. t is the intersection of the center line of the convex lens surface 153 or the concave lens surface 155 and the surface of the third light flux controlling member 116 on the diffusion member 140 side (the top of the convex lens surface 153 or the bottom of the concave lens surface 155) and the diffusion member 140. Distance.

10 and 11, the relationship between the third light flux controlling member 116 and the diffusing member 140 will be described. FIG. 10A is a diagram illustrating a relationship between the third light flux controlling member 116 and the diffusing member 140 according to the present embodiment, and FIG. 10B is a relationship between the third light flux controlling member 116 and the diffusing member 140 according to the comparative example. FIG. 10A and 10B, the third light flux controlling member 116 and the diffusing member 140 are not hatched to show the optical path. Here, the third light flux controlling member 116 having the convex lens surface 153 on the third exit surface 152 will be described as an example, but the third light flux controlling member 116 having the convex lens surface 153 on the third incident surface 151. It is the same. The same applies to the third light flux controlling member 116 having the concave lens surface 155 on the third incident surface 151 or the third emitting surface 152.

As shown in FIG. 10A, in display device 100 in which third light flux controlling member 116 and diffusing member 140 are arranged so that w ² / t is greater than 0 and less than 0.85, In FIG. 5, since the light emitted from the convex lens surfaces 153 overlaps, the luminance unevenness can be suppressed. Further, it is preferable that w ² / t has a smaller value because luminance unevenness when the display device 100 is viewed in plan is reduced. However, w is smaller than the processing limit of the convex lens surface 153 or t is too large. Therefore, w ² / t is more preferably 0.0001 or more.

On the other hand, if w ² / t exceeds 0.85 by increasing w or decreasing t, the overlap of light emitted from the third light flux controlling member 116 on the diffusing member 140 decreases. Thereby, when the display device 100 is viewed in plan, luminance unevenness occurs. Note that FIG. 10B illustrates the case where w increases.

FIG. 11A is a diagram illustrating the relationship between the width w of the third light flux controlling member 116 according to the comparative example and the radius of curvature R of the convex lens surface 153, and FIG. 11B illustrates the third light flux controlling member 116 according to the comparative example. It is a figure which shows the relationship between the width w and the curvature radius R of the convex lens surface 153. FIG. 11A and 11B, the third light flux controlling member 116 and the diffusing member 140 are not hatched to show the optical path.

When w becomes small or w / R becomes 0.4 or less because R becomes large, the power to refract the light becomes small, and the amount of light emitted obliquely with respect to the optical axis OA decreases. When the display device 100 is viewed from an oblique direction, the end portion becomes dark and uneven brightness occurs. Note that FIG. 11A illustrates a case where w is reduced.

On the other hand, when w is increased or w / R is 1.4 or more because R is decreased, the power for refracting light is increased, and the optical axis OA of the light emitted from the third light flux controlling member 116 is increased. The angle with respect to becomes too large. As a result, luminance unevenness when the display device 100 is viewed obliquely is improved, but the amount of light required for the display device 100 cannot be secured.

Although not particularly illustrated, if w / R is more than 0.4 and less than 1.4, luminance unevenness does not occur and the amount of light required for the display device 100 can be secured.

(effect)
As described above, in the display device 100 having the surface light source device 120 according to the first embodiment, the focal length f of the first light flux control member 114, the first central axis CA1 and the first light flux of the first light flux control member 114. The distance d from the optical axis OA of the light emitting element 112 farthest from the first central axis CA1 of the control member 114 satisfies −0.6 <d / f <0. Further, the width w of the convex lens surface 153 or the concave lens surface 155 in the cross section including the third central axis CA3, the radius of curvature R of the convex lens surface 153 or the concave lens surface 155, the center line of the convex lens surface 153 or the concave lens surface 155, and the third light flux. The distance t between the intersection of the control member 116 and the surface on the diffusion member 140 side and the diffusion member 140 satisfies 0 <w ² /t<0.85 and 0.4 <w / R <1.4. As shown in the examples described later, by setting d / f, w ² / t, and w / R within predetermined ranges, the display member 120 is used even when a plurality of light emitting elements 112 are used. Can be illuminated uniformly.

In addition, since the second light flux controlling member 115 includes the refractive type Fresnel lens portion 145, when the display device 100 is assembled, it is possible to absorb an assembly error.

(Preferred modification 1)
Next, conditions for preventing uneven luminance in the display device 100 according to Embodiment 1 will be described. As described above, in the display device 100, the light emitting element 112 and the light flux controlling member 113 are disposed so as to satisfy the following expressions (1) to (3).
-0.6 <d / f <0 (1)
0 <w ² /t<0.85 (2)
0.4 <w / R <1.4 (3)

The display device 100 is configured to further satisfy the following formulas (4) to (6) in addition to the above-described formulas (1) to (3), thereby further preventing luminance unevenness.

