Planar lighting device

Abstract

To realize narrowing of a frame and improvement of luminance uniformity at the same time.SOLUTION: A planar lighting device includes: a substrate; a reflector; and a bottom frame. Multiple light sources are disposed on the substrate in a two-dimensional manner. The reflector is provided on the substrate and has a reflection surface enclosing each of the light sources. The bottom frame houses the light sources, the substrate, and the reflector. In the reflector, a portion, which faces a side wall of the bottom frame, of the reflection surface is removed at an end part facing the side wall of the bottom frame.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Conventionally, so-called direct type planar lighting devices have been known (see, for example, Patent Documents 1 and 2). In a direct type planar lighting device, light sources such as a plurality of LEDs (Light Emitting Diodes) are arranged two-dimensionally on a substrate, a reflector having a reflective surface surrounding each light source is provided on the substrate, and a lens array, a diffuser (diffusion plate), etc. are arranged on the emission side of the reflector.

[0003] Such planar lighting devices are often used as backlights for liquid crystal display devices, and there is a high demand for narrower frame widths, mainly for design reasons. Also, from the perspective of appearance, there is a demand for improved luminance uniformity on the light-emitting surface (exit surface). Regarding luminance uniformity, particularly in the periphery (near the four sides of a rectangle), there is no adjacent light source on one side (two sides at corners), which reduces the luminance uniformity, and this improvement is required.

[0004] In order to simultaneously achieve a narrower frame and improved brightness uniformity, if the size of the case and the number of light sources are the same, it is possible to slightly increase the pitch of the two-dimensional arrangement of the light sources, thereby bringing the edge light sources closer to the edge of the case. By bringing the edge light sources closer to the edge of the case, the brightness of the outer periphery increases, improving brightness uniformity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-4895 A [Patent Document 2] JP 2019-46789 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, by bringing the light source at the edge closer to the edge of the housing, the shape of the reflecting surface of the reflector becomes a thin shape with a short width on the edge side, making it difficult to manufacture by injection molding of resin, etc. As a result, the light source at the edge cannot be brought close enough to the edge of the housing within the manufacturable range, and it is not possible to simultaneously achieve a narrow frame and improved brightness uniformity. Note that although it is possible to improve brightness uniformity by covering the outer periphery with a light-shielding sheet or the like and narrowing the effective area, this goes against the narrow frame.

[0007] The present invention has been made in view of the above, and an object of the present invention is to provide a spread illuminating device that can simultaneously realize a narrower frame and improved luminance uniformity. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, a planar lighting device according to one aspect of the present invention includes a substrate, a reflector, and a bottom frame. A plurality of light sources are arranged two-dimensionally on the substrate. The reflector is provided on the substrate and has a reflective surface surrounding each of the light sources. The bottom frame houses the light sources, the substrate, and the reflector. At an end portion of the reflector facing a side wall of the bottom frame, a portion of the reflective surface facing the side wall of the bottom frame is removed. A reflecting member is provided on a surface of the side wall of the bottom frame facing the light source.

[0009] ADVANTAGEOUS EFFECT OF THE PRESENTLY PREFERRED EMBODIMENTS OF THE PRESENT DISCLOSURE The planar lighting device according to one aspect of the present invention can simultaneously achieve a narrower frame and improved luminance uniformity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of the appearance of a surface illumination device according to one embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the main part of the surface illumination device. [Diagram 3]FIG. 3 is a plan view of a corner of the surface illumination device with the lens array, diffuser, optical sheet, and top frame removed. [Figure 4] FIG. 4 is a cross-sectional view taken along line YY in FIG. [Diagram 5] FIG. 5 is a plan view of a corner of the surface illumination device in the first comparative example with the lens array, diffuser, optical sheet, and top frame removed. [Figure 6] FIG. 6 is a cross-sectional view of a surface illumination device of a first comparative example. [Figure 7] FIG. 7 is a plan view of a corner of the surface illumination device in the second comparative example with the lens array, diffuser, optical sheet, and top frame removed. [Figure 8] FIG. 8 is a cross-sectional view of a surface illumination device of a second comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 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.

