Vehicle headlight

Details Vehicle headlight Vehicle headlight

2002-08-07

2003-06-10

Sember, Thomas M. (Department: 2875)

Illumination

Supported by vehicle structure

Light modifier

C362S297000, C362S346000, C362S512000

Reexamination Certificate

active

06575609

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle lamp, and more particularly to a vehicle headlight generally referred to as a projector-type headlight (Poly Ellipsoid Headlamp; PES) using an ellipse group reflecting surface (e.g., a spheroid reflecting surface), a projection lens with an aspheric surface, and a shutter for adjusting a light distribution characteristic. The light can be configured to switch between a meeting-beam (or low-bean) distribution and a running-beam (or high-beam) distribution.
2. Description of the Related Art
Referring now to
FIG. 1
, a conventional projector-type headlight
90
will be described. The projector-type headlight
90
comprises a light source
91
, an ellipse group reflecting surface
92
, a shutter
93
, and a projection lens
94
. The ellipse group reflecting surface
92
is a reflecting surface configured as a spheroid, a complex ellipse, or the like, having a first focus f
1
and a second focus f
2
. The light source
91
is arranged at a position corresponding to the first focus f
1
, while the shutter
93
is arranged at a position in the vicinity of the second focus f
2
of the ellipse group reflecting surface
92
. The focus of the projection lens
94
is arranged in the vicinity of the shutter
93
. In the projector-type headlight
90
thus constructed, the movement of the shutter
93
allows a desired low-beam distribution pattern and a desired high-beam distribution pattern in a selective manner.
More specifically, in a vehicle headlight constructed as described above, a light beam from the light source
91
is reflected by the ellipse group reflecting surface
92
and is then provided as reflection light having a generally circular cross section that converges at the second focus. A lower half of the reflection light is shaded when the shutter
93
is placed in the optical path of the reflection light. Thus, the resulting reflected light is shaped as a generally upper semicircular part. The generally upper semicircular part of the reflected light is projected in the irradiation direction and turned upside down by the projection lens
94
to become a lower semicircular part of the reflected light. In other words, as shown in
FIG. 2
, a light distribution pattern HS suited for low-beam distribution, which does not include high beam light rays, can be obtained.
On the other hand, the shutter
93
may be configured to be movable. If a high-beam distribution pattern is required, the shutter
93
can be withdrawn from the optical path of the light reflected from the reflecting surface
92
. Thus, the lower semicircular part of the reflected light which can form a high bean and which is shaded by the shutter
93
in low-beam mode is allowed to be projected as irradiation light, resulting in a high-beam distribution pattern HM as shown in FIG.
3
.
In the conventional projector-type headlight
90
, however, the lower half of the reflected light from the ellipse group reflecting surface
92
is shaded at the time of low-beam distribution. As a result, the amount of light provided by the low-beam distribution can be poor in supply. To solve such a disadvantage, in general, an insufficient amount of light is compensated by, for example, inclining the optical axis of the headlight to the lower left side when it is intended for driving on the left-hand side (In Japan, automotive vehicles drive on the left side) such that the portion corresponding to the point P that has a high degree of brightness is not shaded by the shutter
93
(see FIG.
2
).
On the other hand, if the shutter
93
is withdrawn from the above configuration of the headlight which provides adequate low-beam distribution, there is not enough irradiated light directed to the front (see FIG.
3
). Therefore, there is another problem in that there is insufficient distance visibility for high-beam distribution.
In the projector-type headlight
90
, generally, there is a further problem of poor visibility in both left and right directions because the width of irradiation light in these directions is not enough.
SUMMARY OF THE INVENTION
In order to solve the above and other problems of the conventional art, therefore, it is an object of the present invention to provide a projector-type vehicle headlight, by which a low-beam distribution and a high-beam distribution can be selectively employed, and unused light can be effectively used as reflection light in each of the low- and high-beam distributions. The projector-type headlight is especially capable of attaining a sufficient illumination in the high-beam distribution.
Furthermore, it is another object of the present invention to provide a headlight capable of improving visibility by applying a sufficient illumination in both left and right directions at the time of high-beam distribution.
In order to attain the objects of the invention, a vehicle headlight according to the present invention can be embodied in a device that includes a light source; a first ellipse group reflecting surface having an optical axis direction substantially corresponding to the irradiation direction of the headlight, the first ellipse group reflecting surface having a first focus and a second focus, the first focus being located substantially at the light source, the first ellipse group reflecting surface configured to reflect light irradiated from the light source in the irradiation direction of the headlight; a projection lens having a focus in the irradiation direction of the headlight and in the vicinity of the second focus of the first ellipse group reflecting surface, the projection lens configured to project light irradiated from the light source and light reflected from the first ellipse group reflecting surface in the irradiation direction; a second ellipse group reflecting surface having an optical axis crossing the optical axis of the first ellipse group reflecting surface, the second ellipse group reflecting surface having a primary focus and a secondary focus, the primary focus of the second ellipse group reflecting surface located substantially at the light source; a first parabolic group reflecting surface having a focus located substantially at the secondary focus of the second ellipse group reflecting surface, the first parabolic group reflecting surface configured to reflect light reflected from the second ellipse group reflecting surface in the irradiation direction of the headlight; a second parabolic group reflecting surface having an optical axis substantially corresponding to the irradiation direction of the headlight, the second parabolic group reflecting surface having a focus located in the vicinity of-the light source, the second parabolic group reflecting surface being arranged in the irradiation direction side from the first ellipse group reflecting surface; and a shutter provided in the vicinity of the focus of the projection lens, the shutter being capable of being placed in and withdrawn from an optical path of light reflected from the first ellipse group reflecting surface, the shutter having a shutter part and a shade part, the shutter part providing a low-beam light distribution pattern by being placed in the optical path of the reflected light from the first ellipse group reflecting surface and providing a high-beam light distribution pattern by being withdrawn from the optical path, the shade part shading light traveling from the light source to the second parabolic group reflecting surface when the shade is in a first position, and providing light from the light source to the second parabolic group reflecting surface when the shade is in a second position.
In the above configuration of the vehicle headlight, at first, when the headlight is in the low-beam distribution (which is normally used), unused light from the first ellipse group reflecting surface is captured on the second ellipse group reflecting surface, and the captured light is then projected from the first parabolic group reflecting surface toward the irradiation direction to allow the headlight to p

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