FIG. 12 is a diagram for explaining the equations (4) and (5). FIG. 13 is a diagram for explaining the equation (6). In FIG. 12, hatching of the substrate 111, the light emitting element 112, and the first light flux controlling member 114 is omitted to show the optical path. In FIG. 13, hatching of the substrate 111, the light emitting element 112, the first light flux control member 114, and the second light flux control member 115 is omitted to show the optical path.

As shown in FIG. 12, the light emitting device 130 (display device 100) includes the first light beam L1 emitted from the light emission center of the light emitting element 112 arranged so that the optical axis OA coincides with the first central axis CA1. The emission angle is θ1 _n , the first light beam L1 is controlled by the first light beam control member 114, and then is emitted from the first light beam control member 114, and the second light beam L2 is generated with respect to the first central axis CA1. When the angle is θ2 _n , the light emitting device 130 further satisfies the following expression (4). Further, n represents the number of an arbitrary ray in a cross section including the first central axis CA and the second central axis CA2.

In equation (4), 0 ° <θ1 _n <θ1 _{n + 1} <60 °, and θ2 _n is the angle of the light beam corresponding to θ1 _n .

As described above, the display device 100 is configured so that θ2 _n increases as θ1 _n increases. Thereby, since the second light beam L2 generated by being emitted from the first emission surface 132 of the first light flux controlling member 114 does not overlap, continuous light can be incident on the second light flux controlling member 115.

Further, the display device 100 further satisfies the following formula (5).

In Expression (5), 0 ° <θ1 _n−1 <θ1 _n <θ1 _{n + 1} <60 °.

Thus, the light emitting device 130 (display device 100), .theta.1 _n with increasing configured so that the ratio of the amount of increase in .theta.2 _n to increasing .theta.1 _n decreases. This is because when the first central axis CA1 side is the central portion and the first flange 133 side is the peripheral portion, the second light ray L2 emitted from the peripheral portion of the first emission surface 132 is incident on the first emission surface 132. This means that the light beam is emitted so as to have a denser light density than the second light beam L2 emitted from the central portion. Therefore, the light density in the central part where the light beam with high intensity reaches is sparse, and the light density in the peripheral part where the light beam with low intensity reaches is dense. Thereby, the illuminance on the second incident surface 141 of the second light flux controlling member 115 becomes uniform. In the present embodiment, the case where the light emitting element 112 arranged so as to coincide with the first central axis CA1 is shown, but the case where the light emitting element arranged so as to coincide with the first central axis CA1 does not exist. The optical axis OA is the total light beam optical axis that is the center of all three-dimensional total light beams of the plurality of light emitting elements 112 mounted on the same substrate 111 surface, and the light emitting surface of the light emitting element 112 mounted on the same substrate 111 surface Considering the intersection of the extension line and the optical axis OA as a virtual emission point, the emission angle of the first light ray L1 emitted from the virtual emission point as θ1 _n, and satisfying equations (4) and (5) Thus, the first light flux controlling member 114 is designed.

As shown in FIG. 13, in the light emitting device 130 (display device 100), the second light beam L <b> 2 is controlled by the second light flux control member 115 and then emitted from the second light exit surface 142 of the second light flux control member 115. In the case where the angle of the third light beam L3 generated with respect to the first central axis CA1 is θ3, it is preferable to satisfy the following expression (6).
-6 ° <θ3 <10 ° (6)

In Equation (6), 0 ° <θ1 <40 °, θ3 is an angle of the third light beam L3 emitted from the second light beam control member 115 with respect to the first central axis CA. θ3 is a minus “−” angle of the third light ray L3 traveling toward the first central axis CA1 with the angle of the light L0 traveling parallel to the first central axis CA1 being 0 °, with respect to the first central axis CA1. And the angle of the third light ray L3 with respect to the first central axis CA1 traveling away from the first central axis CA1 is a plus “+” value.

Thus, the third light beam L3 generated by being emitted from the second light flux controlling member 115 is emitted so as to be substantially parallel to the first central axis CA1. When θ3 is 10 ° or more, the degree of divergence increases, and the third light ray L3 travels so as to be significantly away from the first central axis CA1. Thereby, the 1st central axis CA1 side (center part) will become dark. On the other hand, when θ3 is less than −6 °, the degree of light collection increases, and the third light ray L3 travels toward the first central axis CA1. As a result, a region (peripheral portion) away from the first central axis CA1 becomes dark.

As described above, since the display device 100 further satisfies the above-described expressions (4) to (6), luminance unevenness is suppressed.

(Preferred modification 2)
Next, in the display device 100 according to the first embodiment, another condition for preventing luminance unevenness from occurring will be described. As described above, in the display device 100, the light emitting element 112 and the light flux controlling member 113 are disposed so as to satisfy the following expressions (1) to (3).
-0.6 <d / f <0 (1)
0 <w ² /t<0.85 (2)
0.4 <w / R <1.4 (3)

The display device 100 is configured to further satisfy the following formulas (7) to (8) in addition to the above-described formulas (1) to (3), thereby further preventing luminance unevenness.

