Vehicle lamp

Abstract

A vehicle lamp comprising a light source, a projection lens that is provided on the vehicle-front side of the light source, a shade that is positioned between the light source and the projection lens and forms a cut-off line in a light distribution pattern, and a reflector that reflects light from the light source to the projection-lens side, wherein: the projection lens is provided with a band-shaped region (9) extending in the width direction of the vehicle on an incident surface of the projection lens, and a plurality of prisms (23) are provided in a row in the region; and the plurality of prisms (23) are composed of two or more kinds of prisms (23) having different radii of curvature in the length direction of the band-shaped region.

Description

Vehicle lighting fixtures

[0001] The present disclosure relates to a vehicle lamp.

[0002] Generally, a vehicle lamp includes a projection lens provided at the front of the vehicle, a light source provided behind the projection lens, a reflector that reflects light from the light source toward the projection lens, a shade that forms a cutoff line in a light distribution pattern, etc. A conventional vehicle lamp of this type is described in Patent Document 1.

[0003] Patent No. 4782064

[0004] Patent Document 1 discloses a vehicle lamp having a vertical diffusion section for adjusting the cutoff line, which is made of a projection lens element extending substantially parallel to the horizontal portion of the upper edge of the shade, and describes how the vertical diffusion section blurs the cutoff line. However, while this vehicle lamp can reduce the brightness difference of the cutoff line, it cannot appropriately set the degree of brightness difference between each section in the left and right directions of the cutoff line. Furthermore, since this vehicle lamp only diffuses light in the vertical direction using the projection lens element, it is prone to uneven light distribution. In this type of technology, it is useful to appropriately set the brightness difference in the left and right directions of the illuminated area to improve driver visibility, and it is also necessary to suppress uneven light distribution.

[0005] The problem that the present disclosure aims to solve is to reduce the difference in brightness of the cutoff line in a light distribution pattern in a vehicle lamp, to appropriately set the difference in brightness in the left and right directions in the light distribution pattern, and to further suppress uneven light distribution.

[0006] The vehicle lamp according to the present disclosure comprises a light source, a projection lens provided on the vehicle front side of the light source, a shade disposed between the light source and the projection lens and forming a cutoff line within a light distribution pattern, and a reflector that reflects light from the light source toward the projection lens, wherein the projection lens has a band-shaped region extending in the width direction of the vehicle on its incident surface, and a plurality of prisms are arranged in a row within that region, and the plurality of prisms are composed of two or more types of prisms with different radii of curvature in the length direction of the band-shaped region.

[0007] FIG. 1 is a front view of a vehicle lamp shown as an embodiment of the present disclosure; FIG. 2 is a configuration diagram showing the basic configuration of the vehicle lamp; FIG. 3 is a view of a projection lens of the vehicle lamp as seen from behind; FIG. 4 is an enlarged rear view of a low beam portion of the vehicle lamp; FIG. 5 is an explanatory diagram showing the shape of a prism of the vehicle lamp; FIG. 6 is an enlarged rear view of a low beam portion of the vehicle lamp, showing a light collection area and a diffusion area; FIG. 7 is an explanatory diagram showing a reflector and projection lens of the vehicle lamp and the direction in which light travels; FIG. 8 is a diagram showing a light distribution pattern of the vehicle lamp; and FIG. 9 is an explanatory diagram showing the diffusion state of light in the vehicle lamp.

[0008] An embodiment of the present disclosure will be described below with reference to the accompanying drawings. Throughout the description of the embodiment described herein, the same elements are designated by the same reference numerals. Furthermore, in the embodiment and in the drawings, unless otherwise specified, "front" and "rear" refer to the "forward direction" and "reverse direction" of the vehicle, respectively, and "up," "down," "left," and "right" refer to the directions as seen by the driver of the vehicle.

[0009] The vehicle lamp according to the embodiment of the present disclosure is a vehicle lamp mounted in each of the left and right headlights of an automobile at the front of the vehicle. In the following, a vehicle lamp for driving on the left side and disposed on the right side of the vehicle will be described.

[0010] 1 is a view of a headlamp 1 as seen from the side facing the front thereof, and the headlamp 1 shown in this figure includes a low beam lamp unit 2 and a high beam lamp unit 3 configured as an AHS (adaptive high beam system). This embodiment focuses on the low beam lamp unit 2 of the headlamp 1, and hereinafter, the low beam lamp unit will be described as a vehicle lamp 2.

[0011] Fig. 2 is a longitudinal cross-sectional view taken along the light irradiation optical axis X of the vehicle lamp 2. As shown in Fig. 2, the vehicle lamp 2 includes a light source 4, a reflector 5 arranged to cover the light source 4 in a semi-dome shape, a projection lens 6A arranged in front of the light source 4, and a shade 7 arranged between the reflector 5 and the projection lens 6A.

