PURPOSE: To prevent toner particles in a developing device from intruding into another developing device which is not submitted for development among plural developing devices or a control electrode from being soiled by toner or toner from adhering to an image forming body from the developing device in the midst of stopping the development.
CONSTITUTION: In an image forming device where the development for a photoreceptive belt 1 being the image forming body is performed by impressing bias voltage on a developing sleeve 81 and the control electrode; the toner is allowed to fly to the belt 1 under conditions that the bias voltage consisting of DC component and AC component is impressed on the sleeve 81 and the DC bias voltage is impressed on the control electrode at the time of forming the image, and the sleeve 81 is stopped and the same bias voltage is impressed on the control electrode and the sleeve 81 at the time of non-forming the image. Then, as for the bias voltage at the time of non-forming the image, only the DC component is impressed after the AC voltage is stopped in the case of selectively operating the plural developing devices 8A to 8D, so that a potential pattern having higher and lower parts than the voltage of the DC component is formed on a non-image area on the belt 1.
SATO YOTARO
HANEDA SATORU
