Patent ID: 7386268

Claim:
An image forming apparatus comprising: an intermediate transfer unit, onto which toner images are formed by at least one photo-receptor; a back up roller, in contact with the intermediate transfer unit in a transfer section, allowing a sheet to pass in-between the back-up roller and the intermediate transfer unit, to transfer toner images from the intermediate transfer unit onto the sheet; a switch back unit, to receive a sheet having a first toner image transferred on one side, and to return the sheet to pass a second time between the back up roller and the intermediate transfer unit so that a second toner image is transferred onto a side of the sheet opposite to a side on which the first toner image was transferred; a fixing unit, operable to fix the toner image on at least one of side of the sheet; and a switching unit, disposed between the transfer section and the fixing unit, operable to direct the sheet received from the transport section toward one of the fixing unit and the switch back unit, wherein if toner images are transferred on both sides of the sheet, the fixing unit fixes the toner images on the sheet during a single pass of the sheet through the fixing unit.