Planar lighting device

Abstract

The present invention provides a planar lighting device that is not easily separated from the combination of a bottom frame and a top frame. The planar lighting device of an embodiment includes a bottom frame, a top frame, a protrusion, a hole, or a blind hole. The bottom frame has a bottom plate and a side wall erected around the periphery of the bottom plate. The top frame has a frame and a side wall erected around the periphery of the frame, and covers the open side of the bottom frame. The protrusion is arranged along the thickness direction of the planar lighting device at the end of the side wall of the bottom frame and the outer peripheral surface. The hole or the blind hole is arranged in the frame and the side wall of the top frame, respectively, corresponding to the protrusion, and the protrusion is fitted into the hole or the blind hole.

Description

Technical Field

[0001] This invention relates to a planar lighting device. Background Technology

[0002] It is known that there are surface lighting devices used as backlights for liquid crystal display devices (see Patent Documents 1-3, etc.).

[0003] Typically, a planar lighting device consists of a box-shaped bottom frame (base frame) and a top frame (outer shell frame) that covers the open side of the bottom frame and has an opening for light emission. Additionally, protrusions (claws) are provided at multiple locations on the outer circumferential surface of the sidewall of the bottom frame. These protrusions engage with holes at multiple locations on the inner circumferential surface of the sidewall of the top frame, thereby connecting the bottom frame and the top frame.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2016-224090

[0005] Patent Document 2: Japanese Patent Application Publication No. 2011-113962

[0006] Patent Document 3: Japanese Patent Application Publication No. 2015-18700

[0007] However, with the increasing size of liquid crystal display devices and other similar applications, planar lighting devices also become larger, leading to the following problem: the connection between the bottom frame and the top frame, achieved through the protrusions and holes on the side walls, easily detaches, making it impossible to maintain the function of a planar lighting device. In particular, for rectangular planar lighting devices, the rigidity of the long side is weaker than that of the short side, making it easy for the protrusions and holes on the long side to detach. For example, if the long side of the housing becomes approximately 800mm due to the increasing size of automotive backlights and the like, the side wall of the top frame bends in an arc shape, opening up between it and the side wall of the bottom frame, causing the protrusions and holes to easily detach. Summary of the Invention

[0008] The present invention was made in view of the above, and its object is to provide a planar lighting device that makes it difficult for the connection between the bottom frame and the top frame to detach.

[0009] To solve the above problems and achieve the object, a surface lighting device according to an embodiment includes a bottom frame, a top frame, protrusions, holes, or blind holes. The bottom frame has a bottom plate and a side wall standing from a periphery of the bottom plate. The top frame has a frame and a side wall standing from a periphery of the frame, and covers an opening side of the bottom frame. The protrusions are arranged along a thickness direction of the surface lighting device at a distal end and a partial outer periphery of the side wall of the bottom frame. The holes or the blind holes are provided at the frame and the side wall of the top frame, respectively, corresponding to the protrusions, and the protrusions are fitted into the holes or the blind holes.

[0010] The surface lighting device according to an embodiment can prevent the bottom frame and the top frame from being separated. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 FIG. 1 is a plan view of a surface lighting device according to an embodiment.

[0012] Figure 2 FIG. 2 is a perspective view of a flat surface lighting device according to an embodiment.

[0013] Figure 3 FIG. 3 is an exploded perspective view of a main part of the flat surface lighting device according to an embodiment.

[0014] Figure 4 FIG. 4 is a perspective view of a curved surface lighting device according to an embodiment.

[0015] Figure 5 FIG. 5 is an exploded perspective view of a main part of the curved surface lighting device according to an embodiment.

[0016] Figure 6 FIG. 6 is an enlarged perspective view of a partial state of a bottom frame and a top frame before fitting according to an embodiment.

[0017] Figure 7 FIG. 7 is a partial cross-sectional view of a state in which the bottom frame and the top frame are fitted according to an embodiment.

[0018] Figure 8 FIG. 8 is a partial cross-sectional view of a surface lighting device according to a comparative example.

