| 摘要 |
PURPOSE:To prevent phase from deviating due to a phase-shifting circuit and a low-pass filter along with the fluctuation of a vibration frequency and the vibration frequency and a resonance frequency from deviating and at the same time suppress the generation of noise. CONSTITUTION:The output signal of a PLL circuit 20 is counted by a counter 61 for generating an address value, the address value is applied to a ROM 62, pseudo sinusoidal wave data retained at the ROM 62 are read successively, and the data are converted to an analog signal SP by a D/A converter 62. The signal SP is used for exciting the vibrator. The output of the PLL circuit 20 is divided to generate a signal SQ, the signal is fed back to the input of the PLL circuit 20, and at the same time a counter 61 is cleared by the signal SQ, thus synchronizing the SQ and SP. The SQ and SP are shifted by 90 degrees. |
