Patent ID: 8565625

Claim:
An image forming apparatus, which is configured to execute a developing operation for forming a developer image, and which is configured to form an image comprising the developer image on a recording medium, the image forming apparatus comprising: an image carrier configured to carry an electrostatic latent image thereon; a developing device, which is configured to accommodate developer for developing the electrostatic latent image into a developer image, and which comprises a developer carrier that carries the developer and supplies the developer to the image carrier; a remaining quantity calculation part configured to calculate a remaining quantity of the developer in the developing device at a developing operation; a deterioration degree storage part that stores, for each of a series of single developing operations, a predetermined relationship between a remaining quantity of the developer in the developing device and a deterioration degree of the developer caused by each of the series of single developing operations, wherein for each remaining quantity of the developer from highest to lowest, the deterioration degree increases; a deterioration quantity calculation part which, every time the remaining quantity calculation part calculates the remaining quantity of the developer, is configured to: determine the deterioration degree of the developer based on the predetermined relationship stored in the deterioration degree storage part; and calculate a deterioration quantity of the developer by adding each of the determined deterioration degrees; and a life determination part configured to determine that the developing device has reached an end of its life when the deterioration quantity calculated by the deterioration quantity calculation part has reached a threshold value.