−15 <w × bfl / t <3 (7)
0.2 <| w / bfl | <1.0 (8)
Here, bfl is a distance between a predetermined point of the third light flux controlling member 116 and the focal point of the optical surface of the third light flux controlling member 116, and the focal point is located closer to the diffusing member 140 than the predetermined point. The case is set to a positive value, and the case located on the second light flux controlling member 115 side is set to a negative value. Accordingly, when the third light flux controlling member 116 has the convex lens surface 153, bfl is a positive value, and when the third light flux controlling member 116 has the concave lens surface 155, bfl is a negative value. When the third light flux controlling member 116 has the convex lens surface 153, bfl is the length of the intersection of the center line of the convex lens surface 153 and the surface of the third light flux controlling member 116 on the diffusing member 140 side and the focal point of the convex lens surface 153. It is (a positive value). When the third light flux controlling member 116 has the concave lens surface 155, bfl is the intersection of the center line of the concave lens surface 155 and the surface of the third light flux controlling member 116 on the diffusing member 140 side, and the focal point of the concave lens surface 155. Is the length (negative value).

Referring to FIG. 14, the relationship between the third light flux controlling member 116 and the diffusing member 140 in this modification will be described. First, bfl described in Equation (7) and Equation (8) will be described. FIG. 14A is a diagram for explaining bfl when the convex lens surface 153 is disposed on the third exit surface 152, and FIG. 14B illustrates bfl when the concave lens surface 155 is disposed on the third exit surface 152. FIG. 14C is a diagram for explaining bfl when the convex lens surface 153 is arranged on the third incident surface 151, and FIG. 14D is a diagram illustrating the concave lens surface 155 on the third incident surface 151. It is a figure for demonstrating bfl when is arrange | positioned. 14A to 14D, only one convex lens surface 153 or one concave lens surface 155 is shown.

As shown in FIG. 14A, when the convex lens surface 153 is disposed on the third exit surface 152, bfl is a positive value. In this case, let P be the intersection of the center line of the convex lens surface 153 and the surface of the third light flux controlling member 116 on the diffusing member 140 side. In the present embodiment, the intersection point P and the midpoint of the convex lens surface 153 are the same. The length between the intersection P and the focal point F of the convex lens surface 153 is bfl.

As shown in FIG. 14B, when the concave lens surface 155 is disposed on the third exit surface 152, bfl is a negative value. In this case, let P be the intersection of the center line of the concave lens surface 155 and the surface of the third light flux controlling member 116 on the diffusing member 140 side. In the present embodiment, the intersection point P and the midpoint of the concave lens surface 155 are the same. The length between the intersection P and the focal point F of the concave lens surface 155 is bfl.

As shown in FIG. 14C, when the convex lens surface 153 is disposed on the third incident surface 151, bfl is a positive value. In this case, let P be the intersection of the center line of the convex lens surface 153 and the surface of the third light flux controlling member 116 on the diffusing member 140 side. In the present embodiment, the intersection point P and the midpoint of the concave lens surface 155 are the same. The length between the intersection P and the focal point F of the convex lens surface 153 is bfl.

As shown in FIG. 14D, when the concave lens surface 155 is disposed on the third incident surface 151, bfl is a negative value. In this case, let P be the intersection of the center line of the concave lens surface 155 and the surface of the third light flux controlling member 116 on the diffusing member 140 side. In the present embodiment, the intersection point P and the midpoint of the concave lens surface 155 are the same. The length between the intersection P and the focal point F of the concave lens surface 155 is bfl.

Next, equation (7) will be described. Expression (7) defines the conditions when the diffusing member 140 is viewed from the front. On the diffusing member 140, the light emitted from the third light flux controlling member 116 overlaps with each other, so that uneven brightness can be suppressed. 15A is a schematic diagram showing the influence of the top of the convex lens surface 153 and the distance t of the diffusing member 140 on the optical path, FIG. 15B is a schematic diagram showing the influence of bfl on the optical path, and FIG. In (7), it is a schematic diagram which shows the influence of the width w of the convex lens surface 153. FIG.

In the display device in which the third light flux control member 116 and the diffusion member 140 are arranged so that (w × bfl) / t is greater than −15 and less than 3, the third light flux control member is disposed on the diffusion member 140. Since the light emitted from 116 overlaps, luminance unevenness can be suppressed. When w or bfl becomes large or t becomes small, and (w × bfl) / t becomes 3 or more, the light emitted from the third light flux controlling member 116 does not overlap, resulting in luminance unevenness. There is a fear. On the other hand, from the viewpoint of processing limit, it is difficult to set (w × bfl) / t to −15 or less.

As shown in FIG. 15A, when w and bfl are constant, the light emitted from the third light flux controlling member 116 overlaps as t increases, so that the luminance unevenness can be suppressed. In addition, the value of t is so preferable that it is large. However, if the value of t is too large, the size of the surface light source device becomes large, which is not preferable.