[0012] (Light Source) A semiconductor light source can be suitably used as the light source 4, and in this embodiment, an LED is used, which is a semiconductor light source having a light emitting chip mounted on a substrate on which electrical wiring for power supply (not shown) is formed.

[0013] The number of light-emitting chips is not particularly limited and may be one or more. The shape of the light-emitting chip is also not particularly limited and may be square or rectangular. Furthermore, although the present embodiment shows an example in which an LED is used as the light source 4, semiconductor light sources such as LDs and ELs (organic ELs) may also be used.

[0014] As shown in FIG. 2, in this embodiment, the substrate is arranged so that the light emitting surface of the light emitting chip faces upward, and light from the light source 4 is irradiated upward.

[0015] (Reflector) The reflector 5 is disposed so as to cover the light source 4 in a semi-dome shape, and light from the light source 4 is reflected toward the projection lens 6A by the reflecting surface 8 of the reflector 5. The material used for the reflector 5 is a metal material (e.g., aluminum) or a resin material with high thermal conductivity, such as polycarbonate.

[0016] The reflecting surface 8 of the reflector 5 is a free-form surface based on a spheroid (ellipse), and in this embodiment, it includes a condensing segment 8A, a diffusing segment 8B, and other segments 8C, as shown in Fig. 7. Fig. 7 will be described in detail later.

[0017] 1, in this embodiment, a low beam projection lens 6A and a high beam projection lens 6B are integrally formed as the projection lens 6 of the entire headlamp 1. When viewed from the side facing the front of the vehicle, the projection lens 6 has a height dimension (width dimension) W1 and extends in the vehicle width direction, and also extends diagonally upward from the center of the vehicle width direction outward.

[0018] 1, the area enclosed by a dashed line on the left side is the low beam projection lens 6A, and the area enclosed by a dashed line on the right side is the high beam projection lens 6B. Details of the low beam projection lens 6A will be described later. This projection lens 6 can be made of a transparent resin material such as polycarbonate or acrylic.

[0019] (Shade) The shade 7 can be suitably formed using a light-opaque material, and as shown in FIG. 2, the upper end of the shade 7 is disposed near the second focal point of the reflector 5 (light-collecting segment 8A) and the rear focal point of the projection lens 6A.

[0020] Then, the light from the light source 4 is reflected by the reflecting surface 8 of the reflector 5, and a portion of the light directed toward the projection lens 6A is blocked, thereby forming cutoff lines CL1 and CL2 of the low-beam light distribution pattern PL.

[0021] The above has been a description of the basic configuration of the vehicular lamp 2, and in this configuration, when the light source 4 shown in Fig. 2 is turned on, light from the light source 4 is reflected by the reflector 5. Then, light illuminating the area ahead of the vehicle including the central side of the cutoff lines CL1 and CL2 of the light distribution pattern PL shown in Fig. 8 and light illuminating the area ahead of the vehicle including the outer side of the light distribution pattern PL in the width direction of the vehicle proceed toward the projection lens 6. In this case, part of the light from the reflector 5 is blocked by the shade 7, and therefore the cutoff lines CL1 and CL2 are formed in the illuminated light distribution pattern PL.

[0022] (Main Parts of the Projection Lens) Next, the details of the aforementioned projection lens 6A will be described. Fig. 3 is a diagram showing the back surface of the projection lens 6, with the portion indicated by the dashed line on the right being the low beam projection lens 6A, and the portion enclosed by the dashed line on the left being the high beam projection lens 6B. As shown in this figure, the low beam projection lens 6A has, on the back surface serving as the incident surface, a plurality of rows (five rows in this embodiment) of strip-shaped regions 9 extending in the left-right direction, spaced apart in the up-down direction, and a plurality of prisms 23, described later, are provided within these regions 9.

[0023] The position where the strip-shaped area 9 is provided within the projection lens 6A, the number of rows of the strip-shaped area 9, etc. are determined to be appropriate positions, number of rows, etc. depending on the configuration and position of the reflector 5 and shade 7 arranged behind the projection lens 6A.

[0024] As shown in Fig. 1, the projection lens 6 has a height (width) W1 as described above, and extends in the width direction of the vehicle, and also extends diagonally upward from the center of the vehicle in the width direction to the outside. The band-shaped region 9 also extends in the width direction of the vehicle along the upper and lower contours of the projection lens 6, and also extends diagonally upward of the vehicle, as shown in Fig. 3, and a plurality of prisms 23 are provided within this region 9.

