JPS6047692B2 - Fast acting cathode structure - Google Patents

Description

[Detailed description of the invention] The present invention relates to an interlocking cathode assembly.

Generally, an interlocking cathode assembly mounted on the first grid of an electron gun for a cathode ray tube is constructed as shown in FIG.

In the figure, 2 is a heater, and 3 is a cathode sleeve in which the heater 2 is housed, and is formed into a thin cylinder made of Ni-Cr alloy. The base metal 4 coated with the electron emitting material 5 is press-fitted so as to close the open end of the head of the cathode sleeve 3 and fixed by welding. Further, below this cathode sleeve 3, an intermediate sleeve 10 is welded and fixed to be interposed between this sleeve 3 and an outer sleeve 6, which will be described later, and to be engaged and supported. The intermediate sleeve 10 is made of an alloy containing Ni as a main component, and is formed into a cylindrical shape that is slightly thicker and shorter than the cathode sleeve 3. Further, this intermediate sleeve 10 is fixed to an outer sleeve 6 fixed to an insulator 7 made of ceramic, for example, which is attached to a first grid of an electron gun (not shown). The outer sleeve 6 is usually formed of an alloy mainly composed of Ni and containing Cr or W, and is fitted into the central through hole of the insulator 7 and firmly fixed by caulking. In addition, the outer sleeve 6 is placed at a predetermined position at the lower end (usually at a position divided into three parts at intervals of 1200 mm).
An incision 11 is provided by making a cut in the sleeve 10, and the incision 11 is crushed inward, and is brought into contact with the intermediate sleeve 10 and fixed by welding. In order to improve the interlocking performance of the cathode assembly configured in this way, a blackened film is formed on the inner and outer surfaces of the cathode sleeve 3 to efficiently absorb heat from the heater 2, and the cathode is switched on after the heater is turned on. The time required for the surface temperature of the sleeve 3 to reach the temperature required for image output is shortened. This blackened film is selectively formed only on the cathode sleeve, and is a black chromium oxide layer obtained by oxidizing Cr contained in the cathode sleeve. When this chromium oxide layer is formed on the entire surface including the part to be welded to the intermediate sleeve, it becomes difficult to join the intermediate sleeve and the cathode sleeve with normal resistance welding, which reduces welding workability and the reliability of the separator structure. It will lower it. Therefore, when the intermediate sleeve is joined to the cathode sleeve and integrated and treated at high temperature in a humid hydrogen atmosphere, the chromium present on the surface of the cathode sleeve easily reacts with oxygen, forming a black oxide film on the surface of the cathode sleeve. be done. On the other hand, since the intermediate sleeve is mainly composed of Ni, no oxide film is formed thereon. However, the blackening film forming process is generally performed at a considerably high temperature (9000 to 110
0'C), and for the sake of mass production, a large number of integrated cathode sleeves, intermediate sleeves, and base metals are processed at the same time. Since the objects (hereinafter also referred to as cathode bodies) are passed through a wet hydrogen atmosphere while in contact with each other, the following disadvantages occur. In other words, when using a metal such as nickel, which is the main component of the intermediate sleeve, it is easy for the intermediate sleeves to weld to each other, especially when the multiple cathode bodies are integrated as described above, and even if the welded parts are removed, there may be unevenness on the surface. This resulted in defects such as deformation of the cylindrical body, resulting in poor yield and low workability. In addition, since the above-mentioned blackening film forming process is performed at a temperature higher than the annealing temperature of the intermediate sleeve (around 650°C), the intermediate sleeve tends to be thermally distorted after welding with the cathode sleeve, and the assembly accuracy of the cathode structure is decreases and a uniform electron beam is no longer emitted. The present invention has been made in order to eliminate the above-mentioned drawbacks, and is designed to prevent surface welding of metal sleeves during high-temperature blackening treatment in a normal humid hydrogen atmosphere, and to provide a method that prevents surface welding between metal sleeves and other methods after high-temperature blackening treatment. The intermediate sleeve is made of a material that forms an extremely thin oxide film that can be firmly welded to metal, and is suitable as a holding material for the cathode sleeve. This improves the yield in manufacturing the cathode structure and enables high-precision, rapid movement. Some provide a type cathode structure.

Embodiments of the present invention will be described below with reference to the drawings.

