| 摘要 |
PURPOSE:To reduce current consumption by masking the output from a VCO untill the frequency thereof reaches to a level for driving an ultrasonic wave motor when the ultrasonic wave motor is started. CONSTITUTION:An ultrasonic wave motor 1 comprises a piezoelectric element. A VCO 6 receives an output from a rectifying/amplifying means 5 as a fre quency control voltage and provides its output to a signal interrupting means 12. The signal interrupting means 12 passes or interrupts an input according to a mask signal provided from a drive control means 10. Output from the VCO 6 is employed for driving a piezoelectric element through a frequency dividing means 7, a phase distribution means 8 and a boosting means 9. When the frequency to be applied on the ultrasonic wave motor 1 is decreased gradu ally from fo, rotation is started at the frequency of fn and peak current consump tion and rotation are reached at resonance frequency fR. The frequency fo is set at a sufficiently high level, and a mask signal is provided during the interval from frequency fo to fn in order to mask the output from the VCO 6. |
