| 摘要 |
PURPOSE:To stably operate the title motor by controlling the frequency of a drive signal at a low level potential at the time of oscillation. CONSTITUTION:A driving circuit for a vibration wave motor 4 is composed to detect the phase of a feedback signal and to maintain the phase of the signal VFB constant. The signal VFB induced in the monitoring electrode 4c of the motor 4 is inputted to a detector 5, and the Q output terminal of its flip-flop FF1 is connected to the UP/DN terminal of an UP/DN counter 6. Its output terminal Q1-Qn are connected to a D/A converter 7. In this case, an analog signal from the converter 7 is inputted to a point P3 to be varied to a low level potential at the time of oscillating a sawtooth wave generated at the end of a capacitor C21, thereby varying its oscillation frequency. Thus, after the signal of the voltage VFB is shaped to a rectangular wave by a waveform shaper 5a, supplied to the FF1, its tracing direction is detected, and inputted as a UP/DN control signal of the counter 6. |
