Patent ID: 8870183

Claim:
An image forming apparatus comprising: a plurality of rotary members: a conveyance belt looped around the plurality of rotary members so as to circulate to intermittently feed a sheet in a sheet transport direction; an image forming device disposed opposing the conveyance belt to form an image on the sheet fed by the conveyance belt; and a switchback device disposed adjacent to the conveyance belt and downstream from the image forming device in the sheet transport direction to feed the sheet having passed the image forming device to a position downstream from the conveyance belt in the sheet transport direction and switch back the sheet again to the conveyance belt disposed adjacent to the switchback device, wherein the switchback device includes plural pairs of output rollers, the plural pairs being serially arranged relative to each other in the sheet transport direction and being configured to rotate in the same direction, wherein, when the sheet is attached by the conveyance belt and nipped by the output rollers at the same time, a drive start timing of the output rollers is delayed from a drive start timing of the conveyance belt, and the sheet is maintained in a bent state between the output rollers and the conveyance belt by not starting driving of the output rollers for a predetermined time after a leading edge of the sheet arrives at the output rollers, and wherein after the predetermined time passes, driving of the switchback device is started at the same speed as the conveyance belt, and the sheet is conveyed by the conveyance belt and the switchback device while the sheet is maintained in the bent state.