Vehicular lighting fixture and manufacturing method of vehicular lighting fixture

Abstract

To provide a vehicular lighting fixture capable of confirming that heat transfer from a base plate to a heat sink is performed correctly, and heat radiation performance of the heat sink is secured without needing an opening for radiation measurement or a sub-assembly process, and to provide a manufacturing method of the vehicular lighting fixture.SOLUTION: A vehicular lighting fixture 1 includes: a light source part having a light emitting body 21 and a base plate in which the light emitting body 21 is provided; a heat sink 10 in which the base plate is installed; a heat radiation grease 50 provided between the base plate and the heat sink 10 so as to overlap the light emitting body 21; and a reflector 30 and a lens 40 for projecting the light emitted by the light emitting body 21 outside a vehicle. The heat sink 10 includes a surface treatment part 111A on a surface opposite to the surface where the baseplate is installed, and the surface treatment part 111A is formed so as to overlap part of an outer peripheral line 50L of the heat radiation grease 50.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle lamp and a method for manufacturing a vehicle lamp. [Background technology]

[0002] A known vehicle lamp has an opening for measuring the radiant heat of a substrate supporting an LED, which is provided in a heat sink for dissipating heat from the LED (see, for example, Patent Document 1). Patent Document 1 describes that in the assembly process of a vehicle lamp, the radiant heat of the substrate is measured through the opening using a radiation thermometer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7036626 Summary of the Invention [Problem to be solved by the invention]

[0004] When thermal grease is placed between the substrate supporting the light-emitting element and the heat sink to improve heat dissipation from the substrate to the heat sink, if a foreign object is sandwiched between the substrate and the heat sink, the thickness of the thermal grease will be greater than the designed value and the area of the thermal grease will be smaller than the designed value. If the thickness or area of the thermal grease is not as designed, it may not be possible to ensure heat dissipation from the substrate to the heat sink. Therefore, it is necessary to perform radiation measurements of the substrate or heat sink after assembling the substrate and heat sink with the thermal grease in between to confirm that heat dissipation from the substrate to the heat sink is ensured.

[0005] Here, in order to measure the radiation of the substrate, it is necessary to provide an opening for radiation measurement in the heat sink as described in Patent Document 1, or to perform radiation measurement by providing a subassembly process in which the substrate and heat sink are assembled with thermal grease in between before the assembly process in which lenses, reflectors, etc. are assembled.

[0006] In view of the above circumstances, an object of the present invention is to provide a vehicular lamp that can confirm that heat is being transferred correctly from a substrate to a heat sink and that the heat dissipation properties of the heat sink are ensured, without requiring an opening or subassembly process for radiation measurement, and a method for manufacturing the vehicular lamp. [Means for solving the problem]

[0007] The vehicle lamp of the present invention comprises a light source unit having an illuminant and a substrate on which the illuminant is provided, a heat sink on which the substrate is mounted, thermal grease provided between the substrate and the heat sink so as to overlap the illuminant, and an optical system that projects the light emitted by the illuminant outside the vehicle, wherein the heat sink has a different surface portion on the surface behind the surface on which the substrate is mounted, the different surface portion having a surface condition different from the surrounding area, and the different surface portion is formed so as to overlap with part of the outer periphery of the thermal grease.

[0008] The method for manufacturing a vehicle lamp according to the present invention is a method for manufacturing a vehicle lamp comprising: a light source unit having an illuminant and a substrate on which the illuminant is provided; a heat sink on which the substrate is mounted; thermal grease provided between the substrate and the heat sink so as to overlap the illuminant; and an optical system that projects the light emitted by the illuminant outside the vehicle, wherein a different surface portion having a surface condition different from that of its surroundings is formed on the surface of the heat sink behind the surface on which the substrate is mounted so as to overlap with part of the outer periphery of the thermal grease, and an assembly process is carried out in which the light source unit, the heat sink, and the optical system are assembled with the thermal grease provided between the light source unit and the heat sink, and after the assembly process is carried out, the different surface portion is subjected to radiation measurement. [Effects of the Invention]

[0009] According to the present invention, it is possible to confirm that heat transfer is occurring correctly and that the heat dissipation properties of the heat sink are ensured, without requiring an opening or subassembly process for radiation measurement. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is an exploded perspective view showing a vehicle lamp according to one embodiment of the present invention. [Figure 2] FIG. 2 is a bottom view showing the vehicle lamp of FIG. [Figure 3] FIG. 3 is an enlarged bottom view of part A in FIG. [Figure 4] FIG. 4 is a graph and a cross-sectional view illustrating the difference in radiation temperature between a sample with normal heat dissipation characteristics and a sample with abnormal heat dissipation characteristics. [Figure 5] FIG. 5 is a process diagram for explaining the manufacturing process of the vehicle lamp shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below and can be modified as appropriate without departing from the spirit of the present invention. In addition, in the embodiments shown below, some components are omitted from illustration and description, but for the details of the omitted technologies, publicly known or well-known technologies are applied as appropriate within the scope of the content described below.

