Vehicle headlights

Abstract

In a vehicle headlamp, a projection lens formed of acrylic resin and a lens holder formed of polycarbonate are joined by laser welding. The projection lens is formed to be transparent and has a joining surface. The lens holder is formed to be transparent and has a welding surface for joining the joining surface. Laser light with a wavelength of 1550nm to 1640nm that can pass through the projection lens is irradiated on the welding surface, thereby joining the projection lens and the lens holder to each other.

Description

Technical Field

[0001] The present invention relates to the technical field of a vehicle headlamp in which a projection lens and a lens holder are joined by laser welding. Background Art

[0002] Among vehicle headlamps, there is a so-called projector type in which a lamp unit is arranged inside a lamp housing composed of a lamp case and a cover, and the lamp unit has a projection lens and a lens holder.

[0003] Among such vehicle headlamps, there are vehicle headlamps in which a projection lens and a lens holder are joined by laser welding (for example, see Patent Document 1). Laser welding has the advantages of being able to obtain high joining strength in a small joining range and being able to suppress manufacturing costs by not requiring consumables such as adhesives and screws, and therefore is widely used as a method for joining a projection lens and a lens holder.

[0004] In order to transmit the light emitted from the light source, the projection lens is made transparent. In order to ensure the light distribution performance, the projection lens is often formed of acrylic resin that is easy to form into a thick-walled shape, and has a hemispherical light control part that controls the incident light and a flange part that extends outward from the light control part. On the other hand, in order to ensure high heat resistance, the lens holder that holds the projection lens is often made of polycarbonate and contains black pigment, which absorbs heat when the laser is irradiated to the lens holder during laser welding.

[0005] When the projection lens and the lens holder are joined by laser welding, the laser is irradiated to the welding surface of the lens holder through the flange of the projection lens, and the black pigment reacts to the laser, and the portion of the lens holder irradiated with the laser generates heat and melts. When the laser is irradiated to the welding surface, the heat generated in the lens holder is transferred to the flange of the projection lens, a part of the flange melts, and the molten portion of the lens holder and the molten portion of the projection lens are welded, thereby joining.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2013-89483

[0009] Technical problem to be solved by the invention

[0010] However, although the projection lens and the lens holder are joined by laser welding, a high joining strength between the two can be ensured, the lens holder is formed black because it contains black pigment, and there is a possibility that it will react with sunlight that may enter the vehicle headlamp. Therefore, when sunlight enters the interior of the vehicle headlamp, the lens holder may accidentally melt depending on the amount of light that enters.

[0011] In addition, in a vehicle headlamp, in order to improve visibility, it is desirable that the lens holder is also formed transparent like the projection lens. Summary of the invention

[0012] Therefore, an object of the vehicle headlamp of the present invention is to prevent the lens holder from melting while ensuring high bonding strength between the projection lens and the lens holder, thereby improving visibility.

[0013] Technical means for solving technical problems

[0014] First, the vehicle headlamp involved in the present invention joins a projection lens formed of acrylic resin and a lens holder formed of polycarbonate by laser welding. The projection lens is formed to be transparent and has a joining surface, and the lens holder is formed to be transparent and has a welding surface for joining the joining surface. Laser light with a wavelength of 1550nm to 1640nm that can pass through the projection lens is irradiated on the welding surface, thereby joining the projection lens and the lens holder.

[0015] Thus, laser light having a wavelength of 1550 nm to 1640 nm that can pass through the transparent projection lens is irradiated onto the welded surface of the transparent lens holder, whereby the projection lens and the lens holder are bonded to each other.

[0016] Secondly, in the above-mentioned vehicle headlamp according to the present invention, it is preferable that a condenser lens is arranged on an optical path of the laser light.

[0017] Thus, the laser can pass through the projection lens in a focused state through the focusing lens, so the energy density of the light on the incident surface of the projection lens becomes low, making it difficult to generate heat, and the energy density of the light on the welding surface of the lens holder becomes high, making it easy to generate heat.

[0018] Thirdly, in the vehicle headlamp according to the present invention described above, it is preferable that a filter formed of acrylic resin is arranged on an optical path of the laser light.

