Mitsubishi Denki Kabushiki Kaisha

Toyokazu Kamata

Keiji Watanabe

Masato Saito

Keiji Fukuyama

Kinjiro Sano

Hisao Nakanishi

Masako Ishida

Ryo Suzuki

Takuya Ohira

Takashi Shinjou

A cathode for use in electron tubes which comprises a base metal made of nickel as a principal component and having a surface on which a porous electron emissive layer is formed. The porous electron emissive layer is of a composition comprising 0.1 to 20 wt % (relative to the total weight of the porous electron emissive layer) of scandium oxide having a layered crystalline structure dispersed in an oxide of alkaline earth metal including at least barium. This cathode can be made by preparing a solution in which nitrocellulose is dissolved with the use of an organic solvent, mixing both of barium carbonate and scandium oxide having a layered crystalline structure into the solution to provide an suspension, pulverizing solid components of the suspension for the adjustment of particle size, and depositing the suspension on a surface of the base metal to form the electron emissive layer.

Cathode in a cathode ray tube

A metal layer of not more than 2.0 .mu.m thick is formed on a base, containing nickel as the main ingredient and a reducing agent such as silicon and magnesium, by depositing tungsten by an electron beam under heating in a vacuum. The base is heat treated in a hydrogen atmosphere at 800.degree. to 1,100.degree. C. An emissive material layer, containing an alkali earth metal oxide and 0.01 to 25 wt % of a rare earth metal oxide, the alkali earth metal oxide containing at least barium oxide, is formed on the metal layer. Thus, life characteristics of the cathode, especially during the operation at a high current density such as not less than 2A/cm.sub.2, are greatly enhanced.

Electron tube cathode

A cathode for an electron tube in accordance with the present invention comprises: a base (2) containing not only nickel as a major element but also a reducing agent; a layer (3) of an electron-emissive substance which is applied to the base (2) and contains not only an alkaline earth metal oxide as a principal component but also a scandium oxide; and a heater for heating the layer (3).

Cathode for electron tube and manufacturing method thereof

A hot cathode in a wire form is useful in a vacuum tube, a CRT or a fluorescent display tube is disclosed. The cathode is composed of a heat-resistant metal in a wire form that holds on it an electron-emitting metal material that is made of 0.2-20 wt % of a rear earth metal oxide in admixture with an alkaline earth metal oxide the balance of which contains at least barium oxide. The reduction of oxide barium to barium as a result of reaction with the cathode wire is so much retarded that an increased emission current will be produced from the cathode not only in its initial operation but also through out its operation.

Hot cathode in wire form

A cathode for an electron tube in accordance with the present invention comprises: a base containing not only nickel as a major element but also a reducing agent; a layer of an electron-emissive substance which is applied to the base and contains not only an alkaline earth metal oxide as a principal component but also a scandium oxide; and a heater for heating the layer.

This invention is a cathode of an indirect heated type having improved electron emission characteristics. A cathode for an electron tube in accordance with the present invention comprises: a base containing Ni as a major element; and a layer of an electron-emissive substance formed on the base, this layer comprising not only alkaline earth metal oxide as a principal component containing at least Ba, but also rare earth metal oxide of 0.1 to 20 wt. % or rare earth metal of 0.05 to 15 wt. %.

Growing community of inventors

Nagaokakyo, Japan

Toyokazu Kamata