Planar lighting device

Abstract

The planar lighting device of the embodiment can stably fix the reflector to the substrate even when a temperature change occurs. A planar lighting device (1) includes a substrate (3) having a plurality of light sources (30) provided on one surface side thereof; a reflector (4) provided on the one surface side of the substrate (3); a bottom frame (21) provided on the opposite surface side of the substrate (3) opposite to the one surface; a first fixing member (6) that fixes a central portion in a long dimension direction of the reflector (4) to the bottom frame (21); and a second fixing member (7) that fixes the one surface of the substrate (3) and the reflector (4). Of forces with which the second fixing member (7) restricts the substrate (3) and the reflector (4), the force at the central portion (42) in the long dimension direction of the reflector (4) is greater than the force at a portion of the reflector (4) away from the central portion (42) in the long dimension direction.

Description

Technical Field

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

[0002] A so-called direct-lit surface lighting device is known, which is used as a backlight for automotive LCD displays, etc. This surface lighting device includes: a substrate with multiple light sources disposed on one side thereon; a reflector disposed on one side of the substrate; and a bottom frame disposed on the side of the substrate opposite to one side.

[0003] In a planar lighting device, there is a planar lighting device that has a substrate through hole on the substrate and a reflector through hole on the reflector, and a pin on one side of the bottom frame that engages with the substrate through hole and the reflector through hole to fix the substrate and the reflector to the bottom frame (for example, Patent Document 1).

[0004] Furthermore, in planar lighting devices, when there is a space (gap) between the reflector and the substrate, light from the light source will enter this space, resulting in light loss. Therefore, in order to suppress light loss, there is a planar lighting device in which the reflector is fixed to the substrate by double-sided tape to prevent the formation of a space between the reflector and the substrate.

[0005] Furthermore, in existing planar lighting devices, double-sided tape is arranged, for example, along the outer periphery of the reflector and the substrate at fixed intervals.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-246988 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, in the operating environment of a surface lighting device mounted on a vehicle (e.g., -40°C to 95°C for automotive use), the coefficient of linear expansion of the reflector differs from that of the substrate (or the frame to which the substrate is fixed). Therefore, when the temperature inside the vehicle changes, the length (change) of the reflector in the longitudinal direction differs from that of the substrate in the longitudinal direction, posing a potential risk that the reflector may warp towards one side or the other side of the substrate, centered on its central portion in the longitudinal direction, potentially causing the reflector to detach from the substrate.

[0011] The present invention was made in view of the above, and its object is to provide a planar lighting device that can stably fix the reflector to the substrate even when temperature changes occur.

[0012] Solution for solving the problem

[0013] To solve the above-mentioned problems and achieve the objective, one aspect of the present invention provides a planar lighting device comprising: a substrate having a plurality of light sources disposed on one side thereof; a reflector disposed on the one side thereof; a bottom frame disposed on the opposite side of the substrate; a first fixing member fixing a central portion of the reflector in the longitudinal direction to the bottom frame; and a second fixing member fixing the one side thereof and the reflector, wherein the force exerted by the second fixing member on the substrate and the reflector is such that the force at the central portion of the reflector in the longitudinal direction is greater than the force at the portion of the reflector away from the central portion in the longitudinal direction.

[0014] One aspect of the present invention provides a planar lighting device that can stably fix the reflector to the substrate even when temperature changes occur. Attached Figure Description

[0015] Figure 1 This is a perspective view of one embodiment of a planar lighting device viewed from the front side.

[0016] Figure 2 Viewed from the back side Figure 1 A three-dimensional view of a planar lighting device.

[0017] Figure 3 It is an exploded perspective view of a planar lighting device.

[0018] Figure 4 This is a front view of the reflector with the optical elements removed.

[0019] Figure 5 This is a front view of the substrate with the optical plates and reflectors removed.

[0020] Figure 6 yes Figure 4 The sectional view at point A-A.

[0021] Figure 7 yes Figure 5 The sectional view at arrow B-B.

[0022] Figure 8 This is a conceptual diagram showing the position of the first fixing member and the difference in the magnitude of the force exerted by the second fixing member on the substrate and the reflector.

[0023] Figure 9 This is an explanatory diagram showing an example of the configuration of the second fixing member.

[0024] Figure 10This is an explanatory diagram showing the configuration of the second fixed member in the comparative example.

[0025] Figure 11 These are illustrative diagrams showing other examples of the configuration of the second fixed member.

[0026] Figure 12 This is an illustrative diagram showing another example of the configuration of the second fixed member.

[0027] Figure 13 This is an illustrative diagram showing yet another example of the configuration of the second fixed member.

[0028] Figure 14 This is a conceptual diagram showing the position of the first fixing member and the difference in the magnitude of the force exerted by the second fixing member on the substrate and the reflector.

[0029] Figure 15 This is an illustrative diagram showing an example of the configuration of the second fixing member in another embodiment.

[0030] Figure 16 This is an exploded assembly view showing another example of the first fixed member, and a perspective view showing one side of the reflector in the short dimension direction, which is orthogonal to the long dimension direction.

[0031] Figure 17 This is an exploded assembly view showing another example of the first fixed member, and a perspective view showing the other side of the reflector in the short dimension direction.

[0032] Figure 18 This is an illustrative diagram showing an example of another embodiment of the second fixing member.

[0033] Figure 19 yes Figure 18 The sectional view at the arrow C-C line.

[0034] Figure 20 This refers to variations in other implementation methods. Figure 19 The same sectional view. Detailed Implementation

[0035] (First Implementation)

[0036] Hereinafter, the planar lighting device 1 of the first embodiment will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the embodiments shown below. Furthermore, the dimensional relationships and proportions of the elements in the drawings may sometimes differ from reality. Sometimes, the drawings may include portions with different dimensional relationships or proportions. Moreover, the content described in one embodiment is generally applicable to other embodiments as well.

[0037] First, use Figures 1 to 3 The overall structure of the planar lighting device 1 of the embodiment will be described. Figure 1 This is a perspective view of the planar lighting device 1 of the first embodiment viewed from the front side. Figure 2 This is a perspective view of the planar lighting device 1 as seen from the rear side of the first embodiment. Figure 3 This is an exploded perspective view of the planar lighting device 1 according to the first embodiment. Figures 1 to 3 For convenience, the long dimension direction of the planar lighting device 1 is set as the X-axis direction, the short dimension direction is set as the Y-axis direction, and the thickness direction is set as the Z-axis direction.

[0038] The planar illumination device 1 described in this embodiment is an illumination device used as the backlight for various liquid crystal display devices. It is a so-called direct-lit planar illumination device 1 in which the light source 30, described later, is positioned directly below the emission surface R. Liquid crystal display devices that are the target of the planar illumination device 1 include, for example, displays such as electronic instruments and indicators mounted in vehicles.

[0039] like Figure 1 As shown, the planar illumination device 1 of this embodiment has an emission surface R defined by the opening 22d of the top frame 22 (described later). The planar illumination device 1 emits light from the emission surface R and functions as the backlight of the liquid crystal display device described above. Furthermore, the emission surface R of the planar illumination device 1 of this embodiment is curved relative to a plane orthogonal to the thickness direction.

[0040] like Figure 3 , Figure 6 , Figure 7 As shown, the planar lighting device 1 of the embodiment includes a frame 2, a substrate 3, a reflector 4, an optical sheet 5, a first fixing member 6, and a second fixing member 7.

