EP2426406A2

EP2426406A2 - Vehicle headlamp

Info

Publication number: EP2426406A2
Application number: EP11179692A
Authority: EP
Inventors: Yuichi Shibata
Original assignee: Koito Manufacturing Co Ltd
Current assignee: Koito Manufacturing Co Ltd
Priority date: 2010-09-02
Filing date: 2011-09-01
Publication date: 2012-03-07
Also published as: JP2012054141A

Abstract

There is provided a vehicle illumination lamp that selectively forms a light distribution pattern (PR) for rain driving and a high beam light distribution pattern (PH). The lamp includes: a light bulb (18) configured to emit light and including: a low beam filament (18a) configured to form the light distribution pattern (PR); and a high beam filament (18b) configured to form the high light distribution (PH), a reflector (20) configured to reflect the light emitted from the light bulb in a vehicle forward direction, a reflective surface of the reflector being divided into, in a vehicle width direction: a first area (Z1) located on a traveling lane-side; a second area (Z2) located on an opposite lane-side; and a third area (Z3,Z4) located between the first area and the second area. A central axis (Ax1) of the light bulb is inclined upward with respect to an optical axis (Ax) of the reflector at a certain angle in the vehicle forward direction. The light distribution pattern (PR) includes: a first light distribution pattern (PR1) formed by the light reflected by the first area (Z1) of the reflective surface of the reflector, wherein the first light distribution pattern is formed to extend obliquely upward toward a lane mark (LM1) in front of the vehicle; and a second light distribution pattern (PR2) formed by the light reflected by the second area (Z2) of the reflective surface of the reflector, wherein the second light distribution pattern is formed to extend obliquely downward toward the lane mark and overlap with the first light distribution pattern in front of the vehicle.

Description

BACKGROUND OF THE INVENTION

Technical Field

The present invention relates to a vehicle illumination lamp capable of selectively forming a light distribution pattern for rain driving and a high beam light distribution pattern.

Related Art

Hitherto, a vehicle illumination lamp, which includes an H4 halogen bulb and a reflector reflecting light emitted from the H4 halogen bulb to the front side, has been known as a vehicle illumination lamp.
In general, this vehicle illumination lamp is adapted to form a low beam light distribution pattern by turning on a low beam filament of the H4 halogen bulb and to form a high beam light distribution pattern by turning on a high beam filament of the H4 halogen bulb.
JP-A-2003-59317 describes a special second vehicle illumination lamp in addition to a general first vehicle illumination lamp.
The second vehicle illumination lamp is adapted to form an additional light distribution pattern for intensifying the brightness of a far shoulder portion of a low beam light distribution pattern, which is formed by the first vehicle illumination lamp, when a low beam filament of an H4 halogen bulb of the second vehicle illumination lamp is turned on. Also, the second vehicle illumination lamp is adapted to form an additional light distribution pattern for intensifying the brightness of a central portion of a high beam light distribution pattern, which is formed by the first vehicle illumination lamp, when a high beam filament of the H4 halogen bulb of the second vehicle illumination lamp is turned on.
If the additional light distribution pattern, which is formed by the second vehicle illumination lamp disclosed in JP-A-2003-59317 and irradiates the far shoulder portion, is formed when a vehicle travels with a low beam in the rain, it may be possible to use the additional light distribution pattern to irradiate lane mark (that is, a white line, a curb, or the like for partitioning a vehicle traveling lane). Accordingly, it may be possible to increase forward visibility when a vehicle travels in the rain.
However, in JP-A-2003-59317 , in order to form the additional light distribution pattern for irradiating the far shoulder portion, a light blocking film is applied to a tube wall of the H4 halogen bulb so that a portion of light emitted from the low beam filament toward the reflective surface of the reflector is blocked. For this reason, the use efficiency of the luminous flux of a light source is low. Therefore, there is a problem in that the additional light distribution pattern excellent in the visibility of the far shoulder portion cannot be formed. Further, since a process for applying the light blocking film is required, there is also a problem in that the cost of the lamp is high.

