Patent ID: 8070155

Claim:
A sheet post-processing apparatus comprising: first rollers that convey a sheet conveyed from an imaging forming apparatus; a sensor that is arranged upstream of the first rollers and detects passage of the sheet: a waiting tray that includes a pair of sheet supporting means movable in a direction orthogonal to a conveying direction of the sheet and on which the sheet conveyed via the first rollers is temporarily stacked; a pair of second rollers provided downstream of the waiting tray along the conveying direction of the sheet and conveys the sheet with nipping in the conveying direction; a processing tray on which the sheet dropped by movement of the pair of supporting means after a trailing end of the sheet is discharged onto the waiting tray by the first rollers and the second rollers is stacked; and a controller which controls to drive the first rollers and the second rollers to be simultaneously suspended, in the conveyance of the sheet, when projection of a leading end of the sheet from the waiting tray reaches a predetermined amount according to a detection signal of the sensor.