| 摘要 |
PURPOSE:To eliminate the necessity of speed adjustment of a motor speed controlling system and, at the same time, to obtain a high-quality reproduced picture, by resetting a frequency-voltage converting characteristic which is set automatically at the time of normal recording and reproduction by changing the output of a speed offset corrector by a prescribed quantity. CONSTITUTION:The number of revolution of a cylinder motor 3 is detected by a signal generator 4 and sent to a speed offset corrector 5 and frequency-voltage (f-v) converter 6. When a voltage offset DELTAv caused by disturbance produces a speed offset DELTAomega and the speed is deviated from a desired frequency f0, the corrector 5 sends an output which moves the f-v characteristic by making cycle measurement and, at the same time, a constant-voltage generating circuit 41 outputs the minute correcting quantity of a DC voltage to a adder 40 at the time of quick-view reproduction and slow-motion reproduction. The minute correcting quantity of the DC voltage is added to the output from the corrector 5 and the added result rotates the cylinder motor 3 at a prescribed speed through the converter 6, amplifier 7, and motor driver 8. A capstan motor 9 is also controlled in the same way. Therefore, the necessity of volume adjustment is eliminated and high-quality reproduced pictures are obtained. |
