Planar lighting device

Abstract

To realize required light distribution properties while securing higher luminance.SOLUTION: A planar illuminating device according to an embodiment comprises a board, a first optical element, and a second optical element. A plurality of light sources are two-dimensionally arranged on the board. The first optical element is arranged on the emitting side of the plurality of light sources, and collects light emitted from the plurality of light sources. The second optical element inclines the distribution of the light collected by the first optical element, with respect to a first axial direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a surface lighting device. [Background technology]

[0002] 2. Description of the Related Art In planar lighting devices used as backlights for liquid crystal display devices, various optical lenses are used to achieve light distribution characteristics suited to the application (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-221605 A [Patent Document 2] JP 2012-203092 A Summary of the Invention [Problem to be solved by the invention]

[0004] As characteristics of the backlight of a liquid crystal display device, in addition to high brightness and high efficiency, special light distribution characteristics such as tilting the optical axis are required. However, with conventional devices, it has been difficult to efficiently control the light distribution for the required viewing range while ensuring high brightness.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a surface lighting device that can realize required light distribution characteristics while ensuring high luminance. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the object, a surface illumination device according to one aspect of the present invention includes a substrate, a first optical element, and a second optical element. The present invention is a surface illumination device used as a backlight for a liquid crystal display device. The substrate is With respect to a first axial direction and a second axial direction perpendicular to the first axial directionA plurality of light sources are arranged two-dimensionally. The first optical element is arranged on the emission side of the plurality of light sources and receives the light emitted from the plurality of light sources. The light is collected and emitted for each row along at least the second axis direction. do. Second The optical element of the second optical element is The light is emitted with its traveling direction tilted to at least the same side with respect to the first axial direction.

[0007] A surface lighting device according to an aspect of the present invention can achieve required light distribution characteristics while ensuring high luminance. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram for explaining the light distribution characteristics required for a planar lighting device according to an embodiment. [Diagram 2] FIG. 2 is a diagram for explaining an outline of the surface illumination device shown in FIG. [Diagram 3] FIG. 3 is a perspective view illustrating a schematic configuration of the surface illumination device illustrated in FIG. [Figure 4] 4 is a cross-sectional view taken along line AA and BB of the surface illumination device shown in FIG. [Diagram 5] FIG. 5 is a perspective view of the reflector shown in FIG. [Figure 6] 6 is a front view, a cross-sectional view taken along line CC and a cross-sectional view taken along line DD of the reflector shown in FIG. [Figure 7] FIG. 7 is a diagram for explaining the first modified example. [Figure 8] FIG. 8 is a diagram for explaining the second modified example. [Figure 9] FIG. 9 is a diagram for explaining the third modified example. [Figure 10] FIG. 10 is a diagram for explaining the fourth modified example. [Figure 11] FIG. 11 is a diagram for explaining the fifth modified example. [Figure 12] FIG. 12 is a diagram for explaining the sixth modified example. [Figure 13] FIG. 13 is a diagram for explaining the seventh modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a planar lighting device according to an embodiment will be described with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, the dimensional relationship of each element in the drawings, the ratio of each element, etc. may differ from reality. The drawings may also include parts with different dimensional relationships and ratios. In principle, the contents described in one embodiment or modified example are similarly applied to other embodiments or modified examples.

[0010] (Embodiment) Fig. 1 is a diagram for explaining the light distribution characteristics required for the planar lighting device 1 according to the embodiment. Fig. 1 is an external view of the planar lighting device 1 according to the embodiment, and for convenience, in Fig. 1, the light emitting surface of the planar lighting device 1 is in the XY plane, and the thickness direction of the planar lighting device 1 is the Z direction.

[0011] In Fig. 1, the surface lighting device 1 has a substantially rectangular plate-like outer shape, and light is emitted from the inside of an opening 9a of a frame 9. Note that the outer shape of the surface lighting device 1 is not limited to that shown in the figure. "Optical axis shift" shown in the figure means tilting the optical axis.

