A standing-wave type ultrasonic motor utilizing flexible standing-wave components. Protuberances are provided nearly at every other intermediate positions of the loops and the nodes of flexible standing-waves generated in the vibration member by the piezo-electric element or the electro-strictive element,...http://www.google.com.au/patents/US5079470?utm_source=gb-gplus-sharePatent US5079470 - Standing-wave type ultrasonic motor and timepiece
