Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
2001-04-25
2003-03-04
Sember, Thomas M. (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S298000, C362S346000
Reexamination Certificate
active
06527426
ABSTRACT:
This invention claims the benefit of Japanese Patent Application No. 2000-126373, filed on Apr. 26, 2000, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle lamp for use in the illumination of a headlamp, fog lamp etc., and more particularly relates to a vehicle lamp that is thin and can form light distribution characteristics in a multi-reflex manner using an ellipse group reflector and a parabolic group reflector with high utilization efficiency of light emitted from a light source.
2. Description of the Related Art
FIG. 7
shows a conventional vehicle headlight
90
including a parabolic group reflecting surface such as a rotated parabolic surface.
FIG. 8
shows another conventional vehicle headlight
80
including an ellipse group reflecting surface such as a rotated elliptic surface.
The conventional vehicle headlight
90
includes a first light source
91
such as a filament of an incandescent lamp, a parabolic group reflecting surface
92
such as a rotated parabolic surface having a focus located at the back of the first light source
91
and a rotation axis on an optical axis X (i.e., an illumination direction of the conventional headlight
90
), a front lens
93
covering an aperture of the parabolic group reflecting surface
92
and having prismatic cuts
93
a
on its inner surface, and a shade
91
a
for formation of the low beam light distribution pattern. Since the first light source
91
is located in front of the focus of the parabolic group reflecting surface
92
, light reflected by an upper half of the reflecting surface
92
is directed downward. The shade
91
a
covers a lower half of the light source
91
to prohibit unnecessary upwardly directed light rays from being reflected by a lower half of the parabolic group reflecting surface
92
. A portion of upwardly directed light rays is required to illuminate the road side for and lighting road signs and/or pedestrians. In the case where the vehicle is driven in the left lane, the shape and location of the shade
91
a
are adjusted so as not to prohibit a predetermined portion of light rays which are to illuminate the upper left front view from the vehicle while prohibiting other portions of the upwardly directed light rays.
The vehicle headlight
90
further comprises a second light source
94
for the high beam light distribution pattern located substantially on the focus of the parabolic group reflecting surface
92
. No shade is arranged for the second light source
94
. A light distribution pattern of the vehicle headlight
90
is changed by switching the light source between the first light source
91
and the second light source
94
.
The conventional vehicle headlight
80
can be referred to as a projection-type headlight
80
and comprises an ellipse group reflecting surface
82
such as a rotated elliptic surface having a first focus and a second focus, a light source
81
on the first focus, a shading plate
84
in the vicinity of the second focus, and a projection lens
83
having its focus in the vicinity of the second focus. The projection lens
83
has a convex lens on the front side, and a planar surface on the rear side relative to an optical axis X of the vehicle headlight
80
. Light reflected by the ellipse group reflecting surface
82
converges to the second focus. An image of the luminous flux at the second focus is projected upside-down in the illumination direction X by the projection lens
83
. On formation of low-beam mode light distribution pattern, the shading plate
84
prohibits a substantial lower half portion of luminous flux that converges at the second focus. The prohibited luminous flux would have been upwardly directed light rays after being projected by the projection lens
83
. Accordingly, the image of luminous flux at the second focus has, in a cross section, a substantial upper chord located in an upper half of a circle. The image of the substantial upper chord is reversed upside-down when the luminous flux passes through the projection lens
83
. Thus, the vehicle headlight
80
provides a low-beam mode light distribution pattern that does not include upwardly-directed light rays.
More specifically, the shading plate
84
prohibits not all of, but an unnecessary portion of, a lower half of the luminous flux at the second focus. A portion of the lower half of the luminous flux at the second focus which is to be upwardly directed light rays after passing through the projection lens
83
is permitted passageway to illuminate a road side. In the case where the vehicle is driven in the left lane, the shape and location of the shading plate
84
are adjusted so as not to prohibit a predetermined portion of the lower half of luminous flux at the second focus that illuminates the upper left front view from the vehicle after passing through the projection lens
83
, while prohibiting other portions of the lower half of luminous flux at the second focus. When the vehicle headlight
80
changes its light distribution pattern mode from low-beam to high-beam, the shading plate
84
is moved away from luminous flux converged at the second focus. In the conventional projection-type vehicle headlight
80
, the shading plate
84
is located perpendicular to the optical axis X of the ellipse group reflecting surface
82
.
Conventional vehicle headlights
90
and
80
have at least the following problems. First, the conventional vehicle headlights
90
and
80
respectively include a shade
91
a
and shading plate
84
. The shade
91
a
and shading plate
84
respectively prohibit substantially half of the total light amount emitted from the first light source
91
and light source
81
. Therefore, utilization efficiency of light emitted from the first light source
91
and light source
81
in low-beam mode is small, giving the impression that the vehicle headlights
90
and
80
are dark in comparison with light amounts emitted from the first light source
91
and light source
81
, respectively.
The conventional vehicle headlights
90
and
80
also have restricted design flexibility. From a view point of automobile body design, it is preferable for the vehicle headlights
90
and
80
to have a large width and a small height in front view. In the conventional vehicle headlight
80
, it is possible to have a smaller height. However, it is difficult, if not impossible, to have a larger width. In the conventional vehicle headlight
90
, there exits a limit to which the height of the headlight can be reduced while satisfying functional requirements of the headlight. Reduction of the height also results in decreasing utilization efficiency of lumen output by the parabolic group reflecting surface
92
. Accordingly, it is difficult to greatly change the current design of the conventional vehicle headlights
90
and
80
.
SUMMARY OF THE INVENTION
In order to solve the aforementioned problems in the related art, in the present invention, a vehicle light can include a light source, at least a pair of ellipse group reflecting surfaces configured to symmetrically surround the light source. Each ellipse group reflecting surface can have a first focus located on the light source, and can have a longitudinal axis that is perpendicular to an optical axis of the vehicle light. The same number of parabolic group reflecting surfaces as ellipse group reflecting surfaces can be located substantially linearly so as to cause light rays to be directed in predetermined directions from the vehicle light. Each parabolic group reflecting surface can have a focus located substantially on the second focus of one of the ellipse group reflecting surfaces, and can have an optical axis that is substantially parallel to the optical axis of the vehicle light. A shading plate can be located in the vicinity of the second focus of one of the ellipse group reflecting surfaces for providing a predetermined shape to luminous flux that converges from the ellipse group reflecting surface.
In accordance with another aspect of the inv
Adachi Go
Kawaguchi Yoshifumi
Okamoto Masahito
Oyama Hiroo
Morgan & Lewis & Bockius, LLP
Sember Thomas M.
Stanley Electric Co., LTD
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