[0012] In the example shown in Fig. 1, the optical axis is tilted toward the negative side of the Y axis of the surface lighting device 1 (diagonally downward right in the figure), indicating that a narrow viewing range is required. On the other hand, in the example shown in Fig. 1, the light distribution characteristics in the X axis direction of the surface lighting device 1 indicate that a wide viewing range is required, with the optical axis being in the normal direction of the light emitting surface.

[0013] Therefore, the surface lighting device 1 includes a first optical element that collects light emitted from a light source, and a second optical element that tilts the light distribution of the light collected by the first optical element with respect to the Y-axis direction. The Y-axis direction is an example of the first axis direction. Note that the embodiment is also applicable to a case where the first axis direction is the X-axis direction. Below, a detailed description is given of a configuration example of the surface lighting device 1 of the embodiment.

[0014] Fig. 2 is a diagram for explaining an overview of the surface lighting device shown in Fig. 1. Fig. 2 is a simplified diagram of an AA cross section of the surface lighting device 1 shown in Fig. 1. The frame 9 is omitted in Fig. 2. In the following, the AA cross section may be referred to as a longitudinal section. Also, the BB cross section of the surface lighting device 1 shown in Fig. 1 may be referred to as a transverse section.

[0015] In Fig. 2, a plurality of light sources 3 such as LEDs (Light Emitting Diodes) are arranged on a substrate 2. Although Fig. 2 shows a plurality of light sources 3 arranged in the Y-axis direction, a plurality of light sources 3 are also arranged in the X-axis direction (see Fig. 4 described later). That is, a plurality of light sources 3 are arranged two-dimensionally on the substrate 2. Each of the plurality of light sources 3 is driven individually, and can support so-called local dimming.

[0016] Then, on the emission side of the multiple light sources 3, a collecting lens 5 provided with a first optical element that collects light emitted from the multiple light sources 3 is arranged, and a light distributing lens 6 provided with a second optical element that tilts the distribution of light collected by the collecting lens 5 with respect to the Y-axis direction is arranged. The collecting lens 5 and the light distributing lens 6 will be described with reference to Figs. 3 and 4.

[0017] Fig. 3 is a perspective view showing the planar lighting device 1 shown in Fig. 1, and Fig. 4 is a cross-sectional view taken along line AA and a cross-sectional view taken along line BB of the planar lighting device shown in Fig. 1. The left diagram in Fig. 4 is a cross-sectional view taken along line AA, which is a vertical cross section, and the right diagram in Fig. 4 is a cross-sectional view taken along line BB, which is a horizontal cross section. The vertical cross section in Fig. 4 shows a schematic view of the behavior of light rays in the Y-axis direction, and the cross-sectional view in Fig. 4 shows a schematic view of the behavior of light rays in the X-axis direction.

[0018] The condenser lens 5 extends in the X-axis direction perpendicular to the Y-axis direction, and has a linear Fresnel lens 5a as a first optical element that condenses light emitted from the multiple light sources 3 in the Y-axis direction. The linear Fresnel lens 5a is provided on the surface opposite to the surface facing the substrate 2 (the emission side surface of the condenser lens 5). The X-axis direction is an example of the second axis direction.

[0019] The linear Fresnel lens 5a has a prism structure in which a cylindrical convex lens is used as the Fresnel lens, and has grooves extending in the X-axis direction. The linear Fresnel lens 5a has grooves formed periodically in accordance with the pitch (pitch in the Y-axis direction) of the light sources 3 arranged directly below it.

[0020] The light distributing lens 6 has a linear prism 6a extending in the X-axis direction as a second optical element that tilts the light distribution of the light collected by the collecting lens 5 with respect to the Y-axis direction. The linear prism 6a is provided on the surface opposite to the surface facing the collecting lens 5 (the surface on the exit side of the light distributing lens 6). The linear prisms 6a have a prism structure of a substantially triangular prism extending in the X-axis direction, and are arranged continuously in the Y-axis direction. As a result, a groove extending in the X-axis direction is formed on the surface on the exit side of the light distributing lens 6. The cross-sectional shape of the YZ surface of the linear prism 6a is triangular, and the base angle of the side connecting the point on the base side on the positive side of the Y-axis and the apex is smaller than the base angle of the side connecting the point on the base side on the negative side of the Y-axis and the apex.