[0041] Frame 2 is, for example, a shell made of high-rigidity stainless steel. It should be noted that frame 2 can also be made of aluminum or magnesium, etc. Frame 2 has a bottom frame 21 and a top frame 22, and an internal space 2s (see reference) formed by the bottom frame 21 and the top frame 22. Figure 6 , Figure 7 The substrate body 31, reflector 4 and optical sheet 5 are contained in the substrate 3.

[0042] The bottom frame 21 is formed in the shape of a bottom box and functions as a base in the frame 2. Furthermore, the bottom frame 21 is composed of a bottom 21a, a pair of first sidewalls 21b, and a pair of second sidewalls 21c. The bottom 21a is rectangular when viewed from the front side, defining the main view shape of the planar lighting device 1. A through hole 21d is formed in the bottom 21a, extending through the bottom 21a in the thickness direction. The through holes 21d are arranged with gaps in the longitudinal direction. The pair of first sidewalls 21b are opposite each other in the longitudinal direction and continuous in the short-length direction. The pair of second sidewalls 21c are opposite each other in the short-length direction and continuous in the longitudinal direction. Outwardly protruding engaging claws 21e (see reference) are formed on the outer peripheral surfaces of the pair of first sidewalls 21b and the pair of second sidewalls 21c. Figure 3 , Figure 5 The locking claw 21e is provided with an open gap in the long dimension direction and also with an open gap in the short dimension direction.

[0043] The top frame 22 is positioned on the light emission side, which is one side of the thickness direction of the bottom frame 21, and functions as a cover in the frame 2. Furthermore, the top frame 22 is composed of a top plate 22a, a pair of first sidewalls 22b, and a pair of second sidewalls 22c. The top plate 22a has an opening 22d formed in its center, which defines the aforementioned emission surface R. In other words, the top frame 22 has a frame portion 22f, which has an opening 22d formed on its inner side as a frame opening. The pair of first sidewalls 22b are opposite each other in the long dimension direction and continuous in the short dimension direction. The pair of second sidewalls 22c are opposite each other in the short dimension direction and are arranged with a gap in the long dimension direction. The pair of second sidewalls 22c are provided with engaging holes 22e (see reference) that can engage with the aforementioned engaging claws 21e. Figure 5 Furthermore, in frame 2, the engaging claw 21e engages with the engaging hole 22e, thereby mounting the top frame 22 onto the bottom frame 21 and forming the internal space 2s (see reference). Figure 6 , Figure 7 ).

[0044] The substrate 3 is, for example, a circuit substrate made of epoxy resin or PI (polyimide), and can be, for example, a flexible printed circuit board (FPC). The substrate 3 is disposed on one side of the bottom frame 21 in the thickness direction. In other words, the planar lighting device 1 has a bottom frame 21 disposed on the opposite side of the substrate 3. Furthermore, a plurality of light sources 30 are provided on one side of the substrate 3 (see reference). Figure 4 In other words, the planar lighting device 1 has a substrate 3 on one side having a plurality of light sources 30.

[0045] like Figure 3As shown, the substrate 3 of this embodiment is configured to be divided into multiple regions 33 along the longitudinal direction. More specifically, the substrate 3 is configured to be divided into four regions 33A, 33B, 33C, and 33D along the longitudinal direction.

[0046] Such a substrate 3 has a substrate body portion 31 and an external connection portion 32 extending from the substrate body portion 31 in the short dimension direction. The substrate body portion 31 has a plurality of light sources 30. The external connection portion 32 is a part that connects the circuit for controlling the illumination of the light sources 30 to external devices (e.g., the ECU of a vehicle).

[0047] like Figure 4 , Figure 5 , Figure 7 As shown, the substrate 3 has a reflective sheet 34 on one side in the thickness direction. The reflective sheet 34 has the function of reflecting light emitted from the light source 30 that has been reflected by the optical sheet 5 back towards the emission surface R. The reflective sheet 34 can be, for example, a multilayer film, a foamed white reflective plate, a white polyethylene terephthalate film, a silver reflective sheet, etc., and a component with a reflectivity of 85% or more can be used. The reflective sheet 34 has a first opening 34a that exposes the head of the light source 30 to one side. The first opening 34a is, for example, formed as a square. In addition, the reflective sheet 34 has a second opening 34b (opening) at a position for the second fixing member 7 described later. The second opening 34b is, for example, formed as a rectangle. The reflective sheet 34 of this embodiment is formed corresponding to a plurality of regions 33 of the substrate 3. That is, the reflective sheet 34 is formed to be divided into four regions 33. And, as Figure 5 As shown, the reflector 34 has a gap 34c between one region 33 and another region 33. A pin of the first fixing member 6 is disposed in the gap 34c.

[0048] The light source 30 is a point light source 30, such as an LED (Light Emitting Diode). The light source 30 can be a packaged LED, a chip LED, or, for example, a chip-type LED, but is not limited to these. It should be noted that the light source 30 is not limited to LEDs; any light-emitting component can be used.

[0049] In this embodiment, the light sources 30 of the planar lighting device 1 are arranged at fixed intervals in the longitudinal direction and at fixed intervals in the short direction. That is, the light sources 30 of the planar lighting device 1 of this embodiment are arranged in a grid pattern with equal intervals in the horizontal and vertical directions. For example, the light sources 30 are arranged in six rows in the short direction and nine columns in the longitudinal direction, for a total of 56.

[0050] The reflector 4, for example, is formed of synthetic resin and has the function of reflecting light emitted from the light source 30 toward the emission surface R to improve the brightness of the emission surface R, thereby improving the emission efficiency of the planar lighting device 1. The reflector 4 is provided on one side of the substrate 3 in the thickness direction. In other words, the planar lighting device 1 includes a reflector 4 provided on one side of the substrate 3. In this embodiment, the reflector 4 is integrally formed, for example, by injection molding of synthetic resin. That is, the planar lighting device 1 of this embodiment includes a reflector 4.

[0051] Furthermore, the reflector 4 has a grid-shaped reflective portion 41 corresponding to each light source 30 mounted on the substrate 3. That is, in this embodiment, the reflective portion 41 of the reflector 4 is arranged in six rows in the short dimension direction and in nine columns in the long dimension direction. Figure 4 As shown, each reflective portion 41 has: a pair of first reflective portions 41a facing each other in the longitudinal direction; a pair of second reflective portions 41b facing each other in the short direction; and a spatial portion 41c formed by the pair of first reflective portions 41a and the pair of second reflective portions 41b (see reference). Figure 4 , Figure 7 ). Figure 7 The second reflective portion 41b shown has an emission surface-side reflective surface 41b1 and a substrate-side reflective surface 41b2 with different angles relative to a plane including the long and short dimensions. Furthermore, the angle between the substrate-side reflective surface 41b2 and the plane including the long and short dimensions is smaller than the angle between the emission surface-side reflective surface 41b1 and the plane including the long and short dimensions. Similarly, the first reflective portion 41a has an emission surface-side reflective surface 41a1 and a substrate-side reflective surface 41a2 with different angles relative to a plane including the long and short dimensions. Furthermore, the angle between the substrate-side reflective surface 41a2 and the plane including the long and short dimensions is smaller than the angle between the emission surface-side reflective surface 41a1 and the plane including the long and short dimensions. Figure 4 , Figure 7 A light source 30 is disposed at the center of the long dimension and the center of the short dimension in the spatial portion 41c shown. A first reflector opening (reflector opening) 41d is formed on one side (emission surface R side) in the thickness direction and a second reflector opening 41e is formed on the other side (substrate 3 side with light source 30). The first reflector opening 41d is formed as a square, for example, and the second reflector opening 41e is formed as a square, for example. Figure 7 The size L1 of the first reflector opening 41d shown is larger than the size L2 of the second reflector opening 41e. Moreover, the size L3 of the first sheet opening (sheet opening) 34a of the aforementioned reflective sheet 34 is smaller than the size L2 of the second reflector opening 41e.

