IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide an image forming apparatus which has a high maintenability and a high image stability without being affected by the environment or the charged amount of carrier even after performing image forming operation for a long period of time and also realizes a long term stability of a developer stored in a developing device with a simple configuration. SOLUTION: In the image forming apparatus which supplies replenishing developer including toner and carrier from a developer cartridge 4 to the developing device 1, a replenishing developer amount predicting means predicts the developer amount supplied to the developing device 1, the fogging extracting potential between the image carrier 28 and a developer carrier 3 at a period of time other than image formation is made larger than at image formation to discharge the carrier from the developing device 1 to the surface of the image carrier 28, and a discharged carrier amount detecting means 11 detects the carrier amount. The carrier amount discharged to the image carrier 28 from the developing device 1 is changed based on the difference between the replenishing developer amount predicted value by the replenishing developer amount predicting means and the discharged carrier amount detected value of the discharged carrier amount detecting means 11. COPYRIGHT: (C)2004,JPO&NCIPI