Control device for ultrasonic motor

Claim 1

A control device for an ultrasonic linear motor for controlling to drive said ultrasonic linear motor to a target position according to a driving signal having a resonance frequency of said ultrasonic linear motor, said control device comprising: detecting means for detecting a moving position of said ultrasonic linear motor; a control unit for outputting a control pulse having a duty ratio changing from 100% to 0% until said ultrasonic linear motor reaches said target position from a start position, according to a detection data from said detecting means; an AND circuit for inputting said driving signal and said control pulse; a driving circuit for driving said ultrasonic linear motor according to an output signal from said AND circuit; a pair of legs substantially parallel to each other; an oscillator having a body portion connecting said legs, said body portion being disposed perpendicular to said legs and forming a pair of corner portions where the body portion is connected to the legs; and a pair of piezoelectric elements disposed at the corner portions of the body portion, wherein each piezoelectric element is oriented at an angle of 45° with respect to both the body portion and each respective leg.