[0019] Thus, the wavelength component of the laser light absorbed by the projection lens is absorbed by the filter before passing through the projection lens.

[0020] Fourth, another vehicle headlamp involved in the present invention joins a projection lens formed of acrylic resin and a lens holder formed of polycarbonate by laser welding, the projection lens is formed to be transparent and has a welding surface, the lens holder is formed to be transparent and has a joining surface for joining the welding surface, and a laser with a wavelength of 1850nm to 1960nm that can pass through the lens holder is irradiated on the welding surface, thereby joining the projection lens and the lens holder.

[0021] Thus, laser light having a wavelength of 1850 nm to 1960 nm that can pass through the transparent lens holder is irradiated onto the welded surface of the transparent projection lens, whereby the projection lens and the lens holder are bonded to each other.

[0022] Fifthly, in the above-mentioned vehicle headlamp according to another aspect of the present invention, it is preferable that a condenser lens is disposed on an optical path of the laser light.

[0023] Thus, the laser can pass through the lens holder in a focused state through the focusing lens, so the energy density of the light on the incident surface of the lens holder becomes low, making it difficult to generate heat, and the energy density of the light on the welding surface of the projection lens becomes high, making it easy to generate heat.

[0024] Sixthly, in the above-mentioned vehicle headlamp according to another aspect of the present invention, it is preferable that a filter made of polycarbonate is disposed on an optical path of the laser light.

[0025] Thus, the wavelength component of the laser light absorbed by the lens holder is absorbed by the filter before passing through the lens holder.

[0026] Effects of the Invention

[0027] According to the present invention, a laser of a specified wavelength that can pass through a projection lens or a lens holder formed to be transparent is irradiated onto the welding surface of a lens holder or a projection lens formed to be transparent, whereby the projection lens and the lens holder are joined together. Therefore, while ensuring a high joining strength between the projection lens and the lens holder, the lens holder can be prevented from melting and visibility can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 and Figures 2 to 9 The present figure is a cross-sectional view showing an embodiment of a vehicle headlamp according to the present invention.

[0029] Figure 2 A diagram showing a projection lens and a lens holder.

[0030] Figure 3 This is a graph showing the spectral transmittance of acrylic resin.

[0031] Figure 4 This is a graph showing the spectral transmittance of polycarbonate.

[0032] Figure 5 This is a diagram showing an example in which a condenser lens and a filter are arranged on the optical path of a laser beam.

[0033] Figure 6 and Figures 7 to 9 This figure shows another structure of the joint portion between the projection lens and the lens holder. The figure shows the projection lens and the lens holder.

[0034] Figure 7 This is a diagram showing an example in which a condenser lens and a filter are arranged on the optical path of a laser beam.

[0035] Figure 8 This is a diagram showing an example of a structure in which a holding portion covers the outer peripheral surface of a filter from the outer peripheral side.

[0036] Fig. 9 This is a diagram showing an example of a structure in which a holding portion covers the front surface of a filter from the front side. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of a vehicle headlamp according to the present invention will be described with reference to the drawings.

[0038] <Structure of vehicle headlight>

[0039] First, the structure of the vehicle headlamp 1 will be described (see Figure 1 ).

[0040] The vehicle headlamp 1 is disposed so as to be mounted on both left and right end portions of the front end portion of a vehicle body.

[0041] The vehicle headlamp 1 includes a lamp housing 2 having an opening at a front end and a cover 3 closing the opening of the lamp housing 2. The lamp housing 2 and the cover 3 form a lamp case 4, and a space inside the lamp case 4 forms a lamp chamber 4a.

[0042] The lamp unit 5 is disposed in the lamp chamber 4 a. The lamp unit 5 includes a bracket 6 , a placement base 7 , a substrate 8 , a light source 9 , a reflector 10 , a lens holder 11 , and a projection lens 12 .

[0043] The bracket 6 is formed in a plate-like ring shape extending in the front-rear direction and has a through hole 6 a.

[0044] The arrangement base 7 is formed of a metal material having high heat dissipation properties and is attached to a lower end portion of the rear surface of the bracket 6. The arrangement base 7 functions as a heat dissipation member and also functions as a light source arrangement portion where the light source is arranged.

