| 摘要 |
PROBLEM TO BE SOLVED: To change a speed stably by frequency control by installing a phase difference generating means which changes at one time the other voltage signal to the one that has specified phase differences from a standard voltage signal. SOLUTION: In this device, a phase difference generating means 7e is installed which also servers as a reversing means which changes the other ultrasonic voltage signal to the one that has phase differences of π/2 and other phase angles around π/2 from a standard ultrasonic voltage signal. In the phase difference generating means 7e, a phase difference between the voltage and the current of the input ultrasonic voltage signal is detected and then the phase difference signal is input into a feedback means 92 through a line L2 and a control signal which generates such frequencies that by have phase differences within specified range is input to an oscillating means 6 through a line L3. By this method, the circuit configuration can be simplified and the speed can be changed linearly over a wide range by a change in phase difference. |
