US Patent 7773922 Image forming apparatus

An image forming apparatus for developing an electrostatic image formed on a photosensitive drum 1 with a developer, so as to form an image includes: a rotatable developing sleeve 44; a developing blade 46 for restricting a layer of a developer borne on the developing sleeve 44; developing member for developing the electrostatic image formed on the photosensitive drum 1 with the developer; vibrating member 50 for vibrating the developing blade 46; and control member for controlling a drive condition of the vibrating means 50 according to a printing ratio of the image formed.