| 摘要 |
PURPOSE:To prevent a playback image from being distorted by detecting the interval of a playback horizontal synchronizing signal and computing and storing a speed distribution state including an irregularity in rotation during recording, and performing open loop control over a motor driving system on the basis of the stored speed distribution state. CONSTITUTION:The AC component of the output of a D/A converter 19 is passed through a power amplifier 23 to apply a control voltage of the same frequency to a disk driving motor 2. When the frequency of the applied voltage is low, the output of an F/V converter 21 is controlled to the same AC waveform with the output of the D/A converter 19 and as the frequency increases, the phase of the output voltage of the F/V converter 21 is delayed. The frequency, gain, and phase of the irregularity in rotation during recording are calculated from the value obtained by counting the interval of the playback horizontal synchronizing signal HD with specific reference clock pulses and they are divided by the transfer function of a motor control means and stored in a motor control means as control references to obtain the same irregularity in rotation with the recording. Consequently, speed control which reproduces the same irregularity in rotation with the recording is performed and an image is prevented from being distorted during reproduction owing to the irregularity in rotation during the recording.
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