Patent ID: 7668471

Claim:
An image forming apparatus comprising: a latent image bearing member configured to bear an electrostatic latent image thereon; a developing device configured to develop the latent image with a two-component developer including a toner and a magnetic carrier, wherein the developing device includes a developer bearing member bearing the two-component developer on a surface thereof; a development potential forming device configured to form a development potential between the electrostatic latent image on the image bearing member and the developer bearing member; a toner replenishing device configured to supply the toner to the developing device; a toner concentration detecting device configured to detect and output a concentration of the toner in the two-component developer in the developing device; a toner concentration controlling device configured to compare the toner concentration output with a toner concentration target to control the toner concentration so as to approach the toner concentration target; an information detecting device configured to obtain information to determine a replacement amount of the toner in the developing device in a predetermined period of time; and a development potential correcting device configured to adjust the development potential on the basis of the information obtained by the information detecting device.