[0045] The substrate 8 is disposed on the upper surface of the arrangement base 7 and has a predetermined circuit pattern (not shown). The substrate 8 is connected to a power supply circuit (not shown).

[0046] The light source 9 is mounted on the upper surface of the substrate 8 and has an emission surface for emitting light upward. For example, a light emitting diode (LED) is used as the light source 9. A driving current is supplied to the light source 9 from a power supply circuit through the substrate 8.

[0047] The lower end of the reflector 10 is attached to the upper surface of the rear end of the arrangement base 7, and the inner surface of the reflector 10 is formed as a reflection surface 10a. The reflector 10 has a function of reflecting light emitted from the light source 9 toward the front at the reflection surface 10a.

[0048] The lens holder 11 is made of transparent polycarbonate, and the rear end portion is mounted on the front surface of the bracket 6. The lens holder 11 has a substantially cylindrical holding portion 13 whose axial direction is set in the front-rear direction and a flange-shaped mounted portion 14 extending outward from the rear end portion of the holding portion 13, and the mounted portion 14 is mounted on the bracket 6. The space inside the lens holder 11 is formed as a light passing space 11a.

[0049] The front surface of the holding portion 13 is formed as a welding surface 13 a.

[0050] The projection lens 12 is made of transparent acrylic resin and is composed of a light control portion 15 formed in a substantially hemispherical shape convex toward the front and a flange portion 16 extending outward from the rear end of the light control portion 15. The rear surface of the flange portion 16 is formed as a bonding surface 16a, and the front surface is formed as an incident surface 16b. The projection lens 12 and the lens holder 11 are joined by laser welding.

[0051] In the vehicle headlamp 1 constructed as described above, when light is emitted from the light source 9, the emitted light is reflected by the reflecting surface 10a of the reflector 10, passes through the through hole 6a of the bracket 6 and the light passing space 11a of the lens holder 11, and is incident on the light control unit 15 of the projection lens 12. The light control unit 15 turns the light into parallel light, and the light passes through the cover 3 and is irradiated forward.

[0052] <Joining of projection lens and lens holder>

[0053] Next, the bonding of the projection lens 12 and the lens holder 11 will be described (see Figures 2 to 4 ).

[0054] The projection lens 12 and the lens holder 11 are joined together by welding the joining surface 16a and the welding surface 13a by laser welding (see Figure 2). Laser welding is performed as follows: a laser beam of a predetermined wavelength is emitted toward the incident surface 16b of the flange portion 16 formed on the projection lens 12, and the laser beam is incident from the incident surface 16b, passes through the flange portion 16, and is irradiated to the welding surface 13a of the lens holder 11. At this time, the laser beam is irradiated to the welding surface 13a, for example, from the P direction orthogonal to the welding surface 13a. When the laser beam is irradiated to the welding surface 13a, the portion of the holder 13 including the welding surface 13a generates heat and is melted, and the generated heat is transferred to the portion of the flange portion 16 including the bonding surface 16a to melt the portion, and the two melted portions are welded.

[0055] The wavelength of the laser is set in the range of 1550nm to 1640nm. Figure 3 and Figure 4 The graph of FIG. 1 illustrates laser light having a wavelength in this range. In the following, a wavelength in the range of 1550 nm to 1640 nm is described as wavelength A.

[0056] Figure 3 : is a graph showing the spectral transmittance of acrylic resin, which is the material of the projection lens 12, and is data on acrylic resin with a thickness of 3 mm as an example. Figure 3 In the figure, the horizontal axis is wavelength and the vertical axis is transmittance. Figure 3 As shown in A1, the laser light of wavelength A has a high transmittance of 60% or more to acrylic resin.

[0057] Figure 4 : is a graph showing the spectral transmittance of polycarbonate, which is the material of the lens holder 11, and is data on polycarbonate having a thickness of 3 mm as an example. Figure 4 In the figure, the horizontal axis is wavelength and the vertical axis is transmittance. Figure 4 As shown in A2, the transmittance of the laser light with wavelength A is extremely small at about 10% or less near 1600 nm, and is low for polycarbonate.

