Patent ID: 7759840
Filing Date: 2010-07-20
Classification: H01L,H02N

Abstract:
1. An ultrasonic motor having an ultrasonic vibrator in which a first piezoelectric element and a second piezoelectric element are alternately laminated and a driven body in contact with the ultrasonic vibrator, the ultrasonic motor configured to simultaneously generate a longitudinal vibration and a flexural vibration in the ultrasonic vibrator to generate a substantially elliptical vibration at an output end of the ultrasonic vibrator, thus causing the ultrasonic vibrator and the driven body to move relative to each other, the ultrasonic motor comprising: a first internal electrode disposed, when the first piezoelectric element is divided into two equal parts in a longitudinal direction and two equal parts in a width direction to form four regions, in two neighboring regions or in all regions such that the surface areas occupied in each region are substantially the same; a second internal electrode disposed on the second piezoelectric element at a position corresponding to the first internal electrode; and a longitudinal vibration detection unit configured to detect the longitudinal vibration independently, in the conditions where the longitudinal vibration and the flexural vibration are simultaneously generated, based on a potential difference between the first internal electrode and the second internal electrode.