JPH09320461A - Sintered electrode for high pressure metal vapor discharge lamp - Google Patents

Abstract

(57) Abstract: The present invention relates to a process for sealing an arc tube by changing the material of a metal container that stores and stores a sintered electrode containing tungsten as a main component when manufacturing the arc tube. It is an object of the present invention to provide a sintered electrode for a metal vapor discharge lamp which eliminates the adhesion of black oxide to the alumina pipe therein and reduces the luminous flux of the lamp throughout the lighting period and has good lamp characteristics. According to the present invention, in a manufacturing process of a sintered electrode in which tungsten powder and tungstate powder containing barium are used as a material of a sintered body, a press body mixed with the powder is heated and baked in a vacuum. It is characterized by using a tantalum container for tying.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered electrode used for an arc tube of a high-pressure sodium lamp as a high-pressure metal vapor discharge lamp, and more particularly, to improve an accommodating container during the manufacturing process, and to use an alumina pipe after arc tube sealing The present invention relates to improvement of a sintered type electrode which eliminates the adhesion of black matter.

[0002]

2. Description of the Related Art Sintered electrodes for high pressure metal vapor discharge lamps are
For example, as compared with a coil-type electrode generally used for a high-pressure sodium lamp, a larger amount of electron-emissive material can be secured, which has the advantage of extending the life of the electrode. Conventionally, this sintered electrode is formed by pressing a mixed powder of tungsten powder and Ba ₂ CaWO _{6 which} is an electron emissive material on one end of a tungsten rod to fix it, putting the pressed body in a container made of molybdenum, and heating it in a vacuum. And then sintered. Then, in a manufacturing process of an arc tube of a high-pressure sodium lamp, after joining the sintered electrode and the niobium pipe, the electrode mount and the alumina pipe are heated at about 1400 ° C. in a vacuum to be made of a refractory oxide. It is hermetically sealed with a frit. However, there is a problem that black oxide adheres to the alumina pipe near the sintered electrode during the arc tube sealing process. When this black matter adheres, the luminous flux is reduced when the lamp is completed, which has the drawback of shortening the life of the lamp.

[0003]

When the cause of the blackening of the arc tube during the arc tube sealing step was investigated, the mixed pressed body is housed in a molybdenum container when it is heated. It was found that the tungsten oxide contained in the body scatters during the arc tube heating process and adheres to the alumina pipe, which is reduced and generated. The present invention has been made in view of the above, and by changing the material of the metal container for storing and storing the sintered electrode containing tungsten as a main component used in manufacturing the arc tube, the arc tube sealing step is performed. It is an object of the present invention to provide a sintered electrode for a metal vapor discharge lamp, which eliminates the adhesion of black oxide to the alumina pipe, which reduces the luminous flux of the lamp throughout the lighting period, and has good lamp characteristics.

[0004]

In order to achieve the above object, the present invention provides a sintered electrode using tungsten powder and tungstate powder containing barium as a material for a sintered body, wherein the powder is It is characterized in that a container made of tantalum is used when the pressed body to be mixed is heated and sintered in a vacuum.

[0005]

With the above structure, by storing the pressed body containing tungsten as the main component in the container made of tantalum having a reducing action, the tungsten oxide can be reduced during the electrode sintering, and the tungsten on the alumina pipe can be reduced. Can be prevented from adhering.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings. FIG. 1 is a side view of a sintered electrode, and FIG. 1 shows a mixed powder 1 of tungsten powder and barium calcium tungstate Ba ₂ CaWO ₆ as an electron emissive material, which is pressed and fixed to one end of a tungsten rod 2. When this pressed body is sintered in a vacuum, it is a sintered electrode that is housed in a tantalum container and sintered.

Next, a high pressure sodium lamp with a lamp power of 150 W is used for each of the sintered type electrode according to the present invention and a conventional sintered electrode which has been sintered in a molybdenum container as an electrode of an arc tube. Five lamps were prepared, and after aging, the initial luminous flux value of the lamp was measured, and the results shown in Table 1 were obtained.

[0008]

[Table 1]

A high-pressure sodium lamp using a sintered type electrode which has been put in a conventional molybdenum container and sintered is
Adhesion of black matter was observed at the end of the alumina pipe,
No blackened substance was observed in the lamp using the sintered electrode which was placed in a tantalum container and sintered. Further, as shown in Table 1, the high pressure sodium lamp according to the present invention has an initial luminous flux value which is about 6% higher than that of the conventional lamp. From this as well, it is confirmed that the electrode material is not scattered during the arc tube manufacturing process.

Although the high-pressure sodium lamp has been described in the above-mentioned embodiments, substantially the same effect has been confirmed for high-pressure metal vapor discharge lamps such as high-pressure mercury lamps and metal halide lamps.

[0011]

As described above, according to the present invention, when a pressed body containing tungsten powder as a main component is sintered in a vacuum, the sintered body is housed in a tantalum container to form a sintered electrode for an arc tube. It is possible to prevent adhesion of the black matter from the lamp, to prevent reduction of the luminous flux of the lamp, and there are advantages that various characteristics of the lamp are excellent.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a sintered electrode according to the present invention.

[Explanation of symbols]

1 Sintered body of tungsten and Ba ₂ CaWO ₆ 2 Tungsten rod

Claims (1)

[Claims] 1. In a process of manufacturing a sintered electrode using tungsten powder and tungstate powder containing barium as a material for a sintered body, when a pressed body for mixing the powder is heated and sintered in vacuum. A sintered electrode for a high-pressure metal vapor discharge lamp, characterized by using a tantalum container.