| 摘要 |
PURPOSE:To eliminate base fogging even if transfer conditions, etc. change and to transfer an image to numbers of sheets with high transfer efficiency by detecting a rise of the surface potential of a photosensitive drum due to a transfer roll and controlling a bias voltage to the transfer roll. CONSTITUTION:When a surface electrometer 9 detects a rise of the surface potential of the photosensitive drum 1 due to the transfer roll 4 during many- sheet copying of the same latent image, a bias conversion control circuit 10 responds to it to control the bias voltage to the roll 4. Consequently, the surface potential of the drum 1 is prevented from rising to a development potential and even if transfer conditions of the resistivity, transfer pressure, etc. of the transfer roll including environmental condition of humidity, etc. change, base fogging in the many-sheet copying of the same latent image is not caused to improve the efficiency of the transfer. |
