Postprocessing device that transports preceding recording medium on sidetrack, with following recording medium transported along sheet transport path stacked on preceding one, to processing tray, and image forming system

Abstract

A postprocessing device includes a processing tray, a first transport roller, a second transport roller, a sidetrack, a sidetrack roller, and a controller. The controller shunts a preceding recording medium to the sidetrack by rotating the sidetrack roller, determines, on a basis of a length of the preceding recording medium in a transport direction, a timing to stop the rotation of the sidetrack roller such that, when the sidetrack roller is made to start rotating at a predetermined timing to start, a leading edge of a following recording medium transported by the second transport roller becomes aligned with a leading edge of the preceding recording medium, stops the rotation of the sidetrack roller at the determined timing, and transports the preceding recording medium with the following recording medium stacked thereon, to the processing tray, by rotating the second transport roller and the sidetrack roller at the reference timing to start.