As shown in FIG. 15B, when w and t are constant, the light emitted from the third light flux controlling member 116 overlaps as the bfl is smaller, so that uneven brightness can be suppressed. Note that when bfl is a positive value, the light diverges as the value of bfl decreases, so that uneven brightness can be suppressed. On the other hand, when bfl is a negative value, if the value of bfl is too small, the overlap of light becomes small and the light becomes substantially parallel to the optical axis, which may cause uneven brightness.

As shown in FIG. 15C, when bfl and t are constant, the light emitted from the third light flux controlling member 116 overlaps as w is smaller, so that uneven brightness can be suppressed.

From the above, the light flux controlling member 116 and the diffusing member 140 are arranged so as to satisfy the above formula (7) from the viewpoint of preventing luminance unevenness when the diffusing member 140 is viewed from the front. It is preferred that

Next, equation (8) will be described. Formula (8) prescribes | regulates the conditions at the time of seeing the diffusion member 140 from diagonally. When the diffusing member 140 is viewed obliquely, the light emitted from the third light flux controlling member 116 is preferably emitted at a predetermined angle with respect to the optical axis of the convex lens surface 153. FIG. 16A is a schematic diagram showing the influence of w on the optical path in relation to equation (8), and FIG. 16B is a schematic diagram showing the influence of bfl on the optical path in relation to equation (8).

In the display device in which the third light flux control member 116 and the diffusion member 140 are arranged so that | w / bfl | is greater than 0.2 and less than 1.0, the third light flux control is performed on the diffusion member 140. Since the light emitted from the member 116 overlaps, luminance unevenness can be suppressed. If w becomes small or the absolute value of bfl becomes large, and | w / bfl | becomes 0.2 or less, the power to refract light becomes too weak, and the optical axis OA becomes smaller. Since the light emitted obliquely decreases, the end portion becomes dark and there is a risk of uneven brightness. On the other hand, if w becomes large or if the absolute value of bfl becomes small, and | w / bfl | becomes 1.0 or more, the power to refract light becomes too strong. Thereby, since the light emitted obliquely with respect to the optical axis OA increases, uneven luminance when the diffusing member 140 is viewed obliquely is suppressed, but since the light is excessively spread, the necessary luminance is reduced. There is a risk that it cannot be secured.

As shown in FIG. 16A, when bfl is constant, as w increases, the amount of light emitted in an oblique direction with respect to the optical axis OA increases. Therefore, luminance unevenness when viewed obliquely with respect to the optical axis OA. Can be suppressed.

As shown in FIG. 16B, when w is constant, the smaller the absolute value of bfl is, the more light is emitted obliquely with respect to the optical axis OA. In this case, uneven brightness can be suppressed.

From the above, the third light flux controlling member 116 and the diffusing member 140 satisfy the above formula (8) from the viewpoint of preventing luminance unevenness when the diffusing member 140 is viewed obliquely. It is preferable to arrange | position.

[Embodiment 2]
The display device according to the second embodiment is different from the display device 100 according to the first embodiment only in the configuration of the third light flux controlling member 216. Therefore, in the second embodiment, only the configuration of the third light flux controlling member 216 will be described.

(Configuration of third light flux controlling member)
FIG. 17 is a diagram illustrating a configuration of the third light flux controlling member 216. 17A is a plan view of the third light flux controlling member 216, FIG. 17B is a bottom view, FIG. 17C is a side view, and FIG. 17D is a sectional view taken along line AA shown in FIG. 17A. It is.

17A to 17D, the third light flux controlling member 216 has a third incident surface 151 and a third outgoing surface 252. The third exit surface 252 includes a plurality of convex lens surfaces 253.

The plurality of convex lens surfaces 253 are arranged along a first direction and a second direction perpendicular to the first direction. In the present embodiment, the convex lens surface 253 has a square shape in plan view, and both have the same size. Further, the convex lens surface 253 has a curvature in any cross section including the central axis CA of the convex lens surface 253. The cross-sectional shape including the central axis CA of the convex lens surface 253 may be an arc, a curve having a radius of curvature that increases with distance from the top, or an arc that intersects the central axis CA. It may be a curve in which the radius of curvature increases with distance from.

As described above, the display device according to the second embodiment has the same effects as those of the display device 100 according to the first embodiment, and both the first direction and the second direction in which the convex lens surfaces 253 are arranged. The viewing angle can be widened.

Although not particularly illustrated, the third light flux controlling member 216 may have a third emission surface 252 including a plurality of concave lens surfaces. Also in this case, the plurality of concave lens surfaces are arranged in the first direction and the second direction. Further, the third light flux controlling member 216 may have a third incident surface 251 including a plurality of convex lens surfaces 253 or a plurality of concave lens surfaces.

