Patent ID: 8213854

Claim:
A sheet processing system including a sheet pre-processing device that includes a space portion as a sheet receiving unit that receives a pre-processed sheet, a first sheet conveying path for discharging the sheet to the sheet receiving unit, and a second sheet conveying path for reversing the sheet after a part of the sheet is discharged to the sheet receiving unit, and a sheet post-processing device that is removably attached into the space portion, the sheet processing system comprising: a conveying path for receiving the sheet from the second sheet conveying path and conveying the sheet to the sheet post-processing device when the sheet post-processing device is attached into the space portion; a reversing path for receiving the sheet from the second sheet conveying path and reversing a sheet conveying direction when the sheet post-processing device is attached into the space portion; a switching unit that switches over the sheet conveying direction to either one of the conveying path and the reversing path; and a reversing/conveying roller that can be rotated forwardly and reversely on the reversing path, wherein the reversing/conveying roller is formed with a pair of rollers that can be brought into contact with or separated from each other, and wherein a controller is configured to control the pair of rollers forming the reversing/conveying roller is implemented in such a manner that the pair of rollers are not separated from each other when a delivery linear velocity between a reversing roller provided in the second sheet conveying path for reversing the sheet and caused to rotate forwardly and reversely and the reversing/conveying roller is constant, and that when the pair of rollers are accelerated or decelerated, the pair of rollers are separated from each other before an acceleration or a deceleration is started.