JPS59105234A - Cathode - Google Patents

Abstract

PURPOSE:To improve an emission life by a simple means while enabling to perform stable electron emission for a long time by preparing a film-shaped barrier layer selected from high melting metals having transmission holes, between the first-and-second layers of an electron emission substance laid on the base metal. CONSTITUTION:A barrier layer 12 made of Ni is a film having one or plural transmission holes 13 while being prepared between the first layer 3 of an electron emission substance made of powder, wherein a ternary oxide of Ba, Sr and Ca is mixed with Zr, and the second layer 4 of the electron emission substance made of powder of the ternary oxide of Ba, Sr and Ca while both layers being prepared on the base metal 2 consisting of Mg acting as a reduction element and Ni containing silicon. Said barrier layer 12 can be obtained by means of vacuum evaporation of Ni on a mixture of the ternary carbonate of Ba, Sr and Ca, which are the starting substances of the ternary oxide laid on the base metal 2, and the hydrogenated zirconium by an ordinary spray method or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode used in a picture tube or the like, and particularly to a cathode with an improved electron emitting layer.

As the performance of picture tubes has improved, various types of cathode tubes have been developed that can withstand high current density operation for long periods of time.

For example, as shown in Figure 1, the first layer of electron emitting material (3) is deposited on the base metal (2) mainly composed of nickel, and then the first layer of electron emitting material (3) is laminated with the electron emitting material. There is a grooved cathode (1) coated with a second layer (4). The base metal (2) contains highly reducing elements such as silicon, zirconium, magnesium, and aluminum, which are at the level of impurities. The electron emitter IR No. 2 (4) is composed of oxides of a plurality of alkaline earth metals, typically sybarium, strontium, and calcium from the alkaline earth metal group. The first layer of electron emitting material (3), like the second layer of electron emitting material (4), mainly contains oxides of alkaline earth metals such as barium, strontium, and calcium, and contains 0.011 - reducing elements such as zirconium.

Contains hafnium, titanium, etc.

By the way, base metal (2), electron emitting material first layer (3)
, the second layer of electron emitting material (4) is heated to 8 by the heater (5).
It is heated to about 00°C. Therefore, base metal (2)
The first layer of electron-emitting material (
A near-element reaction occurs between the alkaline earth metal oxides in 3), and between the alkaline earth metal oxides and the aforementioned sitazirconium, hafnium, etc. Similarly, the reduction reaction proceeds and liberated alkaline earth metals are produced. (The alkaline earth metal diffuses through the first layer of electron-emitting material (3) and the second layer of electron-emitting material (4), reaches the surface of the second layer of electron-emitting material (4), and reaches the nine-level level. An example of the reduction reaction is (
1) and (2).

BaO+Mg: Ba+MgO,...-
...(1)2EaO+Zr 4! 2Ba + Zr
O2-・-・・・・・・・(2) As can be understood from the above explanation, the first layer of electron emitting material (3) is a source of free barium, for example, for the second layer of electron emitting material (4). It becomes.

However, it has been found that the conventional cathode (1) having the above configuration has the following drawbacks in terms of emission life characteristics. That is, when the free barium generated in the first layer of electron emitting material (3) reaches the surface of the second layer of electron emitting material (4), its vapor pressure is high, so that the free barium is consumed by evaporation to a large extent. Taking Equation (1) as an example, the reaction of Equation (1) is an equilibrium reaction, which induces consumption of the silica-reducing element magnesium through diffusion and evaporation of barium. therefore,
If barium is depleted quickly, magnesium is depleted quickly, and the number of emission members decreases quickly. In other words, the emission life characteristics cannot be satisfied.

Furthermore, the high evaporation of barium causes barium to adhere to adjacent electrode components, becoming a source of stray emissions that reduce electrode insulation deterioration and impairing tube properties.

