Lighting device

Abstract

A lighting device (100) comprises: a circuit board (30) on which a light-emitting element (10) is mounted on a first surface; a heat-dissipating member (40) disposed on a second surface of the circuit board (30); and a heat-conductive member (37) disposed between the circuit board (30) and the heat-dissipating member (40). A fastening hole (36) for inserting a fastening member (50) is formed in the circuit board (30). In the surface of the first surface, a line connecting the center of the fastening hole (36) and the center of the light-emitting element (10) is defined as a virtual line, a line perpendicular to the virtual line is defined as a virtual boundary line, a part of a region farther from the fastening hole (36) than the virtual boundary line is defined as a pressing area, and at least one pressing member (71) abutting the inside of the pressing area is provided.

Description

lighting equipment

[0001] The present disclosure relates to a lighting device, and more particularly to a lighting device in which a light-emitting element is mounted on a circuit board.

[0002] In recent years, vehicle lamps that use light-emitting diodes (LEDs) as light sources have become widespread. In addition, in lighting devices used in vehicle lamps, as in Patent Document 1, for example, a plurality of LEDs are sometimes arranged on a circuit board to emit light with a desired brightness and light distribution pattern.

[0003] It is generally known that LEDs generate heat as they emit light, which causes a rise in temperature, resulting in a change in the wavelength of light emitted and a decrease in light emission efficiency. Therefore, in headlights and other devices that emit a large amount of light, it is important to effectively dissipate the heat generated by the LED to the outside and suppress temperature increases. Furthermore, through-hole wiring and heat dissipation wiring are formed on a circuit board made of an insulating material, and heat from the LED is effectively transferred to the heat dissipation wiring on the back side, where it can be dissipated by a heat dissipation member in contact with the heat dissipation wiring.

[0004] Japanese Patent Application Publication No. 2018-073762

[0005] In such lighting devices of the prior art, a thermally conductive member is in contact between the heat dissipation member and the circuit board, improving heat dissipation from the light-emitting element. However, when the circuit board is made thinner to further improve heat dissipation, the rigidity of the circuit board decreases, and the thermally conductive member sandwiched between the heat dissipation member and the circuit board does not expand sufficiently, which can cause the circuit board to warp and reduce heat dissipation.

[0006] The present disclosure aims to provide a lighting device that uses a thin circuit board, which is less likely to warp and has improved heat dissipation properties.

[0007] A lighting device according to one aspect of the present disclosure includes a circuit board having a first surface on which a light-emitting element is mounted, a heat dissipation member arranged on a second surface of the circuit board, and a heat conduction member arranged between the circuit board and the heat dissipation member, wherein the circuit board has fastening holes formed therein for inserting fastening members, and within the plane of the first surface, a line connecting the center of the fastening hole and the center of the light-emitting element is defined as a virtual line, a line perpendicular to the virtual line is defined as a virtual boundary line, a portion of an area farther from the fastening hole than the virtual boundary line is defined as a pressing area, and the lighting device has at least one pressing member abutting within the pressing area.

[0008] In the lighting device according to one aspect of the present disclosure, the pressing member abuts against the first surface of the circuit board in the pressing region located farther from the fastening hole, so that the fastening hole and the pressing member can apply force to the circuit board on both sides of the light-emitting element in the direction of the heat dissipation member, thereby providing a lighting device that uses a thin circuit board and is less likely to warp, resulting in improved heat dissipation.

[0009] Another aspect of the present disclosure provides an illumination device comprising: a circuit board having a light-emitting element mounted on a first surface; a heat dissipation member arranged on a second surface of the circuit board; a heat conduction member arranged between the circuit board and the heat dissipation member; and a pressing member abutting the first surface at a pressing position on the first surface, wherein the circuit board has a plurality of fastening holes formed therein for inserting fastening members, and the center of the light-emitting element is located within a warp reduction region connecting the outer peripheries of the plurality of fastening holes and the pressing position.

[0010] In a lighting device according to another aspect of the present disclosure, the area connecting the outer peripheries of the multiple fastening holes and the pressing positions is defined as a warpage reduction area, and the center of the light emitting element is located within the warpage reduction area, so that the fastening members and the pressing member can press the vicinity of the light emitting element, thereby providing a lighting device that uses a thin circuit board and has a circuit board that is less likely to warp and has improved heat dissipation.

[0011] According to the present disclosure, it is possible to provide a lighting device that uses a thin circuit board, where the circuit board is less likely to warp and has improved heat dissipation properties.

