A multi-phase outer-type permanent magnet stepping motor including a rotor constituted by a cylindrical permanent magnet assembly in which N (north) and S (south) poles are magnetized alternately on an inner circumferential surface of the rotor. Stator cores respectively having pole teeth are disposed...http://www.google.ca/patents/US6259176?utm_source=gb-gplus-sharePatent US6259176 - Multi-phase outer-type PM stepping motor
