| 摘要 |
PURPOSE:To reduce the scale of a circuit and to improve resolution by making only latch parts of synchronous counters independent and using an adder in common on a time-division basis, and correcting low-order digit bits by a counter which operates at the highest frequency. CONSTITUTION:A digital servocontrol circuit controls the rotating speeds of a rotary drum 11 and a capstan 20. This control circuit consists of rotation detectors 12 and 21, frequency dividers 13 and 22, a reference clock generator 17, a time-division control counter 31, latches 32-35 for measurement, etc., the adder 36, an adder control circuit 37, low-order bit correctors 38 and 41, window circuits 40 and 43, etc. Then only the latches are made independent as to the synchronous counters which measure the pulse widths of pulses with length proportional to the rotating speed and phase of the drum 11, etc., and impose phase modulation and the adder 36 is used in common on a time-division basis at timing 1/A. Further, the low-order digit bits of the latches are corrected by the counter which operates at the highest frequency. |
