| 摘要 |
PURPOSE:To drive a motor to a resonance state with a simple constitution by determining the frequency of a driving frequency voltage so that the phase differnece relationship between an output signal from the monitoring electrode and the driving frequency voltage will always be a phase relationship indicating a resonance state. CONSTITUTION:The output power of VCO5 is given to driving electrodes 1-1, 1-2 through a phase shifter 6, output circuits 7, 8 and coils 10, 11. The output power of electrodes 1-3 for detecting a resonance state of stator is given to the phase-comparison circuit 12 through the level comparator 2 and the output power of said circuit is supplied to VCO5 through a low-pass filter 4. The comparator 2, phase-comparison circuit 16, low-pass filter 4 and VCO5 constitute PLL by which the frequency of a driving frequency voltage is determined so that the phase difference relationship between an output signal from electrodes 1-3 and the driving frequency voltage will always be a phase relationship indicating a resonance state. |
