| 摘要 |
PURPOSE:To simplify the composition of a circuit, by using arbitrary sampling frequency, and by setting arbitrary frequency characteristic and gain. CONSTITUTION:By the rotating speed of a motor 2 rotating a CD4 with a phase servo-apparatus, beam detecting signal Li obtained by a pickup 6 with laser beams is applied to a synchronizing signal detecting circuit 8, and is detected as synchronous signal Sr. Besides, reference synchronizing signal S0 is obtained from an oscillator 12 via a frequency divider 14. both the signals Sr, S0 are applied to a phase difference counter 24, and the phase difference of both the signals is detected. The input of the data Dp of the phase difference to a PWM circuit 28 via a filter 26 is provided, and pulse-width-modulated output is obtained on a time base, as pulse to compensate for the phase difference. Then, the output is applied to the motor 2 via driver 30, and is controlled so that the rotating linear velocity of the motor 2 may be set to be constant. |