[0058] Such a laser beam of wavelength A has high transmittance to acrylic resin and low transmittance to polycarbonate. Therefore, when the laser beam of wavelength A is emitted toward the incident surface 16b of the projection lens 12, a high transmittance of the laser beam to the projection lens 12 is ensured, and a high absorptivity of the laser beam to the lens holder 11 is ensured, and a sufficient amount of laser beam is irradiated to the welding surface 13a, generating a sufficient amount of heat on the welding surface 13a, thereby ensuring a good melting state on the welding surface 13a and the joint surface 16a.

[0059] Furthermore, when laser welding is performed using laser light of wavelength A in the range of 1550 nm to 1640 nm, depending on the laser irradiation device, a small amount of light having a wavelength exceeding 1640 nm may be contained in the laser light of wavelength A. When such light having a wavelength exceeding 1640 nm is irradiated, when the laser light enters the flange portion 16 from the incident surface 16 b, a part of the laser light is absorbed by the flange portion 16 formed of acrylic resin, and the incident surface 16 b may be deformed due to heat generation.

[0060] Here, a focusing lens 17 (see Figure 5 ). By arranging the condenser lens 17 on the optical path of the laser light, the laser light is condensed by the condenser lens 17 and irradiated in a state of being focused on the welding surface 13a.

[0061] At this time, the laser light can be transmitted through the flange portion 16 of the projection lens 12 in a condensed state by the condensing lens 17, so that the energy density of the light becomes low on the incident surface 16b, and it is difficult to generate heat, and the energy density of the light becomes high on the welding surface 13a, and it becomes easy to generate heat. Therefore, it is possible to prevent the incident surface 16b from being deformed due to heat, and it is possible to ensure a high bonding strength between the projection lens 12 and the lens holder 11.

[0062] Alternatively, a filter 18 made of acrylic resin, which is the same material as the projection lens 12, may be disposed on the optical path of the laser beam (see Figure 5 ). By arranging the filter 18 on the optical path of the laser light, the laser light can pass through the filter 18.

[0063] At this time, the wavelength component of the laser light absorbed by the flange 16 is absorbed by the filter 18 before passing through the flange 16 . Therefore, the light of the wavelength component does not enter the flange 16 , and deformation of the incident surface 16 b due to heat can be prevented.

[0064] Furthermore, by using the condenser lens 17 and the filter 18 in combination, it is possible to obtain a greater effect of preventing deformation of the incident surface 16 b due to heat, and to ensure a high bonding strength between the projection lens 12 and the lens holder 11 .

[0065] In addition, the filter 18 is formed of acrylic resin, which is the same material as the projection lens 12. Due to the heat generated by light with a wavelength exceeding 1640nm, the filter 18 may be deformed. Therefore, when the filter 18 is deformed and the function of the filter 18 is reduced, it is preferable to replace the filter 18 with a new filter 18.

[0066] Summary

[0067] As described above, in the vehicle headlamp 1 , the laser beam having a wavelength A of 1550 nm to 1640 nm that can pass through the projection lens 12 is irradiated onto the weld surface 13 a , thereby bonding the transparent projection lens 12 made of acrylic resin and the transparent lens holder 11 made of polycarbonate.

[0068] Therefore, the laser beam of wavelength A that can pass through the transparent projection lens 12 is irradiated to the welded surface 13a of the transparent lens holder 11, thereby bonding the projection lens 12 to the lens holder 11. As a result, the lens holder 11 is transparent, has a good appearance, and is less likely to be melted by sunlight, so that the high bonding strength between the projection lens 12 and the lens holder 11 can be ensured, and the lens holder 11 can be prevented from melting, and visibility can be improved.

[0069] <Another Structure of Projection Lens and Lens Holder>

[0070] Next, another structure of the joint portion between the projection lens and the lens holder will be described (see Figure 6 ).