[0012] 1 is a perspective view of the appearance of a surface lighting device 1 according to one embodiment. In the figure, for convenience, the longitudinal direction of the surface lighting device 1 is defined as the X-axis direction, the lateral direction is defined as the Y-axis direction, and the thickness direction is defined as the Z-axis direction.

[0013] 1, the surface lighting device 1 has a substantially rectangular (or substantially square) plate-like outer shape, and the housing is made up of a bottom frame (hidden behind in the figure) in the shape of a box with a floor that houses a substrate and the like described below, and a top frame 11 that covers the opening side of the bottom frame. The top frame 11 has an exit surface 1a formed by a substantially rectangular opening 11a, and light is irradiated from the inside of the surface lighting device 1 to the outside. When the surface lighting device 1 is used as a backlight for an in-vehicle navigation device, indicator, or the like, a liquid crystal display device or the like is attached to the side of the exit surface 1a.

[0014] Fig. 2 is an exploded perspective view of the main parts of the surface lighting device 1, as seen from the light output surface side, similar to Fig. 1. In Fig. 2, the surface lighting device 1 has a reflective member 3, a substrate 4 on which a light source 5 is arranged, a reflector 6, a lens array 7, a diffuser 8, and optical sheets 9 and 10 attached to a bottom frame 2, and a top frame 11 fitted into the bottom frame 2 to form a lid.

[0015] The bottom frame 2 has a bottom 2a and side walls 2b on the four sides of the periphery of the bottom 2a. The bottom 2a is provided with a hole 2c through which an electrical connector (not shown) provided on the back surface of the substrate 4 passes. The bottom frame 2 is formed by die casting, sheet metal, or the like.

[0016] A reflective member 3 made of reflective tape or the like is attached to the inside of the side wall 2b of the bottom frame 2. The reflective tape is a strip-shaped member having a reflective layer formed on one side and an adhesive layer formed on the other side.

[0017] A substrate 4 is fixed to the inside of the bottom 2a of the bottom frame 2 via a fixing member (not shown) such as double-sided tape. On the substrate 4, a plurality (a large number) of light sources 5 such as LEDs (Light Emitting Diodes) are arranged two-dimensionally (for example, in a lattice pattern).

[0018] The back surface of the reflector 6 is fixed between the light sources 5 of the substrate 4 via a fixing member (not shown) such as a plurality of rectangular double-sided tapes extending in the vertical direction (or horizontal direction) of the figure. The reflector 6 has a reflective surface surrounding each light source 5, and reflects the light emitted from the light source 5 at a wide angle toward the light output surface side to increase brightness. The reflective surface of the reflector 6 has a substantially rectangular hole portion through which the light source 5 is placed and four inclined reflective surfaces surrounding the hole portion and opening toward the light output surface side. At the end portion of the reflective surface of the reflector 6 facing the side wall 2b of the bottom frame 2, the portion facing the side wall 2b is removed. The reflector 6 is manufactured by injection molding of resin or the like.

[0019] The rear surface of the lens array 7 is fixed to the lower end side of the reflector 6 in the figure via a fixing member (not shown) made of a plurality of rectangular double-sided tape or the like. The lens array 7 is for adjusting the light distribution and brightness of the light emitted from the reflector 6. The lens array 7 is provided on its outer periphery with a boss (not shown) for maintaining a distance from the diffuser 8.

[0020] A diffuser 8 is fixed via a fixing member (not shown) such as a plurality of rectangular double-sided tapes to the lower end side of the lens array 7 in the figure. The diffuser 8 is also called a diffusion sheet (diffusion film) or a diffusion plate.

