| 摘要 |
PURPOSE:To improve the stability of a latent image control and the stability of a picture quality by switching the target value of a latent image potential control, and also, a developing bias application amount with respect to the dark attenuation amount of the potential, with regard to a photosensitive body whose potential attenuation amount is large. CONSTITUTION:A potential sensor 15 for detecting the surface potential of a photosensitive drum 1 is provided in the vicinity of the photosensitive drum 1, and the output of this sensor 15 is connected to a controlling circuit 17 through a detecting circuit 16. The control circuit 17 determines an electrification amount by an electrifier 2 and an exposure amount, respectively, through a high voltage transformer 14 and a lighting circuit 18 in accordance with the output of the sensor 15. To the control circuit 17, the combination of a potential desired value is inputted from a storing circuit 19, and its combination is selected by a switch 20. The contents of the storing circuit 19 are set in advance in accordance with the dark attenuation amount of an a-Si photosensitive body. The dark attenuation amount is shown by a dark part potential difference in the position of the sensor 15 and a developing device 10, and measured in advance before integrating the photosensitive body into the device. In such way, the stability of a latent image control and a picture quality can be improved.
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