Manual stapling mode for sheet finishing apparatus

A sheet finishing apparatus comprising:

• a processing tray on which sheets supplied from an image forming unit are placed;
• a paper discharge unit configured to discharge the sheets on the processing tray;
• a sensor that includes a front sensor closer to a front reference side of the processing tray and a rear sensor closer to a rear reference side of the processing tray, wherein the sensor detects whether the manually inserted sheets on the processing tray are closer to a front side or closer to a rear side of the processing tray;
• an aligning unit configured to shift the manually inserted sheets to the front reference side in a direction orthogonal to an inserting direction if the rear sensor does not detect the manually inserted sheets, shift the manually inserted sheets to the rear reference side in a direction orthogonal to an inserting direction if the front sensor does not detect the manually inserted sheets, and align the manually inserted sheets onto the processing tray from a paper discharge port of the paper discharge unit;
• and
• a stapler configured to staple the sheets or the manually inserted sheets on the processing tray.

A stapling method comprising:

• inserting sheets manually onto a processing tray through a paper discharge port;
• detecting whether the manually inserted sheets are closer to a front side or a rear side of the processing tray;
• aligning the manually inserted sheets to a front reference side if the manually inserted sheets are closer to the front side of the processing tray and aligning the manually inserted sheets to a rear reference side if the manually inserted sheets are closer to the rear side of the processing tray;
• and
• stapling the manually inserted sheets on the processing tray.