[0021] In the longitudinal section of Fig. 4, light emitted from the light source 3 enters the condenser lens 5, is refracted by the linear Fresnel lens 5a provided on the upper surface of the condenser lens 5, and is emitted as approximately parallel light. Then, in the longitudinal section of Fig. 4, the parallel light emitted from the condenser lens 5 enters the light distribution lens 6, and is emitted with its optical axis tilted by the linear prism 6a provided on the upper surface of the light distribution lens 6.

[0022] On the other hand, in the cross-sectional view of Fig. 4, the light emitted from the light source 3 enters the condenser lens 5 and exits without being substantially refracted by the linear Fresnel lens 5a provided on the upper surface of the condenser lens 5. In the cross-sectional view of Fig. 4, the light emitted from the condenser lens 5 enters the light distribution lens 6 and exits without being substantially refracted by the linear prism 6a provided on the upper surface of the light distribution lens 6.

[0023] In this way, in the Y-axis direction, the condenser lens 5 condenses the light emitted from the multiple light sources 3 and makes it efficiently incident on the light distribution lens 6 as substantially parallel light, and the light distribution lens 6 tilts the optical axis of the incident light and emits it. This allows the surface lighting device 1 to achieve the required light distribution characteristics with high brightness. Note that in the embodiment, no optical axis shift is required in the X-axis direction, and the required field of view is relatively wide, so there is no need to condense the light emitted from the multiple light sources 3 in the X-axis direction. For this reason, the condenser lens 5 of the embodiment is not provided with a linear Fresnel lens extending in the Y-axis direction, and the light distribution lens 6 is not provided with a linear prism extending in the Y-axis direction. The effects of such a configuration will be described in detail later.

[0024] Furthermore, in the planar lighting device 1 according to the embodiment, in order to adjust the light emitted from the light distribution lens 6 to a required field of view, a field of view range adjusting lens 7 is disposed on the exit side of the light distribution lens 6 as shown in Figures 2, 3 and 4. As shown in Figure 4, the field of view range adjusting lens 7 has a first lenticular lens 7a provided on the surface facing the light distribution lens 6 (the surface on the entrance side), and a second lenticular lens 7b provided on the surface opposite to the surface facing the light distribution lens 6 (the surface on the exit side).

[0025] The first lenticular lens 7a extends in the X-axis direction and adjusts the viewing range in the Y-axis direction. The first lenticular lens 7a has a semicylindrical prism structure that extends in the X-axis direction. The second lenticular lens 7b extends in the Y-axis direction and adjusts the luminance distribution in the X-axis direction. The second lenticular lens 7b has a semicylindrical prism structure that extends in the Y-axis direction.

[0026] In this manner, in the embodiment, by combining a linear Fresnel lens that focuses light, a linear prism that tilts the light toward the target optical axis, and a lenticular lens that both focuses and diffuses light to adjust the field of view and luminance distribution, it is possible to control the light distribution to the target field of view while ensuring high luminance and uniformity.

[0027] 3 and 4, the surface illumination device 1 may have a diffusion sheet 8 disposed on the exit side of the field of view range adjusting lens 7 as shown in Fig. 2. The diffusion sheet 8 is useful for eliminating streaky unevenness and the like caused by the first lenticular lens 7a and the second lenticular lens 7b.