[0019] BRIEF DESCRIPTION OF DRAWINGS

[0020] 1... surface lighting device; 2... connecting portion; 3... bottom frame; 3a... bottom plate; 3b... side wall; 3c, 3d... protrusion; 4... reflection sheet; 5... substrate; 6... light source; 7... light guide plate; 8... sheet fixing frame; 9... optical sheet; 9, 9A to 9C... optical sheet; 10... top frame; 10a... frame; 10b... side wall; 10c, 10d... hole. DETAILED DESCRIPTION

[0021] Hereinafter, a planar illumination device according to an embodiment will be described with reference to the drawings. Note that the present application is not limited by this embodiment. Also, the dimensional relationship of each element of the drawings, the ratio of each element, and the like can be different from reality. Also, among the drawings, there can be portions that include a dimensional relationship, a ratio, and the like that are different from each other. Also, in principle, the contents described in one embodiment or modified example can be identically applied to other embodiments or modified examples.

[0022] Figure 1 is a plan view of a planar illumination device 1 according to an embodiment. Also, Figure 1 is a plan view of the planar illumination device 1 according to an embodiment, which also serves as a plan view of a curved type of planar illumination device 1 described later. Figure 2 is a perspective view of the planar illumination device 1 according to an embodiment. Figure 3 is an exploded perspective view of a main part of the planar illumination device 1 according to an embodiment. Also, for convenience, the longitudinal direction of the planar illumination device 1 is set as the X-axis direction, the lateral direction is set as the Y-axis direction, and the thickness direction is set as the Z-axis direction.

[0023] Also, although an example of application to an edge light type of planar illumination device 1 provided with a light guide plate is illustrated, it is needless to say that the application is also possible to a direct type of planar illumination device in which light sources are two-dimensionally arranged along an exit surface. In the direct type of planar illumination device, a substrate on which light sources are two-dimensionally arranged, a reflection plate having a reflection surface that surrounds each light source from the periphery, a lens sheet that is on the exit side of the reflection plate and performs adjustment of optical characteristics, a diffusion sheet, and the like are provided inside a housing.

[0024] Figures 1-3 In the planar illumination device 1 according to an embodiment, a reflection sheet 4, a light guide plate 7, and an optical sheet 9 are sequentially stacked on a bottom frame 3, and the planar illumination device 1 becomes a form in which a top frame 10 serves as a cover. Figure 2 and Figure 3 In the planar illumination device 1 according to an embodiment, the main surfaces of the bottom frame 3 and the top frame 10 become flat shapes. Also, Figure 3 In the planar illumination device 1 according to an embodiment, a plurality of light sources that emit light to the light entrance side surface (the side surface of the long side on the front side of the drawing) of the light guide plate 7 and a substrate on which the light sources are mounted are omitted, but the arrangement thereof will be shown by a cross-sectional view described later. Figure 2 and Figure 3 In the planar illumination device 1 according to an embodiment, the connection portion 2 has one end of the internal substrate connected thereto, and is a member for electrical connection to the outside.

[0025] The bottom frame 3 is formed of metal, for example, by die casting, sheet metal, or the like. The reflective sheet 4 is used to reflect light that leaks from the light guide plate 7 toward the bottom frame 3 side to return toward the light guide plate 7 side. In the case where the bottom plate surface of the bottom frame 3 is applied with white paint or the like and has good reflective properties, the reflective sheet 4 can also be omitted. The light guide plate 7 is formed of a transparent resin such as polycarbonate or acrylic, and guides light that is incident from the long side of the light incident surface to the entire surface and emits it from one main surface (the upper main surface in the drawing).

[0026] The optical sheet 9 is one or a plurality of sheets that exert an optical function, such as a diffusion sheet, a prism sheet, a brightness enhancement film (DBEF: Dual Brightness Enhancement Film), or the like. One end of the long side of the optical sheet 9 (the proximal side in the drawing) is fixed to one sheet of the sheet fixing frame 8 that is bent in a substantially L-shaped cross section, and the other sheet of the sheet fixing frame 8 is sandwiched between the side wall of the bottom frame 3 and the side wall of the top frame 10 and is fixed. The top frame 10 is formed of a resin or the like, for example.

