In an ultrasonic vibrator of structure in which an electro-mechanical energy conversion element for generating a vibration is held by and between electrically conductive blocks and in which a mechanical-electrical energy conversion element for detecting the vibration state of the vibrator is inserted...http://www.google.com.au/patents/US5231325?utm_source=gb-gplus-sharePatent US5231325 - Vibration device for a vibration driven motor
