| 摘要 |
PURPOSE:To prevent the defect of separation of a sheet from a drum and the occurrence of the retransfer phenomenon by making the transfer electrostatic charge output at the rear part in the carrying direction of the sheet larger than that of the part other than the rear end of the sheet. CONSTITUTION:The carried sheet is subjected to transfer electrostatic charge and an image on a photosensitive drum 1 is transferred onto the sheet. The sheet is flowed in the direction of an arrow B when the image is copied to the one surface, and the sheet is flowed in the direction of an arrow C when the images are copied to two surfaces. For the purpose of preventing transfer defects and separation defects, a transfer current is set to 350muA for one surface and is set to 200muA for two surface. Further, the rear end of the sheet carried from an intermediate tray 26 is detected by a form sensor 35 when the images are copied to the two surfaces, and the transfer current is raised from 200muA to 350muA for one surface in accordance with detection of the rear end of the sheet. Thus, the defect of separation of the sheet from the drum and the occurrence of the retransfer phenomenon are prevented. |