[0021] Optical sheets 9 and 10 are fixed to the lower end side of diffuser 8 in the figure via fixing members (not shown) such as multiple rectangular double-sided tapes. The optical sheets 9 and 10 adjust the light distribution and brightness of the light passing through, and are prism sheets (prism films), brightness enhancement sheets (brightness enhancement films), louver sheets (louver films), etc.

[0022] A top frame 11 is disposed on the emission surface side of the optical sheet 10, and the top frame 11 is fixed to the bottom frame 2. The top frame 11 is formed by die casting, sheet metal, or the like.

[0023] Fig. 3 is a plan view of a corner of the surface lighting device 1 with the lens array 7, diffuser 8, optical sheets 9 and 10, and top frame 11 removed. Fig. 4 is a YY cross-sectional view in Fig. 1 (a cross-sectional view of the periphery of the light source 5 at the right end in Fig. 3 with the lens array 7, diffuser 8, optical sheets 9 and 10, and top frame 11 attached).

[0024] 3 and 4, the position of the light source 5 at the edge on the substrate 4 is moved toward the edge compared to the case where no measures are taken to narrow the frame and improve brightness uniformity (first comparative example described later). In addition, the reflective surface of the reflector 6 surrounding the light source 5 has a portion that faces the side wall 2b of the bottom frame 2 removed. That is, at the corners, portions of the reflective surface on two sides are removed, and at the other ends, portions on one side are removed. This eliminates the problem that the reflective surface at the end becomes thin, making manufacturing by resin injection molding or the like difficult, and makes it easier to manufacture the reflector 6.

[0025] This brings the edge light source 5 closer to the edge of the housing (bottom frame 2, top frame 11), making it easier to narrow the frame and increasing the brightness of the outer periphery, improving brightness uniformity. Note that since one side of the housing (for example, the lower side in Figs. 1 and 2) often does not require a narrow frame, part of the reflective surface of the reflector 6 can be left on that side without removing it.

[0026] In addition, the reflective surface at the end of the reflector 6 is removed, and instead of reflection by a portion of the reflective surface of the reflector 6, the light source 5 at the end is directly adjacent to the reflective member 3 attached to the side wall 2b of the bottom frame 2, and the light emitted at a wide angle from the light source 5 is reflected by the reflective member 3 toward the emission surface, compensating for the absence of a portion of the reflective surface of the reflector 6.

[0027] Fig. 5 is a plan view of a corner of the surface lighting device 1' in the first comparative example with the lens array 7', diffuser 8', optical sheets 9', 10', and top frame 11' removed. Fig. 6 is a cross-sectional view of the surface lighting device 1' in the first comparative example (a cross-sectional view of the periphery of the light source 5' at the right end of Fig. 5 with the lens array 7', diffuser 8', optical sheets 9', 10', and top frame 11' attached).

[0028] 5 and 6, the position of the edge light source 5' on the substrate 4' is farther away from the edge of the housing (bottom frame 2', top frame 11') than in the embodiment of FIG. 3. Also, the reflecting surface of the reflector 6' surrounding the light source 5' has a uniform shape over the entire surface. Therefore, at the outer periphery of the housing (near the four sides of the rectangle), there is no adjacent light source 5' on one side (two sides at the corners), which reduces the luminance uniformity.

[0029] FIG. 7 is a plan view of a corner of the surface lighting device 1" in the second comparative example with the lens array 7", diffuser 8", optical sheets 9", 10", and top frame 11" removed. FIG. 8 is a cross-sectional view of the surface lighting device 1" in the second comparative example (a cross-sectional view of the periphery of the light source 5" at the right end of FIG. 7 with the lens array 7", diffuser 8", optical sheets 9", 10", and top frame 11" attached).

[0030] 7 and 8, the position of the edge light source 5" on the substrate 4" has been moved toward the edge compared to the first comparative example in FIG. 5. Therefore, the shape of the reflective surface of the reflector 6" becomes a thin shape with a short width on the edge side, making it difficult to manufacture by resin injection molding or the like. As a result, the edge light source 5" cannot be moved sufficiently close to the edge of the housing as shown in the figures, and it is not possible to simultaneously achieve a narrow frame and improved brightness uniformity.

