| 摘要 |
PURPOSE:To shorten the time for synchronizing a rotational phase difference signal with a reference signal by providing means for outputting a rotational speed signal, means for outputting a rotational phase signal, means for outputting first and second phase difference signals, and means for remarkably varying the rotational speed of motor according to the second phase difference signal. CONSTITUTION:A rotational speed detecting circuit 1 outputs a rotational speed signal 1a corresponding to the rotational speed of a motor 2. A rotational phase detecting circuit 2 detects a single pulse for every revolution of the motor 2 and outputs a rotational phase signal 1b. A phase control circuit 3 compares an externally provided phase reference signal S with the rotational phase signal 1b fed from the rotational phase detecting circuit 2 and outputs a first phase difference signal 3a if the phase difference is small whereas outputs a second phase difference signal 3b if the phase difference is large. A speed modulation circuit 4 outputs a speed modulation signal 4b for varying the rotational speed of the motor 2 remarkably according to the second phase difference signal 3b fed from the phase control circuit 3. A speed control circuit outputs a speed difference signal 5a between the speed modulation signal 4a and the rotational speed signal 1a. |
