Vehicle lamp fitting

Abstract

To provide a vehicle lamp fitting which inhibits influence of aberration and heat in a projection lens to enable highly accurate projection of a light pattern.SOLUTION: A vehicle lamp fitting includes a projection lens 2 which projects light emitted from a light source 3 to project a required light distribution pattern. The projection lens 2 is formed including a first lens 21 and a second lens 22, made of resin, and a third lens 23 and a fourth lens 24, made of glass, from the side opposite to the light source 3 in a written order. A diaphragm 25 which limits a light diameter of the projected light is disposed between the second lens (the resin lens) 22 and the third lens (the glass lens). An aperture of the diaphragm 25 is reduced to reduce aberration of the projection lens 2. Further, the diaphragm 25 inhibits heat of the light source 3 from being transmitted from the third lens 23 side to the second lens 22 side.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a lamp used in vehicles such as automobiles, and more particularly to a vehicle lamp suitable for use as a headlamp that performs ADB (Adaptive Driving Beam) light distribution control. [Background technology]

[0002] ADB light distribution control has been proposed as a technology for controlling light distribution in the headlamps of vehicles such as automobiles. This ADB light distribution control is a technology that controls light distribution so as not to dazzle other vehicles and pedestrians, such as oncoming vehicles and preceding vehicles, detected from images captured by a camera. As one headlamp that performs this ADB light distribution control, a headlamp that uses a multi-segment light-emitting element (multi-segment LED array) in which micro LEDs on the order of μm are arranged in a matrix as the light source has been proposed.

[0003] For example, Patent Document 1 proposes a technology in which a multi-segment LED array, also called a micro LED array, is provided as a light source, and light emitted by the multi-segment LED array is projected by an optical system to form a light distribution pattern. In this technology, the light emitting surface of the emitted micro LED is projected to form a unit light pattern, and the light patterns of the multiple micro LEDs are combined to form a desired light distribution pattern. Therefore, selectively controlling the emission of the micro LEDs enables ADB light distribution control with a desired light distribution pattern. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-068513 Summary of the Invention [Problem to be solved by the invention]

[0005] In such ADB light distribution control, it is preferable to project the unit light pattern of the micro LED to be projected in an accurate shape, that is, as a light pattern corresponding to the shape of the light emitting surface. However, if aberration occurs in the projection lens, the shape of the unit light pattern of the micro LED to be projected changes, making it difficult to control the projection of the light distribution pattern obtained by combining these, that is, to perform high-precision ADB light distribution control. In addition, the projection lens is thermally deformed by the heat generated when the light source emits light, and is affected by the shape of the projected light pattern. In particular, projection lenses equipped with resin lenses are more susceptible to such influence.

[0006] In Patent Document 1, the projection lens is composed of multiple lenses (triplet lenses) and the aberration of the projection lens is reduced. However, when illuminating a wide area in front of the vehicle in ADB light distribution control, a significant amount of light emitted from the small LED passes through the peripheral area of ​​the projection lens, i.e., the light enters the projection lens at a large angle with respect to the optical axis, and it is difficult to reduce the coma aberration caused by this light.

[0007] In addition, in Patent Document 1, the lens closer to the light source is made of a glass lens, and the lens opposite the light source is made of a resin lens, making the resin lens less susceptible to the effects of heat. However, it is difficult to prevent the heat from being transferred through the glass lens to the resin lens, and in particular, it is difficult to prevent the heat from being transferred by radiation, and it is difficult to prevent the shape of the light pattern from being affected by heat.

[0008] An object of the present invention is to provide a vehicle lamp that suppresses the effects of aberration and heat in a projection lens and enables projection of a light pattern with high accuracy. [Means for solving the problem]

[0009] The vehicle lamp of the present invention is a vehicle lamp including a light source and a projection lens that projects light emitted from the light source to project a required light distribution pattern, the projection lens including a resin lens and a glass lens, the resin lens and the glass lens being arranged on the opposite side to the light source, and an aperture that limits the diameter of the projected light being arranged between the glass lens and the resin lens.