In the display device 100 ′, a plurality of light emitting devices 130 may be arranged. FIG. 18 is a diagram illustrating a configuration of a display device 100 ′ according to a modification. 18A is a plan view of the display device 100 ′, and FIG. 18B is a cross-sectional view taken along line AA shown in FIG. 18A.

As shown in FIGS. 18A and 18B, the display device 100 ′ includes a substrate 111 ′, a plurality of light emitting devices 130, a diffusion member 140 ′, (a surface light source device 110 ′), and a display member 120 ′. . In the display device 100 ′, a plurality of light emitting devices 130 are arranged on one substrate 111 ′. In the present embodiment, six light emitting devices 130 are arranged in a matrix on one substrate 111 ′.

Light emitted from the plurality of light emitting devices 130 reaches the diffusion member 140 ′ and the display member 120 ′. In the present embodiment, the diffusing member 140 ′ and the display member 120 ′ are formed, for example, in the same size as the substrate 111 ′ so that the light emitted from the six light emitting devices 130 reaches.

By configuring as described above, the surface light source device and the display device can be enlarged. Instead of providing a plurality of light emitting devices 130 for one diffusion member 140 ′ and display member 120 ′, the display device 100 having one light emitting device 130, diffusion member 140 ′, and display member 120 ′ is arranged in the plane direction. A plurality of the display devices may be arranged to enlarge the display device.

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[Example 1]
In Example 1, in the display device 100 according to Embodiment 1, the width w of the cross section including the third central axis CA3 of the convex lens surface 153, the center line of the convex lens surface 153, and the diffusion member 140 in the third light flux controlling member 116. The relationship between the intersection with the side surface, the distance t from the diffusing member 140, the radius of curvature R of the convex lens surface 153, and the uniformity U0, U5 / U0 was examined.

(Configuration of display device)
FIG. 19 is a schematic diagram illustrating a configuration of the display device 100 used in the example. As shown in FIG. 19, the display device 100 includes a surface light source device 110 and a display member 120. The surface light source device 110 includes a light emitting element 112 and a light flux controlling member 113. The light flux control member 113 includes a first light flux control member 114, a second light flux control member 115, and a third light flux control member 116. In FIG. 19, a = 10 mm, b = 3 mm, c = 1 mm, d = 3 mm, e = 25 mm, f = 5 mm, g = 3 mm, h = 55.5 mm, and i = 16.2 mm. No. The dimension in 17 display apparatuses is shown. In the embodiment, the focal length f of the first light flux controlling member is 1 mm, and the distance d between the first central axis and the optical axis of the light emitting element farthest from the first central axis is −28.14 mm. . That is, d / f in the example is −0.036.

The uniformity in the display area of each display device was obtained by simulation. The uniformity in the display area 121 was calculated by the following formula (9).
Uniformity = minimum brightness / maximum brightness (9)
“Minimum luminance” is the minimum luminance value in the display area, and “maximum luminance” is the maximum luminance value in the display area.

Table 1 shows the parameters for 36 types of display devices that simulate the uniformity.

In Table 1, w is the width of the convex lens surface in the cross section including the third central axis, and t is the intersection of the center line of the convex lens surface and the surface on the diffusing member side of the third light flux controlling member, and the diffusing member. R is the radius of curvature of the convex lens surface, n is the refractive index, U0 is the uniformity when the display area is viewed from the front, and U5 is inclined by 5 °. It is the degree of uniformity when viewed from the position. Although not particularly shown, the display device No. 1 to 36 satisfy the above formula (1).

FIG. 20 shows the relationship between “(the width w of the convex lens surface in the cross section including the third central axis) ² / distance t between the top of the convex lens surface and the diffusing member 140” and the uniformity U0 in each display device. FIG. 20 is a graph in which the results summarized in Table 1 are plotted. The horizontal axis in FIG. 20 indicates “(the width w of the cross section including the third central axis CA3 of the convex lens surface 153) ² / the distance t between the top of the convex lens surface 153 and the diffusing member 140”. The uniformity U0 when the display device is viewed in plan (when viewed from the optical axis LA) is shown.

As shown in Table 1 and FIG. 20, in order for the uniformity U0 required when used for HUD to be 0.7 or more, w ² / t needs to be less than 0.85. I understand.

Further, as shown in Table 1 and FIG. 21, in order for the degree of uniformity U5 / U0 required when used for HUD to be 0.7 or more, w / R is more than 0.4 and 1.4. It turns out that there is a need for less than.

As described above, the width w of the cross section including the third central axis of the convex lens surface, the intersection of the central line of the convex lens surface and the surface on the diffusion member side of the third light flux controlling member, and the distance t between the diffusion member and , 0 <w ² /t<0.85, and the width w of the cross section including the third central axis of the convex lens surface and the curvature radius R of the convex lens surface are 0.4 <w / R <1.4. It was found that the display area can be illuminated uniformly with small luminance unevenness if the above condition is satisfied. Although no particular results are shown, similar results were obtained with a display device having a third light flux controlling member including a concave lens surface.

