JPH0554791A - Cathode body structure for impregnated type cathode - Google Patents

Abstract

PURPOSE:To make a metal sleeve consisting of a high melting point metal into a form easy to work, reduce a thermal loss by radiation, and suppress an increase in heater consumed power by an operation temperature rise. CONSTITUTION:A metal sleeve 2 using a high melting point metal material is formed of a cylinder having the same diameter over the whole length and a metal ring 5 of the same metal provided on the opened end lower part of the cylinder. The sleeve 2 sufficiently covers the heating part of a heater 1. Thus, the metal sleeve 2 can be precisely manufactured by drawing, the thermal loss by radiation from the metal sleeve 2 opened end and the heater 1 lower part can be reduced, and consequently, the consumed power of the heater 1 can be improved by 25%, compared with in the past.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode structure for an impregnated cathode, and more particularly to a cathode structure for an impregnated cathode used as an electron tube as a high current density cathode.

[0002]

2. Description of the Related Art Generally, a cathode assembly for a cathode ray tube is shown in FIG.
It has a structure as shown in. That is, the heater 1 for heating
And a heater 1 for heating, which is made up of a metal sleeve 12 having a stepped open end and made of a metal material such as Ni-Cr, and an electron emitting emitter 6 applied to the outer surface of the closed end of the metal sleeve 12. Also, the metal sleeve 12
Is manufactured by press working and can be manufactured in large quantities with high precision at low cost. On the other hand, in the case of a cathode that operates at a high temperature of over 1,000 ° C. such as an impregnated cathode, heat loss due to radiation from the open end of the metal sleeve 12 and the lower portion of the heater 1 becomes large. Further, it is difficult to use a low melting point metal material such as Ni—Cr for the material of the metal sleeve 12 because of high temperature operation, and it is desirable to use a high melting point metal material.

As a means for solving the above problems caused by high temperature operation, for example, Japanese Patent Laid-Open No. 63-510 shown in FIG.
As disclosed in Japanese Unexamined Patent Publication No. 25, a method of welding a stepped portion using a support structure 7 using a multi-layer laminated plate in which a chromium-based alloy and nickel are combined at the open end of a metal sleeve 22 made of Ta is disclosed. However, with this method, the cutoff voltage fluctuates during operation due to thermal deformation of the stepped portion, which is not a level that can withstand actual use, and the problem of heat loss due to radiation cannot be solved.

[0004]

As described above, in the cathode assembly for the impregnated type cathode, a refractory metal such as W, Mo or Ta must be used as the metal material of the sleeve for high temperature operation. It is difficult to perform molding by conventional press working, and it has been impossible to accurately manufacture a large amount at low cost. Furthermore, in the conventional shape, there is a problem that the heat loss due to radiation from the open end of the metal sleeve and the lower part of the heater is large, and the electric power supplied to the heater becomes very large in order to obtain a high operating temperature.

An object of the present invention is to provide a cathode assembly for an impregnated cathode, which can be manufactured in large quantities with high precision at low cost and which can reduce the power supplied to the heater.

[0006]

The present invention is based on W, Mo, T
An impregnated cathode having a metal sleeve made of a refractory metal containing a, an impregnated cathode that closes one end of the metal sleeve, and a heater that is inserted from multiple open ends of the metal sleeve to heat the impregnated cathode. In the cathode structure for use, the metal sleeve is a cylinder of the same diameter that sufficiently covers the heating portion of the heater, and a metal ring of the same metal is provided that is inscribed in the outer circumference of the open end.

[0007]

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

FIG. 1 is a sectional view of an embodiment of the present invention.

As shown in FIG. 1, a W pellet 3 impregnated with an electron emitting emitter is placed in a metal cup 4 and welded and fixed to the upper portion of a metal sleeve 2 having the same diameter as the metal cylinder and having the same diameter over the entire length. .. Further, a metal ring 5 of the same material that is inscribed in the outer circumference of the metal sleeve 2 is welded and fixed to the lower portion of the open end of the metal sleeve 2.

A heater 1 for heating is inserted in the metal sleeve 2 to energize the pellet 3 to bring the pellet 3 to a cathode operating temperature (about 1,
Heat to 100 ° C. The metal sleeve 2 is, for example, T
It is made of a and is manufactured by drawing, and has a shape that sufficiently covers the heating portion of the heater 1 for heating.

As described above, since the metal sleeve 2 having the same diameter is used over the entire length, it is possible to perform the drawing process, the mass production can be performed at the same low cost as the conventional press process, and the one having the high accuracy can be obtained. Further, in the shapes of the conventional metal sleeves 12 and 22 shown in FIGS. 2 and 3, there was a large amount of heat loss from the open end side and the lower portion of the heater 1, but as described above, the heating portion of the heater 1 should be covered sufficiently. With such a shape, a significant improvement in heat loss can be obtained.

FIG. 4 is a characteristic diagram showing the relationship between the heater power consumption and the cathode temperature of the cathode structure for the impregnated type cathode according to this embodiment.

As shown in FIG. 4, for example, the heater supply power for obtaining a cathode temperature of 1,100 ° C. is 2.15 W when the cathode structure according to this embodiment is used, and when the conventional cathode structure is used. It is a significant improvement of about 25% compared to the 2.85W of.

[0014]

As described above, the cathode assembly for the impregnated cathode according to the present invention has a simple structure in which a metal sleeve made of a refractory metal material has the same diameter over the entire length and a metal ring is provided below the open end of the metal sleeve. Since the structure is employed, the manufacturing cost can be reduced, and it is possible to manufacture a large amount with high accuracy.

Further, since the metal sleeve is structured so as to sufficiently cover the heating portion of the heater, heat loss due to radiation from the open end of the metal sleeve and the lower portion of the heater can be improved, and the power supplied to the heater can be greatly reduced. There is an effect that can be.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an example of a conventional cathode assembly.

FIG. 3 is a cross-sectional view of another example of a conventional cathode assembly.

FIG. 4 is a characteristic diagram showing the relationship between the heater power consumption and the cathode temperature of the cathode structure for the impregnated-type cathode according to the present embodiment.

[Explanation of symbols]

 1 Heater 2,12,22 Metal Sleeve 3 Pellet 4 Metal Cup 5 Metal Ring 6 Electron Emissive Emitter 7 Support Structure Using Multi-Layer Laminates

Claims (1)

[Claims] 1. A metal sleeve made of a refractory metal containing W, Mo and Ta, an impregnated cathode for closing one end of the metal sleeve, and an impregnated cathode inserted from an open end of the metal sleeve. In a cathode structure for an impregnated-type cathode having a heater for heating, the metal sleeve is a cylinder of the same diameter that sufficiently covers the heating portion of the heater, and a metal ring of the same metal that is inscribed on the outer circumference of the open end is provided. A cathode assembly for an impregnated-type cathode, which is characterized in that