[0010] For example, the projection lens includes, in order from the side opposite to the light source, a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens and a fourth lens having a positive refractive power, the first lens and the second lens being made of resin, the third lens and the fourth lens being made of glass, and an aperture is disposed between the second lens and the third lens. Here, it is preferable that the third lens and the fourth lens are each made of a plano-convex spherical lens, and that the spherical surfaces of the lenses are disposed opposite to each other. It is also preferable that the focal length of the third lens is longer than that of the fourth lens.

[0011] The diaphragm is preferably made of a material having a lower thermal conductivity than glass and resin, and is preferably configured as a variable diaphragm whose aperture diameter is variable, and whose aperture value is changed according to the light distribution pattern to be projected. Effect of the Invention

[0012] According to the present invention, it is possible to provide a vehicle lamp that can suppress aberration in the projection lens and the influence of heat on the light pattern, and in particular, can realize highly accurate ADB light distribution control. [Brief description of the drawings]

[0013] [Figure 1] 1 is a perspective view of an automobile equipped with a headlamp to which the present invention is applied, and a schematic configuration of the headlamp; [Diagram 2] FIG. 2 is a schematic perspective view of an ADB lamp unit. [Diagram 3] Schematic vertical cross-sectional view of an ADB lamp unit. [Figure 4] Block diagram of the ADB control system. [Diagram 5] Schematic diagram of a light distribution pattern. [Figure 6] 1A to 1C are schematic cross-sectional views of projection lenses of different configurations; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic configuration of an automobile equipped with a headlamp to which the present invention is applied, and a schematic perspective view of the headlamp. Left and right headlamps R-HL and L-HL are attached to the left and right front parts of the body of an automobile CAR. Each headlamp R-HL and L-HL is equipped with an ADB lamp unit ALU capable of ADB light distribution control and a clearance lamp unit CLU, which are integrally disposed in a lamp housing 100.

[0015] The left and right headlamps R-HL, L-HL have a symmetrical configuration, and a partially cutaway perspective view of the right headlamp R-HL is shown enlarged in Fig. 1. The lamp housing 100 includes a lamp body 101 that opens toward the front of the vehicle, and a light-transmitting cover 102 attached to this opening. An ADB lamp unit ALU and a clearance lamp unit CLU are disposed within this lamp housing 100.

[0016] As described in detail below, the ADB lamp unit ALU is configured to project an ADB light distribution pattern by irradiating light emitted from a light source to a front area of ​​the automobile using a projection lens. In this embodiment, the ADB lamp unit ALU is capable of projecting a light distribution pattern including a low beam light distribution and a high beam light distribution. The clearance lamp unit CLU is configured to also serve as a turn signal lamp, a daytime running lamp, etc. The clearance lamp unit CLU is configured to utilize a light guide, but since this is not particularly relevant to the present invention, detailed description thereof will be omitted.

[0017] Fig. 2 is a perspective view of the schematic configuration of the ADB lamp unit ALU, and Fig. 3 is a longitudinal sectional view thereof. The unit case 1 also serves as a heat sink 10, and a light source section 3 is disposed therein. The light source section 3 is provided with a micro LED (light emitting diode) array 31 as a light source, and this micro LED array 31 is mounted on a light source board 30 that is internally supported by the unit case 1. This micro LED array 31 is a multiplicity of minute LEDs 32 that emit white light, arranged vertically and horizontally in a matrix, and any minute LED is selectively made to emit light by control of an ADB control circuit 41 described later.

