Patent ID: 7149437

Claim:
An image forming apparatus to which a cartridge having a developing apparatus and memory medium is detachably mountable, the image forming apparatus comprising: a detector for detecting toner concentration; and a control unit for selecting an operational mode of the image forming apparatus from a first operational mode and second operational mode, wherein the first operational mode supplies a toner to the developing apparatus on the basis of a value detected by the detector, and the second operational mode to supplies the toner to the developing apparatus on the basis of a cumulative value of image signals for printing, wherein the memory medium stores information to switch an operational mode of the image forming apparatus from the second operational mode to the first operational mode, the information being set in accordance with toner characteristics, and wherein when the image forming apparatus is operative in the second operational mode, the control unit switches the operational mode of the image forming apparatus from the second operational mode in operation to the first operational mode on the basis of information related to the cumulative value of image signals and information stored in the memory medium.