Abstract: To provide an image forming apparatus that includes a plurality of image forming units and executes a mode for image formation by using a selected image forming unit, the image forming apparatus being able to restrict a decrease in productivity and restrict an image defect such as a lack of part of an image output during the execution of the mode. In a monochrome mode for forming an image only with a black toner, in the first image forming unit, a toner is caused to adhere to a region on a photosensitive body corresponding to a sheet interval and hence the toner is supplied to a cleaning blade by applying a development bias to a developing unit without applying a direct-current voltage to a charger of a color image forming unit not used for the image formation. Also, an alternating-current voltage is applied to the charger when the region on the photosensitive body from which the toner is removed by the cleaning blade passes through the charger.

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic image is to be formed; a developing device for accommodating a developer including toner and a carrier and for developing the electrostatic image with the developer; a developer supply container, detachably mountable to a main assembly of the image forming apparatus, for accommodating a supply developer including the toner; a detecting device for detecting a toner content of the developer in the developing device; a supply control device for controlling an operation of supplying the supply developer into the developing device on the basis of a detection result of the detecting device and a density target value; a memory element, provided on the developer supply container, for storing information relating to elapse time from a manufacturing date of the supply developer; and a controller for determining the density target value in accordance with the information, wherein the supply control device controls the supply operation

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic image is to be formed; a developing device for accommodating a developer including toner and a carrier and for developing the electrostatic image with the developer; a developer supply container, detachably mountable to a main assembly of the image forming apparatus, for accommodating a supply developer including the toner; a detecting device for detecting a toner content of the developer in the developing device; a supply control device for controlling an operation of supplying the supply developer into the developing device on the basis of a detection result of the detecting device and a density target value; a memory element, provided on the developer supply container, for storing information relating to elapse time from a manufacturing date of the supply developer; and a controller for determining the density target value in accordance with the information, wherein the supply control device controls the supply operation

Abstract: A developing apparatus of this invention includes development units each including a developing powder accommodating unit for accommodating developing powder, a screw which agitates and conveys developing powder and a developing powder bearing member which bears developing powder to develop an image and a developing powder supply unit which supplies developing powder to the developing powder accommodating unit and develops an electrostatic latent image formed on an image bearing member at a development position. The developing powder supply unit supplies developing powder to a lower area than a screw in the vertical direction of the developing powder accommodating unit in the time the development unit has been in the developing position.

Abstract: A developing apparatus of this invention includes development units each comprising a developing powder accommodating unit for accommodating developing powder, a screw which agitates and conveys developing powder and a developing powder bearing member which bears developing powder to develop an image and a developing powder supply unit which supplies developing powder to the developing powder accommodating unit and develops an electrostatic latent image formed on an image bearing member at a development position. The developing powder supply unit supplies developing powder to a lower area than a screw in the vertical direction of the developing powder accommodating unit in the time the development unit has been in the developing position.