[0012] FIG. 1 is a schematic cross-sectional view illustrating an overview of a lighting device according to a first embodiment. FIG. 2 is a schematic plan view illustrating an example of an arrangement on a circuit board according to the first embodiment. FIG. 3 is a schematic plan view illustrating the position of a pressing region within the surface of the circuit board. FIG. 4 is a schematic perspective view illustrating an example of mounting a circuit board to a housing. FIG. 5 is a schematic partial enlarged view illustrating an example of the structure of a housing to which a circuit board is mounted. FIG. 6 is a schematic perspective view illustrating an example of a pressing member that contacts the circuit board. FIG. 7 is a schematic cross-sectional view illustrating an example of a pressing member that contacts the circuit board. FIG. 8 is a schematic cross-sectional view illustrating an overview of a lighting device according to a second embodiment. FIG. 9 is a schematic plan view illustrating an example of an arrangement on a circuit board according to the second embodiment and the position of a pressing region 12. FIG. 10 is a schematic perspective view illustrating an example of mounting a circuit board to a housing. FIG. 11 is a schematic partial enlarged view illustrating an example of the structure of a housing to which a circuit board is mounted and an example of a pressing member. FIG. 12 is a schematic plan view illustrating fastening holes, pressing positions, and mounting positions of light-emitting elements. Fig. 13 is a schematic plan view illustrating fastening holes, pressing positions, and mounting positions of the light-emitting element 10 in the lighting device according to the third embodiment. Fig. 14 is a schematic plan view illustrating fastening holes, pressing positions, and mounting positions of the light-emitting element in the lighting device according to the fourth embodiment.

[0013] First Embodiment Hereinafter, an embodiment of the present disclosure will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant description will be omitted where appropriate. In the following description, an illumination device 100 according to the present disclosure will be described as being applied to a vehicle lamp. FIG. 1 is a schematic cross-sectional view illustrating an overview of the illumination device 100 according to this embodiment. As shown in FIG. 1 , the illumination device 100 includes a light-emitting element 10, an electronic component 20, a circuit board 30, and a heat dissipation member 40. The circuit board 30 also includes a connection terminal portion 21, a first wiring layer 31, a second wiring layer 32, through-hole wiring 33, a hole-filling resin 34, a protective layer 35, fastening holes 36, and a heat-conducting member 37. The circuit board 30 is fixed to the heat dissipation member 40 with a fastening member 50, and a pressing member 71 abuts against a first surface of the circuit board 30. A connector 60 is connected to the connection terminal portion 21.

[0014] The light-emitting element 10 is a component mounted on the surface of the circuit board 30, which is the first surface, and emits light of a predetermined wavelength when a voltage is applied. While FIG. 1 illustrates a surface-mounted light-emitting element 10 electrically connected to the first wiring layer 31 using solder, the light-emitting element 10 may also be electrically connected to the first wiring layer 31 by wire bonding. For example, when the lighting device 100 is used as a headlamp for a vehicle lamp, a white LED may be used as the light-emitting element 10. When the lighting device 100 is used as a tail lamp or stop lamp, a red LED may be used as the light-emitting element 10. When the lighting device 100 is used as a turn signal lamp, an amber LED may be used as the light-emitting element 10. The structure of the light-emitting element 10 is not limited, and may be a packaged LED chip or a bare LED chip directly mounted. The white LED may be a combination of a GaN-based LED emitting primary light in the blue to ultraviolet wavelength range and a phosphor, or a combination of LED chips of each of the RGB colors.

[0015] The electronic components 20 are mounted on the front surface, which is the first surface, or the back surface, which is the second surface, of the circuit board 30. The electronic components 20 are components that constitute an electronic circuit and realize various functions when supplied with power and control signals. While FIG. 1 illustrates a surface-mounted case in which the electronic components 20 are electrically connected to the first wiring layer 31 using solder, the electronic components 20 may also be electrically connected to the first wiring layer 31 by wire bonding using wires. The type and number of the electronic components 20 are not limited, and known components such as resistors, capacitors, and integrated circuits may be used.

[0016] The connection terminal portion 21 is mounted on the front surface, which is the first surface, or the back surface, which is the second surface, of the circuit board 30. The connection terminal portion 21 is a component to which a connector 60 of a cable (not shown) that transmits power and signals from the outside is electrically connected. The shape and structure of the connection terminal portion 21 are not limited. The shape and structure of the cable are also not limited, and a conventionally known flexible cable or the like may be used. The connector 60 has a shape corresponding to the connection terminal portion 21 and is mechanically and electrically connectable to the connection terminal portion 21.

[0017] The circuit board 30 is a plate-like member having a substantially plate-like base material on which a first wiring layer 31, a second wiring layer 32, through-hole wiring 33, a hole-filling resin 34, a protective layer 35, and fastening holes 36 are formed. A thermally conductive member 37 is disposed between the circuit board 30 and the heat dissipation member 40. The material constituting the base material of the circuit board 30 is not particularly limited, but it is preferable to use a resin material with excellent electrical insulation properties. For example, the base material of the circuit board 30 may be a glass epoxy resin or the like used in ordinary printed wiring boards. More specifically, FR4 (Flame Retardant Type 4) may be used.

[0018] The heat dissipation member 40 is made of a material with a higher thermal conductivity than the base material of the circuit board 30. The heat dissipation member 40 is disposed on the back surface, which is the second surface, of the circuit board 30, and dissipates heat from the circuit board 30. The material constituting the heat dissipation member 40 is not limited, but metals such as anodized aluminum or copper may be used, for example. In the example shown in FIG. 1 , the heat dissipation member 40 has a shape in which multiple heat dissipation fins are erected from a plate-like portion, but the shape and structure of the heat dissipation member 40 are not limited.