[0052] like Figure 1 , Figure 3 As shown, the optical sheet 5 is disposed on one side of the reflector 4 in the thickness direction. The planar illumination device 1 of this embodiment includes, for example, three optical sheets 51, 52, and 53. The optical sheet 5 adjusts the light distribution and brightness of light passing from the other side to one side in the thickness direction, for example, to homogenize the light emitted from the emission surface R. For example, the optical sheet 51 is a diffuser, the optical sheet 52 is a prism sheet, a BEF (Brightness Enhancement Film), etc., and the optical sheet 53 is a reflective polarizing film, a DBEF (Dual Brightness Enhancement Film).

[0053] like Figure 4 , Figure 6 As shown, the first fixing member 6 fixes the central portion 42 of the reflector 4 in the long dimension direction to the bottom frame 21. In other words, the planar lighting device 1 of this embodiment includes a first fixing member 6 that fixes the central portion 42 of the reflector 4 in the long dimension direction to the bottom frame 21. The first fixing member 6 is composed, for example, of the following components: a pin 61 protruding from one side of the bottom 21a of the bottom frame 21 in the thickness direction; and a locking hole 62 penetrating the reflector 4 in the thickness direction, capable of engaging with the pin 61. The size of the locking hole 62 in a plane orthogonal to the thickness direction is larger than the diameter of the pin, allowing the reflector 4 to move relative to the bottom frame 21 in the short dimension direction when the temperature inside the vehicle changes, while restricting the movement of the reflector 4 relative to the bottom frame 21 in the long dimension direction. In this embodiment, the first fixing member 6 is located at a position overlapping the central portion 42 of the reflector 4 in the long dimension direction, and is disposed inside the frame portion 22f. Furthermore, in this embodiment, the two first fixing members 6 are positioned with their fixing centers overlapping the central portion 42 in the longitudinal direction of the reflector 4.

[0054] like Figure 5 , Figure 7 , Figure 9 As shown, the second fixing member 7 fixes one side of the substrate 3 and the reflector 4. That is, the planar lighting device 1 of this embodiment includes a second fixing member 7 for fixing one side of the substrate 3 and the reflector 4. The second fixing member 7 is, for example, double-sided tape.

[0055] Figure 8 This is a conceptual diagram showing the position of the first fixing member 6 and the difference in the magnitude of the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4. In this embodiment, the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4 is the force by which the second fixing member 7 fixes the substrate 3 and the reflector 4. Figure 8As shown, the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4 is divided into multiple fixing regions 9 (eleven fixing regions 9 in this embodiment) with varying magnitudes of fixing force. Among the magnitudes of the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4, the force is greatest at the first fixing region 90 located at the central portion 42 in the longitudinal direction, and second greatest at the second fixing region 91 adjacent to the first fixing region 90 in the longitudinal direction. Furthermore, the magnitude of the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4 in the multiple fixing regions 9 gradually decreases as it moves away from the central portion 42 in the longitudinal direction.

[0056] Figure 9 This is a conceptual diagram illustrating an example of the placement position of the second fixing member 7. The planar lighting device 1 of this embodiment virtually divides the placement area 70 of the second fixing member 7 into five locations. More specifically, it includes: a first placement area 71 located at the center in the longitudinal direction; second placement areas 72 and 73 adjacent to the first placement area 71 in the longitudinal direction; and third placement areas 74 and 75 located on the opposite side of the first placement area 71 in the longitudinal direction relative to the second placement areas 72 and 73. Furthermore, the second fixing member 7 is arranged linearly symmetrically with respect to the central line that bisects the reflector 4 in the longitudinal direction.

[0057] The first configuration area 71, for example, has five second fixing members 7 extending along the longitudinal direction. The second configuration areas 72 and 73, for example, have four second fixing members 7 extending along the longitudinal direction. The third configuration areas 74 and 75, for example, have three second fixing members 7 extending along the longitudinal direction.

[0058] In this embodiment, the adhesive strength per unit area of ​​the second fixing member (double-sided tape) 7 of the planar lighting device 1 is the same in all parts. Furthermore, the width of the second fixing member (double-sided tape) 7, orthogonal to the length direction, is the same in all parts. Moreover, as described above, the arrangement of the second fixing member 7 varies depending on the arrangement region 70; therefore, among the five arrangement regions 70, the first arrangement region 71 has the largest adhesive area. In addition, the adhesive areas of the second arrangement regions 72 and 73 are larger than the areas of the third arrangement regions 74 and 75. That is, the adhesive areas of the third arrangement regions 74 and 75 are the smallest among the five arrangement regions 70. In other words, the adhesive area between the second fixing member 7 and the substrate 3 at the central portion 42 in the long dimension direction is larger than the adhesive area at portions of the substrate 3 that are farther from the central portion 42 in the long dimension direction. Furthermore, in the force by which the second fixing member 7 fixes the substrate 3 and the reflector 4, the force at the central portion 42 in the longitudinal direction of the reflector 4 is greater than the force at the portion 49 in the longitudinal direction of the reflector 4 that is farther from the central portion.

[0059] Figure 10 This is a conceptual diagram showing the arrangement of the second fixing member 7' in the comparative example planar lighting device 1'. The planar lighting device 1' has a first fixing member 6 at its central portion in the longitudinal direction. Furthermore, the second fixing member 7 is arranged with an open fixing interval along the outer periphery of the substrate 3 in the planar lighting device 1'.

[0060] With the second fixing members 7' configured in this way, when each of the second fixing members 7' (double-sided tape) is attached, the force exerted by the double-sided tape on the substrate 3 and reflector 4 is uneven along the entire longitudinal direction. Therefore, the force exerted by each second fixing member 7' on the substrate 3 and reflector 4 will differ. Due to this difference, there is a risk that the virtual fixing center 78' of the second fixing member 7' may shift from the first fixing member 6 (pin) in the longitudinal direction. Furthermore, when a temperature change occurs inside the vehicle while the virtual fixing center 78' of the second fixing member 7' is shifted from the first fixing member 6 in the longitudinal direction, stress will be generated between the first fixing member 6 and the reflector 4, thereby potentially causing the first fixing member (pin) to bend or the reflector 4 to break.