[0018] The projection lens 2 has a lens configuration in which a plurality of lens groups are housed inside a lens barrel 20. It is basically configured as a triplet lens, and is composed of a first lens group LG1, a second lens group LG2, and a third lens group LG3, in that order from the front side of the lamp. The first lens group LG1 is composed of a first lens 21 consisting of a biconvex lens having positive refractive power. The second lens group LG2 is composed of a second lens 22 consisting of a biconcave lens having negative refractive power. The third lens group LG3 is composed of a composite lens (combined lens) of a third lens 23 and a fourth lens 24, each consisting of a plano-convex lens, and is configured as a lens having positive refractive power as a whole.

[0019] Of the four lenses 21 to 24 that make up the projection lens 2, the first lens 21 and the second lens 22 are made of a light-transmitting resin. For example, the first lens 21 is made of PMMA (acrylic resin), and the second lens 22 is made of PC (polycarbonate resin). The third lens 23 and the fourth lens 24 are made of light-transmitting glass, and are made of, for example, N-K9L (borosilicate crown glass).

[0020] In addition, the first lens 21 and the second lens 22 are designed to have aspheric convex and concave surfaces. The third lens 23 and the fourth lens 24 are each composed of a plano-convex spherical lens, and are arranged with their spherical surfaces facing each other. In addition, the positive refractive power (refractive power) of the first lens 21 is set to a value close to the negative refractive power of the second lens 22. The third lens 23 is composed of a lens having a longer focal length than the fourth lens 24, and the refractive power of the fourth lens 24 is made larger than that of the third lens 23, and the entire third lens group LG3, which is a combination of these lenses, is configured as a lens having a positive refractive power in the light emission direction as described above. By configuring each of the lenses 21 to 24 in this way, aberrations in the projection lens 2, that is, chromatic aberration, spherical aberration, astigmatism, and coma aberration, are reduced. Of these aberrations, the configuration related to coma aberration will be described later.

[0021] Furthermore, the projection lens 2 is provided with an aperture 25 between the second lens 22 and the third lens 23. Although detailed illustration of this aperture 25 is omitted, for example, the aperture ring attached to the lens barrel 20 has multiple aperture blades arranged in the circumferential direction, and the aperture ring is rotated by an aperture drive unit to tilt each aperture blade, thereby changing the aperture diameter of the aperture opening formed by these aperture blades. More specifically, the light diameter (diameter dimension of the light beam) of the light transmitted through the projection lens 2 is changed. Alternatively, the aperture may be changed by moving multiple aperture plates in the radial direction.

[0022] The diaphragm 25 is formed of a material with a lower thermal conductivity than the resin or glass that constitutes the lenses 21 to 24. The diaphragm blades of the diaphragm 25 shield the space between the peripheral edges of the second lens 22 and the third lens 23, and are designed so that the F-number of the entire projection lens 2 is at least 0.7 or less when the diaphragm blades are fully open. When the diaphragm 25 is driven to reduce the aperture diameter of the diaphragm opening, the peripheral region of the projection lens 2 is shielded, resulting in a so-called stopped-down state, and the F-number of the entire projection lens 2 becomes large.

[0023] The first lens 21 to the fourth lens 24 are internally supported in the lens barrel 20 with their respective lens optical axes aligned, and this optical axis is configured as the lens optical axis Lx of the entire projection lens 2. The lens barrel 20 is attached to the unit case 1 of the ADB lamp unit ALU with the rear focal point of the projection lens 2 located in a position extremely close to the light emitting surface of the micro LED array 31.

[0024] 4 is a block circuit diagram of the ADB control system 4 in the ADB lamp unit ALU. A lighting control switch 43 operated by the driver is connected to the ADB control circuit 41, and the ADB control circuit 41 controls the light emission of the micro LED array 31 by setting and operating the lighting control switch 43. A vehicle ECU (electronic control unit) 42 to which an in-vehicle camera 44 is connected is connected to the ADB control circuit 41, and the vehicle ECU 42 detects a forward vehicle present in the forward area based on an image of the forward area of ​​the automobile captured by the in-vehicle camera 44. The ADB control circuit 41 is configured to perform ADB light emission control of the micro LED array 31 so as not to dazzle the forward vehicle detected by the vehicle ECU 42 when set to ADB control. Furthermore, an aperture drive unit of the aperture 25 provided in the projection lens 2 is connected to the ADB control circuit 41, and the aperture opening of the aperture 25 is controlled by the setting of the lighting control switch 43.

