Patent ID: 6959156

Claim:
An image forming apparatus comprising: a developing device for developing an electrostatic image formed on an image bearing member with developer including toner and carrier; a density sensor for detecting a density of a toner image; control means for controlling an amount of toner to be supplied to said developing device by comparing an output of said density sensor with a target value; changing means for changing the target value when the output of said density sensor falls into an error level; and recovering means for supplying the toner based on the target value changed by said changing means to perform a recovery operation, wherein when the output of said density sensor falls into the error level, said changing means changes the target value to a second target value, which is lower than a first target value, which is the target value before the output of said density sensor falls into the error level, wherein when the output of said density sensor reaches the second target value, said recovering means performs a detection operation by said density sensor, and finishes the recovery operation.