JPH0279320A - Impregnated cathode structure - Google Patents

Abstract

PURPOSE:To improve accuracy in assembling by forming a metallic fine line out of crossed plate-shaped body. CONSTITUTION:A metallic fine line 10 is brought into contact with the bottom of a cathode base substance 1, and laser beams 12 and applied from below so as to solder both 1 and 10 by lasers, and next while being accorded with a center axis it is placed on the top of a cathode sleeve 3, and laser beams 12 are applied from below so as to welder the cathode sleeve 3 and the metallic fine line 10. Since the metallic fine line 10 is made of plate-shaped body, each member becomes uniform contact condition with each other. Thus, it becomes possible to carry out accurate junction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an impregnated cathode assembly, and particularly to an impregnated cathode assembly having a structure in which a cathode sleeve is lifted and held using a thin metal wire.

[Conventional technology]

Impregnated cathodes are widely used as electrodes capable of obtaining high current density in television picture tubes, image pickup tubes, observation tubes for oscilloscopes, and the like. In this type of cathode, a porous base made of a high-melting point metal is impregnated with an electron-emitting substance, and this is heated by a heater to emit electrons at a high current density. is 1000 to 1
Since it is necessary to maintain the temperature at a high temperature of about 100° C., efforts have been made to create a structure with as little heat loss as possible.

4 and 5 show the structure of a conventional impregnated cathode structure, in which 1 is a porous substrate 2 made of a high melting point metal such as tungsten (W), molybdenum (Mo), etc. Ca) is a cathode substrate impregnated with an electron emitting substance such as aluminate, and 3 is tantalum (Ta).
), a cathode sleeve with one end open made of a high melting point metal such as molybdenum (MO), and a heater 4 built into it.

4 is a tungsten (W) core wire with alumina (hit Os)
) The cathode substrate is heated to about 1000° to 1100° C. using a coated heater. Reference numeral 5 denotes a heat reflection cylinder, which reflects the heat radiation radiated from the heated outer peripheral surface of the cathode sleeve 3 to minimize heat loss caused by fogging of the heat radiation. 6 indicates the heat reflection cylinder described above. This is an eyelet that holds the tube 5.

Further, the cathode sleeve 3 is lifted using two fine metal wires (diameter: 50 μff1) made of high melting point, high toughness such as tungsten-Vnium (W-Re), which are joined to the eyelet 6, and then By holding it without contact with other members, heat loss due to heat conduction is minimized.

Here, the two metal thin wires 7 are crossed in a cross shape between the bottom surface of the cathode base 1 and the top surface of the cathode sleeve 3, and are joined to each of the above two 1 and 2 by welding to hold them. are doing.

Regarding such an impregnated cathode structure, for example, JP-A-56-168316 and JP-A-61-2883 disclose
It is disclosed in Publication No. 39.

[Problem to be solved by the invention]

According to the above-mentioned conventional technology, as shown in FIG. The members 1 and 3 are assembled together by welding them together, but the welding method described above usually involves the welding between the cathode and the cathode sleeve, as shown in Figure 6.
This is carried out by the resistance welding method 1 in which the electrodes 8 and 9 are opposed and pressed together and a current is passed between the two electrodes.

However, since the contact conditions at the portions where the thin metal wire 7 contacts the cathode base l and the cathode sleeve 3 are not the same, the current amount l due to the difference in contact resistance at that portion.
There is a difference in the welding process, and the progress of welding is not the same.
The assembly accuracy of the cathode base 1 and the cathode sleeve 3 deteriorates, and therefore the parallelism between the bottom surface of the cathode base 1 and the top surface of the cathode sleeve 3 is impaired, causing axis misalignment in the cathode base and deteriorating the electron gun characteristics. There was a fear that it would happen.

