| 摘要 |
PURPOSE:To avoid occurrence of the out-of-phase caused by a sudden change of the phase of the input signal, by selecting the pseudo reference pulse having a certain relationship with the input signal having the frequency proportional to the rotating speed of the motor. CONSTITUTION:With input of the reference signal 8 to the pseudo reference pulse generating circuit 23, the pseudo reference pulses 22a, 22b and 22c having a certain phase difference to each other are produced from the signal 8. These pseudo reference pulses are then supplied to the selection circuit 24. Circuit 24 selects the pseudo reference pulse having the closets phase to the reproduced signal 9 among those pseudo reference pulses, and thus produces the selection reference pulse 25. This pulse 25 is supplied to the phase comparator 10, and at the same time the phase information signal 20 is generated to be sent to the digital signal process part. The error signal 11 supplied from the circuit 10 is applied to the motor via the amplifier 12 to give a control to the rotating speed of the motor. |
