Stepping motor

  • US 5,331,237 A
  • Filed: 04/23/1993
  • Issued: 07/19/1994
  • Est. Priority Date: 04/28/1992
  • Status: Expired due to Term
First Claim
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1. In a stepping motor comprising:

  • (a) a housing comprising a pair of can-type stator yokes each of which is provided with a toothed portion in an inner surface thereof for forming a plurality of magnetic poles;

    (b) a rotor provided in said housing;

    (c) a pair of coils disposed around said rotor in said housing; and

    (d) a flat-type stator yoke provided with a toothed portion forming a plurality of magnetic poles which correspond to those of said toothed portions of said can-type stator yokes, said flat-type stator yoke being disposed in said housing;

    the improvement comprising;

    (e) both of said can-type stator yokes being injection molded yokes formed of an injection molded composite powder in which a metal powder of a soft magnetic material is mixed with a powder of a thermoplastic synthetic resin; and

    (f) said flat-type stator yoke being a one-piece, integrated injection molded yoke formed of an injection molded composite powder in which a metal powder of a soft magnetic material is mixed with a powder of a thermoplastic synthetic resin which is the same as that of said can-type stator yokes, and said flat-type stator yoke being provided with its magnetic poles extending from opposite sides thereof and having its magnetic poles correspond to those of said can-type stator yokes.

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