[0012] FIG. 1 is an exploded perspective view showing a vehicle lamp 1 according to one embodiment of the present invention. The vehicle lamp 1 shown in this figure is a low beam headlamp that projects a low beam light distribution pattern ahead of the vehicle. The vehicle lamp 1 is housed in a headlight housing (not shown) together with a high beam headlamp (not shown). Note that while a low beam headlamp will be described as one embodiment of the present invention, other vehicle lamps such as a high beam headlamp may also be used as one embodiment of the present invention.

[0013] 1, the vehicle lamp 1 includes a heat sink 10, a light source unit 20, a reflector 30, a lens 40, and thermal grease 50. The vehicle lamp 1 is attached to a headlight housing as an assembly in which the heat sink 10, the light source unit 20, the reflector 30, and the lens 40 are assembled.

[0014] The heat sink 10 is an aluminum pressed product and includes a base portion 11 to which the light source portion 20, the reflector 30, and the lens 40 are attached, a plurality of bracket portions 12, 13, and 14 for attaching the vehicle lamp 1 to a headlight housing, and a heat sink 15. The base portion 11 includes a first base portion 111 which is a plate-shaped portion on the rear side of the base portion 11, and a second base portion 112 which is a plate-shaped portion on the front side of the base portion 11. A step portion is formed at the boundary between the first base portion 111 and the second base portion 112.

[0015] The light source unit 20, reflector 30, and lens 40 are attached to the first base unit 111. The light source unit 20 is attached to one surface (hereinafter referred to as the board mounting surface) of the first base unit 111 via thermal grease 50, and the reflector 30 is attached to the board mounting surface of the first base unit 111 with a flange portion 40A (see FIG. 2) of the lens 40 sandwiched between them.

[0016] The reflector 30 and the lens 40 are attached to the second base portion 112. The reflector 30 is attached to the board mounting surface of the second base portion 112 with the flange portion 40B of the lens 40 sandwiched between them.

[0017] The bracket portion 12 is provided at the end of the first base portion 111 on the right side of the vehicle, the bracket portion 13 is provided at the end of the first base portion 111 on the left side of the vehicle, and the bracket portion 14 is provided at the end of the first base portion 111 on the rear side of the vehicle. The heat sink 15 is provided at the end of the first base portion 111 on the rear side of the vehicle. The heat sink 15 functions as a heat sink that dissipates heat generated by the light source portion 20. The bracket portions 12, 13, and 14 function as heat sinks that dissipate heat generated by the light source portion 20, in addition to functioning as members for attaching the vehicle lamp 1 to the headlight housing.

[0018] The light source unit 20 includes a plurality of light emitters 21 and a metal substrate 22 on which the plurality of light emitters 21 are mounted. The light emitters 21 are light emitting diodes (LEDs) or the like, and emit light toward the upper part of the vehicle, generating heat as the light is emitted. The substrate 22 is attached to a substrate installation surface of the first base unit 111.

[0019] The reflector 30 has a reflective surface arranged to cover the light source unit 20, and the reflective surface reflects the light emitted from the light emitter 21 toward the front of the vehicle. The reflective surface is formed by aluminum deposition, high-reflection coating, etc. The reflective surface is formed in a three-dimensional free-form surface shape based on an ellipse or a combination of an ellipse and a parabola.

[0020] The lens 40 is disposed on the vehicle front side of the reflector 30, and projects light reflected by the reflective surface of the reflector 30 toward the vehicle front side. The lens 40 is attached to the first base portion 111 of the heat sink 10 while being sandwiched between the reflector 30 and the heat sink 10.

[0021] Here, thermal grease 50 is interposed between the rear surface of the substrate 22 and the substrate installation surface of the first base portion 111. A plurality of light emitters 21 are mounted on the surface of the substrate 22, and a thermal grease 50 is provided for each light emitter 21.

[0022] Fig. 2 is a bottom view showing the vehicle lamp 1 of Fig. 1. As shown in this figure, a pair of positioning holes H1 are formed in the first base portion 111 of the heat sink 10, and a positioning pin P1 formed on the reflector 30 is fitted into each of the positioning holes H1. This positions the reflector 30 with respect to the first base portion 111 of the heat sink 10.

