Ultrasonic step motor

摘要

An ultrasonic step motor includes a stator and a rotor. A vibrator is mounted on the stator and a driving mechanism excites the vibrator causing the stator to induce a vibrating mode on the rotor. The rotor has a vibration mode in a selected direction and the stator exhibits a plurality of vibrating states which are changed in a time sequential manner. The vibrating states of the stator include a composite vibration of a travelling wave formed from two standing wave vibrations and a standing wave vibration. The rotor is formed of a non-uniform rigidity and mass distribution and the stator is formed with relief portions formed therein corresponding to loops of a standing wave vibration and projections corresponding to the nodes of the standing wave vibration.