REVERSAL BIAS DEVELOPING METHOD

摘要

PURPOSE:To prevent deposition of toner on non-image portions by changing over the bias voltage of a developing sleeve in timing to the time when the specified position on the surface of a photosensitive drum opposes to the developing sleeve thereby cutting the application of the voltage or lowering the same. CONSTITUTION:Application of bias voltage to a developing sleeve 3 is accomplished at the time when the position on the surface of a photosensitive drum 1 which is within the charging region of the surface of the drum and does not enter the image region of the photosensitive drum 1 surface arrives at the position oppositing to the developing sleeve 3. On the other hand, changing-over of the developing bias voltage to the OFF state is accomplished at the time when the surface position of the drum 1 opposing to the developing roller 3 is within the charging region after passage of the end part of the image region. Operation in this way reduces the range of the non-image portions where the developing bias voltage is being applied and reduces the pickup of the toner on the non-image parts.