[0061] In contrast, the planar lighting device 1 of the embodiment includes a first fixing member 6 that fixes the central portion 42 of the reflector 4 in the longitudinal direction to the bottom frame 21, and a second fixing member 7 that fixes one side of the substrate 3 and the reflector 4. Furthermore, in the force (adhesive area) of the second fixing member 7 fixing the substrate 3 and the reflector 4, the force at the central portion 42 in the longitudinal direction of the reflector 4 is greater than the force at portions of the reflector 4 farther from the central portion 42 in the longitudinal direction. Therefore, even if the force of the double-sided tape, which serves as each of the second fixing members 7, pressing onto the substrate 3 and the reflector 4 is uneven throughout the longitudinal direction, the virtual fixing center 78 of the second fixing member 7 (see reference) can be made as close as possible to the virtual fixing center 78 (see reference). Figure 9 The second fixing member 7 is aligned with the fixing center of the first fixing member 6. Therefore, even when the temperature inside the vehicle changes, the planar lighting device 1 of this embodiment can suppress the application of a large force to the first fixing member 6 due to the difference in the coefficient of linear expansion. As a result, even when the temperature inside the vehicle changes, the planar lighting device 1 of this embodiment can stably fix the reflector 4 to the substrate 3 (in a manner that does not cause bending or breakage). Moreover, the second fixing member 7 firmly fixes the reflector 4 to the substrate 3 at its central portion 42 in the longitudinal direction, and on the other hand, the portions of the second fixing member 7 that are away from the central portion 42 in the longitudinal direction (including the portions at both ends) also fix the reflector 4 to the substrate 3 to a degree that they do not separate even when the temperature inside the vehicle changes. It should be noted that although the substrate 3 is fixed to the bottom frame 21 using double-sided tape, the difference between the coefficient of linear expansion of the substrate 3 and the coefficient of linear expansion of the bottom frame 21 is small, and the substrate 3 is divided into multiple parts in the longitudinal direction. Therefore, no problems caused by the difference in the coefficient of linear expansion occur between the substrate 3 and the bottom frame 21. Furthermore, although the reflector 34 is fixed to the substrate 3 using double-sided tape, the difference between the coefficient of linear expansion of the reflector 34 and the coefficient of linear expansion of the bottom frame 21 is small, and the reflector 34 is divided into multiple parts along its long dimension. Therefore, no problems arising from the difference in the coefficients of linear expansion occur between the reflector 34 and the bottom frame 21. On the other hand, the reflector 4 is difficult to divide along its long dimension, and the difference in its coefficient of linear expansion with that of the bottom frame 21 is large, but with the above-described structure, no problems arising from the coefficient of linear expansion occur.

[0062] Furthermore, in the planar lighting device 1 of the embodiment, the bonding area between the second fixing member 7 and the substrate 3 at the central portion 42 in the longitudinal direction is larger than the bonding area at the portion farther from the central portion 42 in the longitudinal direction. Therefore, the planar lighting device 1 of the embodiment can achieve the aforementioned functions and effects without complex manufacturing processes by changing the configuration of the second fixing member 7.

[0063] Furthermore, edge-lit surface lighting devices can use reflective sheets with high reflectivity, while direct-lit surface lighting devices can reflect light from the light source by configuring reflector 4 and printing one side of the substrate white. However, even with such white printing on the substrate, there are requirements such as the substrate's resistance to high-temperature processes during installation, resulting in a lower reflectivity compared to the reflective sheets used in edge-lit surface lighting devices. In particular, when using FPC on the substrate, bending resistance is also required, which could further reduce reflectivity.

[0064] In contrast, the planar illumination device 1 of this embodiment, in order to overlap the reflective sheet 34, which is separate from the substrate 3, with the substrate 3, has a first opening (sheet opening) 34a on the reflective sheet 34 that exposes the head of the light source 30, and the size of the first opening (sheet opening) 34a is set to be smaller than the size of the second reflector opening 41e. Therefore, the planar illumination device 1 of this embodiment can, through the reflective sheet 34, reflect light that has been reflected by the optical sheet 5 back to one side as much as possible. As a result, the planar illumination device 1 of this embodiment can improve brightness efficiency. It should be noted that even when the reflective sheet 34 is overlapped, it can also be configured such that a white resist layer is provided on one side of the substrate 3, so that light is reflected back to one side from the substrate 3 exposed from the first opening 34a of the reflective sheet 34.

[0065] Furthermore, in the planar lighting device 1 of this embodiment, by using the above-described structure for the reflector 34, the coefficient of linear expansion of the reflector 34 is closer to that of the substrate 3 than that of the reflector 4. Therefore, even when the temperature inside the vehicle changes, the planar lighting device 1 of this embodiment can prevent the reflector 34 from peeling off from the substrate 3.

[0066] Furthermore, the reflector 34 has a second opening 34b (opening) at the position where the second fixing member 7 is disposed. Therefore, the planar lighting device 1 of this embodiment does not have a useless reflector 34 located on the bottom surface of the reflector 4. As a result, the planar lighting device 1 of this embodiment can suppress material waste of the reflector 34.

[0067] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Various modifications can be made as long as they do not depart from the spirit of the invention.

[0068] (Second Implementation)

[0069] Figure 11 This is an example of the arrangement position of the second fixing member 7A in the planar lighting device 1A of the second embodiment. Figure 9The same conceptual diagram. The second embodiment of the planar lighting device 1A, which will be described next, is an example of the arrangement of other second fixing members 7A that differs from the arrangement of the second fixing member 7 in the planar lighting device 1 of the first embodiment. That is, in the planar lighting device 1A of the second embodiment, the arrangement of the second fixing member 7A is different from that of the planar lighting device 1 of the first embodiment, but the other structures are the same.

[0070] The planar lighting device 1A of this embodiment divides the arrangement area 70A of the second fixing member 7A into four parts. More specifically, it includes: first arrangement areas 71A and 72A, located at the center in the longitudinal direction; and second arrangement areas 73A and 74A, adjacent to the first arrangement areas 71A and 72A in the longitudinal direction. The plurality of arrangement areas 70A, divided into four parts, associated with the second fixing member 7, correspond respectively to the plurality of regions 33 constituting the substrate 3 described above. More specifically, the first arrangement area 71A corresponds to region 33B, the first arrangement area 72A corresponds to region 33C, the second arrangement area 73A corresponds to region 33A, and the second arrangement area 74A corresponds to region 33D.

[0071] The first configuration areas 71A and 72A, for example, have eight second fixing members 7A extending along the longitudinal direction. The eight second fixing members 7A configured in the first configuration areas 71A and 72A have the same length along the longitudinal direction. The second configuration areas 73A and 74A, for example, have four second fixing members 7A extending along the longitudinal direction. The four second fixing members 7A configured in the second configuration areas 73A and 74A have the same length along the longitudinal direction. Furthermore, the second fixing members 7A are arranged linearly symmetrically with respect to the central line that bisects the reflector 4 in the longitudinal direction, such that the fixing center of the second fixing member 7A is located in the central portion 42 in the longitudinal direction, and this fixing center coincides with the fixing center of the first fixing member 6.

[0072] In this embodiment, the adhesive strength per unit area of ​​the second fixing member (double-sided tape) 7A of the planar lighting device 1A is the same in all parts. Furthermore, the width of the second fixing member (double-sided tape) 7A, orthogonal to the length direction, is the same in all parts. Moreover, among the four configuration areas 71A, 72A, 73A, and 74A, the adhesive area of ​​the first configuration areas 71A and 72A is larger than the adhesive area of ​​the second configuration areas 73A and 74A. That is, the adhesive area between the second fixing member 7A of the planar lighting device 1A and the substrate 3 at the central portion 42 in the long dimension direction is larger than the adhesive area at portions of the substrate 3 that are farther from the central portion 42 in the long dimension direction. Furthermore, in the force exerted by the second fixing member 7A on the substrate 3 and the reflector 4, the force at the central portion 42 in the long dimension direction of the reflector 4 is greater than the force at portions of the reflector 4 that are farther from the central portion 42 in the long dimension direction.

[0073] Furthermore, in this embodiment, the substrate 3 of the planar lighting device 1A is configured to be divided into multiple regions 33 along its longitudinal direction, and the second fixing member 7A is double-sided adhesive tape, which is configured to change according to the positions of each of the multiple regions 33. Therefore, in this embodiment, the planar lighting device 1A can place the second fixing member 7A in each of the smaller regions 33 while the substrate 3 is divided into multiple regions 33, thus making the process of placing the second fixing member 7A on the substrate 3 easier.