[0019] The fastening members 50 are members that are inserted into the fastening holes 36 formed in the circuit board 30 and fasten the circuit board 30 to the heat dissipation member 40. The specific configuration of the fastening members 50 is not limited. For example, the fastening members 50 may be screws or bolts that are threaded into screw holes formed in the heat dissipation member 40, or may be crimped portions that protrude from the heat dissipation member 40. By fastening the circuit board 30 to the heat dissipation member 40 with the fastening members 50, the circuit board 30 is fixed in a state where it is pressed toward the heat dissipation member 40 at the positions of the fastening holes 36.

[0020] The pressing member 71 is a member that comes into contact with the surface that is the first surface of the circuit board 30 and applies a force to the circuit board 30 in the direction of the heat dissipation member 40 to press it. In the example shown in Fig. 1, the pressing member 71 has a columnar shape, but the specific shape and structure of the pressing member 71 are not limited to these. As an example, a portion of the housing 70 or the reflector 80, which will be described later, may extend toward the circuit board 30 so that a force is applied to the position where the pressing member 71 comes into contact with the circuit board 30. The position on the circuit board 30 where the pressing member 71 comes into contact will be described in detail below.

[0021] The first wiring layer 31, which is the wiring for elements, is a wiring pattern formed on the surface, which is the first surface, of the circuit board 30. Parts of the first wiring layer 31 function as land portions on which the light-emitting elements 10 and electronic components 20 are mounted, and as terminal portions to which wires are electrically connected. The light-emitting elements 10 and electronic components 20 are electrically connected to the first wiring layer 31, and an electronic circuit is formed on the circuit board 30. In the first wiring layer 31, through-hole wiring 33 is formed in the region of the land portion on which the light-emitting elements 10 are mounted.

[0022] The second wiring layer 32, which is a heat dissipation wiring, is a wiring pattern formed on the back surface, which is the second surface of the circuit board 30. As shown in FIG. 1 , the second wiring layer 32 may be provided with a region electrically connected to the first wiring layer 31 by the through-hole wiring 33 and a region electrically isolated from the through-hole wiring 33, in different regions. The region of the second wiring layer 32 connected to the through-hole wiring 33 functions as a heat dissipation path, as described below. Furthermore, the region of the second wiring layer 32 electrically isolated from the through-hole wiring 33 may be connected to a ground potential.

[0023] The through-hole wiring 33 is an electrically conductive wiring formed on the inner wall of a through-hole (penetrating hole) that penetrates from the front surface side to the back surface side of the circuit board 30. A conventionally known plating method or the like can be used as a method for forming the through-hole wiring 33. The through-hole wiring 33 electrically connects a part of the first wiring layer 31 and a part of the second wiring layer 32. There are no limitations on the region in which the through-hole wiring 33 is provided, but by providing the through-hole wiring 33 at a position in the first wiring layer 31 that corresponds to the land portion on which the light-emitting element 10 is mounted, heat generated by light emission can be efficiently transmitted to the back surface side.

[0024] The hole-filling resin 34 is a resin material that fills the through-holes in which the through-hole wiring 33 is formed. There are no limitations on the material that constitutes the hole-filling resin 34, and a thermosetting epoxy resin may be used as an example. Furthermore, in order to improve the thermal conductivity of the hole-filling resin 34, a filler with high thermal conductivity may be mixed into the resin material.

[0025] The protective layer 35 is a layer made of an insulating material and formed on the back surface of the circuit board 30 so as to cover the second wiring layer 32. There are no particular restrictions on the material for the protective layer 35, and a conventionally known resist material may be used. Although not shown in FIG. 1 , the protective layer 35 may also be formed on the front surface of the circuit board 30 so as to cover a portion of the first wiring layer 31. In the example shown in FIG. 1 , the protective layer 35 is formed over the entire back surface of the circuit board 30, but the back surface of the circuit board 30 may be partially exposed as long as at least the area where the second wiring layer 32 is formed is covered.

[0026] The fastening holes 36 are through holes formed to penetrate from the front surface, which is the first surface, of the circuit board 30 to the back surface, which is the second surface. As described above, the fastening members 50 are inserted into the fastening holes 36 and fastened, thereby fixing the circuit board 30 to the heat dissipation member 40. The position and shape of the fastening holes 36 are not limited, but inserting the fastening members 50 into the fastening holes 36 and fastening them may cause distortion of the circuit board 30 in the vicinity of the fastening holes 36. Therefore, it is preferable that the light emitting elements 10 and electronic components 20 are not disposed within 15 mm of the centers of the fastening holes 36.

[0027] The heat conduction member 37 is a member with high thermal conductivity that is disposed between the circuit board 30 and the heat dissipation member 40. In order to improve the voltage resistance of the lighting device 100, it is preferable that the heat conduction member 37 be insulating. There are no restrictions on the material that constitutes the heat conduction member 37, but as an example, a heat dissipation grease containing a filler of metal particles or metal oxide particles may be used. Alternatively, a heat conduction sheet molded into a sheet shape may be used as the heat conduction member 37.