[0028] In the planar lighting device 1, which is a direct type backlight, as shown in Fig. 2, Fig. 3 and Fig. 4, a reflector 4 is disposed between the plurality of light sources 3 and the condenser lens 5 in order to efficiently cause the light emitted from the plurality of light sources 3 to enter the condenser lens 5. As shown in Fig. 4, the reflector 4 is formed so that openings 4b corresponding to the plurality of light sources 3 are arranged, and has a wall portion 4c whose wall surface surrounding the openings 4b serves as a reflective surface 4a. In the embodiment, the reflector 4 has four reflective surfaces 4a surrounding the openings 4b.

[0029] The surface lighting device 1 of the embodiment is required to have a viewing characteristic of a wide viewing field in the X-axis direction and a narrow viewing field in the Y-axis direction. In the above embodiment, such viewing characteristics are realized by controlling the optical characteristics mainly by the lens functions such as the above-mentioned condenser lens 5, light distribution lens 6, viewing range adjustment lens 7, etc. However, the viewing characteristics obtained through the lens may change depending on the structure of the reflector 4 located between the light source 3 and the lens. Therefore, it is preferable to match the structure of the reflector 4 to the required characteristics in order to ensure the light distribution control to the target viewing range realized by the above-mentioned lens functions.

[0030] The structure of the reflector according to the embodiment will be described below with reference to Fig. 5 and Fig. 6. Fig. 5 is a perspective view of the reflector shown in Fig. 3, and Fig. 6 is a front view, a CC cross-sectional view (longitudinal cross-section) and a DD cross-sectional view (lateral cross-section) of the reflector shown in Fig. 3.

[0031] The wall 4c has a shape in which a plurality of first walls 4c-1 extending in the Y-axis direction and a plurality of second walls 4c-2 extending in the X-axis direction are assembled in a lattice shape. The wall 4c is assembled so that the bottom surface of the first wall 4c-1 and the bottom surface of the second wall 4c-2 are flush with each other. The reflecting surface 4a is a wall surface of the wall 4c. The two reflecting surfaces 4a-1 facing each other between the two adjacent first walls 4c-1 in the X-axis direction are inclined so as to move away from each other toward the positive direction of the Z-axis. The two reflecting surfaces 4a-2 facing each other between the two adjacent second walls 4c-2 in the Y-axis direction are inclined so as to move away from each other toward the positive direction of the Z-axis. The reflector 4 is formed of, for example, a white resin in order to enhance the reflection effect. The reflector 4 of the embodiment is a molded product by injection molding.

[0032] The height of the first wall portion 4c-1 is determined by the range of the field of view in the X-axis direction, and the height of the second wall portion 4c-2 is determined by the range of the field of view in the Y-axis direction. In this embodiment, since a narrow field of view characteristic is required in the Y-axis direction, the height of the second wall portion 4c-2 is increased as shown in the vertical cross section of Fig. 6. By increasing the height of the second wall portion 4c-2, the wide light distribution component from the light source 3 can be reflected by the reflecting surface 4a-2 and collected in the linear Fresnel lens 5a of the segment corresponding to the light source 3.

[0033] In addition, increasing the height of the second wall portion 4c-2 also serves to block light from entering the linear Fresnel lens 5a of the adjacent segment, and also has the function of preventing unintended light distribution from occurring.

[0034] On the other hand, in the embodiment, since a wide viewing angle characteristic is required in the X-axis direction, the height of the first wall portion 4c-1 is reduced so that the wide light distribution component from the light source 3 is utilized without being blocked, as shown in the cross section of Fig. 6. In the embodiment, the height of the second wall portion 4c-2 extending in the X-axis direction (longitudinal direction) is higher than the height of the first wall portion 4c-1 extending in the Y-axis direction (transverse direction).

[0035] 4, the reflector 4 of the embodiment is disposed so that the opening 4b is located on the emission side of the light emitting surface of the light source 3. The light emitting surface of the light source 3 corresponds to the upper surface of the light source 3. In other words, the bottom surface 4d of the wall portion 4c of the reflector 4 is disposed in a floating state above the substrate 2 so as to be higher than the light emitting surface of the light source 3, as shown in FIG.

