Patent ID: 7415214

Claim:
An image forming apparatus, which uses two-component developer constituted of toner and carrier and includes toner density control means for supplying the toner from a supply device to a developing device on the basis of magnetic permeability of the developer so as to cause toner density in the developing device to be constant, said image forming apparatus comprising remaining toner amount detection means for detecting an amount of remaining toner in the supply device, wherein the remaining toner amount detection means includes: toner supply amount calculation means for calculating an amount of toner supply on the basis of an accumulated number of rotations of a supply motor which is rotated so as to supply toner from the supply device to the developing device; toner consumption amount calculation means for calculating an amount of toner consumed by forming an image on the basis of image information; and the toner density control means, wherein the remaining toner amount detection means detects the amount of remaining toner on the basis of (i) a result of calculation carried out by the toner supply amount calculation means till the amount of remaining toner in the supply device reaches a first predetermined value, (ii) a result of calculation carried out by the toner consumption amount calculation means from a time when the amount of remaining toner in the supply device reaches the first predetermined value till the amount of remaining toner in the supply device reaches a second predetermined value, and (iii) a result of control carried out by the toner density control means from a time when the amount of remaining toner in the supply device reaches the second predetermined value.