Patent ID: 8897672

Claim:
An image forming apparatus operable in multiple image formation modes, comprising: a belt stretched and wound around a driving roller and multiple driven rollers; multiple image formation units arranged in a running direction of the belt including photoconductors to form toner images of different colors on the photoconductors, respectively; multiple transfer rollers opposed to a corresponding one of the photoconductors via the belt, respectively, the toner images on the photoconductors being successively transferred onto either the belt or a recording medium transported by the belt by the multiple transfer rollers, respectively; an engagement/disengagement device to bring at least one of the multiple transfer rollers in contact with the belt and separate the at least one of the multiple transfer rollers therefrom in accordance with an image formation mode when the multiple image formation modes are switched; a steering controller to correct displacement of the belt in its widthwise direction by inclining one of the multiple driven rollers in a prescribed direction as a steering roller not to change a perimeter of the belt at least in a first image formation mode in which all of the multiple transfer rollers contact the belt; at least one position adjustment roller extending in the widthwise direction of the belt on the same side as the multiple transfer rollers at a region where a stretching posture of the belt varies when the multiple image formation modes are switched, the at least one position adjustment roller contacting the belt at a first given winding angle in a second image formation mode in which one of the multiple transfer rollers separates from the belt; and a belt position adjuster to adjust a position of the belt in its widthwise direction by inclining the at least one position adjustment roller in a prescribed direction not to change the perimeter of the belt in the second image formation mode.