[Example 2]
In the second embodiment, the display device 100 having the third light flux controlling member 116 in which a plurality of convex lens surfaces 153 or a plurality of concave lens surfaces 155 are arranged on the third incident surface 151, and a plurality of convex lens surfaces 153 on the third output surface 152. Alternatively, the display device 100 having the third light flux controlling member 116 on which the plurality of concave lens surfaces 155 are arranged was examined.

Specifically, in the display device according to the first embodiment, the width w of the cross section including the third central axis of the convex lens surface, the distance t between the top of the convex lens surface and the diffusing member, the center line of the convex lens surface, The relationship between the intersection of the three-beam control member with the surface on the diffusion member side and the length bfl of the focal point of the convex lens surface, the uniformity U0, and the uniformity ratio U5 / U0 was examined. In the display device according to the first embodiment, the width w of the section including the third central axis of the concave lens surface, the distance t between the bottom of the concave lens surface and the diffusing member, the center line of the concave lens surface, and the third light flux control. The relationship between the intersection of the member with the surface on the diffusing member side, the length bfl of the focal point of the concave lens surface, and the uniformity U0 and the uniformity ratio U5 / U0 was examined. The configuration of the display device is the same as that of the first embodiment.

Tables 2 to 5 show the parameters for 101 types of display devices that simulate the uniformity.

In Tables 2 to 5, w is the width of the convex lens surface or concave lens surface in the cross section including the third central axis, and bfl is the center line of the convex lens surface or concave lens surface and the surface on the diffusion member side in the third light flux controlling member. And t is the distance between the top of the convex lens surface or the bottom of the concave lens surface and the diffusion member, and U0 is the distance when the display area is viewed from the front. U5 is the degree of uniformity when the display area is viewed from a position tilted by 5 °. Although not particularly shown, the display device No. 37 to 83 and 88 to 133 satisfy the above formulas (1) to (3).

Tables 2 and 3 show parameters in a display device in which a convex lens surface or a concave lens surface is arranged on the third entrance surface, and Tables 4 and 5 show displays in which a convex lens surface or a concave lens surface is arranged on the third exit surface. The parameters in the device are shown. In Tables 2 and 3, a display device with a positive bfl value is a display device in which a convex lens surface is arranged on the third entrance surface, and a display device with a negative bfl value has a concave lens surface on the third entrance surface. It is the arranged display device. In Tables 4 and 5, a display device having a positive bfl value is a display device in which a convex lens surface is disposed on the third exit surface, and a display device having a negative bfl value is a concave lens on the third exit surface. A display device in which a surface is arranged.

22A and 22B are graphs in which the results summarized in Tables 2 and 3 are plotted, and FIGS. 23A and 23B are graphs in which the results summarized in Tables 4 and 5 are plotted. FIG. 22A is a graph showing the relationship between (w × bfl) / t and the degree of uniformity U0 when a plurality of convex lens surfaces or a plurality of concave lens surfaces are arranged on the third incident surface side, and FIG. It is a graph which shows the relationship between | w / bfl | and the uniformity ratio U5 / U0 when a plurality of convex lens surfaces or a plurality of concave lens surfaces are arranged on the third incident surface side. FIG. 23A is a graph showing the relationship between (w × bfl) / t and the degree of uniformity U0 when a plurality of convex lens surfaces or a plurality of concave lens surfaces are arranged on the third exit surface side, and FIG. It is a graph which shows the relationship between | w / bfl | and the uniformity ratio U5 / U0 when a plurality of convex lens surfaces or a plurality of concave lens surfaces are arranged on the third exit surface side. The horizontal axis of FIGS. 22A and 23A indicates (w × bfl) / t, and the vertical axis indicates the degree of uniformity U0. Moreover, the horizontal axis of FIG. 22B and FIG. 23B has shown | w / bfl |, and the vertical axis has shown the uniformity ratio U5 / U0.

As shown in Tables 2 and 3 and FIGS. 22A and 22B, when the third light flux controlling member having the convex lens surface disposed on the third incident surface is used, the degree of uniformity required when used for HUD. In order for U0 to be 0.7 or more and the uniformity ratio U5 / U0 to be 0.7 or more, (w × bfl) / t is more than −15 and less than 3, and | w / bfl | It can be seen that it needs to be greater than 0.2 and less than 1.0.

For example, display device No. In 84, the uniformity ratio U5 / U0, which is an index when the diffusing member is viewed from an oblique direction, is 0.64, which does not satisfy the standard required for use in HUD. However, the uniformity U0, which is an index when the diffusing member is viewed from the front, is 0.84, which satisfies the standard required for use in HUD. Also, the display device No. 85, the uniformity ratio U5 / U0, which is an index when the diffusing member is viewed obliquely, is 0.76, but the uniformity U0, which is an index when the diffusing member is viewed from the front, is 0.47. It was. Also, the display device No. In 86 and 87, neither the uniformity ratio U5 / U0, which is an index when the diffusing member is viewed from an oblique direction, nor the uniformity degree U0, which is an index when the diffusing member is viewed from the front, were satisfied.