[0036] In the embodiment, since light is only collected in the short-side direction (Y-axis direction) of the substrate 2, only a uniaxial linear Fresnel lens 5a extending in the long-side direction (X-axis direction) of the substrate 2 is used. As a result, in the embodiment, the lens position shift in the long-side direction can be ignored. Note that, in the embodiment, the field of view range adjustment lens 7 has lenticular lenses in both the X-axis direction and the Y-axis direction, but since the lenticular lenses have the same shape and pattern, there is no need to consider the lens position shift.

[0037] When the reflector 4 is grounded to the substrate 2, the wall 4c of the reflector 4 and the light source 3 are in close proximity to each other, and there is a possibility that the reflector 4 and the light source 3 may interfere with each other when they expand and contract. In contrast, in the embodiment, the opening 4b of the reflector 4 is disposed at a position higher than the light emitting surface of the light source 3, so that there is no possibility that the wall 4c of the reflector 4 and the light source 3 may come into contact with each other even if the reflector 4 and the light source 3 expand and contract.

[0038] Since the interval between the light sources 3 is narrow, if the bottom surface 4d of the reflector 4 is disposed on the substrate 2, the bottom surface 4d cannot be made large, and it is difficult to make the wall portion 4c of the reflector 4 high from the viewpoint of moldability of the injection molding. On the other hand, in the embodiment, the opening 4b of the reflector 4 can be made smaller than the outer periphery of the light source 3 as long as it is larger than the light emitting surface of the light source 3 in the top view. That is, in the embodiment, the opening 4b can be made small. In other words, in the embodiment, the bottom surface 4d can be made large, and as a result, the wall portion 4c of the reflector 4 created by injection molding can be made high. As a result, in the embodiment, the effect of high contrast during local dimming and elimination of unnecessary light distribution can be obtained.

[0039] (Modification) The surface illumination device 1 described in the above embodiment is merely an example, and various modifications are possible. Modifications of the surface illumination device 1 will be described below.

[0040] (First Modification) The surface illumination device 1 of the first modification has the same prism structure (linear Fresnel lens 5a, linear prism 6a, first lenticular lens 7a, second lenticular lens 7b) as in the embodiment, but the arrangement of each prism structure is different from that in the embodiment.

[0041] 7 is a diagram for explaining a first modified example. First, the planar lighting device 1 of the first modified example includes, as a first lens, a condenser lens 5 having a linear Fresnel lens 5a provided on a surface opposite to a surface facing a substrate 2, as in the embodiment. The planar lighting device 1 of the first modified example also includes a second lens 60 and a third lens 70.

[0042] The second lens 60 has a second lenticular lens 7b provided on a surface facing the first lens (collecting lens 5), and a linear prism 6a extending in the X-axis direction provided on a surface opposite to the surface facing the first lens (collecting lens 5). The third lens 70 has a first lenticular lens 7a provided on a surface facing the second lens 60.

[0043] In the first modified example, in the Y-axis direction, light emitted from light source 3 is collected at the exit surface of light distribution lens 5 (first lens) to become approximately parallel light, the optical axis is tilted at the exit surface of second lens 60, and the field of view range is adjusted at the entrance surface of third lens 70. Also, in the first modified example, in the X-axis direction, the luminance distribution of light emitted from light source 3 is adjusted at the entrance surface of second lens 60. With such a lens configuration order, it is possible to achieve the required light distribution characteristics while ensuring high luminance, as in the embodiment.

[0044] The third lens 70 has a diffusion surface 80 formed on the surface opposite to the surface facing the second lens 60. In the first modified example, the second lenticular lens 7b is provided on a lens having a linear prism 6a, so that the diffusion surface 80 having the same function as the diffusion sheet 8 can be formed on the upper surface of the third lens 70, thereby reducing the number of parts.

[0045] (Second Modification) The surface illumination device 1 of the second modified example has a prism structure similar to that of the embodiment (linear Fresnel lens 5a, linear prism 6a, first lenticular lens 7a, second lenticular lens 7b), but the arrangement of each prism structure and the number of lenses are different from those of the embodiment.