SUMMARY OF THE INVENTION

An object of the invention is to provide a vehicle illumination lamp capable of selectively forming a light distribution pattern for rain driving and a high beam light distribution pattern and can form a light distribution pattern for rain driving, which is excellent in visibility of a far shoulder portion, with an inexpensive structure
According to the present invention, the above object can be achieved through the research on the disposition of an H4 halogen bulb and the structure of a reflective surface of a reflector while an H4 halogen bulb is used as it is.
According to one or more aspects of the invention, there is provided a vehicle illumination lamp that selectively forms a light distribution pattern (PR) for rain driving and a high beam light distribution pattern (PH). The lamp includes: a light halogen bulb (18) configured to emit light and including: a low beam filament (18a) configured to form the light distribution pattern (PR); and a high beam filament (18b) configured to form the high light distribution (PH), a reflector (20) configured to reflect the light emitted from the light bulb in a vehicle forward direction, a reflective surface of the reflector being divided into, in a vehicle width direction: a first area (Z1) located on a traveling lane-side; a second area (Z2) located on an opposite lane-side; and a third area (Z3,Z4) located between the first area and the second area. A central axis (Ax1) of the light bulb is inclined upward with respect to an optical axis (Ax) of the reflector at a certain angle in the vehicle forward direction. The light distribution pattern (PR) includes: a first light distribution pattern (PR1) formed by the light reflected by the first area (Z1) of the reflective surface of the reflector, wherein the first light distribution pattern is formed to extend obliquely upward toward a lane mark (LM1) in front of the vehicle; and a second light distribution pattern (PR2) formed by the light reflected by the second area (Z2) of the reflective surface of the reflector, wherein the second light distribution pattern is formed to extend obliquely downward toward the lane mark and overlap with the first light distribution pattern in front of the vehicle.
According to the present invention, since the first light distribution pattern includes the cut-off line extending obliquely upward toward the traveling lane, it may be possible to brightly irradiate a traveling lane-side shoulder portion up to a distance without directing glare at drivers of preceding vehicles. Further, since the second light distribution pattern extends obliquely downward toward the lane marker so as to overlap with the first light distribution pattern, it may be possible to efficiently irradiate the lane mark, which is positioned on the lane marker of the road surface on the front side of a vehicle, without directing glare, which is caused by the light reflected from a road surface, at drivers of oncoming vehicles. Therefore, it may be possible to form a light distribution pattern for rain driving that is suitable for increasing forward visibility when a vehicle travels in the rain.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side cross-sectional view of a vehicle illumination lamp according to an embodiment of the invention;
Fig. 2 is a perspective view showing a light distribution pattern for rain driving, which is formed on a virtual vertical screen disposed at a position 25 m ahead of the lamp by light emitted forward from the vehicle illumination lamp, and a reflector unit;
Fig. 3 is the same view as Fig. 2 that shows a process for forming the light distribution pattern for rain driving; and
Figs. 4A to 4C are perspective views showing a high beam light distribution pattern, which is formed on the virtual vertical screen by light emitted forward from the vehicle illumination lamp.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention will be now described with reference to the drawings.
Fig. 1 is a side cross-sectional view of a vehicle illumination lamp 10 according to this embodiment.
As shown in Fig. 1, in the vehicle illumination lamp 10, a reflector unit 16 is assembled in a lamp chamber formed by a plane translucent cover 12 and a lamp body 14.
The reflector unit 16 includes an H4 halogen bulb 18 and a reflector 20 that reflects light emitted from the H4 halogen bulb 18 to the front side. The reflector unit is supported by an aiming mechanism (not shown) so as to be tilted with respect to the lamp body 14. Further, when aiming adjustment is completed, an optical axis Ax of the reflector 20 of the reflector unit 16 is disposed so as to extend in the longitudinal direction of a vehicle.
The H4 halogen bulb 18 includes a low beam filament 18a that is disposed on a central axis Ax 1 of the H4 halogen bulb and extends in the longitudinal direction; a high beam filament 18b that is disposed in the vicinity of the rear of the low beam filament 18a, is displaced slightly downward from the central axis Ax1, and extends in the longitudinal direction; and an inner shade 18c that is disposed in the vicinity of the lower side of the low beam filament 18a and surrounds the low beam filament 18a at a central angle of 165°.
The H4 halogen bulb 18 is inserted into an opening 20b, which is formed at the rear apex of the reflector 20, from the rear side and is fixed to the opening. The H4 halogen bulb is inserted and fixed so that the central axis Ax1 of the H4 halogen bulb 18 is inclined upward with respect to the optical axis Ax of the reflector 20 toward the front side at a predetermined angle θ (specifically, θ is about 30°) and both left and right upper end edges of the inner shade 18c are flush with each other.
The reflector 20 is adapted to reflect light, which is emitted from the low beam filament 18a or the high beam filament 18b, toward the front side in the form of diffuse light or deflected light by a reflective surface 20a thereof. Further, the reflector 20 is adapted to form a light distribution pattern for rain driving (which will be described below) when the low beam filament 18a is turned on, and to form a high beam light distribution pattern (which will be described below) when the high beam filament 18b is turned on.