[0025] In the headlamp HL of the first embodiment having the projection lens 2 configured as above, the light distribution is controlled by the setting of the lighting control switch 43 by the driver. For example, when the high beam light distribution is set, the ADB control circuit 41 causes almost all of the micro LEDs 32 of the micro LED array 31 to emit light, and as shown in FIG. 5(a) as a schematic diagram, the light patterns Ps of the micro LEDs 32 are synthesized to project a high beam light distribution pattern PHi. When the lighting control switch 43 is set to low beam light distribution, the light emission of the micro LED array 31 is controlled so that the light pattern Ps below the cutoff line COL in FIG. 5(a) is projected. This projects a low beam light distribution pattern PLo. In the figure, V is a vertical line passing through the optical axis Lx of the projection lens, and H is a horizontal line passing through an angle position slightly above the optical axis Lx.

[0026] When the lighting control switch 43 is set to the ADB light distribution control, the vehicle ECU 42 detects a leading vehicle Ob1 and an oncoming vehicle Ob2 as vehicles in front of the vehicle based on an image captured by the vehicle-mounted camera 44. When no vehicles in front are detected, the ADB control circuit 41 controls the light emission of the micro LED array 31 to project the high beam light distribution pattern PHi shown in FIG.

[0027] When a forward vehicle is detected, the ADB control circuit 41 projects an ADB light distribution pattern PA in which the micro LEDs corresponding to the illumination area overlapping with the detected forward vehicle are dimmed or turned off. That is, in the ADB light distribution pattern PA, as shown in Fig. 5(b), the illumination area to which the forward vehicles Ob1 and Ob2 belong is selectively dimmed or blocked to prevent dazzling of the forward vehicles Ob1 and Ob2. The illumination area in which the forward vehicles Ob1 and Ob2 do not exist projects the light pattern Ps of the emitted micro LEDs 32, illuminating the corresponding area with a predetermined brightness, and ADB light distribution control with improved visibility is executed.

[0028] Here, in the projection of the low beam light distribution pattern PLo and the high beam light distribution pattern PHi, there is little need to control the sharpness of the boundary at the periphery of the light distribution pattern, so the influence of aberration in the light distribution pattern can be ignored. Therefore, in this case, the aperture 25 is set to a fully open state or a state close to being fully open, and the projection lens 2 is set to a low F-number. This increases the lens brightness of the projection lens 2, i.e., the amount of light transmitted, and enables the projection of a bright light distribution pattern that effectively utilizes the light emitted by the micro LED array 31.

[0029] On the other hand, in the projection of the ADB light distribution pattern PA, it is required to project each light pattern Ps of a large number of small LEDs with high accuracy. That is, as shown in FIG. 5(b), it is required to sharpen the boundary between the shaded or dimmed area where the forward vehicles Ob1, Ob2 are present and the illuminated area where they are not present. If the boundary is not sharp, there is a risk that part of the light pattern will be irradiated to the forward vehicles Ob1, Ob2, and dazzle the occupants of the forward vehicles. In this case, the effect of coma aberration occurring in the projection lens 2 cannot be ignored.

[0030] In the projection lens 2 of the embodiment, an aperture 25 is disposed between the second lens 22 and the third lens 23, and by narrowing the aperture 25 to reduce the opening diameter, it is possible to block or reduce the transmission of light at the lens periphery of the projection lens 2. Therefore, the proportion of light that has passed through the lens periphery, where the angle of incidence with respect to the optical axis Lx of the projection lens 2 is relatively large, that contributes to the formation of the light pattern PA is reduced, and coma aberration caused by light that has passed through the lens periphery can be suppressed. This allows the boundary of the light pattern Ps of the micro LEDs to be projected sharply, and high-precision ADB light distribution control can be achieved.

