Ultrasonic motor

An ultrasonic motor which produces elliptical vibration by inducing longitudinal vibration and flexural vibration at the same time and drives a driven body by obtaining a drive power from the elliptical vibration, comprising:

• a piezoelectric device;
• friction contact members which are provided on one face of the piezoelectric device so as to move a driven body by the elliptical vibration of the piezoelectric device;
• a holder member which positions and holds the piezoelectric device in a casing and is disposed corresponding to a node of the longitudinal vibration or in the vicinity thereof on the other face of the piezoelectric device and a node of the flexural vibration or in the vicinity thereof, the holder member having an engagement convex portion at the front end portion thereof and being provided with a pair of curved sliding contact projection portions which are projected from two faces perpendicular to the moving direction of the driven body;
• a position limiting member which accommodates the piezoelectric device and has accommodation holes each constituted of a sliding contact concave portion for accommodating the sliding contact projection portion of the holder member such that it makes a sliding contact therewith freely and an engagement concave portion for accommodating the engagement convex portion of the sliding contact projection portion, the sliding contact concave portion and the engagement concave portion being provided in each of the inner wall faces in a direction perpendicular to the moving direction of the driven body;
• and
• a pressure member which presses the holder member so as to bring the friction contact members into pressure contact with the driven body.