| 摘要 |
PURPOSE:To prevent the deterioration in characteristics upon transient response, by a method wherein learning is stopped upon the transient response, such as the rise-up of the rotation of a rotating body or the like, and correction for removing it from the error of a speed is prevented. CONSTITUTION:The drum servo circuit of a VTR detects the rotation of a drum motor 1 by detectors 2-4 and controls the driving of the motor 1 by the value of detection through a D/A converter 26 and a drive amplifier 27. The frequency signal FG from the detectors 2-4 is supplied to the forming circuit 5 of the error of speed and is inputted into an adding circuit 9 through a differentiating circuit 6, a multiplying circuit 7, a digital comb type filter circuit 8, the multiplying circuit 10 and a limiter 11 and a correction to remove the amount of proper fluctuation per one rotating period of the motor 1 is effected. On the other hand, a pulse PG is supplied to a phase error forming circuit 21 and the data thereof is inputted into said adding circuit 9 through the multiplying circuit 22, the limiter 23, an integrating circuit 24 and the multiplying circuit 25 respectively. Thus, the drum motor 1 may be rotated with a constant speed and a synchronized phase. |
