Patent ID: 7536119

Claim:
An image forming apparatus including a main body and comprising: a developing cartridge mounted in the main body of the image forming apparatus to receive a developer in accordance with a certain space occupancy of the developer with respect to an inner capacity thereof; a developer supply part connected to the developing cartridge to supply the developer; a sensor detecting an amount of the developer in the developing cartridge; and a control part controlling the developer supply part to restrict an amount of the developer to supply to the developing cartridge according to the amount of the developer detected by the sensor, thereby maintaining the space occupancy of the developer in the developing cartridge, wherein the developing cartridge comprises an agitating screw rotatably mounted to agitate the developer supplied from the developer supply part, a developer mixing roller mounted at one side of the agitating screw to agitate the developer together with the agitating screw and a developing roller for developing the developer onto a photoconductive body, the space occupancy includes a ratio of a space occupied by the developer supplied to the developing cartridge with respect to the whole inner volume of the developing cartridge excluding spaces occupied by the agitating screw, the developer mixing roller and a developing roller, and the space occupancy of the developer is approximately 55˜65%.