[0028] 2 is a schematic plan view showing an example of an arrangement on a circuit board 30 according to this embodiment. In the example shown in FIG. 2, a first wiring layer 31 is patterned on the circuit board 30, and a plurality of light-emitting elements 10 are surface-mounted in a light-emitting element mounting region 11 indicated by a dashed line on the first wiring layer 31. Furthermore, a plurality of electronic components 20 and connection terminal portions 21 are mounted on the first wiring layer 31 on the circuit board 30. Furthermore, a fastening hole 36 is formed near the center of the circuit board 30.

[0029] 2, the light-emitting element mounting region 11 is provided in a position on the surface of the circuit board 30 closer to the outer periphery than the fastening holes 36. Also, as shown in Fig. 1, the heat conduction member 37 is disposed directly below the light-emitting element 10 and the through-hole wiring 33. Therefore, the heat conduction member 37 is disposed in a position overlapping the light-emitting element mounting region 11, the light-emitting element 10, and the through-hole wiring 33 in a plan view of the circuit board 30.

[0030] 1 and 2 , the light-emitting element 10 emits light when power and a control signal are transmitted from the outside to an electronic circuit formed by the first wiring layer 31, the light-emitting element 10, and the electronic component 20 via a cable, a connector 60, and a connection terminal portion 21. Heat generated by the light emission of the light-emitting element 10 is transmitted to the heat dissipation member 40 via the first wiring layer 31, the through-hole wiring 33, the second wiring layer 32, the protective layer 35, and the heat conduction member 37. The heat dissipation member 40 dissipates the heat to the outside of the lighting device 100, thereby cooling the lighting device 100.

[0031] 3 is a schematic plan view showing the position of the pressure area 12 on the surface of the circuit board 30. In the example shown in Fig. 3, the areas indicated by thin dashed lines in the upper left and lower right of the circuit board 30 are the pressure areas 12. The thick dashed lines, dashed lines, and double-dashed lines shown in the figure are all imaginary lines for setting the pressure area 12.

[0032] When setting the pressing area 12, first, a line segment connecting the center of the fastening hole 36 and the center of the light-emitting element 10 is set as a virtual line. Next, a line perpendicular to the virtual line within the plane of the circuit board 30 is set as a virtual boundary line. Finally, a virtual square including the virtual line and the virtual boundary line is imagined. Here, the length of the virtual line is the distance D between the fastening hole 36 and the light-emitting element 10, and the virtual square has one side equal to the distance D. While FIG. 3 shows an example in which virtual lines, virtual boundaries, and virtual squares are set for three light-emitting elements 10, virtual lines, virtual boundaries, and virtual squares may be set in the same manner for all light-emitting elements 10.

[0033] Next, at least a portion of the region farther from the fastening hole 36 than the imaginary boundary line set in the above-described procedure is set as the pressure region 12. In the example shown in FIG. 3 , the lower right region farther from the fastening hole 36 than the imaginary square shown by the dashed-dotted line and the upper left region farther from the fastening hole 36 than the imaginary square shown by the dashed-dotted line are set as the pressure region 12. The upper left pressure region 12 is further from the imaginary boundary line of the imaginary square shown by the thick dashed line. Although not shown in FIG. 3 , pressure regions 12 may be set for each of multiple light-emitting elements 10. As an example, a pressure region 12 may also be set within a larger imaginary square shown by the dashed-dotted line, based on the imaginary boundary line of the thick dashed line. In the example shown in FIG. 3 , the pressure region 12 is set based on the light-emitting element 10 located farther from the fastening hole 36, and the region not included in any of the imaginary squares is set as the pressure region 12.

[0034] As described above, the pressing area 12 is an area farther from the fastening hole 36 than the imaginary boundary line, but since warping of the circuit board 30 is likely to occur if the pressing area 12 is too far from the light emitting element 10, it is preferable to set the pressing area 12 within a predetermined distance from the light emitting element 10. More specifically, the pressing area 12 is preferably set within 50 mm from the center of the light emitting element 10, and more preferably within 30 mm.

[0035] 1 to 3 , in the lighting device 100, the circuit board 30 is fixed to the heat dissipation member 40 by the fastening members 50 at the fastening holes 36, and the pressing members 71 and 81 abut against the surface of the circuit board 30 in the pressing region 12. The pressing region 12 is located farther from the fastening holes 36 than the imaginary boundary line described above, and the light emitting element 10 is located midway between the position where the pressing members 71 and 81 abut and the fastening hole 36. As a result, even if the heat conduction member 37 is located in a position overlapping with the light emitting element 10, the pressing members 71 and 81 and the fastening members 50 apply force toward the heat dissipation member 40 to two locations on the surface of the circuit board 30 that sandwich the light emitting element 10, thereby pressing the light emitting element 10. As a result, even if the circuit board 30 is formed thin and has low rigidity, the circuit board 30 is less likely to warp even when the heat conduction member 37 is sandwiched between the circuit board 30 and the heat dissipation member 40, and the uniform thickness of the heat conduction member 37 is more easily maintained, improving the heat dissipation performance of the lighting device 100.

