| 摘要 |
PURPOSE:To attain the acceleration in the shortest time without malfunction of a motor, by detecting the presence of dropout with the frequency change in a reproducing FM signal and turning off the drive of motor just after the end of the period when high/low levels of a detecting signal are repeated. CONSTITUTION:A latch circuit 17 outputs a high signal with a start signal from a system controller 13 and an accelerating voltage is applied to a motor drive circuit 9 via a switch circuit 14a. On the other hand, the number of revolutions of the motor rises and the frequency of the reproducing FM signal reaches a dropout(DO) detecting frequency, then a DO detecting circuit 2 outputs a high/ low signal and a latch circuit 17 outputs a low signal and the signals are maintained until a clear signal is outputted from the system controller 13. A multivibrator 16 outputs a pulse being high level for a prescribed time, which is set to a time equal to or slightly longer than an output period of the high/low signals of the circuit 2. The circuit 17 is operated with an output of the multivibrator 16. allowing to attain the acceleration in the shortest time without malfunctioning the motor. |
