| 摘要 |
PURPOSE:To reduce the periodical irregularity of speed by varying the delay time of a learning and correcting device learning the periodical error of speed in a speed control loop and adding at a next period with feed-forwarding corresponding to the rotational speed of a reel motor. CONSTITUTION:A signal of the speed of the magnetic tape 1 outputted as a pulse by a speed detecting part 10 is shaved by a waveform shaping circuit 11 and compared with the target value 13 by a comparator circuit 12, then the error signal is outputted. The error signal is inputted in a motor driver 15 through a phase correcting circuit 14, and the driver 15 drives a reel motor 5 and constitutes a speed control loop and controls the motor 5 then drives the tape 1 at a constant speed. The learning and correcting device 20 has a delay circuit 21 with a delay time L and stores the output value of the circuit 12 then adds it to the outputted value of the circuit 12 at L period later. The delay time L is varied by a rotational speed detecting part 22, rotational speed and delay time calculator circuit 24 and 25 corresponding to the variation of the rotational speed of the motor 5. Consequently, the periodical irregularity of the speed is reduced. |
