Patent ID: 6469419
Filing Date: 2002-10-22
Classification: H02N

Abstract:
An ultrasonic motor comprising:a rotor; and a stator generating complex vibrations for rotating said rotor, said complex vibrations including longitudinal vibrations and torsional vibrations, said rotor being rotatably urged against said stator, said stator including: a plurality of piezoelectric drive elements; a plurality of power supply electrode plates for supplying power to said piezoelectric drive elements; a longitudinal-vibration sensing means for sensing said longitudinal vibrations; a first metal block; a second metal block, said piezoelectric drive elements, said power supply electrode plates and said longitudinal-vibration sensing means being securely clamped between said first metal block and said second metal block; and a torsional-vibration sensing means for sensing said torsional vibrations, said torsional-vibration sensing means being provided separately from said piezoelectric drive elements and said power supply electrode plates, wherein said torsional-vibration sensing means includes a torsional-vibration sensing piezoelectric element; each one of said piezoelectric drive elements is polarized in an axial direction of said ultrasonic motor; and said torsional-vibration sensing piezoelectric element is polarized in a torsional direction about a rotational axis of said ultrasonic motor.