KR20010092908A - Indirectly heated cathode assembly - Google Patents

Abstract

PURPOSE: An indirectly heated cathode structure is provided to prevent current leakage between the heater and cathode even at a high temperature of 1400°C or higher. CONSTITUTION: An indirectly heated cathode structure comprises an electron emission member(21) for emitting thermal electron when heated; a base metal(22) including a fixed portion(22a) where the electron emission member is mounted, and a skirt portion(22b) extended downward from an edge of the fixed portion; a heater(23) incorporated into the base metal, and which has a diamond insulation layer(23a) formed at the outer periphery of the heater; and a support member(24) for supporting the heater. The diamond insulation layer has a thickness of 2μm or higher.

Description

Heat dissipation cathode structure

The present invention relates to a heat radiation type negative electrode structure, and more particularly, to a heat radiation type negative electrode structure having excellent insulation properties between the outer peripheral surface of the heater and the inner peripheral surface of the metal substrate.

The cathode structure, which is the electron emission source of the electron gun, emits thermal electrons by thermal energy, and is classified into a heat dissipation type by an indirect heating method and a direct heat type by a direct heating method. That is, the heat dissipation type cathode has a form in which the filament and the electron emitting member are separated, and the direct heat type cathode has a structure in which the filament and the electron emitting member are in direct contact.

1 is a cross-sectional view of a heat dissipating cathode structure commonly used in FIG. 1. Referring to FIG. 1, a cathode structure includes a sleeve 12 having a heater 11 embedded therein, and an electron emitting material ( 13) is provided with a base metal (14) on which the electron-emitting member is applied. The heat dissipating cathode structure configured as described above emits heat electrons by heating the sleeve 12 and the metal substrate 14 by the heater 11 mounted inside the sleeve 12 and then heating the electron emitting member 13. This is done.

At this time, the outer circumferential surface of the heater 11, which is usually made of a W-Re alloy, to coat the allanum insulating layer (11a) to prevent the leakage of current between the heater and the cathode. However, the coating of the alandeum with an insulating layer is not only able to completely prevent leakage of the current, but also may cause the alumne to melt and evaporate, especially when the sleeve 12 is heated to 1400 ° C or higher, and the amount of leakage of the current. Will also increase. This leakage current affects the video signal applied to the cathode and affects the cutoff characteristics of the electron gun.

In particular, when the operating temperature is 1400 ° C. or more, such as an impregnated cathode structure or a metal cathode structure that requires a high current density, the problem of leakage current as described above is increased, and thus, it is necessary to further increase the insulation characteristics of the cathode structure.

Accordingly, the technical problem to be achieved by the present invention is to provide a heat dissipation type cathode structure that can maintain the insulating properties between the heater and the cathode at high temperatures, and further improve the cutoff characteristics of the electron gun in order to solve the above problems.

1 is a schematic cross-sectional view showing the structure of a conventional heat dissipating cathode structure,

2 is a schematic cross-sectional view showing the structure of a heat radiation type cathode structure according to an embodiment of the present invention,

3 is a schematic cross-sectional view showing the structure of a heat radiation type negative electrode structure according to another embodiment of the present invention.

In order to achieve the above technical problem, the present invention provides an electron-emitting member that emits hot electrons when heated; A metal base having a fixing part on which the electron-emitting member is mounted and a skirt part extending downward from an edge of the fixing part; A heater embedded in the metal substrate and having a diamond insulating layer formed on an outer circumferential surface thereof; And it provides a heat dissipation cathode structure comprising a support for supporting the heater.

In the heat radiation type cathode structure according to the present invention, a metal cathode may be used as the electron emission member.

In addition, a diamond insulating layer may be further formed on the inner circumferential surface of the metal substrate.

In addition, the negative electrode structure of the present invention may further include a sleeve in which the skirt portion of the metal substrate is fixed at the top, and may form a diamond insulating layer on the inner peripheral surface of the sleeve.

Hereinafter, a heat dissipating cathode structure and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings, but the scope of the present invention is not limited to the following examples.

Figure 2 is a schematic cross-sectional view showing a heat radiation type negative electrode structure according to an embodiment of the present invention.

Referring to FIG. 2, the heat dissipating cathode structure of the present invention is lowered from the edges of the fixing part 22a and the fixing part 22a on which the electron emitting member 21 and the electron emitting member 21 are mounted, which emit hot electrons when heated. It includes a metal substrate 22 having a skirt portion 22b extending in the form, a heater 23 embedded in the metal substrate 22 and having a diamond insulating layer 23a formed on its outer circumferential surface and a support 24 supporting the heater. do.