[0074] (Third Implementation)

[0075] Figure 12 This is an example of the arrangement position of the second fixing member 7B in the planar lighting device 1B of the third embodiment. Figure 9 The same conceptual diagram. The planar lighting device 1B of the third embodiment described below is an example of a different arrangement of the second fixing member 7B compared to the arrangement of the second fixing member 7 in the planar lighting device 1 of the first embodiment. That is, in the planar lighting device 1B of the third embodiment, the arrangement of the second fixing member 7B is different from that of the planar lighting device 1 of the first embodiment, but the other structures are the same.

[0076] The planar lighting device 1B of this embodiment divides the arrangement area 70B of the second fixing member 7B into four locations. More specifically, it includes: first arrangement areas 71B and 72B, located at the center in the longitudinal direction; and second arrangement areas 73B and 74B, adjacent to the first arrangement areas 71B and 72B in the longitudinal direction. The plurality of arrangement areas 70B, divided into four locations, associated with the second fixing member 7B, correspond respectively to the plurality of regions 33 constituting the substrate 3 described above. More specifically, the first arrangement area 71B corresponds to region 33B, the first arrangement area 72B corresponds to region 33C, the second arrangement area 73B corresponds to region 33A, and the second arrangement area 74B corresponds to region 33D.

[0077] The first configuration areas 71B and 72B, for example, have eight second fixing members 7B extending along the longitudinal dimension. Regarding the second fixing members 7B configured in the first configuration areas 71B and 72B, in… Figure 12 In the second configuration regions 73B and 74B, the lengths of the first, third, fifth, seventh, and eighth second fixing members 7B arranged from top to bottom are longer in the longitudinal direction than the lengths of the second, fourth, and sixth second fixing members 7B arranged in the longitudinal direction. For example, the second configuration regions 73B and 74B have four second fixing members 7B extending along the longitudinal direction. The four second fixing members 7B arranged in the second configuration regions 73B and 74B have the same length in the longitudinal direction. Furthermore, the second fixing members 7B are arranged in a linearly symmetrical manner with respect to the central line that bisects the reflector 4 in the longitudinal direction.

[0078] In this embodiment, the adhesive strength per unit area of ​​the second fixing member (double-sided tape) 7B of the planar lighting device 1B is the same in all parts. Furthermore, the width of the second fixing member (double-sided tape) 7B, orthogonal to the length direction, is the same in all parts. Moreover, among the four configuration areas 71B, 72B, 73B, and 74B, the adhesive area of ​​the first configuration areas 71B and 72B is larger than the adhesive area of ​​the second configuration areas 73B and 74B. That is, the adhesive area between the second fixing member 7B of the planar lighting device 1B and the substrate 3 at the central portion 42 in the long dimension direction is larger than the adhesive area at portions of the substrate 3 that are farther from the central portion 42 in the long dimension direction. Furthermore, in the force exerted by the second fixing member 7B on the substrate 3 and the reflector 4, the force at the central portion 42 of the reflector 4 in the long dimension direction is greater than the force at portions of the reflector 4 that are farther from the central portion 42 in the long dimension direction.

[0079] Furthermore, by using the second fixing member 7B, which is shorter in the long dimension, the bonding area, or bonding strength, between the reflector 4 and the substrate 3 can be finely adjusted. Thus, for example, the bonding area (bonding strength) of the central portion 42 within a configuration area can be increased, or the bonding area (bonding strength) on one side in the short dimension direction can be increased.

[0080] (Fourth Implementation)

[0081] Figure 13 This is an example of the arrangement position of the second fixing member 7C in the planar lighting device 1C of the fourth embodiment. Figure 9 The same conceptual diagram. The fourth embodiment of the planar lighting device 1C, which will be described next, is an example of a different arrangement of the second fixing member 7C compared to the arrangement of the second fixing member 7 in the planar lighting device 1 of the first embodiment. That is, in the planar lighting device 1C of the fourth embodiment, the arrangement of the second fixing member 7C is different from that of the planar lighting device 1 of the first embodiment, and the adhesive strength per unit area of ​​the second fixing member 7C is different, while other structures are the same.

[0082] The planar lighting device 1C of this embodiment divides the arrangement area 70C of the second fixing member 7C into five parts. More specifically, it includes: a first arrangement area 71C located at the center in the longitudinal direction; second arrangement areas 72C and 73C adjacent to the first arrangement area 71C in the longitudinal direction; and third arrangement areas 74C and 75C located on the opposite side of the first arrangement area 71C in the longitudinal direction relative to the second arrangement areas 72C and 73C.

[0083] Furthermore, the second fixing member 7C has: a second fixing member 7C1 extending in the short dimension direction, extending along the short dimension direction and arranged at equal intervals in the long dimension direction; and a second fixing member 7C2 extending in the long dimension direction, extending along the long dimension direction. The second fixing member 7C is, for example, double-sided tape. Moreover, the width of the second fixing member 7C orthogonal to the length direction is the same in any part. The planar lighting device 1C of this embodiment has, for example, thirteen second fixing members 7C1 extending in the short dimension direction and, for example, one second fixing member 7C2 extending in the long dimension direction. The adhesive strength per unit area between the second fixing member 7C of this embodiment and the substrate 3 at the central portion 42 in the long dimension direction is greater than the adhesive strength per unit area at the portion of the substrate 3 away from the central portion 42 in the long dimension direction.

[0084] More specifically, the bonding strength per unit area between the second fixing member 7C disposed in the first configuration region 71C and the substrate 3 is greater than the bonding strength per unit area between the second fixing member 7C disposed in other configuration regions 72C, 73C, 74C, and 75C and the substrate 3.

[0085] Furthermore, the bonding strength per unit area between the second fixing member 7C disposed in the second configuration regions 72C and 73C and the substrate 3 is greater than the bonding strength per unit area between the second fixing member 7C disposed in the third configuration regions 74C and 75C and the substrate 3.

[0086] As described above, the second fixing member 7C of the planar lighting device 1C in this embodiment is double-sided adhesive tape, and its adhesive strength per unit area at the central portion 42 in the longitudinal direction of the substrate 3 is greater than the adhesive strength per unit area at the portion of the substrate 3 away from the central portion 42 in the longitudinal direction. Therefore, the planar lighting device 1C of this embodiment can achieve the above-mentioned functions and effects without complex manufacturing processes by changing the adhesive strength per unit area of ​​the double-sided adhesive tape.

[0087] It should be noted that the planar lighting device 1C in the above embodiment was described with a configuration having a plurality of second fixing members 7C extending along the short dimension direction. However, the planar device of this embodiment is not limited to this, and may also have a plurality of second fixing members extending along the long dimension direction. Furthermore, the adhesive strength per unit area of ​​the plurality of second fixing members extending along the long dimension direction may also be constant throughout the entire long dimension direction.

[0088] (Fifth Implementation)

[0089] Figure 14 This is an accompanying drawing showing a planar lighting device 1D according to another embodiment of the planar lighting device 1 of the first embodiment. More specifically, Figure 14 This is a conceptual diagram showing the position of the first fixing member 6 in the planar lighting device 1D and the difference in the magnitude of the force exerted by the second fixing member 7 on the substrate 3 and the reflector 4. The planar lighting device 1D of the fifth embodiment, which will be described next, is designed such that, by making the arrangement of the second fixing member 7 different from that in the planar lighting device 1 of the first embodiment, the force used to fix the substrate 3 and the reflector 4 varies depending on their positions in the long and short dimensions. The planar lighting device 1D of the fifth embodiment will be described below.

