(19)
(11) EP 0 421 372 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
21.11.1991 Bulletin 1991/47

(43) Date of publication A2:
10.04.1991 Bulletin 1991/15

(21) Application number: 90118910.0

(22) Date of filing: 03.10.1990
(51) International Patent Classification (IPC)5: H01J 1/28, H01J 9/04, H01J 1/14
(84) Designated Contracting States:
DE FR NL

(30) Priority: 06.10.1989 JP 262368/89

(71) Applicant: MITSUBISHI DENKI KABUSHIKI KAISHA
Tokyo (JP)

(72) Inventors:
  • Nakanishi, Hisao, c/o Mitsubishi Denki K.K.
    Chiyoda-ku, Tokyo (JP)
  • Sano, Kinjiro, c/o Mitsubishi Denki K.K.
    Chiyoda-ku, Tokyo (JP)
  • Kamata, Toyokazu, c/o Mitsubishi Denki K.K.
    Chiyoda-ku, Tokyo (JP)
  • Shinjo, Takashi, c/o Mitsubishi Denki K.K.
    Chiyoda-ku, Tokyo (JP)

(74) Representative: Reichel, Wolfgang, Dipl.-Ing. et al
Reichel und Reichel Parkstrasse 13
60322 Frankfurt
60322 Frankfurt (DE)


(56) References cited: : 
   
       


    (54) Method of manufacturing an electrode tube cathode


    (57) An electrode tube cathode (1) having improved electron emission properties is produced by suspending an alkaline earth metal carbonate powder and scandium oxide powder in a solution of nitrocellulose, regulating their particle size, applying the suspension on a nickel base metal surface (1b) such that the coating density is not greater than 2 mg/mm³, and heating the layer of the carbonate in vacuum to a temperature of 800 - 1200°C to decompose to the oxide, thereby forming a porous electron emission layer (30) wherein scandium oxide is dispersed in an alkaline earth metal oxide on the base metal. The resultant electron emission layer (30) has a porous structure, and hence the stress between the layer and the base is reduced. This appears to suppress the swelling of the layer and the peeling of it away from the surface of the base.







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