ve drum based on a resistance of the photosensitive layerUS5636009 *Jun 12, 1996Jun 3, 1997Canon Kabushiki KaishaImage forming apparatus having charging memberUS5678125 *May 16, 1996Oct 14, 1997Ricoh Company, Ltd.Image forming apparatusUS5701551 *Nov 15, 1996Dec 23, 1997Canon Kabushiki KaishaImage forming apparatus including control means for controlling an output from en electrical power source t