| 摘要 |
PURPOSE:To obtain good images using one component type developer without any useless consumption of toner, by applying different specified bias voltages to a developer feeder in developing and in not developing. CONSTITUTION:Photosensitive drum 14 is positively charged with corona charger 15, and a negative latent image is formed by imagewise exposure. Toner having a volume resistivity of above 10<13> ohm.cm in a powder state is fed from hopper 18 to conductive developing roller 17, and the toner is positively charged with toner charger 20 made of friction charging blades. In developing, positive voltage is applied to roller 17 from voltage supply E1 of bias voltage controller 19, and the toner is attached to apparently negative low voltage areas, resulting in effecting reversal development. When development is stopped, negative voltage is applied to roller 17 from voltage supply E2, thereby permitting the toner not to be attached to drum 14, because toner charge polarity is positive, even if residual voltage on drum 14 is as high as several ten volts. |
