Illumination – Supported by vehicle structure – Light modifier
Reexamination Certificate
2000-09-12
2002-10-29
Sember, Thomas M. (Department: 2875)
Illumination
Supported by vehicle structure
Light modifier
C362S518000, C362S298000, C362S299000, C362S356000
Reexamination Certificate
active
06471383
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to headlamps for vehicles, and particularly relates to a headlamp for a vehicle, being capable of improving luminous flux efficiency to a light source and performance of the lamp, and also capable of providing an original design for appearance of the headlamp which has not been existed. Furthermore, the present invention relates to a headlamp for a vehicle, being capable of changing luminous intensity distribution properties for driving and for passing-by (or so-called “high-beam” and “low-beam”) by utilizing a single light source.
2. Detailed Description of the Prior Art
FIGS. 1
to
3
show constructions of conventional a headlamp for a vehicle. Lamp
90
shown in
FIG. 1
is composed of a light source
91
, a revolved parabolic reflector
92
in which the light source
91
is positioned at its focal point, and a lens
93
having lens cuts
93
a
provided thereon. Light emitted from the light source
91
is reflected by the above mentioned revolved parabolic reflector
92
so as to become parallel with reference to the optical axis of the light source. The reflected light is diffused appropriately by the lens cuts
93
a
to obtain a required luminous intensity distribution property.
Moreover, lamp
80
shown in
FIG. 2
is composed of a light source
81
, a composite reflector
82
, and a lens
83
. The composite reflector
82
is composed of a plurality of parabolic columnar reflectors in which a parabola appears in a horizontal cross section when the lamp
80
is installed. Incidentally, the light source
81
is arranged at the focal point of the parabola. Further, the lens
83
is not provided with any lens cut formed thereon and is plain. In this lamp
80
, a luminous intensity distribution property thereof can be adjusted by the above-mentioned composite reflector
82
itself. Furthermore, lamp
70
shown in
FIG. 3
is composed of a light source
71
, an elliptic type reflector
72
, an aspheric lens
73
, and a shade
74
if required. The elliptic type reflector
72
has a first focal point f
1
where the light source
71
is positioned and is composed of elements such as revolved ellipsoidal reflector, composite ellipsoidal surface, ellipsoidal free curved surface or the like. In this case, the major axis of the elliptic type reflector
72
coincides with the illuminating direction and a light source image is generated by focusing it at the second focal point f
2
thereof. Illuminating light can be obtained by enlarging and projecting the light source image by the aspheric lens
73
. A desired luminous intensity distribution property can be obtained by shielding an unnecessary portion of light by means of the shade
74
(in the shown conventional example, the lower half of luminous flux converging at the second focal point f
2
is shielded). Incidentally, the lamp system employing this type of elliptic type reflector
72
is called a projector type lamp.
However, out of the above-mentioned prior art lamps, for the lamp
90
shown in
FIG. 1
the lens cuts
93
a
need to have a large optical power. As a result, the change in thickness of the lens
93
becomes large, which deteriorates transparency thereof. Accordingly, there are problems in that it is impossible to provide a suitable lamp appearance having transparency and a preferable depth to which consumers prefer in the market.
Furthermore, in the lamp
80
shown in
FIG. 2
, since the lens
83
is plain with no lens cut provided thereon, a suitable lamp appearance having a superior transparency can be obtained. However, it is difficult to ensure a luminous intensity distribution property in a width direction because the luminous intensity distribution property is formed by the composite reflector
82
positioned relatively deep. As a result, there is a problem in that formation of luminous intensity distribution property is limited.
Further, it is difficult to install the lamp
70
shown in
FIG. 3
because of its depth. In addition, the illuminating area is small due to the small diameter of the employed aspheric lens
73
. When the lamp
70
is employed as a headlamp, visibility thereof from opposed vehicles may be deteriorated.
In addition to the above-mentioned problems, since the lamps
90
,
80
,
70
having the above-mentioned prior art construction are widely employed, it is difficult to discriminate between these lamps and the other ones and also obtain an original design. Furthermore, each luminous flux efficiency of the lamps
90
,
80
,
70
having the above-mentioned prior art configurations is affected in response to the area of the reflector. Thus, when the lamp is reduced in its dimension (for example, making it thinner in width or both vertical and horizontal dimensions be made smaller) due to the demand in the market, the brightness thereof becomes significantly lower.
Besides, cross-sectional shape of luminous flux in the lamp
70
shown in
FIG. 3
near the shade
74
is a semicircular shape (lower half of circle). When the luminous flux having such the shape is projected toward the illuminating direction by the projector lens
73
having a focal point f
3
near the shade
74
, the luminous flux is made inverted and emitted to have an upper half of circle shape toward the illuminating direction. Thus, a luminous intensity distribution shape suitable for passing-by can be obtained because the projected light does not contain any upward light which is the cause of dazzling light for opposed vehicles. However, in actual operation, in order to readily recognize walkers passing by or road signs, a shade
74
is modified to generate an appropriate light in the upper left-side direction for left-side traffic.
In this lamp
70
, however, almost half of the reflected light from the elliptic type reflector
72
is shielded by the shade
74
as clearly shown in the above-described explanation, as a result the luminous flux efficiency to the light source
71
is lowered and there is another problem in that the lamp
70
is relatively darker for energy consumption.
Moreover, it has been proposed that with this type of a projector headlamp
70
provided is a luminous intensity distribution switching means for changing luminous intensity distribution properties for driving and for passing-by by retreating, for example, a shade
74
from the luminous flux of the light reflected from the elliptic type reflector
72
. In this case, however, any control for the shape of the luminous intensity distribution property is not substantially carried out and there is still another problem in that any luminous intensity distribution property for practical use can not be obtained.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a headlamp for a vehicle being capable of improving luminous flux efficiency to a light source and increasing its brightness further even when the same light source is used. Another object of the present invention is to provide a headlamp for a vehicle being capable of providing an original design for appearance of the headlamp which has not been existed without decreasing the luminous intensity even when the height thereof is decreased.
In order to achieve the above-mentioned objects, the present invention provides a headlamp for a vehicle, comprising a light source; a first reflector formed of a parabolic reflector and having a focal point at which the light source is positioned; a light guide passage for guiding light to the backside of the first reflector, provided at an appropriate position thereof; a second reflector formed of a parabolic reflector and provided outside thereof corresponding to the light guide passage of the first reflector; a third reflector provided in the vicinity of an optical axis of the first reflector for converging and transmitting a light from the light source to the vicinity of the light guide passage; and a lens provided in front of the first and second reflectors in an illuminating direction.
According to the headlamp for a vehicle of the present invention
Adachi Go
Kawaguchi Yoshifumi
Okamoto Masahito
Oyama Hiroo
Choi Jacob Y.
Sember Thomas M.
Stanley Electric Co. Ltd.
Weingarten Schurgin, Gagnebin & Lebovici LLP
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