[0027] Figure 4 is a perspective view of the curved surface lighting device 1, Figure 5 is an exploded perspective view of the main part of the curved surface lighting device 1. The plan view and Figure 1 are the same. Figure 4 and Figure 5 In the curved surface lighting device 1, the bottom frame 3, the reflective sheet 4, the light guide plate 7, the optical sheets 9A to 9C (corresponding to the optical sheet 9), and the top frame 10 are the same as in the flat surface lighting device 1 except that the main surface is curved. In addition, the bottom frame 3 and the top frame 10 are formed in a curved state from the beginning, but the reflective sheet 4, the light guide plate 7, and the optical sheets 9A to 9C are not curved before assembly, are curved when arranged on the bottom frame 3, and are fixed in a state pressed by the top frame 10. Figure 2 and Figure 3 In addition, the bottom frame 3 and the top frame 10 are formed in a curved state from the beginning, but the reflective sheet 4, the light guide plate 7, and the optical sheets 9A to 9C are not curved before assembly, are curved when arranged on the bottom frame 3, and are fixed in a state pressed by the top frame 10.

[0028] Figure 6 is an enlarged perspective view of a part of the bottom frame 3 and the top frame 10 in a separated state before fitting, and is a configuration common to the flat surface (1A) and the curved surface (1B). Figures 1-3 ) and the curved surface (1B). Figure 1 , Figure 4 , Figure 5 Figure 7 is a cross-sectional view of a part of the bottom frame 3 and the top frame 10 in a fitted state. The fitting site is, for example, a site where a black short horizontal line indicating a hole portion is present on the long side of the frame portion of the top frame 10 in the flat surface lighting device 1 (6 sites on the upper long side and 7 sites on the lower long side). Figure 1 The fitting site is on the edge in the long side direction of the frame portion of the surface lighting device 1, and the number is not limited to the case shown in the drawing. Figure 6 and​Figure 7 In response to Figure 1 One of the fitting parts is shown on the lower long side.

[0029] Furthermore, in indicating a curved type Figure 4 In order to increase the bonding strength of the central part where the bond is prone to detachment, a greater number of fitting structures are provided in the central part of the long side on the light-incident side (near the front side in the figure) than in other parts (this is not the same as...). Figure 1 While strictly consistent, the edge along the long side (depth side in the figure) also has more fitting structures in the central portion than in other portions. Furthermore, while the edge along the long side uses fitting structures that restrict movement in the two axial directions described later, the edge along the short side uses fitting structures that restrict movement only in the thickness direction of the planar lighting device 1, rather than in the two axial directions. This is to account for reworkability. Alternatively, the fitting structures can be uniform, in which case fitting structures restricting movement in two axial directions are provided on both the long and short sides.

[0030] Figure 6 and Figure 7 In the bottom frame 3, there is a base plate portion 3a and a side wall 3b erected around the periphery of the base plate portion 3a. In addition, the top frame 10 has a frame portion 10a and a side wall 10b erected around the periphery of the frame portion 10a, and covers the opening side of the bottom frame 3.

[0031] A protrusion 3c is provided at the end of the side wall 3b of the bottom frame 3, and a protrusion (claw) 3d is provided on a portion of the outer peripheral surface of the side wall 3b. The protrusions 3c and 3d are arranged along the thickness direction (Z-axis direction) of the planar lighting device 1. The end protrusion 3c extends in a rectangular shape from the generally flat end face 3e of the side wall 3b of the bottom frame 3, coplanar with the outer peripheral surface of the side wall 3b. The outer peripheral protrusion 3d rises in a rectangular shape outward from the outer peripheral surface of the side wall 3b, with a height that increases in the specified width in the thickness direction on the side of the base plate 3a, and decreases in height as it slopes toward the end of the side wall 3b.

[0032] Further, a hole portion 10c corresponding to the protrusion 3c of the bottom frame 3 is provided in the frame portion 10a of the top frame 10, and a hole portion 10d corresponding to the protrusion 3d of the bottom frame 3 is provided in the side wall 10b of the top frame 10. The hole portions 10c and 10d are substantially rectangular shapes with R processing applied to the corners. Further, in the illustrated example, the hole portions 10c and 10d are through holes, but can also be blind hole portions that are closed on the side opposite the protrusions 3c and 3d. Further, a step portion 10e is provided on the lower surface side of the frame portion 10a of the top frame 10, opposite the end surface 3e of the side wall 3b of the bottom frame 3. Furthermore, when assembled, the protrusion 3c of the bottom frame 3 is fitted into the hole portion 10c of the top frame 10, and the protrusion 3d of the bottom frame 3 is fitted into the hole portion 10d of the top frame 10. The protrusion 3d of the bottom frame 3 is shaped so as to be inclined, so as to easily penetrate the side wall 10b of the top frame 10 when assembled, and so as not to easily come out of the hole portion 10d after fitting.

