Sheet postprocessing apparatus that processes plurality of sheets placed on processing tray, and image processing system

A sheet postprocessing apparatus comprising:

• a transport route through which a sheet is transported;
• a processing tray that receives the sheet transported through the transport route;
• a pair of cursors provided on respective sides of the processing tray, and opposed to each other in a direction orthogonal to a transport direction of the sheet;
• a cursor moving device that reciprocatively moves the pair of cursors toward and away from each other, and brings the pair of cursors into contact with respective side edges of the sheet on the processing tray, thereby aligning the side edges of the sheet;
• a switchback roller that switches back the sheet delivered to the processing tray;
• a control device that includes a processor, and acts, when the processor executes a control program, as a controller that controls operation of the switchback roller and the cursor moving device;
• and
• a siding path that receives, when the sheet delivered to the processing tray through the transport route is switched back by the switchback roller in a reverse direction, the sheet that has passed the processing tray in the reverse direction,
• wherein the controller restricts the cursor moving device from moving the pair of cursors, during a period from start of switchback transport of the sheet, to a time that the sheet conducted toward the siding path reaches a prespecified position where the sheet is kept from interfering with the pair of cursors.