[0036] Fig. 4 is a schematic perspective view showing an example of mounting the circuit board 30 to the housing portion 70. In the example shown in Fig. 4, the heat dissipation member 40 is provided with a flange portion and a frame portion 41, and the circuit board 30 is fastened to the heat dissipation member 40 within the frame portion 41 with fastening members 50. The lighting device 100 also includes a housing portion 70. The frame portion 41 is inserted into an opening formed at a predetermined position in the housing portion 70, thereby mounting the heat dissipation member 40 to the housing portion 70. The specific structure and method for mounting the heat dissipation member 40 to the housing portion 70 are not limited, and conventionally known methods such as fitting or screw fastening may be used.

[0037] Fig. 5 is a schematic partial enlarged view showing an example of the structure of the housing 70 to which the circuit board 30 is attached. In the example shown in Fig. 5, an opening having a shape corresponding to the frame 41 is formed in the housing 70, and the frame 41 is inserted into the opening to attach the heat dissipation member 40 to the housing 70. Also, a reflector 80, pressing members 71, 81, and inner lenses 91, 92 are provided within the opening of the housing 70.

[0038] The housing 70 is a housing portion that forms the outer shape of the lighting device 100 and houses and holds the various components, and is made of a light-blocking material. Although not shown in Fig. 5, the housing 70 has a front opening and an outer lens that covers the front opening. Furthermore, a portion of the housing 70 is erected within the opening as a pressing member 71, and the pressing member 71 extends toward the circuit board 30.

[0039] The reflector 80 is an optical element having a reflective surface that reflects light, and reflects the light emitted from the light-emitting element 10 toward the outer lens, adjusting the light distribution pattern and emitting the adjusted light. Therefore, the reflector 80 corresponds to the light distribution adjusting unit in the present disclosure. Furthermore, a portion of the reflector 80 is erected within the opening as a pressing member 81, and the pressing member 81 extends toward the circuit board 30.

[0040] The inner lenses 91 and 92 are optical members disposed on the light-emitting surface side of the light-emitting element 10, and adjust and emit the light distribution pattern of light emitted from the light-emitting element 10. Therefore, the inner lenses 91 and 92 also correspond to the light distribution adjustment unit in the present disclosure. The shape and size of the inner lenses 91 and 92 are not limited, and conventionally known convex lenses, concave lenses, Fresnel lenses, TIR (Total Internal Reflection) lenses, etc. may be used.

[0041] The pressing member 71 is a part of the housing portion 70 that extends toward the circuit board 30. The pressing member 81 is a part of the reflector 80 that extends toward the circuit board 30. As described above, the pressing members 71 and 81 come into contact with the surface that is the first surface of the circuit board 30 and apply a force toward the heat dissipation member 40 to press the circuit board 30.

[0042] Fig. 6 is a schematic perspective view showing an example of pressing members 71, 81 that contact the circuit board 30. For simplicity, Fig. 6 omits the tip portions of the pressing members 71, 81 that extend from the housing portion 70 and the reflector 80. As shown in Fig. 6 , the multiple pressing members 71, 81 contact the surface that is the first surface of the circuit board 30 that they face at their respective positions. Furthermore, the pressing members 71, 81 provided at positions facing the above-mentioned pressing region 12 contact the surface that is the first surface of the circuit board 30 within the pressing region 12.

[0043] FIG. 7 is a schematic cross-sectional view showing an example of pressing members 71, 81 contacting the circuit board 30. The example shown in FIG. 7 schematically shows the pressing members 71, 81 contacting the circuit board 30 in a region other than the pressing region 12 on the circuit board 30. As shown in FIG. 7, the pressing member 81 extends from a reflector 80 provided around the light-emitting element 10. Inner lenses 91, 92 are disposed in positions facing the light-emitting element 10. The inner lenses 91, 92 may be held by the housing 70 or the reflector 80. While FIGS. 5 and 7 show an example of an extended portion of the reflector 80 as the pressing member 81, an extended portion of the inner lenses 91, 92, which are light distribution adjustment units, may also be used as the pressing member 81.

[0044] As described above, in the lighting device 100 of this embodiment, the pressing members 71, 81 abut against the first surface of the circuit board 30 in the pressing regions 12 located farther from the fastening holes 36. Therefore, the fastening holes 36 and the pressing members 71, 81 apply force to the circuit board 30 on both sides of the light emitting element 10 in the direction of the heat dissipation member 40. This makes it difficult for the circuit board 30 to warp even when made thinner, improving the heat dissipation performance of the lighting device 100.

[0045] Second Embodiment Fig. 8 is a schematic cross-sectional view illustrating an overview of a lighting device 100 according to a second embodiment. As shown in Fig. 8, the lighting device 100 of the second embodiment also includes a light-emitting element 10, an electronic component 20, a circuit board 30, and a heat dissipation member 40. The circuit board 30 includes a connection terminal 21, a first wiring layer 31, a second wiring layer 32, through-hole wiring 33, a hole-filling resin 34, a protective layer 35, fastening holes 36, and a heat-conducting member 37. The circuit board 30 is fixed to the heat dissipation member 40 with a fastening member 50, and a pressing member 71 abuts against a first surface. A connector 60 is connected to the connection terminal 21.

[0046] Also in the second embodiment, the pressing member 71 is a member that comes into contact with the surface that is the first surface of the circuit board 30 and applies a force to the circuit board 30 in the direction of the heat dissipation member 40 to press the circuit board 30. The pressing position 72, which is the position on the circuit board 30 where the pressing member 71 comes into contact, will be described in detail later.

