Sheet folding apparatus and image forming apparatus

A sheet folding apparatus comprising:

• a corner-fold transport path that transports a delivered sheet in a vertical direction while aligning a center line thereof to a center line of the corner-fold transport path;
• a first edge-folding unit that folds back a left corner, in relation to the center line, on a leading end of the sheet that is transported in the vertical direction and to be folded into a regular size and perforated with a filing hole to file the sheet in a regular-size folder, wherein the left corner would otherwise block a portion to be punched when the sheet has been folded;
• a second edge-folding unit that folds back a right corner in relation to the center line on the leading end of the vertically transported sheet, wherein the sheet is to be folded into a regular size and perforated with a hole for filing in a regular-size folder, wherein the right corner would otherwise block a portion to be punched when the sheet has been folded;
• a fan folding unit that fan folds the folded-back sheet into a width or length of the regular size for filing in the regular-size folder such that the sheet forms layers along a traveling direction of the sheet;
• a transport-direction changing unit that changes the transport direction of the sheet having been fan-folded into the width or length of the regular size from the vertical direction to a first horizontal direction and then discharges the sheet;
• a transport unit that transports the sheet discharged in the first horizontal direction along a transport path surface extending in a second horizontal direction perpendicular to the first horizontal direction;
• a first punching unit that includes a puncher that perforates a plurality of holes arranged in the second horizontal direction and a drive unit that moves the puncher back and force in a direction along the transport-path surface and perpendicular to the second horizontal direction;
• a path switching unit that selectively switches the transport direction of the sheet transported along the transport-path surface in the second horizontal direction to a direction perpendicular to the transport-path surface;
• a second punching unit that includes a fixedly positioned puncher, the puncher receiving the leading end of the sheet of which transport direction has been switched by the path switching unit and punching a plurality of holes arranged in a direction perpendicular to the second direction therein;
• and
• a sheet-processing setting unit that selects one of the first edge-folding unit and the second edge-folding unit for use in the corner fold, sets a fan fold mode, and selects one of the first punching unit and the second punching unit for use in punching of the filing hole based on a size and an orientation of the sheet.

An image forming apparatus comprising:

• an edge folding unit that folds back a portion on a leading end of a delivered sheet that is to be folded into a regular size and perforated with a filing hole to file the sheet in a regular-size folder, wherein the portion would otherwise block a portion to be punched when the sheet has been folded;
• a fan folding unit that fan folds the folded-back sheet into a width and length of the regular size to file the sheet in the regular-size folder such that the sheet forms layers along a traveling direction of the sheet;
• a first punching unit that punches the filing hole in the sheet fan folded into the width of the regular size at the portion to be punched to file the sheet in the regular-size folder;
• a second punching unit that punches the filing hole in the sheet fan folded into the length of the regular size at the portion to be punched for filing in the regular-size folder;
• a sheet-processing setting unit that sets a fold mode of the fan fold and selects one of the first punching unit and the second punching unit for use in punching of the filing hole in the sheet based on a size and orientation of the delivered sheet;
• a connecting transport unit that receives the sheet horizontally discharged from an image forming apparatus, and delivers the sheet to the edge-fold transport path of the edge-folding unit;
• and
• an imaging device that forms an image on a sheet larger than the regular size and outputs the sheet with image to the connecting transport unit.