| 摘要 |
A rotation drive device for driving a rotator is disclosed, comprising an electric motor for driving the rotator, a phase detecting circuit for detecting the phase of rotation of the rotator, a reference signal source for forming a reference signal of a constant period, a phase control circuit for controlling the motor in such a manner that the phase difference between the output of the reference signal source and the output of the phase detecting circuit becomes a constant value, a detecting circuit for detecting a fact that the reading-out of the phase difference is not completed in the time interval between the successive two outputs of the phase detecting circuit, a control circuit for varying the number of cycles of phase difference computing operation of the phase control circuit depending on the time interval between the successive two outputs of the phase detecting circuit, another detecting circuit for detecting a fact that the phase detecting circuit has produced no output in one period of the reference signal, and another detecting circuit for detecting a fact that the production of an output of the phase detecting circuit has repeated a plurality of times in one period of the reference signal.
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