Patent ID: 6947681

Claim:
An image forming apparatus comprising: a developing device for developing an electrostatic image formed on an image bearing member with a developer containing nonmagnetic toner and magnetic carrier; toner density detecting means for magnetically detecting a density of the toner in the developing device; control means for controlling an amount of toner to be supplied to the developing device on the basis of an output detected by the toner density detecting means and a target value; and image density detecting means for detecting a density of a predetermined toner image formed by the developing device, wherein the developing device can execute a developing operation at a first speed and a second speed differing from the first speed, and wherein in a case where a last developing operation is executed at the first speed, whereafter a next developing operation is executed at the second speed, the control means determines the amount of toner supply by use of the target value corrected on the basis of the output of the image density detecting means.