Patent ID: 7581803

Claim:
An image forming apparatus, comprising: an image forming unit configured to form an image; a movable member that is a transfer conveyer belt or is an intermediate transfer belt; a driving unit configured to rotationally drive the movable member and to be subjected to feedback control; a moving information detecting unit configured to detect a moving distance or a moving speed of the movable member; a deviation information calculating unit configured to calculate a position deviation based on the moving distance detected or a speed deviation based on the moving speed detected; a drive controlling unit configured to provide control of the position deviation calculated or the speed deviation calculated, to control the driving unit based on a quantity of control; an error determining unit configured to determine an occurrence of a detection error or a control error, based on one of the moving distance detected, the moving speed detected, and the quantity of control; and an error process executing unit configured to execute, when the error determining unit determines the occurrence of the detection error or the control error, a first predetermined error process of switching the driving unit to rotate the driving unit at a predetermined speed and stopping feedback control of the driving unit only when a first mode has been selected by a user and a second predetermined error process only when a second mode has been selected by the user.