Vehicle light capable of changing light distribution pattern...

Details Vehicle light capable of changing light distribution pattern... Vehicle light capable of changing light distribution pattern...

2001-12-26

2003-04-08

Sember, Thomas M. (Department: 2875)

Illumination

Light source and modifier

Including reflector

C362S346000, C362S351000, C362S512000, C362S319000

Reexamination Certificate

active

06543910

ABSTRACT:

This invention claims the benefit of Japanese Patent Applications No. 2000-392979, filed on Dec. 25, 2000, and No. 2001-190196, filed on Jun. 22, 2001, which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle light for use as an automobile headlight, and more particularly relates to a vehicle light including a single light source capable of switching modes of a light distribution pattern between a low-beam mode and a high-beam mode by a movable shutter. The structure of the present invention is directed to a case wherein it may be difficult to have two light sources such as when an incandescent lamp or a discharge lamp is adopted as a light source of the vehicle light.
2. Description of the Related Art
FIG. 18
illustrates a conventional vehicle light
90
comprising a single light source
91
a
capable of switching modes of a light distribution pattern. The vehicle light
90
comprises a high intensity discharge lamp
91
such as a metal halide lamp. A discharge arc
91
a
of the high intensity discharge lamp
91
is the light source for the conventional vehicle light
90
. The vehicle light
90
also comprises a reflector
92
of an ellipse group reflecting surface such as a rotated elliptic surface
92
having a first focus f
1
on the light source
91
a
and a second focus f
2
. The vehicle light
90
further comprises a shutter
93
located in the vicinity of the second focus f
2
of the ellipse group reflecting surface
92
, and a projection lens
94
of a convex lens having a focus in the vicinity of the second focus f
2
.
Light rays emitted from the light source
91
a
directly to the ellipse group reflecting surface
92
are reflected thereby and converge in the vicinity of the focus f
2
of the projection lens
94
. Light rays travel from the ellipse group reflecting surface
92
to its second focus f
2
such that the light rays collectively form luminous flux having a shape of a substantial cone with an apex approximately on the second focus f
2
in a cross-section along an optical axis X of the vehicle light
90
. Light rays converged in the vicinity of the second focus f
2
of the ellipse group reflecting surface
92
provide a focused image of light. Since the second focus f
2
of the ellipse group reflecting surface
92
is also a focus of the projection lens
94
, the projection lens
94
projects the focused image of light upside down with its left side to be the right side in a forward direction while enlarging the focused image, whereby the vehicle light
90
illuminates a predetermined front area on a road. The shutter
93
can be selectively inserted in, and removed from, the cone-like luminous flux. When the shutter
93
is inserted in the luminous flux, the shutter
93
cuts off an unnecessary portion of light to form a low-beam mode light distribution pattern of the vehicle light
90
. The unnecessary portion of light is typically a portion which generally illuminates in an upper right forward direction of the vehicle after being projected by the projection lens
94
, which can be glare light to a driver of a car driving on an on-coming lane (when driving forward on the left side of the road). The shutter
93
in its inserted position cuts off a lower area of a chord located in a lower half of a circular cross-sectional image of the cone-like luminous flux in the vicinity of the second focus f
2
, thereby the remaining luminous flux provides an approximate upper half of the circular cross-section. After passing through the projection lens
94
, the image of an approximate upper half of the circular cross-section becomes an image of an approximate lower half of the circular cross-section. Accordingly, a low-beam mode light distribution pattern of the vehicle light
90
is obtained.
In the high-beam mode of the vehicle light
90
, the shutter
93
is removed from the cone-like luminous flux. When the shutter
93
is removed from the cone-like luminous flux, an image of light rays converged in the vicinity of the second focus f
2
of the ellipse group reflecting surface
92
is substantially circular and is consistent with the circular cross-section of the cone-like luminous flux. At this time, light rays traveling in an upward direction from the vehicle light
90
are included such that a far distant front area is illuminated.
The conventional vehicle light
90
has several drawbacks, some of which include the following problems. In the low-beam mode, a substantial half of the luminous flux from the ellipse group reflecting surface
92
is cut-off by the shutter
93
. Accordingly, a light amount illuminated from the vehicle light
90
is reduced to approximately half of a light amount emitted from the light source
91
a.
In most times of operation, the vehicle light
90
is operated in its low-beam mode due to increased traffic in recent years. Therefore, the loss of light in a low-beam mode operation has become a significant problem from viewpoints of utilization efficiency of light emitted from the light source
91
a
and long distance visibility of the vehicle light
90
.
Further, in the conventional vehicle light
90
comprising an ellipse group reflecting surface
92
, it is difficult to form a large diameter of the projection lens
94
. Since the projection lens
94
converges light rays incident thereto by a predetermined degree, the illumination angle of the vehicle light
90
tends to be laterally small. Additionally, during operation of the vehicle light
90
, the light emitting area of the vehicle light
90
is smaller than that of other types of conventional vehicle lights without the projection lens
94
. Accordingly, visibility from a viewpoint of an on-coming vehicle or people is deteriorated in comparison with other types of conventional vehicle lights without the projection lens
94
.
SUMMARY OF THE INVENTION
In order to resolve the aforementioned drawbacks and problems in the related art, the present invention provides vehicle lights that can include the following structures. In a first aspect of the present invention, a vehicle light includes a single light source capable of switching a light distribution pattern between low-beam mode and high-beam mode by a movable portion, a first reflecting surface whose longitudinal direction is along an optical axis X of the vehicle light, and having a first focus in the vicinity of the light source, for reflecting light rays from the light source forward, a projection lens, and a shutter for providing a predetermined shape to the light rays from the first reflecting surface on formation of a low-beam mode light distribution pattern by being selectively inserted in the luminous flux from the first reflecting surface to the projection lens. The vehicle light can also include a second reflecting surface of an ellipse group reflecting surface having its first focus approximately on the light source and its second focus at a predetermined position; at least one third reflecting surface having a first focus in a predetermined position and at least one second focus in at least one predetermined position; a fourth reflecting surface having a focus approximately on the second focus of the second reflecting surface for reflecting light rays in a predetermined forward direction. When the third reflecting surface is located in its inserted position relative to the luminous flux from the second reflecting surface to the fourth reflecting surface, the first focus of the at least one third reflecting surface is preferably substantially on the second focus of the second reflecting surface, and the movable portion includes the shutter and the at least one third reflecting surface.
In another aspect of the present invention, the corresponding second focus of the at least one third reflecting surface can be located in the horizontal vicinity of the focus of the first reflecting surface.
In yet another aspect of the present invention, the at least one third reflecting surface and its corresponding second focus can be located at the

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