Further, as shown in Tables 4 and 5 and FIGS. 23A and 23B, when the third light flux controlling member having the concave lens surface disposed on the third incident surface is used, it is required when used for HUD. In order for the uniformity U0 to be 0.7 or more and the uniformity ratio U5 / U0 to be 0.7 or more, (w × bfl) / t is more than −15 and less than 3, and | w / It can be seen that bfl | needs to be greater than 0.2 and less than 1.0.

For example, display device No. In 134, the uniformity ratio U5 / U0, which is an index when the diffusing member is viewed from an oblique direction, is 0.76, which satisfies the standard required when used for HUD. However, the uniformity U0, which is an index when the diffusing member is viewed from the front, is 0.47, which does not satisfy the standard required when used for HUD. Also, the display device No. In 135, the uniformity ratio U5 / U0, which is an index when the diffusing member is viewed obliquely, is 0.64, but the uniformity U0, which is an index when the diffusing member is viewed from the front, is 0.84. It was. Also, the display device No. In 136 and 137, neither the uniformity ratio U5 / U0, which is an index when the diffusion member is viewed from an oblique direction, nor the uniformity U0, which is an index when the diffusion member is viewed from the front, was satisfied.

As described above, the width w of the cross section including the third central axis of the convex lens surface or the concave lens surface, the intersection of the center line of the convex lens surface or the concave lens surface and the surface on the diffusion member side of the third light flux controlling member, and the diffusion member And the length bfl of the intersection of the center line of the convex lens surface or the concave lens surface and the surface on the diffusion member side of the third light flux controlling member and the focal point of the convex lens surface or the concave lens surface is −15 <(w Xbfl) / t <3 and the width w of the cross section including the third central axis of the convex lens surface or the concave lens surface, the center line of the convex lens surface or the concave lens surface, and the surface on the diffusion member side of the third light flux controlling member It can be seen that if the length bfl of the intersection of the convex lens surface and the focal point of the convex lens surface or the concave lens surface is 0.2 <| w / bfl | <1.0, the luminance unevenness is small and more uniform illumination is possible. It was.

In the above-described example, an example in which a plurality of convex or concave lens surfaces are arranged on either the third incident surface or the third emission surface of the third light flux controlling member has been described. A plurality of convex lens surfaces or a plurality of concave lens surfaces may be formed on both surfaces of the third entrance surface and the third exit surface. For example, a form in which a convex lens surface is formed on one surface and a plurality of concave lens surfaces are formed on the other surface at the same pitch as the one surface, or a convex lens surface or a concave lens surface is formed on the third incident surface and A form in which both the third emission surfaces are formed at the same pitch is conceivable. In that case, in the relationship between the lens power and the distance bfl from the point intersecting the central axis of the lens surface on the third exit surface to the focal points of the lenses on both surfaces of the third light flux controlling member, the third entrance surface and the third exit surface When the lens power by both surfaces is positive, bfl is a positive value, and when the lens power is negative, bfl is a negative value, and the conditions required for the third light flux controlling member of the present invention (formulas (7) and (7)) It is formed so as to satisfy 8)).

This application claims priority based on Japanese Patent Application No. 2016-243414 filed on Dec. 15, 2016 and Japanese Patent Application No. 2017-048771 filed on Mar. 14, 2017. The contents described in the application specification and the drawings are all incorporated herein.

The surface light source device according to the present invention is useful as a light source for a head-up display (HUD), for example. The display device according to the present invention is useful as, for example, a head-up display (HUD).

10 Surface light source device 11 Substrate 12 LED
DESCRIPTION OF SYMBOLS 14 Lens array 15 Diffusing member 16 Boundary line 17 Uneven part 100 Display device 110 Surface light source device 111 Substrate 112 Light emitting element 113 Light flux control member 114 1st light flux control member 115 2nd light

flux control member

116, 216 3rd light flux control member 120 Display Member 121 Display area 130 Light emitting device 131 First entrance surface 132 First exit surface 132a Inner first exit surface 132b Outside first exit surface 133 First flange 134 First recess 140 Diffusion member 141 Second entrance surface 142 Second exit surface 143 Second flange 145 Fresnel lens portion 146 Convex portion 147 Refraction surface 148 Connection surface 151 Third entrance surface 152 Third exit surface 153 Convex lens surface 154 Third flange 155 Concave lens surface CA Central axis CA1 First central axis CA2 Second central axis CA3 3rd central axis OA Optical axis

