Patent ID: 8131162

Claim:
An image forming apparatus comprising: a developing section which develops an electrostatic latent image formed on an image bearing member with a developer; a cartridge which accommodates the developer and is dismountably mounted to an apparatus main body; a supply section which supplies the developer from the cartridge to the developing section; a detector which detects a density of the developer; a supply controller which controls supply of the developer by the supply section in accordance with a detection result of the detector; an identifying section which performs an electrical communication with the cartridge to determine whether a qualified cartridge is mounted to the apparatus main body; and a determining section which determines if a non-qualified cartridge is mounted or the cartridge is not mounted, in a case where the identifying section identifies that the qualified cartridge is not mounted to the apparatus main body, wherein the supply controller controls the supply section to stop supply of the developer, and controls the supply section to restart supply of the developer at a point of time when a density of the developer detected by the detector becomes equal to or lower than a predetermined density after the supply of the developer is stopped, and in a case where the density of the developer detected by the detector after the supply of the developer by the supply controller is restarted becomes higher than the density immediately before the supply of the developer by the supply section is restarted, the determining section determines that the non-qualified cartridge is mounted to the apparatus main body, and in a case where the density of the developer detected by the detector does not become high, the determining section determines that the cartridge is not mounted.