[0033] Further, a protrusion 10f is provided on the lower surface side of the frame portion 10a of the top frame 10, opposite the end portion of the main surface of the light guide plate 7, and a step portion 10g is provided in connection with the protrusion 10f, opposite the end portion of the optical sheet 9 (9A to 9C). Further, a substrate 5 on which a plurality of light sources 6 are arranged in the longitudinal direction is fixed to the inner surface of the side wall 3b of the bottom frame 3, with the exit surface of the light source 6 opposite the light entry surface 7a of the light guide plate 7. Further, as the light source 6, a top view type LED or the like that emits light from the top surface side is illustrated as an example, but a side view type LED or the like that emits light from the side surface side can also be used. In this case, the substrate 5 is arranged in parallel with the bottom plate portion 3a of the bottom frame 3.

[0034] Figure 6 And Figure 7 Further, the side wall 10b of the top frame 10 is restricted in movement in the Y-axis direction by the fitting of the hole portion 10c and the protrusion 3c of the bottom frame 3, and the side wall 10b is prevented from bending outward in an arc shape. Further, the side wall 10b of the top frame 10 is restricted in movement in the Z-axis direction by the fitting of the hole portion 10d and the protrusion 3d of the bottom frame 3, but because of the restriction in movement in the Y-axis direction described above, the side wall 10b of the top frame 10 does not bend outward in an arc shape, and thus the side wall 10b does not open with respect to the side wall 3b, and the fitting of the hole portion 10d and the protrusion 3d does not easily come apart. As a result, the combination of the bottom frame 3 and the top frame 10 does not easily come apart.

[0035] In particular, in Figure 4 And Figure 5In the curved planar lighting device 1 shown, the internal light guide plate 7 and the like are sandwiched by the combination of the bottom frame 3 and the top frame 10 in a state in which they are bent from a flat state before assembly, and thus a force is applied to the bottom frame 3 and the top frame 10 in a direction in which the combination is to be released by the restoring force of the light guide plate 7 and the like, but the combination is not released and is stably combined by the above-described configuration.

[0036] Figure 8 FIG. 6 is a partial cross-sectional view of a planar lighting device 1' as a comparative example. Figure 8 In the bottom frame 3', the tip of the side wall 3b' is not provided with a protrusion, and the frame portion 10a' of the top frame 10' is not provided with a hole portion. The other configurations are the same as those of the bottom frame 3 and the top frame 10 of the planar lighting device 1. Figure 6 And Figure 7 In this case, the side wall 10b' of the top frame 10' is restricted in movement in the Z-axis direction by the fitting of the hole portion 10d' and the protrusion 3d' of the bottom frame 3, but if the side wall 10b' is bent outward as shown by the dotted line, the side wall 10b' and the side wall 3b' are opened, and the fitting of the hole portion 10d' and the protrusion 3d' is easily released. In this regard, Figure 6 And Figure 7 In the embodiment of the planar lighting device 1, movement is restricted not only in the Z-axis direction but also in the Y-axis direction, and thus the fitting is prevented from being released.

[0037] The above-described embodiments of the present application have been described, but the present application is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

[0038] As described above, the planar lighting device according to the embodiments includes a bottom frame having a bottom plate portion and a side wall erected around the periphery of the bottom plate portion, a top frame having a frame portion and a side wall erected around the periphery of the frame portion and covering the opening side of the bottom frame, a protrusion provided at the tip of the side wall of the bottom frame and arranged along the thickness direction of the planar lighting device at a portion of the outer peripheral surface, and a hole portion or a blind hole portion provided at the frame portion and the side wall of the top frame and corresponding to the protrusion, into which the protrusion is fitted. Thus, the combination of the bottom frame and the top frame is not easily released.

[0039] In addition, a plurality of sets of the protrusion and the hole portion or the blind hole portion are provided on the edges in the long direction of the planar lighting device. Thus, the required strength of the combination can be ensured.

[0040] In addition, a larger number of sets of the protrusion and the hole portion or the blind hole portion are provided at the central portion of the edges in the long direction than at other portions. Thus, the strength of the combination at the central portion, in which the combination is easily released, can be increased, and in particular, the strength of the combination of the curved planar lighting device can be ensured.

