| 摘要 |
PURPOSE:To prevent deposition of a large amount of developer on the entire surface and achieve the reduction in the burden of cleaning process by applying developing bias of opposite polarity while the surface whose potentials have lowered owing to dark attenuation fully passes by the developing part. CONSTITUTION:Aside from a power source E1 for developing bias, a DC power source E2 of polarity opposite from that of said source is provided and while a natural discharging part D fully passes a developing device 4, a switch is dhanged over to the power source E2 side of the opposite polarity. Since the switch changes over to the power source E1 for bias development after the dischrage part D has passed the developing device 4, deposition of toner on one surface of the discharging part D is prevented. As a result, the burden of the cleaning part 7 is reduced and there is no likelihood of giving adverse influence to the latent image forming part owing to cleaning defects and degrading printing quality. In addition, the constitution and operation become simple. |