[0031] In contrast, in the embodiment of Figures 3 and 4, the reflector 6 has a manufacturable shape, so that the light source 5 can be placed sufficiently close to the edge of the housing, thereby simultaneously achieving a narrow frame and improved brightness uniformity.

[0032] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0033] As described above, the planar lighting device according to the embodiment includes a substrate on which a plurality of light sources are arranged two-dimensionally, a reflector provided on the substrate and having a reflective surface surrounding each of the light sources, and a bottom frame that houses the light sources, the substrate, and the reflector, and at an end portion of the reflector that faces the side wall of the bottom frame, a portion of the reflective surface that faces the side wall of the bottom frame is removed. This makes it possible to simultaneously achieve a narrower frame and improved brightness uniformity.

[0034] In addition, a reflective member is provided on the side wall of the bottom frame facing the light source, thereby compensating for the removal of the reflective surface of the reflector, and no reduction in brightness occurs.

[0035] The reflective member is formed of a strip of reflective tape having a reflective layer formed on one side and an adhesive layer formed on the other side, which makes it easy to attach the reflective member.

[0036] In addition, a lens array, a diffuser, and an optical sheet are provided on the output side of the reflector, which allows the light distribution and luminance distribution to be adjusted.

[0037] The device also includes a top frame that fits into the side wall of the bottom frame, thereby enabling the bottom frame and the top frame to form a sturdy housing.

[0038] 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]

[0039] REFERENCE SIGNS LIST 1 Planar lighting device, 2 Bottom frame, 3 Reflective member, 4 Substrate, 5 Light source, 6 Reflector, 7 Lens array, 8 Diffuser, 9, 10 Optical sheet, 11 Top frame

Claims

1. A substrate on which a plurality of light sources are arranged in two dimensions; a reflector provided on the substrate and having a reflective surface surrounding each of the light sources; a bottom frame that houses the light source, the substrate, and the reflector; Equipped with the reflector has an end portion facing the side wall of the bottom frame, the end portion being removed from the reflective surface of the reflector, the end portion facing the side wall of the bottom frame being removed from the reflective surface of the reflector, A reflective member is provided on a surface of the side wall of the bottom frame facing the light source. Surface lighting device.

2. A top frame is provided which fits onto a side wall of the bottom frame.

2. The spread illuminating device according to claim 1.

3. A substrate on which a plurality of light sources are arranged in two dimensions; a reflector provided on the substrate and having a reflective surface surrounding each of the light sources; a bottom frame that houses the light source, the substrate, and the reflector; a top frame having at least a narrow frame portion and fitted to a side wall of the bottom frame; Equipped with The reflector has an end portion facing the side wall of the bottom frame corresponding to the narrowed frame portion, and a portion of the reflective surface facing the side wall of the bottom frame is removed. Surface lighting device.

4. A reflective member is provided on a surface of the side wall of the bottom frame facing the light source.

4. The spread illuminating device according to claim 3.

5. The reflective member is composed of a strip-shaped reflective tape having a reflective layer formed on one side and an adhesive layer formed on the other side.

5. A spread illuminating device according to claim 1 or 4.

6. A lens array, a diffuser and an optical sheet are provided on the output side of the reflector.

6. The spread illuminating device according to claim 1.

7. The light source at the end where the reflective surface of the reflector is removed is disposed near the side wall of the bottom frame.

7. The spread illuminating device according to claim 1.

8. The reflective surface of the reflector is removed along the entire length of at least one side constituting the outer periphery.

8. The spread illuminating device according to claim 1.

9. The top view shape is approximately rectangular, The reflecting surface of the reflector is removed along the entire length of at least three sides constituting the outer periphery.

8. The spread illuminating device according to claim 1.

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