| 摘要 |
PURPOSE:To prevent dust-like stains in copying by applying bias voltage same as a toner in polarity to a conductive surface layer upstream from a blade, allowing an accumulated toner on the upstream side to flow down by the repulsing action of said layer, and eliminating a toner turning around on the reverse side. CONSTITUTION:A blade 10 is provided with upper and lower conductive layers 13, 14 and kept in a contact with the surface of a photosensitive drum 12. A bias voltage of 100-200V in a practicable level and same in polarity as a toner 17 is applied to the layer 13. The toner 17 on the underside of the blade 10 is dropped by the repulsive action of the layer 13, and its accumulation amt. decreases in accordance with increase of the voltage to be applied. A bias voltage reverse in polarity to the toner 17 is applied to the layer 14 of the blade 10 at the time of ordinary copying to prevent the toner from turning around the blade and attaching to the drum 12, and when the blade 10 is released, turning around of the toner 17 is prevented by reversing the polarity. |
