Patent ID: 7366430

Claim:
An image forming apparatus comprising a rotary unit having a plurality of development devices provided around a rotary shaft, the development device having a constituent unit; wherein: a plurality of the development devices sequentially move to a development position, where the, development devices oppose an image carrier by rotation of the rotary unit, and a development device located at the development position develops an electrostatic latent image on the image carrier; each of the plurality of development devices has a state detection unit that detects at least one of a state of the development device and a state of a constituent unit of the development device; and a prediction unit that predicts changes in the state of the development device or the state of a constituent unit of the development device, wherein the state detection unit takes a result of the prediction performed by the prediction unit as one of the conditions for detecting the state of the development device or the state of a constituent unit of the development device.