[0023] Furthermore, positioning holes H2 (see FIG. 1) are formed in the flange portions 40A and 40B of the lens 40, and positioning pins P2 formed on the reflector 30 are fitted into the positioning holes H2. This positions the reflector 30 relative to the lens 40.

[0024] A pair of positioning holes H3 are formed in the first base portion 111, and positioning pins P3 formed on the back surface of the substrate 22 are fitted into the positioning holes H3. This positions the substrate 22 relative to the first base portion 111.

[0025] Here, the surface of the heat sink 10 is not anodized, but is made of an aluminum base. However, the other surface of the first base portion 111 (hereinafter, the backside of the substrate mounting surface) is subjected to surface treatment to form a surface treatment portion 111A whose surface condition is different from that of the surrounding aluminum base.

[0026] In contrast, on the board mounting surface of the first base portion 111 of the heat sink 10, the thermal grease 50 spreads radially from the light emitter 21. The surface treatment portion 111A is arranged so as to overlap a part of the outer periphery 50L of the thermal grease 50 on the back side. Note that the surface treatment portion 111A is provided corresponding to any one of the multiple thermal grease portions 50, but may be provided corresponding to two or more thermal grease portions 50.

[0027] Fig. 3 is an enlarged bottom view of portion A in Fig. 2. As shown in this figure, surface treatment portion 111A is formed in a circular shape on the backside of the substrate mounting surface of first base portion 111, and is disposed so that the center of surface treatment portion 111A overlaps with part of outer periphery 50L of thermal grease 50. Here, when the application position and application area of thermal grease 50 are as designed, part of outer periphery 50L of thermal grease 50 overlaps with the center of surface treatment portion 111A.

[0028] The diameter of the thermal grease 50 is 10 to 15 mm. In this embodiment, the diameter of the thermal grease 50 is approximately 11 mm. In contrast, the diameter of the surface treatment portion 111A is smaller than the diameter of the thermal grease 50, being 2 to 5 mm. In this embodiment, the diameter of the surface treatment portion 111A is approximately 3 mm. The surface treatment portion 111A may be formed in a rectangular or polygonal shape.

[0029] The surface-treated portion 111A has been roughened and carbonized by the surface treatment, and has larger irregularities and a darker black color than the surrounding aluminum base. The emissivity of the aluminum base is low and unsuitable for radiation measurement with a radiation thermometer due to the small surface roughness and low density of the black color. In contrast, the emissivity of the surface-treated portion 111A is high enough to be suitable for radiation measurement with a radiation thermometer because the surface roughness and density of the black color have been increased by the surface treatment.

[0030] Examples of surface treatments for forming the surface-treated portion 111A on the backside of the substrate mounting surface of the first base portion 111 include laser irradiation, chemical conversion treatment, and roughening plating. In this embodiment, the surface-treated portion 111A is formed by laser irradiation. Alternatively, a black or gray resin sheet may be provided instead of the surface-treated portion 111A. In this case, the resin sheet may be adhered to the backside of the substrate mounting surface of the first base portion 111.

[0031] 4 is a graph and cross-sectional view illustrating the difference in radiation temperature between a sample with normal heat dissipation characteristics and a sample with abnormal heat dissipation characteristics. The middle section of FIG. 4 shows a sample with normal heat dissipation characteristics, and the bottom section of FIG. 4 shows a sample with abnormal heat dissipation characteristics. In the sample with abnormal heat dissipation characteristics, the thickness of the thermal grease 50 is greater than the design value and the area of the thermal grease 50 is smaller than the design value due to foreign matter such as hair or dust being caught between the first base portion 111 and the substrate 22. In contrast, in the sample with normal heat dissipation characteristics, the thickness and area of the thermal grease 50 are equivalent to the design values.

[0032] As shown in the middle and bottom rows of FIG. 4, heat from the light emitter 21 is transferred to the surface treatment portion 111A via the thermal grease 50. In samples with abnormal heat dissipation characteristics, the thickness of the thermal grease 50 is greater than the design value, causing heat to accumulate in the thermal grease 50. This reduces the heat transfer to the surface treatment portion 111A compared to samples with normal heat dissipation characteristics, resulting in a lower radiation temperature from the surface treatment portion 111A. Furthermore, in samples with abnormal heat dissipation characteristics, it is possible that foreign matter has entered between the first base portion 111 and the substrate 22, reducing the adhesion between the first base portion 111 and the substrate 22, or that the thermal grease 50 spreads less smoothly, reducing the contact area between the first base portion 111 and the substrate 22.

