Electric lamp and discharge devices – With envelope – Having base and connector
Reexamination Certificate
1998-12-01
2001-09-25
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With envelope
Having base and connector
C313S318090, C313S318100, C439S611000
Reexamination Certificate
active
06294861
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric discharge lamp apparatus having a structure that a front end of an arc tube is supported by a lead support extending from an insulating plug and a rear end of the arc tube is directly supported by the insulating plug. More particularly, the present invention relates to an electric discharge lamp apparatus incorporating an arc tube which has a structure that an ultraviolet-ray-shielding globe for surrounding and enclosing an enclosed glass bulb is integrally welded to the body of an arc tube having an enclosed glass bulb in which electrodes are disposed opposite to each other, and a rear end of the ultraviolet-ray-shielding globe of the arc tube is supported by a metal support member secured to the insulating plug.
As shown in
FIG. 15
, a conventional electric discharge lamp apparatus has a structure that a pair of long and short lead supports
2
a
and
2
b
projecting over an insulating plug (an insulating base)
1
made of synthetic resin supports the front and rear ends of an arc tube body
5
. Electrodes
6
opposite to each other are disposed in an enclosed glass bulb
5
a
of an arc tube body
5
. Pinch seal portions
5
b
for sealing molybdenum foil members
7
connected to the electrodes
6
are provided for the enclosed glass bulb
5
a.
Lead wires
8
a
and
8
b
connected to the molybdenum foil members
7
are outwards extended from the pinch seal portions
5
b
. The lead wires
8
a
and
8
b
are, directly or through a metal support member
9
, secured to lead supports
2
a
and
2
b
by welding, the lead supports
2
a
and
2
b
being passages for electric power.
The enclosed glass bulb
5
a
includes metal halide, for example, a sodium-thallium-indium material or a scandium-sodium material. An ultraviolet-ray shielding globe
3
is secured and held by the insulating plug
1
such that the globe
3
surrounds the enclosed glass
5
a
of the arc tube. The globe
3
cuts ultraviolet rays in wavelength regions of light emitted from the arc tube body
5
which are harmful to the human body or elements constituting the lamp.
However, the metal lead supports
2
a
and
2
b
disposed in the ultraviolet-ray shielding globe
3
are exposed to ultraviolet rays emitted in the electric discharge portion of the arc tube. Thus, free electrons having negative electric charges are excited and discharged from the inside portion of the lead support. When the free electrons reach the portion in the vicinity of the outer surface of the enclosed glass bulb
5
a
, metal atoms (Na+) having positive electric charges in the enclosed glass bulb
5
a
are pulled by the free electrons having the positive electric charges, and then allowed to pass through the wall of the glass bulb. Thus, the metal atoms are discharged to the outside of the glass bulb. As a result, the steam pressure of light emitting substances in the enclosed glass bulb
5
a
is lowered. Thus, there arises a problem in that the lifetime of the arc tube is shortened.
Accordingly, an electric discharge lamp apparatus has been suggested which has a structure as shown in
FIG. 16
such that the arc tube incorporates the arc tube body
5
to which the ultraviolet-ray shielding globe
3
is integrally welded so as to surround and enclose the enclosed glass bulb
5
a
. Moreover, the front surface of the insulating plug
1
directly supports the rear end of the arc tube and the outer surface of the globe
3
.
A dish-shape disc
4
made of ceramics is secured to the front end of the insulating plug
1
with screws. The rear end of the arc tube penetrates an arc-tube insertion hole
4
a
formed in the disc
4
so as to be engaged to an engaging hole la formed in the insulating plug
1
. Moreover, the globe
3
is held by an inorganic bond layer
4
b
injected into the disc
4
. A screw
4
c
secures the disc
4
to the insulating plug
1
. A focusing ring
1
b
integrally secures to the outer surface of the insulating plug
1
.
The ultraviolet-ray shielding globe
3
cuts ultraviolet rays of light emitted by the enclosed glass bulb
5
a
in the wavelength regions harmful to the human bodies and the elements constituting the lamp. Therefore, an adverse influence on the human body and the elements constituting the lamp can be eliminated. Moreover, the problem can be prevented which has been experienced with the conventional structure in that free electrons are discharged from the lead support exposed to the ultraviolet rays and thus excited, and, therefore, the steam pressure of the light emitting substances in the enclosed glass bulb
5
a
is lowered. In
FIG. 16
, the same elements as those shown in
FIG. 15
are given the same reference numerals and the same elements are omitted from description.
The electric discharge lamp apparatus shown in
FIG. 16
has the structure that the rear end of the arc tube is supported by the disc
4
secured to the front surface of the insulating plug
1
. However, inclination of the arc tube with respect to the disc
4
is substantially inhibited. Therefore, an axis (hereinafter called a “discharge axis”) L connecting the opposite electrodes
6
of the arc tube to each other cannot accurately be positioned with respect to the disc
4
. Since the ceramic disc
4
integrating the arc tube is secured to the insulating plug
1
with the screws
4
c
, the positions of the disc
4
and the insulating plug
1
cannot be adjusted in the radial direction. Therefore, the conventional technique encounters a difficulty in accurately positioning the discharge axis L of the arc tube with respect to the central axis of the focusing ring
1
b.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide an electric discharge lamp apparatus which is capable of easily and accurately position the electric discharge axis of an arc tube thereof with respect to the central axis of a focusing ring.
To achieve the above-mentioned object, according to a first aspect of the present invention, there is provided an electric discharge lamp apparatus comprising: an arc tube having a glass bulb, electrodes being opposite to each other, an ultraviolet-ray shielding globe for surrounding and shielding the glass bulb; an insulating plug having a focusing ring, wherein the insulating plug made of synthetic resin; a metal lead support forwardly extending over the insulating plug, for supporting a front end of the arc tube; and a metal support member secured to the insulating plug and arranged to support a portion of the arc tube adjacent to a rear end of the globe, wherein the metal support member includes, a metal base plate secured to the insulating plug and forming a reference plane running parallel to the focusing ring, and a vertically-holding member made of metal, joined integrally with the metal base plate and vertically holding an electrically-discharging axis of the arc tube with respect to the reference plane of the metal base plate.
The base plate has the reference plane which runs parallel to the focusing ring, which is a reference member for performing positioning with respect to the reflector. The electric discharge axis of the arc tube is, by the vertically-holding member made of metal, held vertically with respect to the reference plane of the base plate. Therefore, movement of the vertically-holding member which is holding the arc tube, along the reference plane of the base plate enables the electrically-discharging axis to be positioned to a predetermined required position (to a position on the central axis of the electric discharge lamp apparatus) with respect to the focusing ring.
That is, when the vertically-holding member which is holding the arc tube is moved along the base plate until the electrically-discharging axis coincides with the central axis of the electric discharge lamp apparatus, the vertically-holding member is joined and integrated with the base plate. Thus, the electrically-discharging axis can be brought to a predetermined required position with respect to the focusing ring.
Acco
Fukuyo Takeshi
Harazaki Masato
Irisawa Shinichi
Mochiduki Kunimasa
Numajiri Yasuyoshi
Day Michael H.
Gerike Matthew J.
Koito Manufacturing Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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