Sheet post-processing unit and image forming apparatus

摘要

There is provided a sheet post-processing unit having a simple structure, capable of stably conveying sheets on a tray and causing less ruggedness in conveying and aligning the sheets discharged one after another to the tray to form a bundle of sheets and to staple it. The sheet post-processing unit is provided with sheet conveying means for conveying the sheet stacked on the post-processing tray in the same and reverse directions with/from the sheet conveying direction and intersectional moving means for conveying the sheet in the direction orthogonal to the sheet conveying direction by moving the sheet conveying means in the direction orthogonal to the sheet conveying direction. It conveys the sheet while keeping rollers of the sheet conveying means in contact with the sheet and aligns the sheet by hitting the trailing edge thereof against a trailing edge stopper and by hitting the side edge of thereof against a wall by moving the rollers in the intersecting direction. In aligning the sheet by hitting the edges thereof against the stopper or the wall, the unit conveys the sheet slightly more than an actual extent of movement thereof obtained from the specific size of the sheet and slides the rollers on the sheet after hitting the sheet against the stopper or the wall.