| 摘要 |
PURPOSE:To provide a driving device for ultrasonic motors which is excellent in conformity and stability and the stator of which can be controlled so that its vibrating amount can be controlled within a prescribed target range. CONSTITUTION:The output of each comparator 12 and 13 from which the vibrating amount of a piezoelectric element is supplied to a comparison- discriminating means 10 and differentiationdiscriminating means 17 is outputted to a microcomputer 9 by means of a monitor electrode 1d which monitors the vibrating amount of the piezo-electric element through a rectifier circuit 11 and the outputs of the comparator 21 and code discrimination circuit 20 of the means 17 are also outputted to the microcomputer 9. The microcomputer 9 makes overall control and its control signal is supplied to a stator 1 through a voltage-controlled oscillation circuit 7, phase shifting circuit 6, and switching circuit 5. When such constitution is used, the vibrating amount can be reduced by raising the frequency when the vibrating amount is higher than its upper limit and can be increased by lowering the frequency when the vibrating amount is lower than its lower limit. In addition, by finding the temporally differentiated value of the vibrating amount, the controlling width is decided on the basis of the magnitude and sign of the temporally differentiated value. |