[0090] In the planar lighting device 1D of this embodiment, among the two first fixing members 6, located in Figure 14The first fixing member 6 below is configured in the same way as in the first embodiment. On the other hand, among the two first fixing members 6 in the planar lighting device 1D of this embodiment, the one located below... Figure 14 The engagement hole 62 of the first fixing member 6 above is formed in a circular shape to allow the pin 61 provided on the bottom frame 21 to be inserted, and to restrict the movement of the reflector 4 relative to the bottom frame 21 in the long and short directions when the temperature inside the vehicle changes.

[0091] In the planar lighting device 1D of this embodiment, such as Figure 14 As shown, the magnitude of the force by which the second fixing member 7 fixes the substrate 3 and the reflector 4 is such that it is located at... Figure 14 Centered on the first fixing member 6 above, the substrate 3 is divided into multiple fixing regions 9D (fourteen fixing regions 9D in this embodiment) with varying fixing forces. Regarding the force exerted by the second fixing member 7 on the substrate 3 and reflector 4, the force is greatest at the first fixing region 90D located at the central portion 42 in the longitudinal direction, and second greatest at the second fixing region 91D adjacent to the first fixing region 90D in the longitudinal direction. Furthermore, among the multiple fixing regions 9D, the force exerted by the second fixing member 7 on the substrate 3 and reflector 4 gradually decreases as it moves away from the central portion 42 in the longitudinal direction.

[0092] Of the two first fixing members 6, one first fixing member 6 (located in Figure 14 The engaging hole 62 of the upper first fixing member 6) is formed in a circular shape such that the pin 61 is inserted and, in the event of a temperature change inside the vehicle, the reflector 4 is restricted from moving relative to the bottom frame 21 in both the longitudinal and longitudinal directions. Of the two first fixing members 6, the other first fixing member 6 (located in...) Figure 14 The engaging hole 62 of the first fixing member 6) below is formed as an elongated hole through which the allowable pin 61 is inserted, and allows the reflector 4 to move relative to the bottom frame 21 in the short dimension direction when the temperature inside the vehicle changes. Thus, when the temperature inside the vehicle changes, the reflector 4 is positioned at... Figure 14 The first fixed member above it serves as a fixed reference for telescoping in the short dimension direction and allows the reflector 4 to telescop in the long dimension direction.

[0093] (Sixth Implementation Method)

[0094] Figure 15 The accompanying drawing shows an example of the configuration of the second fixing member 7E in another embodiment of the planar lighting device 1 of the first embodiment.

[0095] In this embodiment, the force by which the second fixing member 7E restricts the substrate 3 and the reflector 4 is based on the elasticity of the second fixing member 7E. Furthermore, the elasticity of the second fixing member 7E relative to the substrate 3 at the central portion 42 in the longitudinal direction is less than the elasticity at portions in the longitudinal direction away from the central portion 42 of the substrate 3. More specifically, the elasticity of the second fixing member 7E disposed in the first placement regions 71E, 72E located at the center in the longitudinal direction differs from the elasticity of the second fixing member 7E disposed in the second placement regions 73E, 74E adjacent to the first placement regions 71E, 72E in the longitudinal direction.

[0096] The elongation of the second fixing member 7E configured in the first configuration regions 71E and 72E is less than that of the second fixing member 7E configured in the second configuration regions 73E and 74E.

[0097] As a method to vary the elasticity of the second fixing member 7E according to its position in the long dimension, one approach is to use different materials for the double-sided adhesive tapes used as the second fixing member 7E in both cases. For example, the second fixing member 7E disposed in the first placement regions 71E and 72E may have a polyethylene terephthalate (PET) matrix material. On the other hand, the second fixing member 7E disposed in the second placement regions 73E and 74E may be formed without a PET matrix material. By configuring the second fixing member 7E in this way, the force by which the second fixing member 7E restricts the substrate 3 and the reflector 4 is increased in the central portion 42, while the force by which the second fixing member 7E restricts the substrate 3 and the reflector 4 is decreased in the portions of the second fixing member 7E that are away from the central portion 42 in the long dimension.

[0098] It should be noted that, as a method for varying the elasticity of the second fixing member 7E according to its position in the long dimension, the second fixing member 7E disposed in the first placement regions 71E and 72E has a polyethylene terephthalate matrix material, while the second fixing member 7E disposed in the second placement regions 73E and 74E has, for example, a foamable acrylic matrix material. In other words, by making the matrix materials different for each member, the elasticity (flexibility) of the second fixing member 7E located away from the center in the long dimension is greater than that of the second fixing member 7E located at the center in the long dimension. Furthermore, the adhesive layer of the second fixing member 7E uses an acrylic material.

[0099] The first configuration regions 71E and 72E, for example, have four second fixing members 7E extending along the longitudinal direction. The four second fixing members 7E in the first configuration regions 71E and 72E have the same length in both the longitudinal and short-length directions. The second configuration regions 73E and 74E, for example, have four second fixing members 7E extending along the longitudinal direction. The four second fixing members 7E in the second configuration regions 73E and 74E have the same length in both the longitudinal and short-length directions. Furthermore, the lengths of the second fixing members 7E in the first configuration regions 71E and 72E in both the longitudinal and short-length directions are the same as those in the second configuration regions 73E and 74E. Moreover, the second fixing members 7E are arranged linearly symmetrically with respect to the central line that bisects the reflector 4 in the longitudinal direction, such that the fixing center of the second fixing member 7E is located in the central portion 42 in the longitudinal direction, and this fixing center coincides with the fixing center of the first fixing member 6.

[0100] In this embodiment, the adhesive strength per unit area of ​​the second fixing member (double-sided tape) 7E of the planar lighting device 1E is the same in all parts. Furthermore, the width of the second fixing member (double-sided tape) 7E in the short dimension direction orthogonal to the length direction is the same in all parts. Moreover, among the four configuration regions 71E, 72E, 73E, and 74E, the elasticity of the second fixing member in the first configuration regions 71E and 72E is less than that in the second configuration regions 73E and 74E. Furthermore, in the force exerted by the second fixing member 7E on the substrate 3 and the reflector 4, the force at the central portion 42 in the long dimension direction of the reflector 4 is greater than the force at portions of the reflector 4 farther from the central portion 42 in the long dimension direction.

[0101] Furthermore, in this embodiment, the substrate 3 of the planar lighting device 1E is divided into multiple regions 33 along its longitudinal direction, and the second fixing member 7E is double-sided adhesive tape, which is similarly arranged in the multiple regions 33. Moreover, the second fixing member 7E used in the central portion 42 has less elasticity than that used in the portion farther from the central portion 42 in the longitudinal direction. Therefore, even when the temperature inside the vehicle changes, the second fixing member 7E firmly fixes the reflector 4 to the substrate 3 in the central portion 42 in the longitudinal direction, while in the portion farther from the central portion 42 in the longitudinal direction, (despite the elasticity of the second fixing member 7E) the reflector 4 and the substrate 3 are fixed to a degree that prevents them from separating.

[0102] It should be noted that in the above-described planar lighting device 1E, an example in which a second fixing member 7E is provided in a portion of the reflector 4 has been described. However, the planar lighting device 1E of this embodiment is not limited to this, and the second fixing members 7E may be arranged more densely. More specifically, an additional second fixing member 7E may be provided between two second fixing members 7E in the short dimension direction. Furthermore, an additional second fixing member 7E extending along the short dimension direction may also be provided.