[0047] FIG. 9 is a schematic plan view showing an example of an arrangement on a circuit board 30 according to the second embodiment and the position of a pressure region 12. FIG. 9 shows a first wiring layer 31, but the pattern shape has been partially omitted for simplicity. In the example shown in FIG. 9, the first wiring layer 31 is patterned on the circuit board 30, and a plurality of light-emitting elements 10 are surface-mounted on the first wiring layer 31 near the center of the circuit board 30. Furthermore, a plurality of electronic components 20 and connection terminal portions 21 are mounted on the first wiring layer 31 on the circuit board 30. Furthermore, a plurality of fastening holes 36 are formed near the lower right and upper left of the circuit board 30.

[0048] In the example shown in FIG. 9 , a pressing area 12 is set near the light-emitting element 10 on the surface of the circuit board 30. Furthermore, the plurality of light-emitting elements 10 are arranged in positions sandwiched between the plurality of fastening holes 36. As will be described later, the pressing area 12 is an area where a pressing position 72, where a pressing member 71 abuts, can be set on the surface, which is the first surface of the circuit board 30. In FIG. 9 , the pressing area 12 is depicted as a rectangle using dashed lines, but the specific shape of the pressing area 12 is not limited. Furthermore, the pressing area 12 is a virtual area in the design, and a specific structure does not need to be provided on the circuit board 30.

[0049] 8, the heat conductive member 37 is disposed directly below the light emitting element 10 and the through-hole wiring 33. Therefore, the heat conductive member 37 is disposed at a position overlapping the light emitting element 10 and the through-hole wiring 33 in a plan view of the circuit board 30.

[0050] 8 and 9 , the light emitting element 10 emits light when power and a control signal are transmitted from the outside to an electronic circuit including the first wiring layer 31, the light emitting element 10, and the electronic component 20 via a cable, a connector 60, and a connection terminal portion 21. Heat generated by the light emission of the light emitting element 10 is transmitted to the heat dissipation member 40 via the first wiring layer 31, the through-hole wiring 33, the second wiring layer 32, the protective layer 35, and the heat conduction member 37. The heat dissipation member 40 dissipates the heat to the outside of the lighting device 100, thereby cooling the lighting device 100.

[0051] FIG. 10 is a schematic perspective view showing an example of mounting the circuit board 30 to the housing 70. FIG. 11 is a schematic partial enlarged view showing an example of the structure of the housing 70 to which the circuit board 30 is mounted, and examples of pressing members 71 and 81. In the example shown in FIGS. 10 and 11 , the heat dissipation member 40 is provided with a flange portion and a frame portion 41, and the circuit board 30 is fastened to the heat dissipation member 40 within the frame portion 41 with fastening members 50. The lighting device 100 also includes the housing 70, and the frame portion 41 is inserted into an opening formed at a predetermined position in the housing 70, and the heat dissipation member 40 is mounted to the housing 70. The specific structure and method for mounting the heat dissipation member 40 to the housing 70 are not limited, and conventionally known methods such as fitting and screw fastening can be used.

[0052] The housing 70 is a housing portion that forms the outer shape of the lighting device 100 and houses and holds the various components, and is made of a light-blocking material. Although not shown in Figures 10 and 11, the housing 70 has a front opening that is covered by an outer lens. Furthermore, a portion of the housing 70 is erected within the opening as a pressing member 71, and the pressing member 71 extends toward the circuit board 30.

[0053] 10 and 11 , a reflector may be provided in the opening of the housing portion 70. The reflector has a reflective surface that reflects light, and is an optical element that reflects light emitted from the light-emitting element 10 toward the outer lens, adjusting the light distribution pattern and emitting the adjusted light. Therefore, the reflector corresponds to the light distribution adjustment portion in the present disclosure. Furthermore, within the opening, a portion of the reflector is erected as a pressing member 81, and the pressing member 81 extends toward the circuit board 30.

[0054] The pressing member 71 is a part of the housing portion 70 that extends toward the circuit board 30. The pressing member 81 is a part of the reflector that extends toward the circuit board 30. As described above, the pressing members 71 and 81 come into contact with the surface that is the first surface of the circuit board 30 and apply a force toward the heat dissipation member 40 to press the circuit board 30.

[0055] For simplicity, the distal end portions of the pressing members 71, 81 extending from the housing portion 70 and the reflector are omitted from Fig. 11. As shown in Fig. 11, the multiple pressing members 71, 81 abut against the surface, which is the first surface of the circuit board 30, at their respective positions. Furthermore, the pressing members 71, 81 provided at positions facing the above-described pressing region 12 abut against the surface, which is the first surface of the circuit board 30, within the pressing region 12.

[0056] Fig. 12 is a schematic plan view illustrating the fastening holes 36, the pressing positions 72, and the mounting positions of the light-emitting elements 10. In the example shown in Fig. 12, two fastening holes 36 are formed on the front surface, which is the first surface of the circuit board 30, and multiple light-emitting elements 10 are mounted between the two fastening holes 36. In Fig. 12, an imaginary diagonal line is drawn on one of the light-emitting elements 10 to indicate the center position of the light-emitting element 10 in a planar view. Although Fig. 12 shows an example in which rectangular light-emitting elements 10 are arranged in a row, the shape and arrangement of the light-emitting elements 10 are not limited.

