(19)
(11) EP 0 388 934 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
12.05.1993 Bulletin 1993/19

(43) Date of publication A2:
26.09.1990 Bulletin 1990/39

(21) Application number: 90105364.5

(22) Date of filing: 21.03.1990
(51) International Patent Classification (IPC)5: H01J 29/07
(84) Designated Contracting States:
FR NL

(30) Priority: 23.03.1989 JP 73131/89

(71) Applicants:
  • TOHOKU GAKUIN UNIVERSITY
    Sendai-shi, Miyagi (JP)
  • MITSUBISHI DENKI KABUSHIKI KAISHA
    Chiyoda-ku Tokyo (JP)

(72) Inventors:
  • Haga, Akira
    Sendai-shi, Miyagi (JP)
  • Nasuno, Hiroshi
    Kurihara-gun, Miyagi (JP)
  • Nakanishi, Hisao, c/o Mitsubishi Denki K.K.
    Babazusho, Nagaokakyo-shi, kyoto (JP)

(74) Representative: Tiedtke, Harro, Dipl.-Ing. et al
Patentanwaltsbüro Tiedtke-Bühling-Kinne & Partner Bavariaring 4
80336 München
80336 München (DE)


(56) References cited: : 
   
       


    (54) Cathode ray tube


    (57) A cathode ray tube (101) in which an electron beam rectangular shape discharged from an electron gun (102) passes through holes (e.g. circular or) of a shadow mask (104) and then strikes on a fluorescent substance (103) on the front surface of a tube body. During that time the electron beam is shielded from a magnetic field generated by magnetizing the shadow mask. Preferably said magnetic shielding means includes a magnetic shield layer plated over the inner front surface of each hole of the shadow mask, said magnetic shielding means consisting of a material (e.g. nickel-iron-alloy) higher in magnetic permeability than the magnetic material of the bulk material of the shadow mask.






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