[0103] (Seventh Implementation)

[0104] Figure 16 This is an exploded assembly view showing another example of the first fixing member 6F in another embodiment of the planar lighting device 1 of the first embodiment, and a perspective view showing one side of the reflector 4 in the short dimension direction orthogonal to the long dimension direction. Figure 17 This is an exploded assembly view showing another example of the first fixing member 6F in another embodiment of the planar lighting device 1F of the first embodiment, and a perspective view showing the other side of the reflector 4 in the short dimension direction.

[0105] The first fixing member 6F fixes the central portion 42 of the reflector 4 in the long dimension direction to the bottom frame 21. That is, the planar lighting device 1F of this embodiment includes a first fixing member 6F that fixes the central portion 42 of the reflector 4 in the long dimension direction to the bottom frame 21. In the planar lighting device 1F of this embodiment, when viewed from a direction orthogonal to a plane including the long dimension direction of the reflector 4 and the short dimension direction orthogonal to the long dimension direction, the first fixing member 6F is provided at a position overlapping with the frame portion 22f.

[0106] On one side in the short dimension direction, the first fixing member 6F is composed of: a locking claw 63a formed on the reflector 4; and a locking receiving portion 63b formed on the bottom frame 21, which can be engaged with the locking claw. Furthermore, on the other side in the short dimension direction, the first fixing member 6F is composed of: a locking claw 64a formed on the bottom frame 21; and a locking receiving portion 64b formed on the reflector 4, which can be engaged with the locking claw. In the event of temperature changes inside the vehicle, the first fixing member 6F of this embodiment restricts the movement of the reflector 4 relative to the bottom frame 21 in the short dimension direction and also restricts the movement of the reflector 4 relative to the bottom frame 21 in the long dimension direction. The first fixing member 6F of this embodiment is disposed in the central portion 42 of the reflector 4 in the long dimension direction.

[0107] In this embodiment, the planar lighting device 1F has a first fixing member 6F located on the frame portion 22f, thus preventing the structure inside the opening portion 22d from becoming complex. It should be noted that the engaging claw 63a can also be formed on the bottom frame 21, and the locking receiving portion 63b can be formed on the reflector 4.

[0108] (Eighth Implementation Method)

[0109] Figure 18 The accompanying drawing shows an example of the second fixing member 7G in another embodiment of the planar lighting device 1 of the first embodiment. Figure 19 yes Figure 18 The sectional view at the arrow C-C line.

[0110] The second fixing member 7G in this embodiment is composed of the following components: a pin 71a; an elongated hole 71b through which the pin 71a can be inserted, extending in the longitudinal direction; a locking recess 71c that engages with the pin 71a; and a through hole 71d provided on the substrate 3 for the pin 71a to be inserted through. In the planar lighting device 1G of this embodiment, the locking recess 71c is provided on the bottom frame 21, and the elongated hole 71b is provided on the reflector 4. The through hole 71d is an elongated hole whose length in the longitudinal direction is longer than its length in the short direction.

[0111] The planar illumination device 1G of this embodiment includes, for example, four second fixing members 7G. The planar illumination device 1G of this embodiment has two second fixing members 7G located near the central portion 42 and two second fixing members 7G located away from the central portion 42 in the longitudinal direction of the reflector 4, and their structures differ. Furthermore, in the planar illumination device 1G of this embodiment, the four second fixing members 7G are arranged linearly symmetrically with reference to the central portion 42 in the longitudinal direction of the reflector 4. That is, in the longitudinal direction, the two second fixing members 7G located near the central portion 42 are spaced equidistant from the central portion 42, and the two second fixing members 7G located away from the central portion 42 are spaced equidistant from the central portion 42. It should be noted that the spaced length is the distance between the central portion 42 and the center of the pin 71a.

[0112] For the second fixing member 7G located near the central portion 42 in the longitudinal direction of the reflector 4, the first pin 71a1 can move a distance L4 inside the first elongated hole 71b1 in the longitudinal direction. On the other hand, for the second fixing member 7G located away from the central portion 42 in the longitudinal direction of the reflector 4, the second pin 71a2 can move a distance L5 longer than L4 inside the second elongated hole 71b2 in the longitudinal direction. In other words, in the planar lighting device 1G of this embodiment, the distance L4 that the first pin 71a1 can move inside the first elongated hole 71b in the second fixing member 7G located near the central portion 42 in the longitudinal direction of the reflector 4 is shorter than the distance L5 that the pin 71a can move inside the elongated hole 71b in the second fixing member 7G located away from the central portion 42 in the longitudinal direction of the reflector 4. In other words, the length of the elongated holes 71b1 and 71b2 in the longitudinal direction increases as the position of the second fixing member 7G moves further away from the central portion 42 in the longitudinal direction.

[0113] With the above structure, when a temperature change occurs inside the vehicle from low to high, resulting in a predetermined temperature, firstly, the first pin 71a1 of the second fixing member 7G, located near the central portion 42 in the longitudinal direction of the reflector 4, contacts the end of the first elongated hole 71b1 in the longitudinal direction. In this state, the second pin 71a2 of the second fixing member 7G, located away from the central portion 42 in the longitudinal direction of the reflector 4, is not in contact with the end of the second elongated hole 71b2 in the longitudinal direction. That is, in this state, the force exerted by the second engaging member located near the central portion 42 in the longitudinal direction of the reflector 4 on the substrate 3 and the reflector 4 is greater than the force exerted by the second engaging member located away from the central portion 42 in the longitudinal direction of the reflector 4 on the substrate 3 and the reflector 4.

[0114] With the above structure, even when the temperature inside the vehicle changes, the second fixing member 7G in the planar lighting device 1G of this embodiment will firmly fix the reflector 4 to the substrate 3 at the central portion 42 in the longitudinal direction. On the other hand, the portion in the longitudinal direction away from the central portion 42 will also be fixed to the extent that the reflector 4 and the substrate 3 are not separated.

[0115] Figure 20 This refers to a variation of the aforementioned planar lighting device 1G. Figure 19 The same cross-sectional view. In the second fixing member 7G of this embodiment, the engaging recess 71c is provided on the reflector 4, and on the other hand, the elongated hole 71b is provided on the bottom frame 21. Moreover, the planar lighting device 1G of this embodiment has a through hole 71d on the substrate 3 through which the pin 71a passes.

[0116] (Other implementation methods)

[0117] Regarding the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G described in the above embodiments, a scheme using a flexible FPC for the substrate 3 and having a bent injection surface R has been described. However, the injection surface R of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in this embodiment can also be formed as a flat surface along a plane orthogonal to the thickness direction. Planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G having a flat injection surface R can use a rigid substrate. Of course, even when the injection surface R is bent, a rigid substrate can still be used.

[0118] Furthermore, regarding the first fixing member 6 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in the above embodiments, its configuration consisting of a pin 61 provided on the bottom frame 21 and a locking hole 62 formed in the reflector 4 has been described. However, the first fixing member 6 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in this embodiment is not limited to this; a locking recess that engages with the pin 61 but does not penetrate the reflector in the thickness direction may also be formed in the reflector 4.

[0119] Furthermore, regarding the first fixing member 6 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in the above embodiments, a scheme in which a pin 61 is provided on the bottom frame 21 and a locking hole 62 is formed on the reflector 4 has been described. However, the first fixing member 6 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in this embodiment may also have a pin protruding to the other side in the thickness direction on the bottom surface of the reflector 4, and a locking recess for engaging with the pin is provided on the bottom 21a of the bottom frame 21.

