Electric lamp and discharge devices – With temperature modifier – Double wall – jacket or casing for envelope
Reexamination Certificate
2002-11-05
2003-11-25
O'Shea, Sandra (Department: 2875)
Electric lamp and discharge devices
With temperature modifier
Double wall, jacket or casing for envelope
C313S318010, C313S318020, C313S318100
Reexamination Certificate
active
06653764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a discharge bulb to be used in a headlamp for a vehicle and a method of manufacturing the discharge bulb.
2.Description of the Related Art
Since a discharge bulb can carry out high luminance irradiation, it has recently been used in a headlamp for a vehicle very often.
As described in Japanese laid open publication Hei 11-176319, for example, there has been known a discharge bulb to be used in a headlamp for a vehicle which comprises an arc tube unit
102
including an arc tube
104
and a shroud tube
106
cylindrically surrounding the arc tube
104
, and a plug member
108
for fixing and supporting a base end
102
a
of the arc tube unit
102
as shown in FIG.
6
.
In such a discharge bulb, it is optically important that a discharge light emitting section
104
a
of the arc tube
104
is provided with a predetermined positional relationship with an optical datum plane Po of the plug member
108
. For this reason, the arc tube unit
102
is fixed and supported on the plug member
108
in the following manner.
More specifically, a metal band
110
is fastened and fixed to the shroud tube
106
on the base end
102
a
of the arc tube unit
102
, and furthermore, a slider fixture
112
is welded to the metal band
110
. In such a state that the slider fixture
112
is set into a predetermined jig (not shown), the metal band
110
is caused to slide with respect to the slider fixture
122
, thereby carrying out a necessary position adjustment. Thus, the welding is carried out in such a state that the discharge light emitting section
104
a
of the arc tube
104
and the optical reference plane Po of the plug member
108
have a predetermined positional relationship. Then, the slider fixture
112
is caused to abut on a metallic base plate
114
which is previously fixed to the plug member
108
and both of them are thus welded to each other. Consequently, the arc tube unit
102
is fixed and supported on the plug member
108
.
In the conventional discharge bulb, however, there is a problem in that a structure for fixing and supporting the arc tube unit
102
on the plug member
108
is complicated, and furthermore, a manufacturing process is also complicated.
In addition, the metal band
110
is to be tightly fastened and fixed to the shroud tube
106
so as not to be loosened easily. Therefore, there is a problem in that the shroud tube
106
is often damaged, for example, broken by the fastening force.
SUMMARY OF THE INVENTION
The invention has been made in consideration of the circumstances and has an object to provide a discharge bulb capable of fixing and supporting an arc tube unit to a plug member with a simple structure in a simple process without damaging, for example, breaking a shroud tube, and a method of manufacturing the discharge bulb.
The invention achieves the object by such a structure that the arc tube unit is fixed and supported on the plug member through a predetermined glass tube.
More specifically, the invention provides a discharge bulb comprising an arc tube unit including an arc tube and a shroud tube cylindrically surrounding the arc tube, and a plug member for fixing and supporting a base end of the arc tube unit,
wherein a glass tube is fixed to the plug member, the base end of the arc tube unit is inserted in the glass tube and the shroud tube of the arc tube unit and the glass tube are bonded and fixed to each other.
Moreover, the invention provides a method of manufacturing a discharge bulb comprising an arc tube unit including an arc tube and a shroud tube cylindrically surrounding the arc tube, and a plug member for fixing and supporting a base end of the arc tube unit, comprising the steps of:
inserting the base end of the arc tube unit in a glass tube which is previously fixed to the plug member; and
bonding and fixing the shroud tube and the glass tube to each other in such a state that an amount of insertion of the arc tube unit is regulated in order to set a dimension between an optical reference plane of the plug member and a predetermined position of a discharge light emitting section of the arc tube to be a predetermined set dimension.
If the “glass tube” in which the base end of the arc tube unit can be inserted and which can be bonded and fixed to the shroud tube is used, a specific structure such as a length, a sectional shape or a material is not particularly restricted. Moreover, the method of fixing the “glass tube” to the plug member is not particularly restricted.
If the “predetermined position of the discharge light emitting section” of the arc tube can be specified, a specific position thereof is not particularly restricted. For example, it is possible to employ a tip position of one of a pair of electrodes constituting the arc tube or a central position between a pair of electrodes.
REFERENCES:
patent: 5386173 (1995-01-01), Kosmatka
patent: 5757110 (1998-05-01), Motiduki et al.
patent: 8-162007 (1996-06-01), None
patent: 11-176319 (1999-07-01), None
Iwai Takahiro
Kato Ken
Koito Manufacturing Co. Ltd.
Krishnan Sumati
O'Shea Sandra
Sughrue & Mion, PLLC
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