| 摘要 |
<p>In a bias device for a copying machine, the surface potential of the photo-sensitive member is detected and stored, a bias voltage is obtained by superposing a certain potential on the potential thus stored, the surface potential of an electrode confronting the photo-sensitive member is stored in a non-image period occurring with the photo-sensitive member, and the bias voltage is applied to the electrode in an image period occurring with the photo-sensitive member, whereby troubles due to the residual voltage of the photo-sensitive member are effectively overcome.</p> |