Note that the same parts as in FIG. 1 are indicated by the same numbers. FIG. 2 shows the cathode body of the rapid-acting cathode assembly according to the present invention. 4 is a base metal formed into a disk shape of N1 alloy containing Mg or Si as a ring agent; Electron emissive substances 5 such as barium oxide and strontium oxide are formed. The base metal 4 is press-fitted and fixed into the open end of the cathode sleeve 3 on the head side, which is formed into a thin cylinder made of Ni--Cr alloy. This cathode sleeve 3 has a heater 2 inside, and a shorter cylindrical intermediate sleeve 15 is fixed to its lower end. This intermediate sleeve 15 has a weight ratio of 54% Fe, 29% Ni, 7% CO1, Si, M
It is made of Kovar made of n, c, etc., and is fitted and fixed to the cathode sleeve 3. In this way, the cathode body 16, in which the cathode sleeve 3 and the base metal intermediate sleeve 15 were assembled and integrated, was heated to a high temperature of around 1100°C in a humid hydrogen atmosphere as in the past, and was blackened for about 2 gin. Process. Through this blackening treatment, a black chromium oxide layer 14 is formed on the inner and outer surfaces of the cathode sleeve 3.
On the other hand, the intermediate sleeve 15 is made of S contained in the Kovar.
1 is diffused and oxidized on the surface, and a very thin oxide film 1 is formed on the surface.
3 (hereinafter also referred to as an oxide thin film) is formed. Therefore, even if a large number of cathode bodies are processed in a wet hydrogen atmosphere in contact with each other, a chromium oxide layer 14 and a thin oxide film 13 will be formed on each surface, and even if the cathode bodies are in contact with each other, there will be The presence of the oxide thin film prevents surface welding of the intermediate sleeves 15 to each other. After the blackening treatment has been carried out in this manner, an outer sleeve (corresponding to the sleeve 6 fixed to the ring-shaped insulator 7 and having the cutout 11 shown in FIG. 1) is fixed by welding to the outer peripheral wall of the intermediate sleeve 15. Therefore, the oxide thin film 13 is formed on the intermediate sleeve 15, and this oxide thin film 13 prevents surface welding of the intermediate sleeves 15 to each other in a high-temperature hydrogen atmosphere as described above, and at the same time can be welded to the outer sleeve. Must. In this respect, when Kovar is used, as mentioned above, Sj and the like are diffused and oxidized on the surface, preventing the sleeves from welding together, and can be sufficiently firmly fixed to other metals by ordinary welding means. Additionally, the alloy has greater mechanical strength than conventional intermediate sleeves, and is resistant to thermal effects. Therefore, it can sufficiently withstand high temperature treatment after being integrally fixed with the cathode sleeve, the temperature or pressure when welding with the outer sleeve, and can improve assembly accuracy. Deformation is also suppressed. In addition, as mentioned above, the intermediate sleeve is made of an iron alloy (Kovar) mainly consisting of iron, nickel, and cobalt containing small amounts of silicon, manganese, and carbon, and a thin silicon oxide film is formed on its surface. has a low thermal conductivity of approximately 113 to 115 compared to nickel or iron, and since this silicon oxide film is almost transparent, heat radiation loss from this intermediate sleeve is suppressed, and the temperature increase efficiency of the base metal part is high. Excellent speed. The thermal expansion coefficient of this intermediate sleeve is also approximately 1/2.5 compared to nickel or iron, and when incorporated into a cathode ray tube, etc., the gap between the electron emitter layer and the first grid adjacent thereto is small. There is little fluctuation, and the effect of suppressing fluctuations in the amount of electron beam is excellent. As explained above, according to the present invention, it is possible to suppress the undesirable adhesion phenomenon between cathode bodies during the simultaneous high-temperature treatment process of a large number of cathode bodies in the production of the cathode assembly, and also to prevent the cathode assembly from being exposed to high temperatures due to the material of the intermediate sleeve. Deformation during operation is suppressed, and thermal radiation loss from the intermediate sleeve is suppressed, resulting in high efficiency in temperature rise of the base metal portion and excellent speed.

Furthermore, since this intermediate sleeve has a relatively small coefficient of thermal expansion, it has an excellent effect of suppressing fluctuations in the amount of electron beam when it is installed in close proximity to an electron beam control electrode of a cathode ray tube or the like.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view illustrating a conventional fast-acting cathode structure.
FIG. 2 is a partial cross-sectional view of the cathode body of the fast-acting cathode assembly according to the present invention. 2... Heater, 3... Cathode sleeve, 4... Base metal, 13... Oxide thin film, 14... Chrome oxide layer, 15... ...Middle sleeve.

Claims (1)

[Claims] 1. A base metal to which an electron emitting material is adhered, a cathode sleeve to which the base metal is bonded to the upper end and a heater is housed inside, an outer sleeve fixed to a ring-shaped insulator, and the cathode sleeve. A quick-acting cathode assembly comprising an intermediate sleeve fitted to the lower end to support the cathode sleeve and fixed to the outer sleeve, wherein the cathode sleeve is made of an alloy mainly consisting of nickel and chromium. At the same time, a blackened film of chromium oxide is formed on the surface of the intermediate sleeve. A fast-acting cathode structure characterized by a thin silicon oxide film formed on the surface.