Fig. 2 is a perspective view showing a light distribution pattern PR for rain driving, which is formed on a virtual vertical screen disposed at a position 25 m ahead of the lamp by light emitted forward from the vehicle illumination lamp 10, and the reflector unit 16.
As shown in Fig. 2, the reflective surface 20a of the reflector 20 is bilaterally symmetrical with respect to the optical axis Ax and has a horizontally long outer shape.
A reflective area of the reflective surface 20a, which is shown in Fig. 2 by a broken line, is a reflective area where light emitted from the low beam filament 18a does not enter due to the light blocking function of the inner shade 18c. On the reflective surface 20a, a boundary line L between a reflective area where the light emitted from the low beam filament 18a enters and a reflective area where the light emitted from the low beam filament does not enter extends obliquely downward from the optical axis Ax to both the left and right sides in a symmetrical shape as shown in Fig. 2 by a dashed-dotted line. This is due to the fact that both the left and right upper end edges of the inner shade 18c are positioned so as to be flush with each other.
The reflective surface 20a includes an upper reflective area 20a1 that is slightly larger than the upper half of the reflective surface 20a and a lower reflective area 20a2 that is the rest of the reflective surface. In this case, a boundary line between the upper reflective area 20a1 and the lower reflective area 20a2 is set to a position where the boundary line L is shifted somewhat downward in parallel.
The upper reflective area 20a1 of the reflective surface 20a has a structure where a plurality of reflective elements 20s is formed on the paraboloid of revolution having the optical axis Ax as a central axis. In this case, a focus F of the paraboloid of revolution is set to the position of the front end portion of the high beam filament 18b on the optical axis Ax as shown in Fig. 1.
As shown in Fig. 2, the upper reflective area 20a1 is divided substantially in the shape of a lattice by curves extending in a direction orthogonal to the boundary line L and curves extending substantially parallel to the boundary line L. Further, the plurality of reflective elements 20s are allocated to a plurality of segments, which is divided in this way, respectively.
Meanwhile, the lower reflective area 20a2 is formed of a single curved surface that is formed using the paraboloid of revolution as a reference surface.
The light distribution pattern PR for rain driving, which is shown in Fig. 2, is formed of four light distribution patterns PR1, PR2, PR3, and PR4.
The first light distribution pattern PR1 is a bright and small light distribution pattern that is formed by light reflected from a traveling lane-side peripheral area Z1 (an area shown in Fig. 2 by a two-dot chain line) of the upper reflective area 20a1.
The right end edge of the light distribution pattern PR1 is positioned in the vicinity of a line V-V that passes through H-V in the vertical direction, and the upper end edge of the light distribution pattern PR1 is formed as a cut-off line CL that has a high contrast ratio and extends obliquely upward from the vicinity of H-V toward the traveling lane. Further, the light distribution pattern PR1 is formed so that the right end portion of the light distribution pattern PR1 extends over a traveling lane-side lane mark LM1.
The second light distribution pattern PR2 is a bright and small light distribution pattern that is formed by light reflected from an opposite lane-side peripheral area Z2 (an area shown in Fig. 2 by a two-dot chain line) of the upper reflective area 20a1.
The right end edge of the light distribution pattern PR2 is positioned in the vicinity of the line V-V. The light distribution pattern PR2 is formed so as to extend obliquely downward from the vicinity of the lower portion of H-V toward the traveling lane. In this case, the light distribution pattern PR2 is formed so as to extend substantially along the traveling lane-side lane mark LM1, and the right end portion of the light distribution pattern PR2 overlaps with the light distribution pattern PR1.
The third light distribution pattern PR3 is a relatively large light distribution pattern that is formed by light reflected from a traveling lane-side general area Z3 (that is, an area except for the peripheral area Z1) of the upper reflective area 20a1.
The light distribution pattern PR3 is formed to extend obliquely downward toward the opposite lane at the position that is significantly displaced from the line V-V toward the opposite lane. In this case, the light distribution pattern PR3 is adapted to irradiate an opposite lane-side lane mark LM3.
The fourth light distribution pattern PR4 is a relatively large light distribution pattern that is formed by light reflected from an opposite lane-side general area Z4 (that is, an area except for the peripheral area Z2) of the upper reflective area 20a 1.
The light distribution pattern PR4 is formed so as to extend substantially along the traveling lane-side lane mark LM1 from the position that is slightly distant from H-V toward the left lower side, and the right end portion of the light distribution pattern PR4 overlaps with the light distribution patterns PR1 and PR2.
Fig. 3 is a perspective view showing a light distribution pattern PR₀, which is formed on the virtual vertical screen, and the reflector unit 16 if the upper reflective area 20a1 of the reflective surface 20a of the reflector 20 is formed in the surface shape of the paraboloid of revolution.