[0071] The lens holder 11A involved in another structure is formed of polycarbonate and is transparent, and the projection lens 12A involved in another structure is formed of acrylic resin and is transparent. The upper end portion of the outer peripheral surface of the holding portion 13 of the lens holder 11A is formed as an incident surface 13b. The lens holder 11A is formed with a bonding surface 13c instead of the welding surface 13a, and the projection lens 12A is formed with a welding surface 16c instead of the bonding surface 16a. The bonding surface 13c and the welding surface 16c are inclined with respect to the front-back direction and are positioned opposite to each other.

[0072] The projection lens 12A and the lens holder 11A are joined by welding the welding surface 16c and the joining surface 13c by laser welding. The laser welding is performed by emitting a laser beam of a predetermined wavelength toward the incident surface 13b of the holder 13 formed on the lens holder 11A, and irradiating the laser beam to the welding surface 16c of the projection lens 12A through the holder 13. At this time, the laser beam is irradiated to the welding surface 16c from, for example, the P direction orthogonal to the welding surface 16c. When the laser beam is irradiated to the welding surface 16c, the portion of the flange portion 16 including the welding surface 16c generates heat and is melted, and the generated heat is transferred to the portion of the holder 13 including the joining surface 13c to melt the portion, and the two melted portions are welded.

[0073] The wavelength of the laser is set to the range of 1850nm to 1960nm. Figure 3 and Figure 4 The graph of FIG. 1 illustrates laser light having a wavelength in this range. In addition, the wavelength in the range of 1850 nm to 1960 nm is described as wavelength B below.

[0074] like Figure 3 As shown in B1, the transmittance of the laser with wavelength B is extremely low at about 10% near 1900nm, which is low transmittance for acrylic resin. Figure 4 As shown in B2, the transmittance of the laser light with wavelength B is as high as 60% or more at around 1900 nm, which is a high transmittance for polycarbonate.

[0075] Such a laser beam of wavelength B has low transmittance to acrylic resin and high transmittance to polycarbonate. Therefore, when the laser beam of wavelength B is emitted toward the incident surface 13b of the lens holder 11A, a high transmittance of the laser beam to the lens holder 11A is ensured, and a high absorptivity of the laser beam to the projection lens 12A is ensured, and a sufficient amount of laser beam is irradiated to the welding surface 16c, generating a sufficient amount of heat on the welding surface 16c, thereby ensuring a good melting state on the joint surface 13c and the welding surface 16c.

[0076] In addition, when using a laser with a wavelength B, depending on the laser irradiation device, the laser with a wavelength B may contain a small amount of light with a wavelength exceeding 1960nm. When the laser is incident on the retaining portion 13 from the incident surface 13b, a portion of the laser is absorbed by the retaining portion 13 formed of polycarbonate, which may cause deformation of the incident surface 13b due to heat.

[0077] Here, a focusing lens 17 (see Figure 7 ). By arranging the condensing lens 17 on the optical path of the laser light, the laser light is condensed by the condensing lens 17 and irradiated in a state of being focused on the welding surface 16c.

[0078] At this time, the laser light can be transmitted through the holding portion 13 of the lens holder 11A in a condensed state by the condensing lens 17, so that the energy density of the light becomes low on the incident surface 13b, and heat is difficult to generate, and the energy density of the light becomes high on the welding surface 16c, and heat is easily generated. Therefore, the incident surface 13b can be prevented from being deformed due to heat, and a high bonding strength between the projection lens 12A and the lens holder 11A can be ensured.

[0079] Alternatively, a filter 19 made of polycarbonate, which is the same material as the lens holder 11A, may be disposed on the optical path of the laser beam (see Figure 7 ). By arranging the filter 19 on the optical path of the laser light, the laser light can pass through the filter 19.

[0080] At this time, the wavelength component of the laser light absorbed by the holding portion 13 is absorbed by the filter 19 before passing through the holding portion 13 , so that the light of the wavelength component does not enter the holding portion 13 , thereby preventing the incident surface 13 b from being deformed due to heat.

[0081] Furthermore, by using the condenser lens 17 and the filter 19 in combination, it is possible to obtain a greater effect of preventing deformation of the incident surface 13 b due to heat, and to ensure a high bonding strength between the projection lens 12A and the lens holder 11A.