[0025] The back surface (light incidence surface) of the projection lens 6A is shown in detail in Fig. 4. As shown in the figure, a strip-shaped area 9 is set to extend left and right in the figure, i.e., in the width direction of the vehicle. This area 9 is divided into upper and lower horizontal dividing lines 21, 21, and a plurality of vertical dividing lines 22 are set at intervals in the direction in which the horizontal dividing lines 21 extend. A prism 23 is formed within a parallelogram-shaped area enclosed by these horizontal dividing lines 21, 21 and vertical dividing lines 22, 22.

[0026] 5, when the rear surface of the projection lens 6A is taken as a reference surface 24, the prism 23 is formed so as to be convex or concave with respect to this reference surface 24 (FIG. 5 shows the case where the reference surface 24 is convex). The reference surface 24 is a gently curved convex surface with a radius of curvature r1, and the relationship with the radius of curvature r2 of the prism 23 is r1 > r2.

[0027] The prism 23 is formed in a parallelogram region surrounded by the horizontal dividing lines 21, 21 and the vertical dividing lines 22 in the band-shaped region 9 shown in Fig. 4, and is formed so as to bulge (or recess) from the four horizontal dividing lines 21, 21 and the vertical dividing lines 22, 22 toward the center of the parallelogram. Therefore, the prism 23 diffuses light incident on the rear side of the projection lens 6A in the vertical direction as well as the horizontal direction.

[0028] For ease of explanation, Fig. 5 shows a case where the plurality of prisms 23 are arranged in a state where adjacent prisms 23 are in contact with each other. The arrangement of the plurality of prisms 23 may include not only the case where prisms 23 are arranged in all of the adjacent parallelogram regions shown in Fig. 4, but also the case where adjacent prisms 23, 23 are arranged with an appropriate gap therebetween regardless of the parallelogram region.

[0029] In this way, by leaving or not leaving a gap between adjacent prisms 23 and further adjusting the thickness, size, etc. of the prisms 23, the degree of light diffusion in the left and right directions of the light distribution pattern PL can be adjusted and set appropriately.

[0030] 6, the rear surface of the projection lens 6A is divided into a light-collecting area 25 on the right side and a diffusion area 26 on the left side by a vertical dividing line. In this case, the light-collecting area 25 is longer in the horizontal direction and has a larger area than the diffusion area 26. The strip-shaped area 9 is formed between the light-collecting area 25 and the diffusion area 26, and the plurality of prisms 23 are formed within this area 9.

[0031] In this embodiment, the plurality of prisms 23 have a relationship in the length direction of the band-shaped region 9 where the radius of curvature of the prisms 23 in the light-collecting area 25 is equal to or smaller than the radius of curvature of the prisms 23 in the diffusion area 26. By employing this configuration, in the left-right direction of the cutoff lines CL1, CL2 formed in the light distribution pattern PL, the degree to which the difference in brightness of light near the centers of the cutoff lines CL1, CL2 is alleviated becomes greater, and the degree to which the difference in brightness of light outside the vehicle is alleviated becomes less.

[0032] A horizontal cross section of this projection lens 6A is shown in Figure 7. As shown in Figure 7, the rear surface 27 (reference surface 24) has a shape that bulges outward toward the rear. A light-collecting area 25 and a diffusion area 26 are formed within this bulging area. The radius of curvature of the light-collecting area 25 and the radius of curvature of the diffusion area 26 are such that the radius of curvature of the light-collecting area 25 is greater than the radius of curvature of the diffusion area 26.

[0033] 7, the reflector 5 includes a condensing segment 8A, a diffusing segment 8B, and other segments 8C. The condensing segment 8A is configured to reflect light from the light source 4 toward the condensing area 25 of the projection lens 6. The diffusing segment 8B is configured to reflect light from the light source 4 toward the diffusing area 26 of the projection lens 6. The other segments 8C are configured to reflect light from the light source 4 mainly toward the condensing area 25 of the projection lens 6.

[0034] In this configuration, light reflected by the focusing segment 8A enters the focusing area 25, then passes through the lens, and travels forward, including toward the center of the vehicle. Light reflected by the diffusing segment 8B enters the diffusing area 26, then passes through the lens and travels in a diffusing direction toward the outside of the vehicle. Light reflected by the other segments 8C mainly enters the focusing area 25, then passes through the lens and travels forward across the entire width of the vehicle. In this case, the focusing segment 8A is configured so that the first focus of its light is near the light source 4 and the second focus is located between the focusing segment 8A and the projection lens 6. Furthermore, the diffusing segment 8B is configured so that the first focus of its light is near the light source 4 and the second focus is located near the front surface of the projection lens 6.

[0035] 8 is a diagram showing a light distribution pattern emitted from the projection lens 6. As shown in this figure, part of the light from the reflector 5 is blocked by the shade 7 within the light distribution pattern PL, so cutoff lines CL1 and CL2 are formed in the emitted light distribution pattern PL. In the figure, the area indicated by reference numeral 61 is the concentrated illumination area of ​​light reflected by the converging segment 8A, the area indicated by reference numeral 62 is the side illumination area of ​​light reflected by the diffusing segment 8B, and the area indicated by reference numeral 63 is the diffuse illumination area of ​​light reflected by the other segment 8C.