[0046] 8 is a diagram for explaining the second modified example. The surface illumination device 1 of the second modified example includes a first lens 51 and a second lens 61. The first lens 51 has a linear Fresnel lens 5a provided on a surface facing the substrate 2, and a linear prism 6a provided on a surface opposite to the surface facing the substrate 2. The second lens 61 is disposed on the exit side of the first lens 51, has a second lenticular lens 7b provided on a surface facing the first lens, and has a first lenticular lens 7a provided on a surface opposite to the surface facing the first lens 51.

[0047] In the second modified example, in the Y-axis direction, the light emitted from the light source 3 is collected at the entrance surface of the first lens 51 to become approximately parallel light, the optical axis is tilted at the exit surface of the first lens 51, and the viewing range is adjusted at the exit surface of the second lens 61. On the other hand, in the second modified example, in the X-axis direction, the luminance distribution of the light emitted from the light source 3 is adjusted at the entrance surface of the second lens 61. With such a lens configuration order, it is possible to achieve the required light distribution characteristics while ensuring high luminance, as in the embodiment.

[0048] (Third Modification) The surface illumination device 1 of the third modified example is composed of two lenses, like the second modified example, and has prisms similar to those of the embodiment (linear Fresnel lens 5a, first lenticular lens 7a, second lenticular lens 7b), but the shape of the linear prism for shifting the optical axis is different from that of the linear prism 6a.

[0049] 9 is a diagram for explaining the third modified example. The planar illumination device 1 of the third modified example includes a first lens 52 and a second lens 62. The first lens 52 has a linear Fresnel lens 5a on a surface facing the substrate 2, and a second lenticular lens 7b on a surface opposite to the surface facing the substrate 2. The second lens 62 has a linear prism 62a extending in the X-axis direction as a second optical element, and has the linear prism 62a on a surface facing the first lens 52, and the first lenticular lens 7a on a surface opposite to the surface facing the first lens 52.

[0050] The linear prisms 62a have a prism structure of a substantially triangular prism extending in the X-axis direction and are arranged continuously in the Y-axis direction. The cross-sectional shape of the YZ plane of the linear prisms 62a is an inverted triangle, and the base angle of the side connecting the point of the base on the positive side of the Y-axis and the vertex is larger than the base angle of the side connecting the point of the base on the negative side of the Y-axis and the vertex.

[0051] In the third modified example, in the Y-axis direction, the light emitted from the light source 3 is collected at the entrance surface of the first lens 52 to become approximately parallel light, the optical axis is tilted at the entrance surface of the second lens 62, and the viewing range is adjusted at the exit surface of the second lens 62. On the other hand, in the third modified example, in the X-axis direction, the luminance distribution of the light emitted from the light source 3 is adjusted at the exit surface of the first lens 52. With such a lens configuration order, it is possible to achieve the required light distribution characteristics while ensuring high luminance, as in the embodiment.

[0052] The lens configuration is not limited to the above-mentioned modified examples 1 to 3. For example, the first lens 52 may have any configuration, such as a second lenticular lens 7b provided on the entrance surface and a linear Fresnel lens 5a provided on the exit surface. In the above-mentioned embodiment and modified examples 1 to 3, the bottom surface of the reflector 4 is disposed at a position higher than the light emitting surface of the light source 3, but the bottom surface of the reflector 4 may be grounded to the substrate 2 as long as interference between the reflector 4 and the light source 3 can be avoided and the field of view can be adjusted.

[0053] (Fourth Modification) In the fourth modified example, a modified reflector will be described. FIG. 10 is a diagram for explaining the fourth modified example. As described above, the height of the first wall portion 4c-1 is adjusted to match the viewing range in the X-axis direction, and the height of the second wall portion 4c-2 is adjusted to match the viewing range in the Y-axis direction. In the fourth modified example shown in FIG. 10, the viewing range is narrow in both the Y-axis direction and the X-axis direction, so the height of the first wall portion 4c-1 and the height of the second wall portion 4c-2 are the same.

