| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an ultrasonic motor drive device having stable drive characteristics even if the impedance of a piezoelectric element changes due to self-heat generation and a change in temperature of an environment in driving without impairing piezoelectric characteristics. <P>SOLUTION: The ultrasonic motor drive device has a drive circuit B for supplying an AC voltage having a predetermined drive frequency to an ultrasonic motor AA, a measuring circuit C for measuring the impedance of a piezoelectric element A changing based on vibration; a changeover switch E for connecting any one of a first electrode group 5A and a second electrode group 5B to the drive circuit B and connecting the other of the first electrode group 5A and the second electrode group 5B to the measuring circuit C, and a correcting circuit D for correcting the drive frequency of the AC voltage to be applied to the piezoelectric element A on the basis of the impedance measured by the measuring circuit C. <P>COPYRIGHT: (C)2009,JPO&INPIT |
