| 摘要 |
PURPOSE:To change the driving properties of a motor by producing a control signal based on a clock signal supplied from outside and a reproduced information signal concerning the rotational speed of a motor and changing the frequency of the clock signal supplied to a signal producing circuit. CONSTITUTION:A disk 21 is driven into rotation by the motor 22 and a signal outputted from a pickup 23 is supplied to a signal processing circuit 25 through an amplifier circuit 24. The signal outputted from the circuit 24 is supplied to a motor control signal producing circuit 27 and the circuit 27 compares a frame synchronizing signal with a referee signal and supplies H-level and L-level pulse signals to a counter circuit 28 when the rotational speed of the disk 21 becomes slower and faster than the regular rotational speed, respectively. A clock signal CLK and a clock signal CLK are supplied to the circuit 28 depending on whether the circuit 27 is or is not continuously sensing the frame synchronizing signal, respectively. The count value is supplied to the motor 22 through a PWM modulating circuit 35, a time constant circuit 37 and an amplifier 38 for changing the driving properties.
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