[0031] If it is not possible to completely prevent coma in the projection lens 2, it is preferable to design it so that inward coma (coma that trails along the optical axis) remains. For example, as described in JP 2017-16928 A, inward coma can be controlled by making the curvature of the principal surface of the projection lens larger than the curvature of a circular arc that is centered on the focal point and passes through the principal point.

[0032] By applying such a design to the projection lens 2, the coma aberration occurring in the light pattern Ps of each micro LED 32 is controlled to inward coma aberration. This makes it possible to sharpen the boundary between the illumination area and the light blocking area of ​​the light pattern, where the inside toward the center of the light distribution pattern is the illumination area and the outside is the light blocking area. For example, in the case of the low-beam light distribution pattern PLo in Fig. 5(a), as shown by enlarging the portion c1 in Fig. 5(c1), the boundary of the light pattern Ps, i.e., the cutoff line COL, can be projected sharply by the inward coma aberration.

[0033] In the case of the ADB light distribution pattern PA in Fig. 5(b), as shown in Fig. 5(c2) enlarged view of the portion c2, even if inward coma aberration occurs at the boundary between the illuminated area and the shaded area, the margin between the front vehicle Ob2, that is, the margin for preventing the illuminated area from overlapping the front vehicle, can be reduced. Therefore, the boundary can be moved closer to the front vehicle Ob2 side to expand the illuminated area on the host vehicle side, thereby improving the safety when the host vehicle travels.

[0034] Considering the environmental temperature of the projection lens 2, when the micro LED array 31 is off, the temperature of the projection lens 2 is almost equal to the outside air temperature, and is generally between 0°C and 40°C. On the other hand, when the micro LED array 31 is emitting light, the temperature of the projection lens 2 rises to about 80°C due to the heat generated by the micro LED array 31. Therefore, the fourth lens 24 and the third lens 23 close to the micro LED array 31 are easily affected by heat, but these third lens 23 and fourth lens 24 are glass lenses, and the thermal expansion coefficient is about two orders of magnitude smaller than that of resin, so the effect on the refractive power can be ignored.

[0035] On the other hand, first lens 21 and second lens 22 are easily affected by heat via third lens 23, and in particular, heat is transferred through lens barrel 20 that supports each lens. Aperture 25 is disposed between second lens 22 and third lens 23 in lens barrel 20, and this aperture 25 suppresses heat transfer through lens barrel 20. In particular, when aperture 25 is formed from a material with low thermal conductivity, the effect of suppressing heat transfer is enhanced.

[0036] Heat conduction by radiation from the third lens 23 to the second lens 22 is also considered, and in particular, the second lens 22, which is a biconcave lens, and the third lens 23, which is a plano-convex lens, are close to each other in their respective peripheral regions, and heat conduction in these peripheral regions is considered. The diaphragm 25 arranged in the projection lens 2 has the diaphragm blades of the second lens 22 and the third lens 23 extending to the peripheral regions, so that the conduction of radiant heat in such peripheral regions is suppressed. Therefore, the influence of heat on the refractive power of the first lens 21 and the second lens 22, which are made of resin lenses, can also be ignored. In this way, the influence of heat on the light distribution pattern of the projection lens 2, particularly on the ADB light distribution pattern, can be suppressed, and high-precision ADB light distribution control can be realized.

[0037] In the present invention, the third lens group LG3 of the projection lens 2 may be composed of one lens. That is, as shown in Fig. 6, the first lens 21 of the first lens group LG1 and the second lens 22 of the second lens group LG2 have the same configuration, but the third lens group LG3 is composed of a third lens 23A consisting of a biconvex lens having positive refractive power. When the first lens 21 and the second lens 22 are configured in the same manner as in the embodiment, the third lens 23A is configured as a lens equivalent to a composite lens obtained by combining the third lens 23 and the fourth lens 24 of the embodiment. By designing in this way, a projection lens 2A that provides the same effects as the embodiment can be obtained.

