JPS6269436A - Cathode structure of magnetron - Google Patents

Abstract

PURPOSE:To intend to reduce the stress in the brazed portion by brazing fixedly the wide aperture end of a terminal shaped like a cup to the member to which the said end is contacted in butt-seal form and the center hole of the said terminal to the center lead and the side lead which are fitted into the said hold respectively. CONSTITUTION:The terminal 10 shaped like a cup is brazed to the insulator 6 at the open end 10a of which contacted to the insulator 6. The center lead 4 and the side lead 5 are fitted into the center hole 10b of the each said terminal 10 and brazed to the terminal respectively. And the supply wire 8 of the cathode current is fixed to the center lead 4 and the side lead 5 with such as the metal part 9 respectively, and welded fixedly to the each lead by arc welding and so on. The stress generated in the brazed portion of the insulator 6 and the terminal 10 can be relaxed in the wide aperture part of the said terminal 10, therefore the arising of a crack caused by a temperature rising of the brazed portion or an external force can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a magnetron cathode structure, and particularly to a terminal structure for relaying cathode current.

[Background of the invention]

FIG. 1 shows a cathode structure of a magnetron that has been widely used in the past. An example is the cathode structure disclosed in Japanese Patent Application Laid-open No. 35838/1983.

As shown in the figure, in order to efficiently generate thermoelectrons, both ends of a cathode 1 made of a spiral thorium tungsten wire are connected to upper and lower end shields 2 and 3 made of molybdenum or the like.
It is held and fixed by.

These upper and lower end shields 2 and 3 each have a center lead 4. The side lead 5 is an insulator 6 made of ceramic.
The end portion is soldered to the insulator 6 together with a terminal 7 made of Kovar or Furni material to achieve vacuum sealing. The terminal 7 is formed with a supply line connection part 7a for connecting the supply line 1wl8 for relaying the cathode current, in addition to being used for the soldering and sealing described above. Then, the terminal 7 and the supply line 8 are welded together by arc welding or the like. In the cathode assembly configured as described above, the terminal 7, the insulator 6, the center lead 4. This is excellent in that the side lead 5 is brazed together with one piece of brazing material sandwiching the terminal 7 and the insulator 6, but the insulator 6 and the terminal 7 are brazed flat to each other. Due to the structure of the so-called surface mounting, the material of the terminal 7 is Kovar or Furni, which has a coefficient of thermal expansion close to that of the ceramic of the insulator 6, but it tends to be subject to a considerable amount of stress, and the process such as the exhaust process Cracks may occur on the bonding surface due to the temperature rise inside and external force applied when connecting the terminal 7 and the supply line 8.

In extreme cases, serious defects such as peeling may occur that can lead to tube leaks.

[Purpose of the invention]

An object of the present invention is to provide a terminal structure in which brazing of the terminal part reduces stress on the part.

[Summary of the invention]

The surface mounting of the terminal is a magnetron cathode assembly that instead of the structure makes the terminal structure a butt seal structure that can relieve stress.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIG. 2. In FIG. 2, the same reference numerals as in FIG. 1 refer to the same functions.
Explanation will be omitted.

Reference numeral 10 denotes a cup-shaped terminal according to the present invention, and the cup-shaped open end 10a is brought into contact with the insulator 6 and brazed. Center lead 4. Each side lead 5 has a cup-shaped terminal 10.
is fitted into the central hole 10b and brazed. Further, the cathode current supply line 8 is the center lead 4. They are each fixed to the side leads 5 with metal fittings 9, etc., and fixed by arc welding or the like.

According to the structure described above, the stress generated at the brazed portion between the insulator 6 and the terminal 7, which was the problem in FIG. The material of the terminal portion connected to the insulator 6 may be of course the conventional Kovar or Furni, but also iron or the like, and it is possible to prevent cracks from occurring due to an increase in temperature of the brazed portion or from the outside.

Another embodiment is shown in FIG. 3, in which the cup-shaped terminal 11 has a cylindrical portion through which the center lead 4 and side leads 5 are inserted, and its extending portion is cut out as shown in FIG. 3(b). ,
A supply line connecting portion 11a for connecting to the supply line 8 is integrally formed. According to this, special members such as the metal fittings 9 used in FIG. 2 are not required.

〔Effect of the invention〕

According to the above configuration, it is possible to obtain an electron tube whose bulb is vacuum-sealed with high reliability.

In addition, in manufacturing the cup-shaped terminal 10.11, the wall thickness of the cup-shaped wide-mouthed part is made thinner than the wall thickness of the part to be brazed to the center lead 4 and side leads 5, thereby further reducing stress. here

[Brief explanation of drawings]

Fig. 1 is a schematic side view of a conventional magnetron cathode assembly, Fig. 2 is a side view showing one embodiment of the magnetron cathode assembly according to the present invention, and Fig. 3(a) shows another embodiment of the present invention. The side view (b) is a plan view of the cup-shaped terminal portion. 1... Cathode, 4... Center lead, 5... Side lead, 6... Insulator, 10.11... Cup-shaped terminal. Figure 1 Figure 2 Figure 3 (lost)

Claims (1)

[Claims] 1. A center lead and a side lead holding both ends of a cathode that emits thermoelectrons are passed through an insulator made of ceramic, and a cup-shaped terminal for relaying a cathode current to the cathode is attached to the In the electron tube cathode assembly formed by brazing and fixing the center lead and the side leads to the insulator, the cup-shaped terminal has the cup-shaped wide-mouth end abutted against the insulator in a butt-sealing manner when viewed from a cross section; A magnetron cathode assembly characterized in that the center lead and the side leads are respectively inserted through holes in the center and fixed by brazing at the wide mouth end and the holes, respectively. 2. The extending part of the cylindrical part through which the center lead and side leads of the cup-shaped terminal are inserted is cut out to integrally form a supply line connection part for connecting a supply line that relays the cathode current. Magnetron cathode structure.