[0036] 9A and 9B are diagrams showing how the difference in brightness between light and dark is reduced. In these diagrams, the difference in brightness between light and dark is indicated by density. FIG. 9A shows the case where the prism 23 is not provided, and the difference in brightness between areas A1 and A2 in the cutoff lines CL1 and CL2 is clear. FIG. 9B shows the case where the prism 23 is provided, and it can be seen that the difference in brightness between areas A1 and A2 is reduced.

[0037] As described above, the vehicle lamp 2 is configured such that a strip-shaped region 9 is defined on the rear surface of the projection lens 6, and a plurality of concave or convex prisms 23 are provided along the length of the region. Therefore, when light from the light source 4 enters and exits the prisms 23, it is diffused in the vertical and horizontal directions. This reduces the difference in brightness near the cutoff lines CL1 and CL2 in the light distribution pattern PL and suppresses uneven light distribution. Therefore, the driver's long-distance visibility can be improved.

[0038] Furthermore, the prism 23 that irradiates light toward the center of the vehicle is configured to have a smaller radius of curvature than the prism 23 that irradiates light toward the outside, so that the brightness difference near the center of the cutoff lines CL1 and CL2 can be more significantly alleviated, and the brightness difference outside the vehicle can be less alleviated, thereby appropriately alleviating the brightness difference in the left and right directions of the cutoff lines CL1 and CL2.

[0039] The prisms 23 are arranged adjacent to each other at intervals in the direction in which the strip-shaped region 9 extends, and the length of the intervals is adjusted as appropriate. This allows the degree to which the contrast is reduced to be appropriately set, preventing the contrast from becoming too strong or too weak.

[0040] Moreover, the strip-like area 9 where the prism 23 is provided is arranged along the contour line of the projection lens 6 and is configured along the design slant, so that it can have a good-looking appearance without any sense of incongruity in design.

[0041] DESCRIPTION OF SYMBOLS 1 Headlamp 2 Low beam lamp unit (vehicle lamp) 3 High beam lamp unit 4 Light source 5 Reflector 6 Projection lens 6A Low beam projection lens 6B High beam projection lens 7 Shade 8 Reflective surface of reflector 8A Concentrating segment 8B Diffusion segment 8C Other segments 9 Strip-shaped area 21 Horizontal dividing line 22 Vertical dividing line 23 Prism 24 Reference surface 25 Concentrating area 26 Diffusion area 27 Back surface 61 Concentrating irradiation area 62 Side irradiation area 63 Diffusion irradiation area PL Light distribution pattern CL1 Cut-off line CL2 Cut-off line

Claims

1. A vehicle lamp comprising: a light source; a projection lens provided on the vehicle front side of the light source; a shade disposed between the light source and the projection lens and forming a cut-off line in a light distribution pattern; and a reflector that reflects light from the light source towards the projection lens, wherein the projection lens has a band-shaped area extending in the vehicle width direction on its incident surface and a plurality of prisms are provided in a row within the area, and the plurality of prisms are composed of two or more types of prisms having different radii of curvature in the length direction of the band-shaped area.

2. The vehicle lamp according to claim 1, wherein the projection lens comprises a focusing area which irradiates the light reflected by the reflector as focused light toward the front of the vehicle, and a diffusion area which irradiates the light reflected by the reflector as diffused light toward the outside of the front of the vehicle, the plurality of prisms comprise focusing prisms provided in the focusing area and diffusing prisms provided in the diffusion area, and the radius of curvature of the focusing prisms is configured to be equal to or smaller than the radius of curvature of the diffusing prisms.

3. The vehicle lamp according to claim 1, wherein the plurality of prisms include prisms arranged adjacent to each other with a gap in between in the longitudinal direction.

4. A vehicle lamp as claimed in claim 1, wherein the band-shaped regions are arranged in a plurality of rows spaced apart in the vertical direction of the projection lens, and a plurality of the prisms are provided within each of the band-shaped regions.

5. A vehicle lamp as described in claim 1, wherein the projection lens extends in the width direction of the vehicle with a vertical height dimension when viewed from the side facing the front of the vehicle, and is shaped to extend diagonally upward from the center side of the vehicle's width direction towards the outside, and the multiple prisms are arranged in the direction in which the projection lens extends.

6. The vehicle lamp according to claim 2, wherein the reflector comprises: a focusing segment that directs light from the light source to the focusing area of ​​the projection lens; and a diffusing segment that directs light from the light source to the diffusing area of ​​the projection lens.

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