In addition, the welding described above at the contact portions between the thin metal wire 7, the cathode base 1, and the cathode sleeve 3 tends to be insufficient, which may lead to peeling due to heating during cathode operation, which may reduce the lifespan of the electron gun. It was believed that one of the reasons for the decline was that it was low.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an impregnated cathode assembly that can uniformly and reliably weld a thin metal wire, a cathode base, and a cathode sleeve, and improve the assembly accuracy of the cathode base and cathode sleeve. It's about doing.

[Means to solve the problem]

The above object has a heater, a cathode sleeve containing the heater, and a cathode base attached to the top surface of the cathode sleeve, and the cathode sleeve is held up by a thin metal wire. This is achieved by forming the thin metal wire into a cross-shaped plate in the impregnated cathode structure.

[Effect]

By the above means, the thin metal wire can be brought into surface contact with the bottom surface of the cathode base and the top surface of the cathode sleeve, so that these members are in stable contact with each other,
High-precision assembly becomes possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. Incidentally, the same members as in FIGS. 4 and 5 are given the same reference numerals and their explanations will be omitted.

FIG. 1 shows a thin metal wire 10 according to the invention, having a thickness of about 3
Molybdenum (Mo) about 0 to 100 μm.

Tungsten (W), or these metals and Vnium (R
It is formed by punching a metal material made of a high-melting-point, high-toughness alloy such as e) into a cross-shaped plate-like body having a width of about 30 to 100 μm, which is orthogonal to each other in the vertical and horizontal directions.

As a result, there is no difference in level between the portions 11 that intersect at right angles, so that it is possible to make good surface contact with the mating member to be joined thereto.

Such surface contact enables laser welding with high welding precision, which is impossible with the conventional wire rods having a circular cross section.

That is, as shown in FIG. 2, first, the fine metal wire 10 of the present invention is brought into contact with the bottom surface of the cathode substrate 1,
Apply the laser beam 12 to the lower blade 1 to laser weld both parts 1°10 (Figure A).Next, place it on the top surface of the cathode sleeve 3 while aligning it with the central axis, and apply the laser beam 12 from below. The cathode sleeve 3 and the thin metal wire 10 are welded (Figure B).

FIG. 3 shows an assembly of the cathode base 1 and the cathode sleeve 3 which are joined together in this way.
Lift up and hold it.

In the embodiments described above, the case where the members are assembled by laser welding each other has been described, but since the thin metal wire is formed into a plate-shaped body, each member is in uniform contact with each other, and therefore, Even with conventional resistance welding, it is possible to perform more precise joining than in the past.

〔Effect of the invention〕

According to the present invention described above, the accuracy of assembling the cathode base and the cathode sleeve is improved, and there is no risk of welding peeling, etc., so that an impregnated cathode structure with high performance and high reliability can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an embodiment of the present invention (a thin metal wire), Fig. 2 is an explanatory diagram of the assembly process of an embodiment Q of a cathode sleeve according to the present invention, and Fig. A shows the cathode base and the metal wire. Figure B shows the welding process between the thin metal wire and the cathode sleeve, and Figure B shows the welding process between the thin metal wire and the cathode sleeve. The figure is a vertical sectional view of the main part of a conventional impregnated cathode structure, FIG. 5 is a perspective view of the main part of a conventional impregnated cathode structure, and FIG. 6 is an explanatory diagram of a joining method using resistance welding.1. ... Cathode base, 3... Cathode sleeve, 4... Heater, 5... Heat reflector,
6... Tite, 7... Fine metal wire, 8,
9... Electrode, 10... Metal thin wire, 12...
laser light. Figure 4 Figure 5 Figure 6 Figure 4.・、. 99.1

Claims (1)

[Claims] 1. A heater, a cathode sleeve containing the heater, and a cathode base attached to the top surface of the cathode sleeve, and the cathode sleeve is held up by a thin metal wire. An impregnated cathode assembly comprising: the above-mentioned thin metal wire formed into a cross-shaped plate-like body. 2. The impregnated cathode assembly according to claim 1, wherein the thin metal wire is provided between the cathode base and the cathode sleeve and joined to each other by laser welding.