Patent ID: 8582989

Claim:
An image forming apparatus, comprising: an image forming unit including a developer reservoir; a first controller for calculating a consumed amount of developer material based on image data; a developer holder attached to the image forming unit and including a developer chamber that holds the developer material therein and supplying the developer material into the developer reservoir, the developer holder including a first memory that holds first amount information on an amount of developer material remaining in the developer chamber and that holds first identification information on the developer holder; a second memory that holds second amount information on an amount of developer material remaining in the developer reservoir and second identification information on the developer holder; a second controller for determining whether the first identification information and second identification information coincide, wherein if the first identification information and the second identification information do not coincide, the second controller determines that the developer holder has been replaced, wherein if the second controller determines that the developer holder has been replaced, the second controller determines a remaining capacity of the developer reservoir based on the second amount information and a full capacity of the developer reservoir, compares the remaining capacity and the first amount information, and updates the first amount information and the second amount information respectively to the first amount information and the second amount information on condition that the developer material of an amount determined based on a result of comparison is supplied from the developer chamber to the developer reservoir.