[0054] (Fifth Modification) In the fifth modified example, a modified reflector will also be described. Fig. 11 is a diagram for explaining the fifth modified example. As shown in Fig. 11, the fifth modified example has a reflector structure in which a reflective surface extending in the Y-axis direction is not provided between adjacent light sources 3 in the X-axis direction which is a direction in which a wide field of view is achieved.

[0055] 11, the wall portions 4c extend in the X-axis direction, and are arranged along the Y-axis direction at intervals corresponding to the distances at which the light sources 3 are arranged in the Y-axis direction. The height of the wall portions 4c is determined by the field of view in the Y-axis direction.

[0056] (Sixth Modification) In the sixth modified example, a modified example of the condenser lens 5 described in the embodiment will be described. Fig. 12 is a diagram for explaining the sixth modified example. In the above, light is only condensed in the Y-axis direction of the substrate 2, but light may also be condensed in the X-axis direction of the substrate 2 as long as the required light distribution characteristics can be realized.

[0057] In the sixth modified example, as shown in FIG. 12, the first optical element includes a linear Fresnel lens 5a that is a first linear Fresnel lens extending in the X-axis direction and focusing in the Y-axis direction, and a second linear Fresnel lens 5b that extends in the Y-axis direction and focuses in the X-axis direction. The second linear Fresnel lens 5b has a prism structure in which a cylindrical convex lens is used as the Fresnel lens, and has grooves extending in the Y-axis direction. The second linear Fresnel lens 5b has grooves formed periodically in accordance with the pitch in the X-axis direction of the light source 3 disposed directly below. The focusing lens 5 of the sixth modified example shown in FIG. 12 has the second linear Fresnel lens 5b on the incident side and the first linear Fresnel lens 5a on the exit side, but the arrangement may be reversed.

[0058] (Seventh Modification) In the seventh modification, a modification of the condenser lens 5 that condenses light in both the Y-axis direction and the X-axis direction with a different prism structure from that of the sixth modification will be described. In the seventh modification, as shown in FIG. 13, a concentric Fresnel lens 5c that condenses light in both the Y-axis direction and the X-axis direction is provided as the first optical element. The concentric Fresnel lens 5c is a lens in which a convex lens is divided into concentric regions to reduce its thickness, and has a sawtooth cross section. The concentric Fresnel lenses 5c are provided in the same number as the number of light sources 3, corresponding to the light sources 3 arranged directly below. The condenser lens 5 of the seventh modification shown in FIG. 13 has the concentric Fresnel lens 5c on the exit side, but it may be provided on the entrance side.

[0059] In the above embodiment and modified examples, in order to realize the required light distribution characteristics, the light distribution control by the prisms such as the linear Fresnel lens 5a, the first lenticular lens 7a, the second lenticular lens 7b, etc. is combined with the light distribution control by the wall height of the reflector 4, but the present invention is not limited to this. If the required light distribution characteristics are to be realized, only the light distribution control by the prism or only the light distribution control by the wall height of the reflector 4 may be performed.

[0060] Furthermore, the present invention is not limited to the above-mentioned embodiment. The present invention also includes a configuration in which the above-mentioned components are appropriately combined. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-mentioned embodiment, and various modifications are possible. [Explanation of symbols]

[0061] REFERENCE SIGNS LIST 1 Planar lighting device, 2 Substrate, 3 Light source, 4 Reflector, 4a, 4a-1, 4b-1 Reflecting surface, 4b Opening, 4c Wall portion, 4c-1 First wall portion, 4c-2 Second wall portion, 5 Condenser lens, 5a Linear Fresnel lens (first linear Fresnel lens), 6 Light distribution lens, 6a Linear prism, 7 Field of view adjustment lens, 7a First lenticular lens, 7b Second lenticular lens, 8 Diffusion sheet, 9 Frame

