Sheet folding device

A sheet folding device comprising:

• sheet transportation means for transporting a sheet along a predetermined route;
• sheet deceleration means for decelerating at least a part of the sheet while being transported by the sheet transportation means;
• folding means for folding a part of the sheet that is bent as the result of deceleration by the sheet deceleration means;
• and a control unit for controlling the sheet deceleration means;
• wherein
• the sheet deceleration means comprises
• a guide member for receiving the sheet while being transported by the sheet transportation means;
• a stopping member that comprises:
• a plate-like pressing member having a predetermined thickness and a pressing member attachment having the pressing member on an end surface facing the sheet and is rotatably held at a predetermined fulcrum, wherein an edge of the pressing member presses the sheet traveling along the guide member against the guide member;
• and
• a stopping member driving part for rotating the stopping member around the fulcrum;
• wherein
• the stopping member is positioned at a waiting location where the pressing member does not touch the sheet or at a pressing location where the edge of the pressing member touches the sheet but the surface of the pressing member does not entirely touch the sheet;
• the stopping member moves from the waiting location to the pressing location by rotating in the same direction as the traveling direction of the sheet, and returns from the pressing location to the waiting location by rotating in the opposite direction to the traveling direction of the sheet;
• and
• the stopping member driving part rotates the stopping member from the waiting location to the pressing location in compliance with an instruction from the control unit.