This invention was made to eliminate these conventional drawbacks, and by providing a barrier layer with holes between two electron-emitting material layers, it not only improves the emission lifetime characteristics but also improves the tube efficiency. The purpose is to provide a cathode that does not cause insulation deterioration or the like.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG. In Figure 2, (2) is 0.05 as a reducing element.
Substrate gold Jfi, consisting of 0.11 mn thick nickel containing weight percent magnesium and silicon (
3) is a 0.06 m thick radioactive material consisting of a powder of ternary oxides of barium, strontium, and calcium mixed with 0.1% by weight of zirconium.
, (4) is a second layer of electron-emitting material made of powder of ternary oxides of barium, strontium, and calcium with a thickness of 0.04 mm, and (b) is a barrier made of nickel with a thickness of about 500 deer. It is a layer. Barrier J ('70) is a thin film provided between the first layer of electron emitting material (3) and the second layer of MffV (4) and having one or more through holes a3.

The barrier layer (6) is coated with the base metal (
2) is obtained by vacuum evaporation of nickel onto a mixture of ternary carbonates of barium, strontium, calcium and zirconium hydride, which are the starting materials for the ternary oxide deposited on 2).

In the case of a vaporized M film with a thickness of about 500 deer, it has many through holes. After providing the barrier layer (material), apply the second stain emitter (4) on top of the barrier layer (material) using the usual spray method.
The ternary carbon a salts of barium, strontium, and calcium, which are the starting materials, are coated in a layered manner to form the shade +fi (1). Thereafter, the cathode (b) is assembled as a part of an electron gun, and subjected to the well-known evacuation process and cathode activation process in electron tube manufacturing to provide an electron emission function.

The free barium generated by the reactions of formulas (1) and (2) above is heated by the heater (5) to form the first layer of electron emitting material (3) and the second layer of simulator emitting material (4). However, the diffusion is restricted by the barrier 1301), and the electron emitting material 2nd n(4) is supplied only through the through hole (1?1). The size and number can be determined as appropriate in consideration of the usage conditions such as the current extraction hole, etc. The free barium that has passed through the through-hole α field reaches the surface of the second layer of electron emitting material (4) and contributes to electron emission. .

Thus, due to the presence of the barrier layer), the amount of free barium consumed due to diffusion and evaporation is drastically reduced, and stable electron emission can be obtained over a long period of time. Further, properties such as deterioration of electrode insulation due to adhesion of barium do not occur.

The t43 diagram is a guffaw representing the lifetime characteristics of electron radiation.

It can be seen that in the case of the picture tube equipped with the cathode (uniform) according to the present invention shown by the protruding plug a, the life characteristics are significantly improved compared to the case of the picture tube mounted with the conventional cathode (1) shown by the broken line. .

In the above example, nickel was used as the metal forming the barrier layer θ frame, but (Ba, Sr).

0a) It is possible to arbitrarily select a group of high-melting point metals that are unlikely to undergo a reduction reaction with O, such as Koba/l/), Puchina, molybdenum, platinum, and the like. Further, although only one layer of barrier layer (J5'J) was used in the above embodiment, it goes without saying that the same effect can be obtained even with several layers.

As described above, according to the present invention, the emission life can be improved by simply providing a barrier having through holes, and a cathode that emits electrons stably over a long period of time and does not cause deterioration in the characteristics of the electron tube can be obtained. can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part of a conventional cathode, Fig. 2 is a cross-sectional view of the main part showing an embodiment of the cathode of the present invention, and Fig. 3 is a comparison of the life characteristics of the conventional cathode and the cathode of the present invention. This is a graph shown as follows. (2)...Base metal, (3)...Second layer of electron emitting material, (4)...Second layer of electron emitting material, (Foundation)...Barrier η, (1 frame... Through hole. In addition, the same reference numerals in the drawings indicate the same or corresponding parts. Agent: Makoto Kuzuno (1 other person)

Claims (1)

[Claims] (1) A first layer of electron emitting material deposited on the base metal IF containing a trace amount of reducing element, and an electron emitting material provided in a layered manner on the first layer of electron emitting material. The first layer of the electron number WJ material is made of a powder of a single or multiple oxide of an alkaline earth metal mixed with a trace amount of a universal element, and the second layer of the electron emitting material is a cathode made of oxide powder of one or more kinds of alkaline earth metals, with a high melting point having one or more through holes between the first layer of electron emitting material and the second layer of electron emitting material. A cathode characterized by having a thin film barrier layer selected from metal.