Seiko Epson Corporation

Tomoo Ueda

Osamu Miyazawa

Joji Kitahara

Tsuneaki Furukawa

An ultrasonic motor comprising a rotor and a stator driven by a piezoelectric element is disclosed. The rotor includes a plurality of gaps which correspond to periods in which piezoelectric sub-element rows are formed. A plurality of level differences on the surface of the stator have rotational symmetry in prescribed periods. Standing waves generated on the stator exert stress on the level differences of non-contact areas of the rotor so as to provide for rotor rest at a relative position where the stress becomes balanced. Stepping operation of the rotor is achieved by movement of the standing waves employing a plurality of level differences with rotational symmetry. The positions where the stress becomes balanced always occur at the same interval thereby facilitating precise stepping operation.

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Suwa, Japan

Tomoo Ueda