(19)
(11) EP 0 476 609 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
19.11.1992 Bulletin 1992/47

(43) Date of publication A2:
25.03.1992 Bulletin 1992/13

(21) Application number: 91115830.1

(22) Date of filing: 18.09.1991
(51) International Patent Classification (IPC)5: H01F 7/02
(84) Designated Contracting States:
DE FR GB IT

(30) Priority: 19.09.1990 JP 249040/90

(71) Applicants:
  • TDK Corporation
    Chuo-ku, Tokyo-to 103 (JP)

    DE FR GB IT 
  • KABUSHIKI KAISHA TOSHIBA
    Kawasaki-shi, Kanagawa-ken 210 (JP)

    DE FR GB 
  • TOKYO ELECTRON LIMITED
    Shinjuku-ku, Tokyo (JP)

    DE FR GB IT 

(72) Inventors:
  • Oguriyama, Masami, c/o TDK Corporation
    Tokyo (JP)
  • Ishigaki, Yoshio, c/o TDK Corporation
    Tokyo (JP)
  • Okano, Haruo
    Minato-ku, Tokyo (JP)
  • Hasegawa, Isahiro
    Minato-ku, Tokyo (JP)
  • Arami, Jun-ichi, c/o Tokyo Electron Limited
    Tokyo (JP)
  • Harada, Hiromi, c/o Tokyo Electron Limited
    Tokyo (JP)

(74) Representative: Vogeser, Werner, Dipl.-Ing. et al
Patent- und Rechtsanwälte Hansmann, Vogeser, Dr. Boecker, Alber, Dr. Strych, Liedl Albert-Rosshaupter-Strasse 65
D-81369 München
D-81369 München (DE)


(56) References cited: : 
   
       


    (54) Permanent magnet magnetic circuit


    (57) A permanent magnet magnetic circuit is provided capable of producing a unidirectional magnetic field substantially free of unnecessary perpendicular magnetic field components. A pair of main magnetic poles of opposite polarities are situated at a pair of opposite edge surfaces of a permanent magnet block for producing lines of magnetic force. One major surface of the block between the edge surfaces is provided with a channel where a pair of auxiliary magnetic poles are situated at opposed inner surface portions of the channel for controlling a middle portion of the lines of magnetic force to be linear.





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