JPH0869750A - Manufacture of electrode for metal halide lamp - Google Patents

Abstract

PURPOSE: To prevent dispersion in the manufacture of cathodes by inserting a coil in a groove formed in a jig, setting a tip arbor through a groove provided previously in the coil in such an arrangement as to suit the diameter of the arbor, and inserting a support rod from the coil end on the opposite side. CONSTITUTION: A groove 2 to admit insertion of a tungsten coil 14 is formed in a coil case 1 as a jig. After the coil 14 is inserted in the case 1, the case 1 is inverted upon setting a lid using a base metal piece 3, and the opening 4 where a thin arbor is threaded is arranged as facing up. The groove 2 is fitted with taperes 5a, 5b, and upon contacting the arbor 12 with the coil 14, a pressure is given from above by the use of a hand press machine, and then arbor 12 is inserted. The metal piece 3 is used as a receptacle, and only the case 1 is inverted, and a support rod inserting tool 7 having a groove 6 is put as covering the case 1. The arbor 13 is inserted from the groove 6, and upon contacting with the coil end, a pressure is applied by hand press machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electrode for a metal halide lamp, and more particularly to an improvement in a method for manufacturing a cathode of a short arc metal halide lamp for direct current lighting.

[0002]

2. Description of the Related Art Recently, a liquid crystal projector has been developed which is configured to project an image on a large screen by combining a liquid crystal panel and an optical system such as a lens. And
As a light source device of the device, a device combining a short arc metal halide lamp and a parabolic reflector is mainstream from the viewpoint of ease of use, color reproducibility and brightness. Further, in order to make the entire liquid crystal projector a compact design, it is possible to use a DC lighting lamp. This is because a small and inexpensive DC lighting ballast can be used as the ballast built into the device.

In this type of lamp, an anode is sealed at one end in a quartz arc tube and a cathode is sealed at the other end, and a metal halide is enclosed therein together with mercury and a rare gas. And, one end of a short arc metal halide lamp consisting only of this arc tube is arranged at the bottom of a parabolic reflector made of hard glass, the anode of the arc tube is on the bottom side of the reflector, and the cathode is on the opening side. Fixed to be in position. Further, the external lead wire of the cathode is connected to a terminal block attached to the outer surface of the side portion of the reflecting mirror, and the external lead wire of the anode is connected to the base on the bottom portion of the reflecting mirror to form a light source device. FIG. 1 shows an example of a cathode of a DC lighting lamp. The cathode 11 is configured by connecting a tip core rod 12 and a supporting core rod 13 with a predetermined gap 15 provided therebetween through a tungsten coil 14. The core rod having this gap has an advantage that the starting point of the arc is less swayed when the lamp is lit, as compared with a cathode in which the core rod is integrated.

[0004]

Conventionally, in manufacturing the cathode, first, the support core rod 13 is chucked with a pin vise, and the support core rod is rotated while the tungsten coil 1 is wound.
4 was grasped and inserted with tweezers or the like to integrate the support core rod coil, and then the tip core rod 12 was grasped and inserted with tweezers while further rotating. However, since it is done by hand, it is difficult to set a constant distance between the tip core rod 12 and the support core rod 13, and the total length of the cathode varies, which causes arcing with the anode when the lamp is sealed. In many cases, the length varied and the light emission characteristics changed. Also, when the gap of the core rod largely varies, the temperature of the cathode tip is greatly affected with respect to cooling of the cathode tip, and when it is lower than the lamp design value, the cathode spot is not stable and the arc fluctuates and the color on the screen The optical characteristics are deteriorated due to unevenness. On the contrary, when the value is higher than the design value, arc fluctuation does not occur, but there is a problem that the arc tube becomes black at an early stage because the arc spot at the tip of the cathode becomes hot.

The present invention has been made in view of the above, and by improving the manufacturing method of the cathode having the above-mentioned structure, the manufacturing variation is prevented at the time of assembling the cathode, and the quality is high and the yield is good. Not only that, it provides a long-life short arc metal halide lamp that is easy to manufacture and does not cause arcing of the arc tube electrodes or blackening of the arc tube when it is sealed and lighted. The purpose is to do.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a method for manufacturing an electrode in which a tip core rod and a supporting core rod are connected via a tungsten coil so as to form a predetermined gap, and a coil is previously attached to a jig. Insert the coil into the groove formed according to the length, insert the tip core rod through the groove previously aligned with the core rod diameter into the coil, and then insert the tip core rod from the opposite coil end. The supporting core rod is inserted through a groove that matches the diameter of the core rod. Further, the jig comprises a base metal fitting, a coil case, a cathode support core rod insertion tool, and an axis alignment core rod, and is characterized in that a plurality of electrodes are manufactured at the same time.

