Patent ID: 8107848

Claim:
An image forming apparatus, comprising: an image carrier carrying a toner image on its surface; a transfer unit for transferring said toner image on said image carrier to an intermediate transfer body rotating in a prescribed direction; a cleaning unit that can be brought into contact with and separated from said intermediate transfer body, for cleaning a surface of said intermediate transfer body in a contact state; a detecting unit detecting density of the toner image transferred to said intermediate transfer body; a contact/separation mechanism performing an operation of setting said cleaning unit to a state in contact with or a state separated from said intermediate transfer body; and a control unit configured to cause said transfer unit to transfer a plurality of toner images spaced by a prescribed distance in said direction of rotation on said intermediate transfer body, cause, when said plurality of toner images pass through said cleaning unit, said contact/separation mechanism to perform said operation to set said cleaning unit to the state in contact with or the state separated from said intermediate transfer body, alternately said toner image by toner image, detect presence/absence of each toner image on said intermediate transfer body using said detecting unit, after said operation of said contact/separation mechanism, and determine, based on the result of detection, state of contact/separation of said cleaning unit to/from said intermediate transfer body.