Fluent material handling – with receiver or receiver coacting mea – Processes – Gas or variation of gaseous condition in receiver
Reexamination Certificate
2000-06-23
2001-11-27
Douglas, Steven O. (Department: 3751)
Fluent material handling, with receiver or receiver coacting mea
Processes
Gas or variation of gaseous condition in receiver
C141S067000
Reexamination Certificate
active
06321799
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for supplying a predetermined amount of mercury to a chamber part of an arc tube during production of the arc tube which is used for a discharge lamp as a light source of a lighting tool such as a head lamp for an automobile, the arc tube having a sealed chamber part with electrodes provided facing each other, a light emitting substance such as mercury and a metal halide sealed therein.
2. Description of the Related Art
FIG. 10
is a cross-sectional view of a conventional discharge valve to be used in a head lamp for an automobile comprising an arc tube for a discharge lamp. An arc tube
1
comprises a sealed chamber part
2
c
including electrode bars
3
a
,
3
b
facing each other, a light emitting substance such as mercury and a metal halide sealed therein, formed between a pair of front and rear pinch seal parts
2
a
,
2
b.
An insulating base
5
, and a pair of long and short metal lead supports
6
a
,
6
b
for supporting the front and rear end part of the arc tube
1
, with lead lines
4
a
,
4
b
, elongating from the arc tube
1
electrically connected to lead supports
6
a
,
6
b
. A globe G surrounds the arc tube
1
and blocks ultraviolet rays that are emitted from the arc tube
1
that can be hazardous to the human body. The mark
2
e
is the trace of the pinch part remained on the chamber part
2
c
at the time of pinching the straight tube provided for introducing mercury or a metal halide.
Since the amount of the mercury sealed in the sealed chamber
2
c
influences the value of the lamp voltage, which is one of the characteristics of the arc tube, it is preferable that a predetermined amount of mercury is supplied into the chamber part
2
c
in the production process of the arc tube in order to obtain a rated lamp voltage.
As shown in
FIGS. 11A and 11B
, a conventional method for supplying a predetermined amount of mercury to a chamber part of an arc tube comprises the steps of inserting a tube
7
with a mercury droplet P, held at the tip part by adsorption, through a straight tube
2
d
integrally bonded with a chamber part
2
c
of an arc tube, to the vicinity of the chamber part
2
c
, and poking the mercury droplet P with a poking bar
8
fitted in the tube
7
for dropping the same into the chamber part
2
c.
For holding the mercury droplet P at the tip part of the tube
7
by adsorption, as shown in
FIG. 12A
, the tip part of the tube
7
is put in the mercury liquid surface in a container
9
filled with mercury so that a predetermined amount of mercury is introduced into the tube tip part by withdrawing the poking bar
8
. Then, by lifting up the tube
7
above the liquid surface, as shown in
FIG. 12B
, a mercury droplet P can be held by adsorption at the tube tip part, utilizing the surface tension and the vacuum.
However, according to the conventional method and apparatus for supplying mercury, since the operation for holding the mercury by adsorption needs to be executed at a site different from that for ejecting the mercury, a problem is involved in that the operation is troublesome as well as time-consuming.
Furthermore, since it is necessary to put the tip part of the tube
7
into the mercury liquid surface in the container
9
, withdraw the poking bar
8
for introducing the mercury into the tube
7
tip part, and lift up the tube
7
and move it above the straight tube
2
d
, the apparatus structure is complicated.
Moreover, according to the conventional method and apparatus, since the mercury is measured by withdrawing the poking bar
8
with respect to the tube
7
for introducing a predetermined amount of mercury into the tube
7
tip part and it is supplied into the chamber part
2
c
by poking the mercury droplet P by advancing the poking bar
8
with respect to the tube
7
, the mercury cannot be supplied in accurate amounts. That is, the bulging shape of the lower part of the mercury droplet held by adsorption at the tube tip part differs each time, and thus the amount of the mercury droplet held by adsorption is often irregular. Furthermore, in some cases, the mercury may adhere and remain on the tube
7
tip part to the poking bar
8
tip at the time of dropping and supplying the mercury droplet P into the chamber part
2
c
so that all the mercury droplet held by adsorption may not be supplied into the chamber part
2
c.
Furthermore, the volume of the chamber part
2
c
is as small as about 20 to 50 &mgr;l in an arc tube for a discharge valve to be used in a head lamp for an automobile, and the mercury amount to be sealed is slight (1 mg or less). Therefore, the tube
7
and the poking bar
8
need to be processed extremely narrowly. This process is difficult. Furthermore, the technique for smoothly sliding the narrow poking bar
8
in the narrow tube
7
is also demanding.
Accordingly, as a result of the problems of the conventional technique, the present invention supplies a predetermined amount of mercury, corresponding to the high pressure gas application time, by filling the inside of a small diameter pipe with mercury and pressing and ejecting the mercury in the small diameter pipe with a high pressure gas.
SUMMARY OF THE INVENTION
The invention solves many of the problems associated with conventional techniques by providing a method and an apparatus which supplies an accurate amount of mercury to an arc tube for a discharge lamp by ejecting a predetermined amount of mercury in a small diameter pipe by a gas pressure.
The apparatus and method of the present invention supplies mercury to an arc tube for a discharge lamp by inserting a small diameter pipe, which is used as a mercury supply path, through a glass tube opened upward, so that the tip part of the small diameter pipe reaches into the chamber part wherein the upstream side of the mercury supply path is connected to a gas pressure adjuster. The gas pressure adjuster keeps the inside of the mercury supply path at a predetermined pressure, which maintains the inside of the small diameter pipe in the state filled with mercury, and applies a heightened gas pressure on the mercury for ejecting a predetermined amount of mercury from the small diameter pipe tip part.
One form of a glass tube to be used with the above mentioned apparatus and method opens upward, elongating from a chamber part of the arc tube, a glass straight tube elongating from the other end part side of a chamber part of an arc tube with one end part pinch-sealed (see
FIGS. 2A
to
2
D) and a glass straight tube integrally bonded with a chamber part of an arc tube with both end parts pinch-sealed (see
FIGS. 11A and 11B
) are both included.
One type of mercury supply path can be a configuration wherein a small diameter pipe elongates from a sealed container filled with mercury (see FIG.
6
). The inside of the sealed container is set at a predetermined pressure via the gas pressure adjuster with the mercury in the sealed container introduced also into the small diameter pipe so that the surface tension of the mercury, the pressure in the sealed container (pressure applied on the liquid surface of the mercury), and the gravity are in balance, holding the mercury in the small diameter pipe without flowing out. Further, in the case where the pressure applied on the liquid surface of the mercury in the sealed container (mercury in the small diameter pipe) is heightened by introducing a high pressure gas into the sealed container by the gas pressure adjuster, the mercury in the small diameter pipe is pressed and is ejected from the tip end opening part, dropping into the chamber part.
Moreover, since the amount of mercury ejected into the chamber part is determined by the increased pressure in the sealed container (amount of increased pressure applied on the mercury in the small diameter pipe) and the increased pressure application time, a predetermined amount of mercury can be ejected by using the gas pressure adjuster to set the gas pressure to be applied in the sealed container and the amount
Fukai Kunio
Fukuyo Takeshi
Nagasawa Masakazu
Nagata Akihiro
Douglas Steven O.
Huynh Khou
Koito Manufacturing Co. Ltd.
Sughure, Mion, Zinn, Macpeak & Seas, PLLC
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