| 摘要 |
PURPOSE:To enable to preferably control a motor speed by selecting a comparison signal in response to the rotating state of the motor. CONSTITUTION:When a speed detector 7 detects that the rotating speed of a disk is largely fast, the output (e) of a comparison signal generator 17 passes gates 12, 13, 15, and is applied as a comparison signal (b) to a phase comparator 2. Since the frequency of the output (e) is higher than a reference signal (a), the phase comparator 2 outputs a signal for decelerating the rotating speed of the motor. On the other hand, when it is largely lower than the rotating speed of the disk, a comparison signal selector 11 does not select any of comparison signals (d), (e). Accordingly, a signal for accelerating the rotating speed of the motor is outputted from the comparator 2. In this manner, the motor is rotatably driven substantially near the prescribed speed. |
