Patent ID: 8175470

Claim:
An image forming apparatus comprising: an acquiring unit that acquires a plurality of types of operation control information of the image forming apparatus; an index value calculating unit that calculates an index value indicating a state of the image forming apparatus based on the acquired operation control information; an abnormality judging unit that judges whether an image forming apparatus abnormality has occurred and predicts an occurrence of a failure based on the index value; and a surface state detecting unit that includes a light-emitting element that emits light toward a predetermined position on an image carrier surface carrying a toner image, and a light-receiving unit that receives light emitted from the light-emitting unit and reflected by the image carrier surface, wherein the index value calculating unit calculates the index value based on the acquired operation control information that includes detection data from the light-receiving unit and an exposure light amount correction parameter P, a development potential shift correction parameter Q, and an emitted light amount R of the light emitting element.