A brushless motor comprises a rotor having multipolar magnets magnetized, a stator coil having a plurality of phases of winding, a rotor position detecting circuit to detect a specified position of the rotor and to output a signal having levels which alternately change in accordance with revolution of...http://www.google.com/patents/US5093891?utm_source=gb-gplus-sharePatent US5093891 - Brushless motor and an axial flow fan with the brushless motor
