Patent ID: 8867961
Filing Date: 2014-10-21
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a first and a second image bearing members configured to carry toner images; a belt configured to move along a predetermined direction; a steering roller configured to steer the belt in a width direction perpendicular to the predetermined direction; a tilting unit configured to tilt a shaft of the steering roller; a detection unit configured to detect a position of the belt in the width direction; a changing portion configured to change an abutment between the belt and the first and the second image bearing members to at least a first mode in which the belt abuts to the first and the second image bearing members and a second mode in which the belt abuts to the first image bearing member and the belt is separated from the second image bearing member; an execution portion configured to execute an acquisition mode to acquire a first tilted position value of the shaft of the steering roller and a second tilted position value of the shaft of the steering roller at a timing other than performing an image forming operation while the belt is conveyed, wherein the first tilted position value is acquired when a predetermined time has elapsed in a state that an output of the detection unit is in a predetermined range, as a first tilted position value at which meandering of the belt is prevented in the first mode, the second tilted position value is acquired when a predetermined time has elapsed in a state that an output of the detection unit is in a predetermined range, as a second tilted position value at which meandering of the belt is prevented in the second mode; and a control unit configured to control the tilting unit to tilt the shaft of the steering roller based on an output of the detection unit while the image forming operation is performed so as to tilt the shaft of the steering roller to a first tilted position by using the first tilted position value when the changing portion changes the second mode to the first mode while the belt is conveyed and so as to tilt the shaft of the steering roller to a second tilted position by using the second tilted position value when the changing portion changes the first mode to the second mode while the belt is conveyed.