[0007]

With the above structure, it is possible to prevent variations in the production of the cathode, the arc of the lamp does not fluctuate at the time of lighting after sealing the arc tube, and the blackening is small. or,
The cathode is easy to manufacture and there are few defective products.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. Similarly to the above, FIG. 1 shows an example of the cathode of a DC lighting lamp. The cathode 11 has a tip core rod 12 and a support core rod 13 provided with a predetermined gap 15 in a tungsten coil 14.
It is configured by connecting via. Then, a method for producing the cathode will be described. First, a groove 2 into which a tungsten coil 14 having a coil inner diameter of 0.39 mm, a core rod diameter of 0.3 mm and a coil length of 2.5 mm can be inserted is formed in a coil case 1 as a jig. However, the inner diameter of the coil is 0.39 mm, but the diameter of the tip core rod and the support core rod is 0.4 mm, so considering the size after insertion, 0.4 + 0.3 x 2 =
Groove 2 with a diameter of 1.1 mm, slightly larger than 1.0 mm
Is desirable. Next, as shown in FIG.
After inserting the coil 14, attach the coil case 1 to the base metal fitting 3
Then, the two are paired upside down with the use of, and the opening 4 through which the thin core rod passes is peeled upward. The groove 2 has tapered portions 5 at both ends.
a and 5b are formed, and the diameter of the opening 4 is 0.42 mm in diameter so that the tip core rod 12 can be inserted.
a is formed. The coil 14 fitted into the coil case 1 after the tip core rod is inserted from the taper portion
After the tip core rod comes into contact with the tip, it is pressed from above with a hand press to expand the inside of the coil and the tip core rod 12
Insert.

Further, as shown in FIG. 2 (c), the base metal fitting 3 is used as a receiving member, only the coil case 1 is turned upside down, and the taper portion 5b for inserting the coil is made the upper surface, and further the center of the coil is formed. A support core rod insertion tool 7 having a groove 6 formed at the center of the support core rod 13 is placed on the coil case 1.
In addition, the groove 6 formed in the supporting core rod insertion tool is
Since the diameter of the supporting core rod is 0.4 mm, the inner diameter of the groove is 0.4 mm so that the supporting core rod can be easily inserted into the coil fitted in the coil case 1. 42 mm
It is as a slot hole. Further, the length of the cathode is designed to be 6.5 mm, and the distance from the upper surface of the base to the front end of the supporting core rod is designed to be exactly 6.5 mm. Then, in the same manner as when the end of the tip end core rod 12 hits the coil end and then presses it, the support core rod 13 hits the coil end and then pushes it using a hand press machine to push the support core rod into the coil. Insert.

In the cathode 11 thus produced, the length of the gap 15 does not vary, the length of the support core rod 13 fitted to the coil 14 and the length of the tip core rod 12 do not vary, and the cathode 11 There is no variation in the total length. Therefore, the diameter of the central part of the quartz tube is 11.0 mm and the internal volume is 0.4.
An anode is attached to one end of an arc tube having a substantially spheroidal shape of cc, and the cathode is attached to the other end so that the arc length between the electrodes is 0.5 mm. A lamp is constructed by enclosing prosium, neodymium iodide, and cesium iodide. The anode is prepared by closely winding a tungsten coil at a position 0.4 mm away from the tip of a tungsten core rod having a core rod diameter of 0.6 mm and a length of 7 mm, and winding it to a length of 2.5 mm.

The lamp and the parabolic reflector are combined to form a light source device for direct current lighting, and the rated power is 1
When 100 short arc metal halide lamp devices with 50 W, starting lamp current of 3.8 A, and stable lamp current of 1.8 A were prototyped and subjected to lighting test, almost no arc fluctuation of the arc tube occurred even in the initial lighting stage. Also, in the life test, no blackening of the arc tube was observed even after 2000 hours of lighting, and there was no arc fluctuation, and there was no problem in the starting performance.

Further, a jig for mass production as shown in FIG. 3 was prepared and used for manufacturing. When the completed lamp was lighting-tested in the same manner as described above, there was no variation in manufacturing and the productivity was improved. Was planned. The jig includes a base metal piece 21, a coil case 22, a cathode support core rod insertion tool 23, and a shaft alignment core rod 2.
4 is a hardened product of tool steel, and a plurality of cathodes can be manufactured at the same time.

[0013]

As described above, the method of manufacturing an electrode for a metal halide lamp according to the present invention is as follows:
There is no variation in dimensional accuracy, workability is good, yield is good, and even if the short arc metal halide lamp using the cathode is lit by direct current, the arc of the arc tube fluctuates throughout the life and the starting failure and There are advantages such as no blackening of the arc tube.

[Brief description of drawings]

FIG. 1 is a side view of a cathode used as an electrode for a metal halide lamp.

FIG. 2 is an explanatory view showing an example of a method for manufacturing a metal halide lamp electrode according to the present invention.

FIG. 3 is a side view showing an example of an apparatus for manufacturing an electrode for a metal halide lamp according to the present invention.

[Explanation of reference numerals]

 1 Coil Case 2 Groove 3 Base Metal Fitting 4 Opening 5a, 5b Tapered Part 6 Groove 11 Cathode 12 Tip Core Rod 13 Support Core Rod 14 Tungsten Coil 15 Gap 21 Base Metal Fitting 22 Coil Case 23 Cathode Support Core Rod Insert 24 Core rod

Claims (2)

[Claims] 1. A method of manufacturing an electrode, which comprises connecting a tip core rod and a supporting core rod through a tungsten coil so as to form a predetermined gap, in a groove formed in advance in a jig in accordance with the coil length. Insert the coil, insert the tip core rod through a groove preliminarily adjusted to the core rod diameter into the coil, then from the opposite coil end into which the tip core rod is inserted,
A method of manufacturing an electrode for a metal halide lamp, characterized in that the supporting core rod is inserted through a groove corresponding to the diameter of the core rod. 2. A method of manufacturing a cathode, wherein the jig comprises a base metal fitting, a coil case, a cathode support core rod inserter, and an axis alignment core rod, and simultaneously manufactures a plurality of electrodes.