Patent ID: 8229315

Claim:
An image forming apparatus comprising: an input unit adapted to input a one-sided print job to form an image on one side of a sheet or a two-sided print job to form images on both sides of a sheet; a sheet feeding unit adapted to feed a sheet; an image forming unit adapted to form an image on a sheet based on a print job input by said input unit; a sheet re-feeding conveyance path adapted to re-feed a sheet, on which an image is formed on a first side, to said image forming unit in order to form an image on a second side thereof; and a printing mode switching unit adapted to selectively switch a printing mode between a two-sided printing mode to form images on both sides of sheets by continuously forming images on the first sides of a predetermined number of sheets and by alternately forming images on the second sides of sheets conveyed from said sheet re-feeding conveyance path and on the first sides of sheets fed from said sheet feeding unit, and a one-sided printing mode to form images on one sides of sheets without using said sheet re-feeding conveyance path; wherein said printing mode switching unit determines, when the one-sided print job is performed between the two-sided print jobs, whether the one-sided print job is performed in the two-sided printing mode or in the one-sided printing mode, depending on whether the number of sheets continuously printed by the one-sided print job is more than a predetermined number.