Claims

A light emitting device having a plurality of light emitting elements, and a light flux controlling member that includes a first light flux controlling member, a second light flux controlling member, and a third light flux controlling member, and controls light distribution of light emitted from the plurality of light emitting elements. When,
A surface light source device having a diffusing member that is disposed via the light emitting device and an air layer and irradiated with light emitted from the light emitting device,
The first light flux controlling member is
A concave first incident surface disposed to face the plurality of light emitting elements so as to intersect the first central axis of the first light flux controlling member;
An inner emission surface arranged to intersect the first central axis, and an outer emission surface arranged so as to surround the inner emission surface and having a convex shape in a cross section including the first central axis, A first exit surface disposed on the opposite side of the first entrance surface,
The second light flux controlling member controls the light emitted from the first light flux controlling member to be directed in a direction along the first central axis;
The third light flux controlling member is
A third incident surface on which light emitted from the second light flux controlling member is incident;
A third exit surface disposed on the opposite side of the third entrance surface;
A plurality of convex lens surfaces or a plurality of concave concave lens surfaces having a convex shape in a cross section including the third central axis of the third light flux controlling member are two-dimensionally formed on the third incident surface or the third output surface. Arranged,
When the focal length of the first light flux controlling member is f and the distance between the first central axis and the optical axis of the light emitting element farthest from the first central axis is d, the following formula (1) The filling,
The width of the convex lens surface or the concave lens surface in the cross section including the third central axis is w, the radius of curvature of the convex lens surface or the concave lens surface is R, the center line of the convex lens surface or the concave lens surface and the third When the intersection between the light flux controlling member and the surface on the diffusion member side and the distance from the diffusion member is t, the following expressions (2) and (3) are satisfied:
Surface light source device.
-0.6 <d / f <0 (1)
0 <w 2 /t<0.85 (2)
0.4 <w / R <1.4 (3)
The second light flux controlling member is
A second entrance surface disposed opposite the first exit surface;
A second emission surface that is disposed on the opposite side of the second incidence surface and has a refractive Fresnel lens portion that emits incident light in a direction along the first central axis.
The surface light source device according to claim 1.
3. The surface light source device according to claim 1, wherein the first central axis, the second central axis of the second light flux controlling member, and the third central axis coincide with each other.
The first entrance surface and the first exit surface are rotationally symmetric with the first central axis as a rotation axis,
The second entrance surface and the second exit surface are rotationally symmetric with the second central axis as a rotation axis.
The surface light source device according to claim 3.
The plurality of light emitting elements are arranged such that the total light beam optical axes of the plurality of light emitting elements, which are the centers of the total light beams emitted from the plurality of light emitting elements, coincide with the first central axis and the second central axis. And
Each of the plurality of light emitting elements emits light most strongly in a direction along the first central axis,
In a cross section including the first central axis and the second central axis,
The intersection of the total luminous flux optical axis and the extended line of the light emitting surface of the plurality of light emitting elements is a virtual emission point, the emission angle of the first light beam emitted from the virtual emission point is θ1,
After the first light beam is controlled by the first light beam control member, an angle of the second light beam generated by being emitted from the first light beam control member with respect to the first central axis is θ2.
When the angle with respect to the first central axis of the third light beam generated by being emitted from the second light beam control member after the second light beam is controlled by the second light beam control member is θ3, The following expressions (4) to (6) are satisfied.
The surface light source device according to any one of claims 1 to 4.

[In Expression (4), 0 ° <θ1 n <θ1 n + 1 <60 °, and θ2 n is the angle of the light beam corresponding to θ1 n . ]

[In the formula (5), 0 ° <θ1 n−1 <θ1 n <θ1 n + 1 <60 °. ]
−6 ° <θ3 <10 ° (6)
[In Expression (6), 0 ° <θ1 <40 °, and θ3 is the angle of the light beam corresponding to θ1. θ3 is set to 0 ° as an angle of light traveling parallel to the first central axis, and a negative value with respect to the first central axis of the third light beam traveling closer to the first central axis, The angle of the third light ray with respect to the first central axis that travels away from the first central axis is a positive value. ]
The convex lens surface includes a ridge line extending linearly in a first direction perpendicular to the thickness direction of the third light flux controlling member, and is a second perpendicular to the thickness direction and the first direction. The surface light source device according to any one of claims 1 to 5, wherein the surface light source device is a curved surface having a curvature only in a direction or a curved surface having a curvature in any cross section including a central axis of the convex lens surface.
When the third light flux controlling member has the plurality of convex lens surfaces, the intersection of the center line of the convex lens surface and the surface on the diffusion member side of the third light flux controlling member, and the focal point of the convex lens surface When the third light flux control member has the plurality of concave lens surfaces, the center line of the concave lens surface and the surface on the diffusion member side of the third light flux control member When the length of the intersection with the focal point of the concave lens surface is a negative bfl, the following expressions (7) and (8) are satisfied:
The surface light source device according to any one of claims 1 to 6.
−15 <(w × bfl) / t <3 (7)
0.2 <| w / bfl | <1.0 (8)
A surface light source device according to any one of claims 1 to 7,
A display member that is irradiated with light emitted from the surface light source device;
A display device.