[0033] 4 shows a graph illustrating the relationship between the difference in radiation temperature ΔT (°C) between a sample with normal heat dissipation characteristics and a sample with abnormal heat dissipation characteristics (hereinafter referred to as the temperature difference) and the horizontal distance (mm) from the center of the light emitter 21 to the measurement point (hereinafter referred to as the measurement distance). The threshold temperature shown in this graph is a threshold for determining whether the temperature difference ΔT is correct or not.

[0034] As shown in this graph, the temperature difference ΔT varies depending on the measurement distance. Specifically, when the measurement distance is less than 3 mm or more than 8 mm, the temperature difference ΔT is less than the threshold temperature, resulting in an incorrect value. On the other hand, when the measurement distance is 3 mm or more and 8 mm or less, the temperature difference ΔT is greater than the threshold temperature, resulting in a correct value.

[0035] That is, when the measurement distance is set to less than 3 mm or more than 8 mm, samples with abnormal heat dissipation characteristics are erroneously determined to have normal heat dissipation characteristics. On the other hand, when the measurement distance is set to 3 mm or more and 8 mm or less, samples with abnormal heat dissipation characteristics are correctly determined to have abnormal heat dissipation characteristics.

[0036] Therefore, in this embodiment, in order to set the measurement distance within a range where the temperature difference ΔT is equal to or greater than the threshold temperature (the settable range indicated by the arrow in the graph), the position of the surface treatment part 111A is set so that the center of the surface treatment part 111A overlaps with the center of the settable range. In this embodiment, the relative positions of the surface treatment part 111A and the thermal grease 50 are set so that the center of the surface treatment part 111A overlaps with a part of the outer periphery 50L of the thermal grease 50.

[0037] 1 and 2. First, a process for producing the heat sink 10, the light source unit 20, the reflector 30, and the lens 40 is carried out (step S1). In this process, the heat sink 10 is produced by pressing aluminum, and then a surface treatment portion 111A is formed on the rear surface of the first base portion 111 of the heat sink 10 opposite to the substrate mounting surface by surface treatment processing such as laser irradiation.

[0038] Next, a process (assembly process) of assembling the heat sink 10, the light source unit 20, the reflector 30, and the lens 40 is performed (step S2). In this process, the thermal grease 50 is applied between the board mounting surface of the first base unit 111 of the heat sink 10 and the back surface of the board 22 of the light source unit 20 to the designed thickness and area.

[0039] Next, a step (radiation measurement step) of measuring the radiation temperature from the first base portion 111 of the heat sink 10 with a radiation thermometer is performed (step S3). In this step, the radiation temperature from the surface treatment portion 111A formed on the back side of the substrate mounting surface of the first base portion 111 is measured with the radiation thermometer.

[0040] Next, it is determined whether the measurement value of the radiation thermometer is equal to or greater than a threshold value (step S4). If the measurement value of the radiation thermometer is equal to or greater than the threshold value (YES in step S4), it is determined that the heat dissipation characteristics of the vehicle lamp 1 are normal (step S5). On the other hand, if the measurement value of the radiation thermometer is less than the threshold value (NO in step S4), it is determined that the heat dissipation characteristics of the vehicle lamp 1 are abnormal (step S6).

[0041] As described above, in the vehicle lamp 1 according to this embodiment, the surface treatment portion 111A, which has a different surface condition from the surrounding area, is formed on the surface of the heat sink 10 behind the surface on which the substrate 22 of the light source unit 20 is installed, so as to overlap with part of the outer circumferential line 50L of the thermal grease 50. This allows the radiation temperature from the surface treatment portion 111A to be measured with a radiation thermometer, and based on the measurement value, it can be confirmed that heat is being transferred correctly from the substrate 22 to the heat sink 10 and that the heat dissipation properties of the heat sink 10 are ensured. Therefore, the success or failure of the heat dissipation characteristics of the vehicle lamp 1 can be determined without providing an opening for radiation measurement in the heat sink 10 to measure the radiation of the substrate 22 or without providing a subassembly process for assembling the substrate 22 and the heat sink 10 to measure the radiation of the substrate 22.

[0042] Furthermore, in the vehicle lamp 1 according to this embodiment, the area around the surface-treated portion 111A on the surface of the heat sink 10 on which the surface-treated portion 111A is formed is made of aluminum, whereas the surface-treated portion 111A serves as a heat-dissipating surface with a higher emissivity than the aluminum base. In particular, the surface-treated portion 111A has a high emissivity because it is black or gray. This makes it possible to measure the radiation temperature from the surface-treated portion 111A with a radiation thermometer even when the surface of the aluminum heat sink 10 is made of a base that has not been anodized.