[0120] Furthermore, regarding the first fixing member 6 of the planar lighting device 1 in the above embodiment, its configuration consisting of a pin 61 provided on the bottom frame 21 and a locking hole 62 provided on the reflector 4 has been described. However, the first fixing member 6 of the planar lighting device 1 in this embodiment is not limited to this; for example, it may also consist of a bolt provided on the bottom frame 21 and a threaded connection to the reflector for bolt engagement. Of course, it is not limited to this; it may be an adhesive component provided between the bottom frame 21 and the reflector 4, or the reflector 4 may be fused to the bottom frame 21.

[0121] Furthermore, the second fixing members 7, 7A, 7B, and 7C of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, and 1F in the above embodiments have been described as being double-sided adhesive tape. However, the second fixing members 7, 7A, 7B, and 7C of the planar lighting device 1 in this embodiment are not limited to this; for example, they may also be adhesives or the like.

[0122] Furthermore, regarding the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G described above, the first opening 34a of the reflector 34 is described as rectangular. However, the shape of the first opening 34a of the reflector 34 in the planar lighting device 1 of this embodiment is not limited to this, and can be changed to a suitable shape such as circular, elliptical, or polygonal, corresponding to the shape of the light source 30.

[0123] Furthermore, the shapes of the injection surface R (opening 22d) and the bottom 21a of the bottom frame 21 do not need to be precise rectangles. For example, they can be parts that lack a portion of the outer corners, as long as the long dimension direction and the short dimension direction can be determined as a whole.

[0124] Furthermore, regarding the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of the above embodiments, a scheme in which a reflective sheet 34 separate from the substrate 3 is provided on the substrate 3 has been described. However, the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of this embodiment are not limited to this, and it is not necessary to provide a reflective sheet 34 on the substrate 3.

[0125] Furthermore, the substrate 3 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in the above embodiments has been described as being divided into four regions 33. However, the substrate 3 of the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G in this embodiment is not limited to this; it can be integrally formed, or it can be formed into multiple regions divided into two regions, three regions, or six or more regions.

[0126] Furthermore, regarding the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of the above embodiments, a scheme in which the arrangement areas 70, 70A, 70B, 70C, and 70D of the second fixing member 7 are divided into four or five arrangement areas has been described. However, the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of this embodiment are not limited to this, and may also be formed into multiple arrangement areas divided into three or six or more arrangement areas.

[0127] Furthermore, regarding the second fixing members 7, 7A, 7B, and 7C in the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of the above embodiments, a configuration has been described in which the bonding area of ​​the second fixing members 7, 7A, 7B, and 7C with the substrate 3 at the central portion in the longitudinal direction is larger than the bonding area at the portion farther from the central portion in the longitudinal direction. Additionally, a configuration has been described in which the bonding strength per unit area with the substrate 3 at the central portion in the longitudinal direction is greater than the bonding strength per unit area at the portion farther from the central portion in the longitudinal direction. However, the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, 1F, and 1G of this embodiment are not limited to this. For example, the bonding area of ​​the second fixing members 7, 7A, 7B, and 7C can be varied according to their position in the longitudinal direction, and the bonding strength per unit area can also be varied.

[0128] Furthermore, regarding the first fixing member 6 in the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, and 1G of this embodiment, a configuration in which it is disposed on the inner side of both ends in the short-length direction within the central portion in the long-length direction has been described. However, the first fixing member 6 in the planar lighting devices 1, 1A, 1B, 1C, 1D, 1E, and 1G of this embodiment is not limited to this configuration; for example, it may also be disposed at both ends in the short-length direction (the so-called frame portion 22f) within the central portion in the long-length direction.

[0129] Furthermore, the present invention is not limited to the embodiments described above. Solutions constructed by appropriately combining the aforementioned components are also included in the present invention. Moreover, those skilled in the art can readily derive further effects and modifications. Therefore, the present invention is not limited to the embodiments described above, and various modifications can be made.

[0130] Explanation of reference numerals in the attached figures

[0131] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G: Planar lighting device; 2: Frame; 21: Bottom frame; 22: Top frame; 3: Substrate; 30: Light source; 33: Area; 34: Reflector; 34a: First sheet opening; 4: Reflector; 41d: First reflector opening; 42: Central part; 6: First fixing member; 7, 7A, 7B, 7C: Second fixing member.

Claims

1. A planar lighting device, comprising: The substrate has multiple light sources on one side. A reflector is disposed on one side of the substrate; The bottom frame is located on the opposite side of the substrate, opposite to the first side. The first fixing member fixes the central portion of the reflector along its long dimension to the bottom frame; as well as The second fixing member fixes one side of the substrate and the reflector. In the force exerted by the second fixing member on the substrate and the reflector, the force at the central portion of the reflector in the long dimension direction is greater than the force at the portion of the reflector in the long dimension direction away from the central portion.

2. The planar lighting device according to claim 1, wherein, The force by which the second fixing member restricts the substrate and the reflector is the force by which the second fixing member fixes the substrate and the reflector.

3. The planar lighting device according to claim 2, wherein, The bonding area between the second fixing member and the substrate at the central portion in the longitudinal direction is larger than the bonding area at the portion in the longitudinal direction away from the central portion of the substrate.

4. The planar lighting device according to claim 2, wherein, The adhesive strength per unit area between the second fixing member and the substrate at the central portion in the longitudinal direction is greater than the adhesive strength per unit area at the portion of the substrate away from the central portion in the longitudinal direction.

5. The planar lighting device according to any one of claims 1 to 4, wherein, The substrate is configured to be divided into multiple regions along the longitudinal direction. The second fixing member changes its configuration according to the respective positions of the multiple regions.

6. The planar lighting device according to any one of claims 1 to 4, wherein, The substrate has a reflective sheet on one side. The reflector has a reflector opening that exposes the head of the light source toward one side. The reflector has an opening that exposes the head of the light source toward one side. The size of the opening in the plate is smaller than the size of the opening in the reflector.

7. The planar lighting device according to claim 6, wherein, The reflector has an opening at the location where the second fixing member is positioned.

8. The planar lighting device according to claim 6, wherein: The reflector has a grid-shaped reflective portion that corresponds to each of the plurality of light sources.

9. The planar lighting device according to any one of claims 1 to 4 and 7, wherein, The second fixing member for fixing one side of the substrate and the reflector is double-sided adhesive tape.

10. The planar lighting device according to claim 1, wherein, The force by which the second fixing member restricts the substrate and the reflector is a force based on the extensibility of the second fixing member. The second fixing member has less stretchability at the central portion of the substrate in the longitudinal direction than at the portion of the substrate away from the central portion in the longitudinal direction.

11. The planar lighting device according to claim 1, wherein, The second fixing member consists of a pin and a hole into which the pin can be inserted. The length of the hole in the longitudinal direction increases as the position of the second fixing member moves further away from the central portion in the longitudinal direction.

12. The planar lighting device according to any one of claims 1 to 4, 7, 10, and 11, wherein, It includes: a frame, consisting of a top frame and a bottom frame, wherein the top frame has a border portion, and the border portion has a frame opening formed on its inner side. When viewed from a direction orthogonal to a plane including the long dimension direction of the reflector and the short dimension direction orthogonal to the long dimension direction, the first fixing member that fixes the central portion of the reflector in the long dimension direction to the bottom frame is located at a position overlapping the frame portion.

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