Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-06-15
2004-02-03
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S022000, C220S00210R, C220S002200, C174S017050, C065S054000, C065S055000
Reexamination Certificate
active
06685525
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an incandescent lamp.
BACKGROUND OF THE INVENTION
A conventional incandescent lamp, for example, a tungsten halogen lamp which lights up with a commercial voltage comprises, as shown in the front view of FIG.
8
and the side view of
FIG. 9
, a bulb
11
having an overall length of 55 mm. The bulb
11
has a spheroidal expanded portion
11
a
, a narrowed portion
11
b
and a pinch-sealed portion
11
c
. The bulb
11
contains inside thereof a filament assembly
12
comprised of a filament coil. The maximum outside diameter of the expanded portion
11
a
is 14 mm.
A method for manufacturing such a tungsten halogen lamp is as follows.
As shown in
FIG. 10
, a cylindrical glass bulb
14
communicating at one end thereof with an exhaust tube
13
is heated to be softened by a burner (not shown). Afterwards, while closing the end opposite to the exhaust tube
13
of the glass bulb
14
with a closing member
15
and charging a protective gas from the exhaust tube
13
, dies (not shown) are pressed to the end on the exhaust tube
13
side of the glass bulb
14
, thereby forming the expanded portion
11
a
and the cylindrical narrowed portion
11
b.
Then, as shown in
FIG. 11
, the closing member
15
is detached and the filament assembly
12
is disposed inside the glass bulb
14
. A cylindrical portion
14
a
opposite to the exhaust tube
13
of the glass bulb
14
is heated to be softened by a burner
16
, and as shown in
FIG. 12
, the cylindrical portion
14
a
is pinch-sealed by dies
17
having an L shape in cross section, thereby forming the pinch-sealed portion
11
c
as shown in FIG.
13
.
The glass bulb
14
is pumped through the exhaust tube
13
and is filled with a predetermined amount of a filling gas, and the exhaust tube
13
is sealed. In this manner, a tungsten halogen lamp is manufactured.
Such a conventional method for manufacturing the tungsten halogen lamp does not pose a problem when it is applied to a lamp which burns with a commercial voltage. In the case of manufacturing a smaller tungsten halogen lamp which burns with a lower voltage of, for example, about 12V or 24V, however, the following problems arise. When the expanded portion
11
a
and the narrowed portion
11
b
are formed in advance and then the pinch-sealed portion
11
c
is formed, due to the effects of heat of the burner
16
at the time of pinch-sealing and of the pinch-sealing itself, the expanded portion
11
a
and the narrowed portion
11
b
are distorted, and the commercial value of the lamp deteriorates.
The distortion of the expanded portion
1
la and the narrowed portion
11
b
causes the thickness of each of the expanded portion
11
a
and the narrowed portion
11
b
to vary. As a result, a problem arises that the bulb
11
is broken due to the pressure of the filling gas (higher than 1 atmospheric pressure) when the lamp is burned.
Further, it is necessary to close the end opposite to the exhaust tube
13
of the glass bulb
14
with the closing member
15
in order to form the expanded portion
11
a
and the narrowed portion
11
b
. It causes a problem that the number of manufacturing steps increases and the cost becomes higher. The present invention has been achieved to solve these problems and has an object to provide a method for manufacturing an inexpensive lamp capable of preventing distortion of the bulb, decrease in the commercial value and breakage of the bulb.
SUMMARY OF THE INVENTION
According to the invention, there is provided a method for manufacturing a lamp comprising a bulb containing therein a filament assembly and having an expanded portion and a pinch-sealed portion, the method comprising the steps of: softening a bulb communicating at one end thereof with an exhaust tube, with the filament assembly disposed inside the bulb; pinch-sealing the end opposite to the exhaust tube of the bulb; and then forming the expanded portion by pressing dies each having a predetermined shape to the bulb by charging a protective gas from the exhaust tube.
Consequently, distortion of the bulb can be prevented and the manufacturing process can be simplified.
REFERENCES:
patent: 2235515 (1941-03-01), Carpenter
patent: 3594884 (1971-07-01), Siegel
patent: 3685880 (1972-08-01), Sobieski
patent: 3810684 (1974-05-01), Robinson
patent: 4434386 (1984-02-01), Lowe
patent: 4723092 (1988-02-01), Heider et al.
patent: 4756701 (1988-07-01), Danko et al.
patent: 5133682 (1992-07-01), Gilligan et al.
patent: 6517404 (2003-02-01), Lamouri et al.
patent: 05-174710 (1993-07-01), None
patent: 06-181048 (1994-06-01), None
Matsushita Electric - Industrial Co., Ltd.
Ramsey Kenneth J.
Santiago Mariceli
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