As the electron-emitting member 21, an electron-emitting material such as an alkaline earth metal oxide containing barium oxide as a main component may be applied, and in particular, a metal cathode or a dispenser cathode may be mounted.

In addition, a diamond insulating layer may be further formed on the inner circumferential surface of the metal base 22. By forming a diamond insulating layer on the inner circumferential surface of the metal base 22 in addition to the heater 23, the leakage current can be almost completely prevented from occurring even at a high temperature of 1400 ° C or higher.

In addition, the heat dissipation cathode structure of the present invention may further include a sleeve 34 is fixed to the top of the skirt portion 32b of the metal base, as shown in Figure 3 diamond insulating layer on the inner peripheral surface of the sleeve 34 34a can be further formed. The inner surface of the sleeve 34 may be blackened to improve heat absorption.

As shown in FIG. 2, a heater 23 supported by a support 24 and coated with an insulating material made of diamond is inserted into an inner circumferential surface of the metal substrate of the anode structure of the present invention. By forming the diamond insulating layer 23a on the outer circumferential surface of the heater, current leakage can be prevented even at a high temperature of 1400 ° C or higher, unlike a cathode structure in which a conventional allanum insulating layer is formed. At this time, considering the heat transfer characteristics of the electron-emitting member 21, the thickness of the diamond insulating layer 23a is preferably 2㎛ or more.

In the heat dissipating cathode structure configured as described above, there are various methods for forming a diamond insulating layer on the outer circumferential surface of the heater. However, the method of forming the insulating layer on the outer circumferential surface of the heater by the vacuum deposition method will be described below. .

First, an electron-emitting member made of a metal cathode is welded or bonded to a metal substrate made of a metal material having high melting point (molybdenum or the like). Next, one end of the ribbon is welded to one end of the skirt of the metal substrate, and then the other side of the ribbon is welded to the upper part of the holder and suspended. At this time, it is preferable to use Ta etc. as a material of a ribbon in consideration of workability. This series of steps can be carried out before and after the step of forming the diamond insulating layer in the heater.

Subsequently, a heater is put in a substrate part of a vacuum chamber into which a mixed gas mixed with methane and hydrogen is injected and maintained at about 800 to 1000 ° C. When a reverse bias voltage is applied to the heater such that carbon radicals decomposed and generated in the mixed gas adhere to the surface of the heater, diamond crystals grow on the surface of the heater to form a diamond insulating layer.

In order to increase the insulation effect, the diamond insulation layer may be further formed on the inner circumferential surface of the metal substrate by the above-described method.

In the same manner as described above, a heater having a diamond insulating layer formed thereon may be inserted into a metal substrate, thereby manufacturing a heat dissipating cathode structure having excellent insulation characteristics as shown in FIG. 2. That is, in the heater in which the conventional allanum insulation layer is formed, the leakage current increases when the temperature of the sleeve becomes 850 ° C or higher. In particular, at about 1200 ° C, a leakage current of 350 mA flows, and at about 1400 ° C, a leakage current of several mA flows, and the leakage current amount increases rapidly. However, in the heater in which the diamond insulation layer is formed according to the present invention, even when the sleeve temperature reaches 1500 ° C, leakage current hardly occurs. This is because diamonds have very good electrical insulation properties.

Since the heat dissipating cathode structure according to the present invention can prevent the leakage current between the heater and the cathode even at a high temperature, it is particularly useful for metal cathode structures that require a high operating temperature of 1400 ° C or more.

Claims (6)

An electron emitting member emitting hot electrons when heated; A metal base having a fixing part on which the electron-emitting member is mounted and a skirt part extending downward from an edge of the fixing part; A heater embedded in the metal substrate and having a diamond insulating layer formed on an outer circumferential surface thereof; And A heat dissipation type cathode structure, characterized in that it comprises a support for supporting the heater. The heat radiation type cathode structure according to claim 1, wherein the electron emission member is a metal cathode. The heat dissipating cathode structure according to claim 1, wherein a diamond insulating layer is formed on an inner circumferential surface of the metal substrate. The heat dissipating cathode structure according to claim 1, wherein the thickness of the diamond insulating layer formed on the outer circumferential surface of the heater is about 2 µm or more. The heat dissipating cathode structure according to claim 1, further comprising a sleeve fixed to an upper end of the skirt portion of the metal substrate. The heat dissipating cathode structure according to claim 5, wherein a diamond insulating layer is formed on an inner circumferential surface of the sleeve.