[0057] In the example shown in Figure 12, one pressing position 72 is shown as an imaginary rectangle. A virtual line segment connecting the outer peripheries of two fastening holes 36 is shown as a dashed line 73a, and a virtual line segment connecting the pressing position 72 and the outer periphery of the two fastening holes 36 is shown as a dashed line 73b. If the area surrounded by dashed lines 73a and 73b in a plan view of the circuit board 30 is defined as a warp reduction region, all of the multiple light-emitting elements 10 are disposed within the warp reduction region. While Figure 12 shows an example in which each light-emitting element 10 is entirely located within the warp reduction region, the light-emitting elements 10 may be disposed such that a portion of the light-emitting element 10 is outside the warp reduction region, as long as at least the center of the light-emitting element 10 is located within the warp reduction region.

[0058] 12 , fastening members 50 are inserted into two fastening holes 36, respectively, and fastened. As a result, the circuit board 30 is fixed to the heat dissipation member 40. Furthermore, when a pressing member 71 abuts against one pressing position 72, the circuit board 30 is pressed by a force applied in the direction of the heat dissipation member 40 at at least three points, in addition to the fastening by the fastening members 50. As a result, even if the circuit board 30 is formed thin and has low rigidity, the circuit board 30 is less likely to warp within the warpage reduction region even when the heat conduction member 37 is sandwiched between the circuit board 30 and the heat dissipation member 40, and the heat conduction member 37 is more likely to maintain a uniform thickness, improving the heat dissipation performance of the lighting device 100.

[0059] As described above, the thermally conductive member 37 is disposed at a position overlapping the light emitting elements 10 and the through-hole wiring 33 in a plan view of the circuit board 30, and therefore the fastening holes 36 and the pressing positions 72 are preferably provided within a predetermined range from the center of any one of the light emitting elements 10. Specifically, the fastening holes 36 are preferably provided within 50 mm, and more preferably within 30 mm, from the center of any one of the light emitting elements 10. Furthermore, the pressing positions 72 are preferably provided within 50 mm, and more preferably within 30 mm, from the center of any one of the light emitting elements 10.

[0060] In addition, in the lighting device 100, an inner lens may be disposed opposite the light emitting element 10, and a reflector may be provided around the light emitting element 10. While an example in which the pressing member 71 abuts against the pressing position 72 is shown in Fig. 12, a pressing member 81 formed by extending from a light distribution adjustment unit such as a reflector or an inner lens may abut against the pressing position 72.

[0061] As described above, in the lighting device 100 of this embodiment, the area connecting the outer peripheries of the multiple fastening holes 36 and the pressing positions 72 is the warp reduction area, and the center of the light emitting element 10 is located within the warp reduction area. Therefore, the fastening members 50 and the pressing members 71, 81 can press down the vicinity of the light emitting element 10, making it difficult for the circuit board 30 to warp even if it is made thinner, and improving the heat dissipation performance of the lighting device 100.

[0062] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to FIG. 13 . Description of content overlapping with the first and second embodiments will be omitted. FIG. 13 is a schematic plan view illustrating fastening holes 36, pressing positions 72, and mounting positions of light-emitting elements 10 in a lighting device 100 according to this embodiment. In the example shown in FIG. 13 , similar to the second embodiment, two fastening holes 36 are formed on the front surface, which is the first surface of the circuit board 30. Unlike the second embodiment, in the third embodiment, pressing positions 72 are provided in two locations. In FIG. 13 , the two pressing positions 72 are shown as virtual rectangles.

[0063] The plurality of light-emitting elements 10 are mounted between the two fastening holes 36 and the two pressing positions 72. An imaginary line segment connecting the pressing positions 72 and the outer peripheries of the two fastening holes 36 is indicated by a dashed line 73b. If the area surrounded by the dashed line 73b is defined as a warp reduction area in a plan view of the circuit board 30, all of the plurality of light-emitting elements 10 are disposed within the warp reduction area. While Fig. 13 shows an example in which each light-emitting element 10 is entirely located within the warp reduction area, the light-emitting elements 10 may be disposed such that a portion of the light-emitting element 10 is outside the warp reduction area, as long as at least the center of the light-emitting element 10 is located within the warp reduction area.

[0064] In the example shown in FIG. 13 , fastening members 50 are inserted into two fastening holes 36 and fastened. This fixes the circuit board 30 to the heat dissipation member 40. When the pressing members 71 abut against the two pressing positions 72, the circuit board 30 is pressed at at least four points in the direction of the heat dissipation member 40, in addition to the fastening by the fastening members 50. As a result, even if the circuit board 30 is thin and has low rigidity, the circuit board 30 is less likely to warp within the warpage reduction region even when the thermal conduction member 37 is sandwiched between the circuit board 30 and the heat dissipation member 40. This makes it easier to maintain a uniform thickness of the thermal conduction member 37, improving the heat dissipation performance of the lighting device 100. In the example shown in FIG. 13 , the region surrounded by two fastening holes 36 and two pressing positions 72 is defined as the warpage reduction region, but the number of fastening holes 36 and pressing positions 72 is not limited.

