A stapling stacker has a sheet infeed, a pivoted shelf on which the trailing ends of sheets are assembled with the leading ends supported by previously stacked sets, the sets are side edge aligned, stapled into sets and offset with respect to previously stapled sets, and the shelf then is operated to dump the trailing ends onto previously stapled sets of sheets on the stacker.
A sheet post-processing apparatus and an image forming apparatus according to the present invention are equipped with discharge rollers for discharging a sheet, a fixed stacking portion for supporting one corner of the sheet discharged by the discharge rollers, a storage tray disposed below the fixed stacking portion with an area larger than the fixed stacking portion, and a stapler for binding the sheet while the sheet straddles the fixed stacking portion and the storage tray. It is possible to configure a more compact size in the sheet transport direction. Further, it is possible to stabilize the sheet bundle when post-processing the sheet bundle straddling the sheet single corner portion support tray and the sheet storage tray, thereby enabling the accurate post-processing.
A sheet processing apparatus, which is configured in a simple construction and at low cost, includes a first sheet stacking portion for temporarily stacking a sheet discharged thereon, an alignment member for aligning the sheet discharged on the first sheet stacking portion, a sheet processing member for performing a predetermined process on the sheet stacked on the first sheet stacking portion, and a second sheet stacking portion located substantially vertically below the first sheet stacking portion. The alignment member acts to cause the aligned sheet to drop to the second sheet stacking portion.