[0041] Further, the protrusion is provided on the outer circumferential surface of the side wall of the bottom frame, and the hole portion or the blind hole portion is provided on the side wall of the top frame and is fitted with the protrusion. The end of the side wall of the bottom frame and the corresponding portion of the frame portion of the top frame do not have a structure for fitting. Thus, the portion not requiring the joining strength does not use a complicated structure for fitting, and the manufacturing, assembling, and reworking operations can be made easier.

[0042] Further, the protrusion of the end of the side wall of the bottom frame extends in a rectangular shape in the thickness direction from the substantially flat end surface of the side wall of the bottom frame and is coplanar with the outer circumferential surface of the side wall of the bottom frame. The protrusion of the outer circumferential surface of the side wall of the bottom frame protrudes in a rectangular shape toward the outside from the outer circumferential surface of the side wall of the bottom frame. The height of the thickness direction of the bottom plate portion side of the bottom frame is high, and the height is low toward the end side of the side wall of the bottom frame. Thus, the specific shape of the protrusion and the hole portion or the blind hole portion can be provided.

[0043] Further, the bottom frame and the top frame are in a flat shape or a curved shape. Thus, the applicable surface lighting device can be expanded, and the joining strength of the curved type, which is particularly likely to be easily separated, can be improved.

[0044] Further, the optical element constituting the edge light type surface lighting device or the optical element constituting the direct type surface lighting device is housed in the housing formed by the bottom frame and the top frame. Thus, the applicable surface lighting device can be expanded.

[0045] Further, the present application is not limited to the above-described embodiments. The present application also includes a mode in which the above-described technical features are appropriately combined. Further, further effects, modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the present application are not limited to the above-described embodiments, and various modifications can be made.

Claims

1. A planar lighting device, characterized by comprising: Possessing: a bottom frame having a bottom plate portion and a side wall erected to a periphery of the bottom plate portion; a top frame having a frame portion disposed along the bottom plate portion and a side wall erected to a periphery of the frame portion, and covering an open side of the bottom frame; a first protrusion portion provided in a manner that protrudes outward from an outer peripheral surface of the side wall of the bottom frame a second protrusion portion provided in a manner that protrudes from an end surface of a tip end of the side wall of the bottom frame at a position offset in a thickness direction perpendicular to the bottom plate portion with respect to the first protrusion portion; a first hole portion provided in the side wall of the top frame in correspondence with the first protrusion portion, and into which the first protrusion portion is fitted; and a second hole portion provided in the frame portion of the top frame at a position offset in the thickness direction with respect to the first hole portion in correspondence with the second protrusion portion, and into which the second protrusion portion is fitted.

2. The planar illumination device according to claim 1, wherein a plurality of sets of the first protrusion portion and the first hole portion are provided on an edge in a long side direction of the planar illumination device, and a plurality of sets of the second protrusion portion and the second hole portion are provided on the edge in the long side direction.

3. The planar illumination device according to claim 2, wherein the number of sets of the first protrusion portion and the first hole portion is larger in a central portion of the edge in the long side direction than in other portions, and the number of sets of the second protrusion portion and the second hole portion is larger at the central portion of the edge in the long side direction than in other portions.

4. The planar illumination device according to claim 2 or 3, wherein the first protrusion portion and the first hole portion are provided on an edge in a short side direction of the planar illumination device, and a portion corresponding to a tip end of the side wall of the bottom frame and a portion corresponding to the frame portion of the top frame do not have a configuration for fitting.

5. The planar illumination device according to claim 1, wherein the second protrusion portion extends in a rectangular shape in the thickness direction from a substantially flat end surface of the side wall of the bottom frame to be coplanar with an outer peripheral surface of the side wall of the bottom frame, and the first protrusion portion protrudes in a rectangular shape from the outer peripheral surface of the side wall of the bottom frame toward the outside, a height of a prescribed width of the thickness direction on the bottom plate portion side of the bottom frame becomes higher, and the height becomes lower toward a tip end side of the side wall of the bottom frame.

6. The planar illumination device according to claim 1, wherein the bottom frame and the top frame are in a flat shape or a curved shape of a main surface.

7. The planar illumination device according to claim 1, wherein an optical element constituting an edge light type planar illumination device or an optical element constituting a direct type planar illumination device is housed in a housing formed by the bottom frame and the top frame. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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