JPS6010539A - Cathode structure - Google Patents

Abstract

PURPOSE:To improve the withstanding voltage and life characteristics by providing the first layer densely formed with an electron emitting material in contact with a base metal held at one end of a sleeve, providing the second layer thinly formed on the first layer, and providing the third layer densely formed on the second layer. CONSTITUTION:A cathode structure holds a base metal 2 at the tip of a sleeve, and an electron emitting material layer 50 is deposited and formed on the metal 2. The layer 50 is constituted with the first layer 50-1 densely formed with the electron emitting material in contact with the metal 2, the second layer 50-2 thinly formed with the electron emitting material on the layer 50-1, and the third layer 50-3 densely formed with the electron emitting material on the layer 50-2. Accordingly, a cathode structure excellent in both the withstanding voltage and life characteristics can be obtained.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in cathode structures.

[Technical background of the invention and its problems]

Oxide cathode structures are used in color cathode ray tubes and many other electron tubes.

As shown in Figure 1, the structure of a conventional oxide cathode structure is such that a base metal (2) is welded to the tip of a sleeve (1), and the sleeve (1) is attached to a holder (4) via three straps (3).
) is supported. An electron emitting material layer (5) is formed on the surface of the base metal (2). This electron emitting material layer (5) is formed by a so-called spray method in which a liquid mixture of carbonates such as BaCO3, CaCO3, 8rCO8, nitrocellulose, and butyl acetate is sprayed with a spray gun. Electron emitted particles are formed depending on spray conditions such as the composition ratio of the liquid mixture, the air flow rate of the spray gun, the distance from the gun to the base metal, etc. ! The surface and internal conditions of the layer change, and the result changes the life characteristics and voltage resistance characteristics of the cathode (electrical voltage resistance characteristics between the cathode and the first bridge).
Therefore, it is important to control spray conditions at a constant level.

Now, with the accumulation of various technologies, the life characteristics and voltage resistance characteristics of oxide cathodes have been improved, and further improvements are required.

[Object of the Invention] An object of the present invention is to provide an excellent cathode structure with improved life characteristics and pressure resistance characteristics.

[Summary of the invention]

In order to achieve the above object, the inventors conducted various experiments and found that forming the electron emitting material layer in the order of high-density layer, low-density layer, and high-density layer can improve both life characteristics and voltage resistance characteristics. Completed the invention.

- That is, the present invention provides a cathode assembly having a base metal held at one end of a sleeve and an electron emissive material layer deposited on the base metal, wherein the electron emissive material layer is in contact with the base metal. Consisting of a first layer in which a radiation material is formed in a high density, a second layer in which an electron radiation material is formed in a low density on the first layer, and a third layer in which an electron radiation material is formed in a high density on the second layer. This is a cathode structure characterized by the following.

If the high-density layer and low-density layer of the present invention are exemplified by the density of the electron emitting material, the high-density layer has a density of 4 to 1.6 p/cyx.

The low density layer preferably has a thickness of 1.0 to 1.2V^32, the high density layer preferably has a thickness of 3 to 15 μm, and the low density layer has a thickness of approximately 45 to 60 μm.

Embodiments of the Invention] This is an enlarged view of the vicinity of the electron emissive material layer (50) of the cathode assembly according to the present invention, in which a high-density first layer (50
-1), a low-density second layer (50-2) is formed thereon, and a high-density third layer (50-3) is formed on top.

The distance from the spray gun to the surface of the base metal arranged on the chuck was 110M, the same liquid mixture as above was used, the liquid ejection rate was 0.2cc/s, and the other conditions were the conventional product (density 1.1). ~1.3) Same as AI), coating layer 10
Obtain a counterlayer of μIII. The density is 1.552/male. Next, the distance from the spray gun to the base metal surface is 1
70 dew, and using the same mixed liquid, the amount of liquid jetted was 0.4c.
c/s, and the other conditions were the same as those of the conventional product, to obtain two coffin layers with a coating layer of 50 μm. The density is 1.1y, 4'. A third layer with a coating thickness of 10 μm is formed under the same conditions as the first layer. The density is 1.5y, 43.

At the same time, we make conventional products. Using the same mixture, the distance from the spray gun to the base metal surface was 170 gll, and the ejection rate of the liquid was 0.45 cc/s, and the other conditions were the same as in the example to obtain a cathode structure with a coating thickness of 70 μm.

FIG. 3 shows the voltage resistance test characteristics of the cathode structure of the present invention and the conventional cathode structure. The breakdown voltage characteristic is that when the cathode assembly is properly assembled into the first grid electrode, a DC high voltage is applied between the cathode and the first grid electrode and the pressure is increased (positive on the cathode side, heater not lit), and the insulation is broken. The ratio of the emission to the initial emission at each time is called the emission capacity.

As shown in the figure, the cathode structure of the present invention is superior in both pressure resistance characteristics and life characteristics.

In the above embodiment, the density of the first layer, second layer and third layer is 1.
2, 1.5, 1.2 (fI voice 3), but the density of the first and third layers was 1.4 to 1.6 y/4s.
Within the range of , the density of the second layer is 1.0 to 1.2y7at?
It would be good if it was within the range.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a conventional cathode structure, FIG. 2 is an enlarged view of the vicinity of the electron emitting material layer of the cathode structure of the present invention, FIG. 3 is a breakdown voltage characteristic diagram of the cathode structure of the present invention and the conventional cathode structure, and FIG. The figure is a life characteristic diagram of the present invention and a conventional cathode assembly. Agent Patent Attorney Kensuke Chika (and 1 other person) Figure 1 Figure 3

Claims (1)

[Claims] In a cathode structure having a base metal held at one end of a sleeve and an electron emissive material layer deposited on the base metal, the electron emissive material layer is made of a high-density ml of electron emissive material in contact with the base metal. The first layer formed on
A cathode structure comprising a second layer on which an electron emitting material is formed at a low density, and a third layer on which an electron emitting material is formed at a high density on the second layer.