Patent ID: 8529423

Claim:
A sheet folding apparatus that is disposed between an image formation apparatus and a post-processing apparatus and that performs folding processing on a sheet with an image formed to carry to the post-processing apparatus, comprising: a casing having a carry-in entrance to carry in a sheet from the image formation apparatus and a carrying-out exist to carry out the sheet to the post-processing apparatus; a first transport path disposed inside the casing to carry the sheet from the carry-in entrance to the carrying-out exist without performing the folding processing; a second transport path disposed in a direction crossing the first transport path to perform the folding processing on the sheet fed from the first transport path; a folding roller pair disposed in the second transport path to perform the folding processing on the sheet; and sheet deflecting means for guiding a fold position of the sheet to the folding roller pair, wherein the casing is divided into an upper unit and a lower unit, the upper unit is provided with an upper sheet guide constituting the first transport path, and a sheet front end switchback path that constitutes part of the second transport path and that reveres the side of the sheet fed from the first transport path to carry toward the folding roller pair, the lower unit is provided with a lower sheet guide constituting the first transport path, the folding roller pair, and a sheet discharge path for guiding the sheet subjected to the sheet folding in the folding roller pair to the carrying-out exit, and the upper unit is coupled to the lower unit to be openable and closable by a hinge shaft rotating around one side end portion orthogonal to a sheet transport direction of the first transport path.