Claims

1. A surface illumination device used as a backlight for a liquid crystal display device, comprising: a substrate on which a plurality of light sources are two-dimensionally arranged with respect to a first axis direction and a second axis direction perpendicular to the first axis direction; a first optical element that is disposed on the emission side of the plurality of light sources and that collects and emits light emitted from the plurality of light sources at least for each row along the second axial direction; a second optical element that outputs the light collected by the first optical element with a traveling direction inclined at least to the same side with respect to the first axial direction; A surface lighting device comprising:

2. The first optical element which collects and emits light emitted from the plurality of light sources for each row along the second axial direction; the second optical element that outputs the light collected by the first optical element with a traveling direction inclined to the same side with respect to the first axial direction; Equipped with The first optical element that collects and emits the light emitted from the plurality of light sources for each row along a first axial direction is not provided, and the second optical element that inclines the light emitted from the plurality of light sources with respect to a second axial direction is not provided.

2. The spread illuminating device according to claim 1.

3. The first optical element is a lens extending in a uniaxial direction.

3. A spread illuminating device according to claim 1 or 2.

4. The first optical element is a linear Fresnel lens.

3. A spread illuminating device according to claim 1 or 2.

5. A focusing lens having a linear Fresnel lens as the first optical element; a light distribution lens including a linear prism as the second optical element; Equipped with 3. A spread illuminating device according to claim 1 or 2.

6. The first optical element includes a first lens extending in the second axial direction and focusing in the first axial direction, and a second lens extending in the first axial direction and focusing in the second axial direction.

2. The spread illuminating device according to claim 1.

7. The first optical element has a lens that focuses light in the first axial direction and the second axial direction.

2. The spread illuminating device according to claim 1.

8. The first optical element has a concentric Fresnel lens that focuses light in the first axial direction and the second axial direction.

2. The spread illuminating device according to claim 1.

9. A reflector is provided having a wall portion in which openings corresponding to the plurality of light sources are arranged, and a wall surface surrounding the openings serves as a reflective surface. The spread illuminating device according to any one of claims 1 to 8.

10. Each of the plurality of light sources is driven individually. The surface illumination device according to any one of claims 1 to 9.

11. A substrate on which a plurality of light sources are two-dimensionally arranged with respect to a first axial direction and a second axial direction perpendicular to the first axial direction; a first optical element that is disposed on an emission side of the plurality of light sources and that collects and emits light emitted from the plurality of light sources for each row along the second axis direction; a reflector having a wall portion in which openings corresponding to the plurality of light sources are arranged, the wall portion surrounding the openings being a reflective surface; Equipped with The wall portion includes a wall portion that forms an overall outer shape and a wall portion other than the wall portion that forms the overall outer shape, The wall portions, excluding the wall portion that forms the overall outer shape, have a shape in which a plurality of first wall portions extending in the first axial direction and a plurality of second wall portions extending in a second axial direction perpendicular to the first axial direction are assembled in a lattice pattern, The height of the first wall portion and the height of the second wall portion are different from each other, The height of the second wall portion is greater than the height of the first wall portion. Surface lighting device.

12. a substrate on which a plurality of light sources are two-dimensionally arranged with respect to a first axis direction and a second axis direction perpendicular to the first axis direction; a first optical element that is disposed on an emission side of the plurality of light sources and that collects and emits light emitted from the plurality of light sources for each row along the first axis direction and / or the second axis direction; a reflector having a wall portion in which openings corresponding to the plurality of light sources are arranged, the wall portion surrounding the openings being a reflective surface; Equipped with The wall portion has a shape in which a plurality of first wall portions extending in a first axial direction and a plurality of second wall portions extending in a second axial direction perpendicular to the first axial direction are assembled in a lattice pattern, the spread of the light emitted from the first optical element is different in the first axis direction and in the second axis direction; a wall portion along an axial direction in which the light emitted from the first optical element spreads more widely is higher than a wall portion along an axial direction in which the light emitted from the first optical element spreads less widely; Surface lighting device.

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