| 摘要 |
PURPOSE:To obtain a prescribed scanning pitch, and also, to prevent the expansion and contraction of an image written in a photosensitive body by executing a control of a photosensitive body driving motor while using an oscillation frequency of a self-oscillation circuit which is brought to self-oscillation by feeding back counter electromotive force generated by a Miller vibrator as a reference. CONSTITUTION:The speed of revolution of a motor 1 is controlled while using an output frequency of a self-oscillation circuit 350 which is brought to self- oscillation by feeding back counter electromotive force generated by a Miller vibrator 310 (driving coil 311) as a reference. Therefore, the speed of revolution of a photosensitive drum and the oscillation frequency of a Miller vibrator 312 always correspond to each other by one-to-one. Accordingly, even when there is a variance in a natural frequency of each Miller vibrator 310 and output frequencies of the self-oscillation circuit 350 are different, respectively, the speed of revolution of the photosensitive drum and the oscillation frequency of the Miller vibrator 312 always hold the corresponding relation of one-to-one. In such a way, the expansion and contraction of an image which is written in the photosensitive drum are prevented. |
