JPS6362128A - Manufacture of electrode for flash discharge tube - Google Patents

Abstract

PURPOSE:To eliminate attachment of impurities on a sintered body by inserting the tip of a glass-wound core wire into the recessed part of the cylindrical sintered body together with a metal of a lower fusing point than that of the base metal of the sintered body, and heating the sintered body so as to activate the sintered body and also to fuse the metal for welding and fixing of the sintered body and the core wire to each other. CONSTITUTION:Mixture of powder of high fusing point metal such as tungsten, tantalum, molybdenum, etc., and powder of electron emission matter is pressurized and molded into a cylindrical form and it is sintered in vacuum at a high temperature to form a sintered body 12. Next a tungsuten core wire 1 is wound with sealing glass 3 roughly on its center, and then impurities are removed from the surface with organic solvent such as acetone. One end of the core wire 1 is inserted into the recessed part of the cylindrical sintered body 12 together with a metal foil 7 of a lower fusing point than that of the base metal of the sintered body such as platinum and niobium. By heating, the sintered body 12 is activated, and the metal foil 7 is fused, so that the sintered body 12 and the core wire 1 are fused to be fixed to each other. Thus attachment of impurities on the sintered body is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing electrodes for flash discharge tubes used in photography, copying machines, and the like.

BACKGROUND OF THE INVENTION Conventionally, a sintered electrode in which a sintered body is impregnated with an electron radioactive material has been used as an electrode for this type of flash discharge tube. A standard flash discharge tube using sintered electrodes is shown in FIG. In FIG. 2, a sintered body 2 is fixed to the tip of a core wire 1 made of tungsten, hermetically sealed with a glass bulb 4 at a sealing glass 3, and a rare gas 5 such as xenon is sealed inside. A trigger electrode 6 is attached to the outer surface of the glass bulb 4.

FIG. 3 shows a method of manufacturing a sintered electrode for this flash discharge tube. In FIG. 3A, ``First, the core wire 1 is placed on the press table 8.
A mixed powder of a high melting point metal powder 9 and an electron radioactive substance 1o is filled around the tip of the core wire, and the mixed powder is pressed and compacted with a presser 11 to form the core wire. Integrate into 1. Next, the sintered body 1 is taken out in the state shown in FIG. 3B and sintered at high temperature in a vacuum.
Form 2. Subsequently, as shown in FIG. 3C, the sealing glass 3 is wrapped around the core wire 1 by heating with a gas burner in an inert gas atmosphere. Thereafter, the sintered body is activated by heating in an inert gas atmosphere, and the process proceeds to sealing with the glass bulb.

Problems to be Solved by the Invention However, the conventional method of integrating the sintered body onto the core wire 1 by pressing it together and then wrapping the sealing glass 3 in a molten state around the core wire 1 by heating with a gas burner does not solve the problem. , water generated during combustion of gas and evaporated matter from the core wire 1 adhere to the sintered body. Since the sintered body is porous, it is difficult to remove deposits. If water or evaporated matter adheres to the sintered body, it becomes difficult to start the flash discharge tube, and
There was a problem in that deposits on the surface of the sintered body diffused into the flash discharge tube during lighting, resulting in a significant decrease in the amount of light.

The present invention has been made to solve these problems, and the problem is that water and evaporated substances from the core wire adhere to the sintered body during gas combustion when the core wire is wrapped with sealing glass. (Thus, the present invention provides a method for manufacturing an electrode for a flash discharge tube that is easy to start and maintains an excellent amount of light.

Means for Solving the Problem In order to solve this problem, the method for manufacturing an electrode for a flash discharge tube of the present invention provides a method for manufacturing an electrode for a flash discharge tube, in which a sintered body is placed in a concave portion of a cylindrical sintered body containing an electron radioactive substance. A step of inserting the tip of a core wire wrapped in glass in advance together with a metal having a melting point lower than that of the base metal, and heating the sintered body to activate the sintered body and melt the metal at the same time to form a -C sintered body. The method includes a step of fusing and fixing the core wire.

Function: With this configuration, the core wire that has been wrapped in glass in advance and the sintered body are fused and fixed with a metal that has a lower melting point than the base metal of the sintered body, so it is protected from water and the core wire when the core wire is wrapped in glass by heating with a gas burner. evaporated matter will not adhere to the sintered body. Further, since the glass-wound core wire and the sintered body are fused and fixed at the same time as the sintered body is activated, the electrode can be manufactured efficiently.

Embodiment FIGS. 1A to 1C show a method of manufacturing an electrode for a flash discharge tube, which is an embodiment of the present invention. In FIG. 1A, high melting point metal powder such as tungsten, tantalum, molybdenum, etc. and BaO
A mixed powder with an electron radioactive substance having a composition of -Ca0-AhO3 or the like is pressurized and formed into a cylindrical shape, and this is sintered at high temperature in a vacuum to form a sintered body 12. Next, in FIG. 1B, approximately the center of the tungsten core wire 1 has an expansion coefficient of 8 to 1.
After a 7×10 −7 sealing glass 3 is wrapped with a gas burner at about 2000° C., impurities on the surface are removed using an organic solvent such as acetone. Next, in FIG. 1C, one end of the core wire 1 is inserted into the recess of the cylindrical sintered body 12 together with a metal foil 7 made of a metal having a lower melting point than the base metal, such as platinum, niobium, etc., or an alloy thereof. Then, the sintered body 12 is heated. This heating activates the sintered body 12 and at the same time melts the metal foil 7, so that the sintered body 12 and the core wire 1 are fused and fixed.

According to the manufacturing method of the embodiment of the present invention as described above, there is no possibility that impurities will adhere to the sintered body.

Note that the same effect can be obtained by using metal powder instead of the metal foil.

Detailed Description of the Invention As described in detail, the present invention provides a method for placing the tip of a glass-wound core wire together with a metal having a lower melting point than the base metal of the sintered body in the recess of a cylindrical sintered body containing an electron radioactive substance. Impurities are removed by sintering by including a step of inserting the sintered body, and a step of heating the sintered body to activate the sintered body and melt the metal at the same time to fuse and fix the sintered body and the core wire. It is possible to provide a method for manufacturing an electrode for a flash discharge tube that does not adhere to the body (therefore, is easy to start and maintains an excellent amount of light).

[Brief explanation of the drawing]

Figures 1A-C are process diagrams showing a method of manufacturing an electrode for a flashlight discharge tube according to an embodiment of the present invention, and Figure 2 is a partially cutaway front view of a typical conventional flashlight discharge tube using a sintered electrode. 3 are process diagrams of a conventional method for manufacturing electrodes for flash discharge tubes. 1...Core wire, 3...Glass for sealing, 7
...Metal foil, 12...Sintered body. Name of agent: Patent attorney Toshio Nakao and 1 other person! -・Also use line 3-i-

Claims (1)

[Claims] Inserting into a recess of a cylindrical sintered body containing an electron radioactive substance, the tip of a core wire that has been previously wrapped in glass together with a metal having a lower melting point than the base metal of the sintered body;
An electrode for a flash discharge tube comprising the step of heating the sintered body to activate the sintered body and simultaneously melt the metal to fuse and fix the sintered body and the core wire. Production method.