[0082] In addition, filter 19 is formed of polycarbonate which is the same material as lens holder 11A. Due to the heat generated by light with a wavelength exceeding 1960nm, filter 19 may be deformed. Therefore, when filter 19 is deformed and the function of filter 19 is reduced, it is preferable to replace filter 19 with a new filter 19.

[0083] When the projection lens 12A and the lens holder 11A are joined by laser welding using a laser beam having a wavelength B, any structure may be adopted as long as the laser beam is transmitted through the lens holder 11A and irradiated onto the projection lens 12A. For example, the laser welding may be performed by setting a structure in which the holding portion 13 covers the outer peripheral surface of the flange portion 16 from the outer peripheral side (see Figure 8 In this case, the outer peripheral surface of the flange portion 16 in the projection lens 12A is formed as the welding surface 16c, and the surface of the lens holder 11A that contacts the welding surface 16c is formed as the bonding surface 13c. At this time, the laser is irradiated to the welding surface 16c, for example, from the P direction orthogonal to the welding surface 16c.

[0084] Furthermore, when the projection lens 12A and the lens holder 11A are joined by laser welding using a laser beam having a wavelength B, for example, the laser welding may be performed by setting a structure in which the holder 13 covers the front surface of the flange 16 from the front side (see Fig. 9 In this case, the front surface of the flange portion 16 in the projection lens 12A is formed as the welding surface 16c, and the surface of the lens holder 11A that contacts the welding surface 16c is formed as the bonding surface 13c. At this time, the laser is irradiated to the welding surface 16c, for example, from the P direction orthogonal to the welding surface 16c.

[0085] As described above, in another structure of the vehicle headlamp 1, laser light of a wavelength B of 1850 nm to 1960 nm that can pass through the lens holder 11A is irradiated onto the weld surface 16c, thereby bonding the transparent projection lens 12A formed of acrylic resin to the transparent lens holder 11A formed of polycarbonate.

[0086] Therefore, the laser beam of wavelength B that can pass through the transparent lens holder 11A is irradiated to the welded surface 16c of the transparent projection lens 12A, thereby joining the projection lens 12A and the lens holder 11A. As a result, the lens holder 11A is transparent, has a good appearance, and is unlikely to be melted by sunlight. Therefore, while ensuring a high bonding strength between the projection lens 12A and the lens holder 11A, the lens holder 11A can be prevented from being melted, and visibility can be improved.

[0087] Explanation of symbols

[0088] 1…vehicle headlamp, 11…lens holder, 12…projection lens, 13a…welding surface, 16a…joining surface, 16b…incident surface, 17…condenser lens, 18…filter, 19…filter, 11A…lens holder, 13b…incident surface, 13c…joining surface, 12A…projection lens, 16c…welding surface.

Claims

1. A vehicle headlamp, wherein a projection lens formed of acrylic resin and a lens holder formed of polycarbonate are joined by laser welding, wherein: The projection lens is formed to be transparent and has a bonding surface. The lens holder is formed to be transparent and has a welding surface to be joined by the joining surface. The projection lens and the lens holder are bonded to each other by irradiating the welded surface with laser light of a wavelength of 1550 nm to 1640 nm that can transmit the projection lens, wherein the laser light of the wavelength has a transmittance of 60% or more in the acrylic resin.

2. The vehicle headlamp according to claim 1, characterized in that: A condenser lens is arranged on the optical path of the laser light.

3. The vehicle headlamp according to claim 1 or 2, characterized in that: A filter made of acrylic resin is arranged on the optical path of the laser light.

4. A vehicle headlamp, wherein a projection lens formed of acrylic resin and a lens holder formed of polycarbonate are joined by laser welding, wherein: The projection lens is formed to be transparent and has a fusion surface. The lens holder is formed to be transparent and has a joining surface to be joined by the welding surface. The projection lens and the lens holder are bonded to each other by irradiating the welded surface with laser light having a wavelength of 1850 nm to 1960 nm that can transmit the lens holder.

5. The vehicle headlamp according to claim 4, characterized in that: A condenser lens is arranged on the optical path of the laser light.

6. The vehicle headlamp according to claim 4 or 5, characterized in that: A filter made of polycarbonate is arranged on the optical path of the laser light.

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