[0038] Since the total number of lenses in this projection lens 2A can be reduced, the structure can be expected to be simplified. On the other hand, when controlling coma aberration, the shape of the biconvex surface of the third lens 23A needs to be designed aspheric, which may make design and manufacturing difficult. In contrast, in the projection lens of the above-mentioned embodiment, the third lens group LG3 is configured as a composite lens of the third lens 23 and the fourth lens 24, so that each lens surface of the third lens 23 and the fourth lens 24 can be designed as a spherical surface, which makes it possible to simplify design and manufacturing. In addition, since the spherical surfaces of the third lens 23 and the fourth lens 24 are arranged opposite each other, design to reduce aberration is also easy.

[0039] Here, in the embodiment of the ADB lamp unit, an example is shown in which the light source is configured with a micro LED array, i.e., a multi-segment LED, to form an ADB light distribution, but the present invention can also be applied to a lamp using a MEMS (micro electro mechanical systems) mirror array as a light source. Alternatively, the present invention can be applied not only to a lamp configured to directly project light from a light source with a projection lens, but also to a lamp using a projection lens that projects light scanned with reflected light from a rotating mirror and a swinging mirror. [Explanation of symbols]

[0040] 1 ADB lamp unit 2,2A Projection lens 3 Light source section 4. ADB Control System 10 Heat sink 20 Lens barrel 21~24 1st lens~4th lens 25 Aperture 30 Substrate 31 Micro LED Array 32 Micro LED 41 ADB control circuit 42 Vehicle ECU 43 Lighting control switch 44 In-vehicle camera L-HL, R-HL headlamp LG1~LG3 1st to 3rd lens groups PHi High beam light distribution pattern PLo low beam light distribution pattern PA ADB light distribution pattern Ps Light Pattern (Micro LED) Ob1, Ob2 Front vehicle

Claims

1. A vehicle lamp including a light source and a projection lens that projects light emitted from the light source to project a required light distribution pattern, the projection lens including a resin lens and a glass lens, the resin lens and the glass lens are arranged on the opposite side to the light source, and an aperture that limits the diameter of the projected light is arranged between the glass lens and the resin lens.

2. 2. The vehicle lamp according to claim 1, wherein the projection lens includes, in order from the side opposite the light source, a first lens having positive refractive power, a second lens having negative refractive power, and a third lens and a fourth lens having positive refractive power, the first lens and the second lens being made of resin, the third lens and the fourth lens being made of glass, and the aperture is disposed between the second lens and the third lens.

3. 3. The vehicle lamp according to claim 2, wherein the third lens and the fourth lens are each formed as a plano-convex spherical lens, and the spherical surfaces of the third lens and the fourth lens are disposed opposite to each other.

4. The vehicular lamp according to claim 3 , wherein a focal length of the third lens is longer than a focal length of the fourth lens.

5. 2. The vehicle lamp according to claim 1, wherein the projection lens includes, in order from the side opposite the light source, a first lens having positive refractive power, a second lens having negative refractive power, and a third lens having positive refractive power, the first lens and the second lens being made of resin, and the third lens being made of glass.

6. 2. The vehicle lamp according to claim 1, wherein the aperture is made of a material having a lower thermal conductivity than glass and resin.

7. 2. The vehicle lamp according to claim 1, wherein the diaphragm is a variable diaphragm whose aperture diameter is variable, and whose aperture value is changed according to the light distribution pattern to be projected.

8. 8. The vehicle lamp according to claim 1, wherein the light source is composed of a multi-segment light-emitting element in which a large number of minute light-emitting elements are arranged, and ADB light distribution control is performed by controlling the light emission of the minute light-emitting elements.

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