As shown in Fig. 3, the light distribution pattern PRo is formed substantially in the shape of a fan and includes a pair of (left and right) light/dark boundary lines PRo1 and PRo2 at the upper ends thereof. As described above, this is due to the fact that the central axis Ax1 of the H4 halogen bulb 18 is inclined upward with respect to the optical axis Ax of the reflector 20 at a predetermined angle θ and both the left and right upper end edges of the inner shade 18c are positioned so as to be flush with each other. In this case, the pair of (left and right) light/dark boundary lines PRo1 and PRo2 extends obliquely downward from the vicinity of H-V to both the left and right sides, and the downward angle of each of the light/dark boundary lines is set to a value of about 15°.
The four light distribution patterns PR1, PR2, PR3, and PR4 shown in Fig. 2 are formed by the diffusion deflection control of the light distribution pattern PRo that is performed by the plurality of reflective elements 20s that forms the upper reflective area 20a1. However, in this case, the light distribution pattern PR1 is formed so that the light/dark boundary line PRo1 of the light distribution pattern Pro is used as a cut-off line CL as it is.
Fig. 4A is a perspective view showing a high beam light distribution pattern PH, which is formed on the virtual vertical screen by light emitted forward from the vehicle illumination lamp 10.
The high beam light distribution pattern PH is formed of a composite light distribution pattern of five light distribution patterns PH1, PH2, PH3, PH4, and PA, and includes a hot zone HZ in the vicinity of H-V.
The four light distribution patterns PH1, PH2, PH3, and PH4 shown in Fig. 4B are light distribution patterns that correspond to the light distribution patterns PR1, PR2, PR3, and PR4 of the light distribution pattern PR for rain driving shown in Fig. 2, respectively.
In this case, these four light distribution patterns PR1, PR2, PR3, and PR4 are formed at a position that is optimal for forming the light distribution pattern PR for rain driving. Accordingly, the four light distribution patterns PH1, PH2, PH3, and PH4 are formed at positions that are somewhat deviated from H-V.
The light distribution pattern PA shown in Fig. 4C is a light distribution pattern that is formed by light reflected from the lower reflective area 20a2. The light distribution pattern PA is formed of a horizontally long light distribution pattern that extends from H-V as a center to the left and right sides, and includes a hot zone HZa in the vicinity of H-V. The hot zone HZ of the high beam light distribution pattern PH is mainly formed of the hot zone HZa of the light distribution pattern PA.
As described above, the vehicle illumination lamp 10 has been adapted to form the light distribution pattern PR for rain driving when the low beam filament 18a of the H4 halogen bulb 18 is turned on, and to form the high beam light distribution pattern PH when the high beam filament 18b of the H4 halogen bulb 18 is turned on. However, the vehicle illumination lamp 10 has been adapted to form the first light distribution pattern PR1, which includes the cut-off line CL extending obliquely upward toward the traveling lane, by the light reflected from the traveling lane-side peripheral area Z1 of the reflective surface 20a of the reflector 20; and to form the second light distribution pattern PR2, which extends obliquely downward toward the traveling lane so as to overlap with the first light distribution pattern PR1, by the light reflected from the opposite lane-side peripheral area Z2, as a part of the light distribution pattern PR for rain driving. Accordingly, it may be possible to obtain the following operational advantages.
That is, since the first light distribution pattern PR1 includes the cut-off line CL extending obliquely upward toward the traveling lane, it may be possible to brightly irradiate a traveling lane-side shoulder portion up to a distance without directing glare at drivers of preceding vehicles. Further, since the second light distribution pattern CL extends obliquely downward toward the traveling lane so as to overlap with the first light distribution pattern PR1, it may be possible to efficiently irradiate the lane mark LM1, which is positioned on the traveling lane of the road surface on the front side of a vehicle, without directing glare, which is caused by the light reflected from a road surface, at drivers of oncoming vehicles. Therefore, it may be possible to form a light distribution pattern PR for rain driving that is suitable for increasing forward visibility when a vehicle travels in the rain.
According to this embodiment, in the vehicle illumination lamp 10 capable of selectively forming the light distribution pattern PR for rain driving and the high beam light distribution pattern PH, it may be possible to form the light distribution pattern PR for rain driving, which is excellent in visibility of a far shoulder portion, with an inexpensive structure.
In the above-mentioned embodiment, it has been described that a specific value of a predetermined angle θ (that is, an upward angle of the central axis Ax1 of the H4 halogen bulb 18 with respect to the optical axis Ax) is about 3° (θ ≅3°). However, as long as the predetermined angle θ is in a range of 1 to 5°, the predetermined angle may be set to other values except for 3°.
In the above-mentioned embodiment, the first, second, and fourth light distribution patterns PR1, PR2, and PR4 and the third light distribution pattern PR3, which are formed at the positions separated from each other in the lateral direction, have been described as the light distribution pattern PR for rain driving. However, the third light distribution pattern PR3 may be used to irradiate the traveling lane-side lane mark LM 1.
Meanwhile, numerical values described as data in the above-mentioned embodiment are merely an example, and it goes without saying that these may be set to other appropriate values.
Further, the structure of the vehicle illumination lamp 10 for a vehicle that should keep to the left, has been described in the above-mentioned embodiment. However, if the vehicle illumination lamp 10 has a structure bilaterally symmetrical to the above-mentioned structure, the vehicle illumination lamp 10 may be suitable when vehicles should keep to the right.

