Two-phase unipolar drive type brushless DC motor

摘要

A two-phase unipolar drive type brushless DC motor has an armature including a stator yoke with salient poles around which coils are wound, and a rotor having a retainer with a rotor magnet which faces the armature at a predetermined small interval defined between the rotor magnet and the armature. The retainer is made of a polymeric material containing magnetic powder and formed integral with a rotor magnet. The rotor magnet is made of a highly efficient magnetic material or a rare earth magnetic material and consists of segment type permanent magnet pieces which are arranged circumferentially in the retainer. The motor is manufactured at a low cost and provides a stable magnetic wave form which can be used as a spindle motor in various kinds of memory apparatuses.