[0065] As described above, in the lighting device 100 of this embodiment, the area connecting the outer peripheries of the multiple fastening holes 36 and the pressing positions 72 is the warp reduction area, and the center of the light emitting element 10 is located within the warp reduction area. Therefore, the fastening members 50 and the pressing members 71, 81 can press down the vicinity of the light emitting element 10, making it difficult for the circuit board 30 to warp even if it is made thinner, and improving the heat dissipation performance of the lighting device 100.

[0066] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to FIG. 14. Description of content that overlaps with the first, second, and third embodiments will be omitted. FIG. 14 is a schematic plan view illustrating fastening holes 36, pressing positions 72, and mounting positions of light-emitting elements 10 in a lighting device 100 according to this embodiment. In the example shown in FIG. 14, two fastening holes 36 and one pressing position 72 are provided on the front surface, which is the first surface of a circuit board 30. In FIG. 14, one pressing position 72 is shown as a virtual rectangle.

[0067] The plurality of light-emitting elements 10 are mounted between the two fastening holes 36. Although some of the light-emitting elements 10 are located outside the warp reduction region surrounded by the dashed line 73b, the centers of the light-emitting elements 10 are located within the warp reduction region. Therefore, even when the heat conductive member 37 is sandwiched between the circuit board 30 and the heat dissipation member 40, the circuit board 30 is less likely to warp, and the heat conductive member 37 is more likely to maintain a uniform thickness, thereby improving the heat dissipation performance of the lighting device 100.

[0068] As described above, in the lighting device 100 of this embodiment, the area connecting the outer peripheries of the multiple fastening holes 36 and the pressing positions 72 is the warp reduction area, and the center of the light emitting element 10 is located within the warp reduction area. Therefore, the fastening members 50 and the pressing members 71, 81 can press down the vicinity of the light emitting element 10, making it difficult for the circuit board 30 to warp even if it is made thinner, and improving the heat dissipation performance of the lighting device 100.

[0069] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

[0070] This application claims priority based on Japanese Patent Application No. 2024-029236 filed on February 28, 2024 and Japanese Patent Application No. 2024-029237 filed on February 28, 2024. All contents of the above applications are incorporated herein by reference.

Claims

1. A lighting device comprising: a circuit board having a first surface on which a light-emitting element is mounted; a heat dissipation member arranged on a second surface of the circuit board; and a heat conduction member arranged between the circuit board and the heat dissipation member, wherein fastening holes for inserting fastening members are formed in the circuit board; within the plane of the first surface, a line connecting the center of the fastening hole and the center of the light-emitting element is defined as an imaginary line, a line perpendicular to the imaginary line is defined as an imaginary boundary line, a part of an area farther from the fastening hole than the imaginary boundary line is defined as a pressing area, and at least one pressing member abutting within the pressing area.

2. A lighting device according to claim 1, wherein the pressing area is within 50 mm from the center of the light-emitting element.

3. A lighting device according to claim 1 or claim 2, wherein the circuit board has through-hole wiring formed to penetrate from the first surface to the second surface, and the light-emitting element is mounted in a position overlapping the through-hole wiring in a plan view.

4. A lighting device according to claim 3, wherein the heat conduction member is arranged in a position overlapping the through-hole wiring in a plan view.

5. A lighting device according to any one of claims 1 to 4, wherein a plurality of combinations of the pressing area and the pressing member are provided.

6. A lighting device according to any one of claims 1 to 5, comprising a housing portion to which the circuit board is attached, and a light distribution adjustment portion that adjusts the light distribution pattern from the light-emitting element, and the pressing member is formed integrally with the housing portion or the light distribution adjustment portion.

7. A lighting device comprising: a circuit board having a light-emitting element mounted on a first surface; a heat dissipation member arranged on a second surface of said circuit board; a heat conduction member arranged between said circuit board and said heat dissipation member; and a pressing member abutting said first surface at a pressing position on said first surface, wherein said circuit board is formed with a plurality of fastening holes for inserting fastening members, and the center of said light-emitting element is located within a warpage reduction region connecting the outer peripheries of said plurality of fastening holes and said pressing position.

8. A lighting device according to claim 7, wherein the pressing position is within 50 mm from the center of any one of the light-emitting elements.

9. A lighting device according to claim 7 or claim 8, wherein the circuit board has through-hole wiring formed to penetrate from the first surface to the second surface, and the light-emitting element is mounted in a position overlapping the through-hole wiring in a plan view.

10. A lighting device according to claim 9, wherein the heat conduction member is arranged in a position overlapping the through-hole wiring in a plan view.

11. A lighting device according to any one of claims 7 to 10, comprising a plurality of said pressing members and said pressing positions.

12. A lighting device as claimed in any one of claims 7 to 11, comprising a housing portion to which the circuit board is attached, and a light distribution adjustment portion that adjusts the light distribution pattern from the light-emitting element, and the pressing member is formed integrally with the housing portion or the light distribution adjustment portion.

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