Illumination – Supported by vehicle structure – Adjustable lamp or lamp support
Reexamination Certificate
2002-12-02
2004-03-23
Tso, Laura K. (Department: 2875)
Illumination
Supported by vehicle structure
Adjustable lamp or lamp support
C362S286000, C362S523000, C362S532000
Reexamination Certificate
active
06709140
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a vehicle headlamp unit with a light source of a discharge lamp, and to a vehicle headlight with the headlamp unit.
DESCRIPTION OF THE RELATED ART
A conventional headlight for a motor vehicle typically used was a projector type headlight or a multi-reflector type headlight with a light source of a halogen light bulb (iodine light bulb), a lens and a precisely condensing reflector arranged around the halogen bulb.
The projector type headlight adopts a standardized PE (poly-ellipsoid) reflector or DE (three dimensional ellipsoid) reflector, and the multi-reflector type headlight adopts a MS (multi-surface) reflector.
The halogen light bulb used for the headlight is nearly a point source of light with a relatively high efficiency of about 20 lumens/watt and a consumption power of 35-60 watts. Such halogen bulb operates at a low power voltage of 12 or 24 volts and therefore no specific electrical insulation is required. An average lifetime of the halogen bulb is about 400 hours. Due to the difference of bulb shapes, there are a plurality of specifications in the halogen bulb such as H-1 type, HB-1 type, H-4 type, HB-4 type, HB-5 type and H-7 type. For each type, a shape and a dimension of a light-bulb base made of plastic or ceramic are standardized.
In the past, the switching between high beam mode and low beam mode in the halogen bulb vehicle headlight had been performed by selectively turning-on one of two halogen bulbs respectively disposed at centers of the high beam reflector and the low beam reflector. Recently, such switching is performed by selectively turning-on one of two filaments in a single halogen light bulb, which are disposed with a distance of several millimeters each other. Namely, high beam light distribution is obtained by tuning-on only the high beam filament and by reflecting light from the filament at a reflector, whereas low beam light distribution is obtained by tuning-on only the low beam filament and by reflecting light from the filament at the same reflector in different condensing manner. The halogen bulbs of H-4 type, HB-1 type and HB-5 type are such two filaments bulbs.
FIGS. 1
a
and
1
b
show a cross sectional view and a side view of a HB-1 type halogen bulb with two filaments for high beam and low beam, and
FIG. 2
shows a side view of the halogen bulb fitted in a socket that is fixed to a base.
As shown in these figures, the HB-1 type halogen bulb
10
has a high beam filament
12
and a low beam filament
13
in a glass capsule
11
. The high beam filament
12
and the low beam filament
13
are located at different positions each other along a direction substantially perpendicular to the light axis Z of the halogen bulb. The halogen bulb
10
is fitted in the specific socket
14
that is fixed to the specific base
15
. A black lightproof coating
16
is applied to the top end section of the glass capsule
11
to provide no glare from the filaments. Three terminal electrodes (including common grand electrode)
17
for the two filaments are formed in the rear of the base
15
as shown in FIG.
2
. These electrodes
17
are electrically connected to a lighting circuit through lead lines, connectors and ground (not shown).
FIGS. 3
a
and
3
b
show a cross sectional view and a side view of a HB-5 type halogen bulb with two filaments for high beam and low beam.
As shown in these figures, the HB-5 type halogen bulb
30
also has a high beam filament
32
and a low beam filament
33
in a glass capsule
31
. The high beam filament
32
and the low beam filament
33
are located at different positions each other along a direction substantially perpendicular to the light axis Z as well as in HB-1 type halogen bulb. A black lightproof coating
36
is applied to the top end section of the glass capsule
31
to provide no glare form the filaments.
The high beam filament
12
and the low beam filament
13
of the above-mentioned halogen bulb
10
are spaced by several millimeters from each other along a direction substantially perpendicular to the light axis Z as well as the high beam filament
32
and the low beam filament
33
of the halogen bulb
30
. The filaments
12
and
13
of the HB-1 type halogen bulb
10
run along a direction perpendicular to the light axis Z whereas the filaments
32
and
33
of the HB-5 type halogen bulb
30
run along a direction parallel to the light axis Z. The length of these filaments
12
,
13
,
32
and
33
is about 5 millimeters.
Recently, the adoption of a headlamp unit with a high intensity discharge (HID) lamp is studied and put partially to practical use as a next-generation vehicle headlight instead of the vehicle headlight using the halogen bulb(s).
The discharge lamp used in such vehicle headlamp unit operates with a high power voltage of about 20,000 volts, and radiates light with a extremely high efficiency of about 100 lumens±15%/watt for example. Thus, the discharge lamp provides light flux substantially twice as strong as that of the halogen bulb and low power consumption, typically about 35 watts. Further, the discharge lamp has a lifetime of about four times as long as that of the halogen bulb. Therefore, the discharge lamp saves energy and thus is extremely ideal for a vehicle headlight.
However, a conventional vehicle headlamp unit using such discharge lamp has following disadvantages:
(1) It is impossible to form two light sources in a single bulb like as H4 type, HB-1 type and HB-5 type halogen bulbs;
(2) Mounting of two individual discharge lamps near the center of a reflector is difficult due to no enough space and causes the design of the reflector to make difficult and the manufacturing cost of the reflector to increase; and
(3) Glare cannot be prevented if a discharge lamp is substituted for a halogen bulb in the vehicle headlamp unit.
The applicant of this application has proposed, in U.S. Pat. Ser. No. 09/562,863, a vehicle headlamp unit with a discharge lamp, a shade arranged near the discharge lamp and a moving means for relatively moving the discharge lamp and the shade relative to each other by sliding one of them in a direction along the light axis of the headlamp unit or by rotating one of them so as to switch between high beam mode and low beam mode.
However, this proposed headlamp unit cannot be compatible with a headlamp unit with a halogen bulb having a high beam filament and a low beam filament located at different positions each other along a direction substantially perpendicular to the light axis Z, such as an HB-5 type halogen bulb or an HB-1 type halogen bulb. Namely, in case of the proposed headlamp unit relatively moving the discharge lamp and the shade by sliding one of them in a direction along the light axis, positions of the light source will differ from the filament positions of the HB-5 type or HB-1 type halogen bulb as a matter of course. In case of the proposed headlamp unit for relatively moving the discharge lamp and the shade by rotating one of them, the light axis direction will change causing its light distribution to differ from that of the headlamp unit with the HB-5 type or HB-1 type halogen bulb.
For the halogen bulb used for vehicle headlight, a black lightproof coating is in general applied to its top end section so as to shield light along the light axis Z and thus to prevent glare from the filaments, as shown in
FIGS. 1
b
,
2
and
3
b
. However, in case of the discharge lamp, it is impossible to apply such black lightproof coating to its top end section due to its shape and size.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a vehicle headlamp unit with a discharge lamp and a vehicle headlight with the headlamp unit, whereby it is compatible with a headlamp unit with a halogen bulb that has a high beam filament and a low beam filament located at different positions each other along a direction substantially perpendicular to the light axis, and can provide correct light distributions of high beam mode and low beam mode as well as the halogen bulb
Arent Fox Kintner & Plotkin & Kahn, PLLC
Asahi Rise Co., Ltd.
Tso Laura K.
LandOfFree
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