| 摘要 |
PURPOSE:To compensate a variation error of a printing magnification generated by variation of a galvanomirror with simple constitution, by providing a reference frequency generating means of a copy machine driving motor for synchronizing the revolving speed of the copy machine driving motor with a resonance frequency of the galvanomirror. CONSTITUTION:A home pulse 12 for showing a fact that light has passed through a home sensor is inputted to a reference time pulse generating circuit 18, and a reference time pulse 14 is generated. This reference time pulse 14 and an end pulse 13 for showing a fact that light has passed through an end sensor are compared by a phase comparing part 19a, and when the reference time pulse 14 has risen earlier than the end pulse 13, an output voltage 15 of the phase comparing part 19a outputs a high voltage, and in case of the contrary, a low voltage is outputted. A speed control system is formed so that the resonance frequency of the galvanomirror obtained in such a way coincides with a speed signal 21 generated by frequency-dividing or multiplying by a reference frequency generating part 66. In such a way, a variation error of a printing longitudinal magnification generated by variation of a galvanomirror resonance frequency can be compensated with simple constitution.
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