Patent ID: 7635940

Claim:
An ultrasonic motor for causing elliptical vibrations at a contacting point with a driven object by utilizing bending vibrations and longitudinal vibrations, comprising: a vibrator formed by stacking a plurality of rectangular piezoelectric plates in a thickness direction; a driving circuit for applying a driving signal to a piezoelectric plate; and a detection circuit for detecting an electromotive force generated when a piezoelectric plate deforms, wherein: the plurality of rectangular piezoelectric plates include a first piezoelectric plate and a second piezoelectric plate; in each of the first piezoelectric plate and the second piezoelectric plate, a longitudinal vibration polarization portion that can excite the longitudinal vibrations and a bending vibration polarization portion that can excite the bending vibrations are polarized in a thickness direction; the first piezoelectric plate is connected to the driving circuit and the detection circuit, and the second piezoelectric plate is connected to the driving circuit and is not connected to the detection circuit; and in each of the first piezoelectric plate and the second piezoelectric plate, a longitudinal vibration electrode provided for the longitudinal vibration polarization portion and a bending vibration electrode provided for the bending vibration polarization portion are not included in a same plane that is perpendicular to a vibration direction of the longitudinal vibrations.