Claims

A vehicle illumination lamp that selectively forms a light distribution pattern (PR) for rain driving and a high beam light distribution pattern (PH), the lamp comprising:
a light bulb (18) configured to emit light and comprising:
a low beam filament (18a) configured to form the light distribution pattern (PR); and

a high beam filament (18b) configured to form the high light distribution (PH),

a reflector (20) configured to reflect the light emitted from the light bulb in a vehicle forward direction, a reflective surface of the reflector being divided into, in a vehicle width direction:
a first area (Z1) located on a traveling lane-side;

a second area (Z2) located on an opposite lane-side; and

a third area (Z3,Z4) located between the first area and the second area,

wherein a central axis (Ax1) of the light bulb is inclined upward with respect to an optical axis (Ax) of the reflector at a certain angle in the vehicle forward direction,

wherein the light distribution pattern (PR) comprises:
a first light distribution pattern (PR1) formed by the light reflected by the first area (Z1) of the reflective surface of the reflector, wherein the first light distribution pattern is formed to extend obliquely upward toward a lane mark (LM1) in front of the vehicle; and

a second light distribution pattern (PR2) formed by the light reflected by the second area (Z2) of the reflective surface of the reflector, wherein the second light distribution pattern is formed to extend obliquely downward toward the lane mark and overlap with the first light distribution pattern in front of the vehicle.
The lamp according to claim 1, wherein the light bulb (18) further comprises:
an inner shade (18c) disposed below the low beam filament to surround the low beam filament so as to partially block light emitted from the low beam filament.
The lamp according to claim 1 or 2, wherein the reflector comprises a plurality of reflective elements (20s) that are allocated to a plurality of segments of the reflective surface.
The lamp according to any one of claims 1 to 3, wherein the light distribution pattern (PR) further comprises:
a third light distribution pattern (PR3) formed by the light reflected by the third area (Z3, Z4) of the reflective surface of the reflector, wherein the third light distribution pattern is formed to extend along the lane mark and overlap with the first and second light distribution patterns in front of the vehicle, and an irradiation area of the third light distribution pattern is larger than those of the first and second light distribution patterns.
The lamp according to any one of claims 1 to 4, wherein the light bulb is an H4 halogen bulb.