[0043] Furthermore, the surface-treated portion 111A has been roughened and carbonized, resulting in a larger unevenness and a darker black color than the surrounding aluminum base, which makes it possible to increase the emissivity of the surface-treated portion 111A to a level that allows radiation measurement using a radiation thermometer.

[0044] Furthermore, the vehicle lamp 1 according to this embodiment is configured as an assembly including the heat sink 10, the light source unit 20, the reflector 30, the lens 40, and the thermal grease 50, and the success or failure of the heat dissipation characteristics can be determined by radiation measurement after the assembly process. This eliminates the need for a sub-assembly consisting of the heat sink 10, the light source unit 20, and the thermal grease 50, thereby reducing the manufacturing cost of the vehicle lamp 1.

[0045] Furthermore, in the manufacturing method for the vehicle lamp 1 according to this embodiment, a surface treatment portion 111A, which has a different surface condition from the surrounding area, is formed on the surface of the heat sink 10 behind the surface on which the substrate 22 is installed, so as to overlap with part of the outer circumferential line 50L of the thermal grease 50. Then, an assembly process is performed in which the light source unit 20, the heat sink 10, the reflector 30, and the lens 40 are assembled with the thermal grease 50 interposed between the substrate 22 of the light source unit 20 and the heat sink 10. Thereafter, radiation measurement is performed on the surface treatment portion 111A. This makes it possible to determine whether the heat dissipation characteristics of the vehicle lamp 1 are correct or not without providing an opening for radiation measurement in the heat sink 10 to measure the radiation of the substrate 22 or without providing a sub-assembly process in which the substrate 22 and the heat sink 10 are assembled to measure the radiation of the substrate 22.

[0046] Although the present invention has been described above based on the above-mentioned embodiments, the present invention is not limited to the above-mentioned embodiments, and modifications may be made without departing from the spirit of the present invention, and techniques from the embodiments or well-known or publicly known techniques may be combined.

[0047] For example, in the above embodiment, the surface of the heat sink 10 is made of aluminum and the measurement points for radiation measurement are surface-treated, but this is not essential. For example, the surface of the heat sink 10 may be anodized to form an oxide film, and the measurement points for radiation measurement may be colored black or gray.

[0048] Furthermore, in the above embodiment, the optical system is composed of a reflector 30 and a lens 40, but instead of the reflector 30, a lens such as a primary lens may be provided so that light from the light emitter 21 passes through. [Explanation of symbols]

[0049] 1: Vehicle lighting fixtures 10: Heat sink 20: Light source section 21: Light-emitting body 22: Substrate 30: Reflector (optical system) 40: Lens (optical system) 50: Thermal grease 50L: Outer line 111A: Surface treatment part (different surface part)

Claims

1. a light source unit including a light emitter and a substrate on which the light emitter is provided; a heat sink on which the substrate is placed; a thermal grease provided between the substrate and the heat sink so as to overlap the light emitter; an optical system that projects light emitted by the light emitter outside the vehicle; Equipped with the heat sink has a surface opposite to the surface on which the substrate is placed, the surface having a different surface condition from the surrounding area; The different surface portion is formed so as to overlap a part of the outer periphery of the thermal grease. Vehicle lighting fixtures.

2. The periphery of the different surface portion is an aluminum base material, The different surface portion has a higher emissivity than the aluminum base material.

2. A vehicle lamp according to claim 1.

3. The different surface portion is black or gray.

3. A vehicle lamp according to claim 2.

4. The different surface portion is subjected to a roughening treatment and a carbonization treatment.

4. A vehicle lamp according to claim 2 or 3.

5. an assembly including the light source unit, the heat sink, the thermal grease, and the optical system; 3. A vehicle lamp according to claim 1 or 2.

6. a light source unit including a light emitter and a substrate on which the light emitter is provided; a heat sink on which the substrate is placed; a thermal grease provided between the substrate and the heat sink so as to overlap the light emitter; an optical system that projects light emitted by the light emitter outside the vehicle; A method for manufacturing a vehicle lamp comprising: A surface of the heat sink that is different from the surrounding surface is formed on the back side of the surface on which the substrate is placed, so as to overlap a part of the outer periphery of the thermal grease. performing an assembly process of assembling the light source unit, the heat sink, and the optical system in a state where the thermal grease is provided between the light source unit and the heat sink; After the assembly step is performed, the different surface portion is subjected to radiation measurement. A method for manufacturing a vehicle lamp.

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