Patent ID: 8505903

Claim:
A sheet folding device that performs a folding process on one of a sheet member and a bundle of sheet members, the sheet folding device comprising: a folding unit that folds the one of the sheet member and the bundle of the sheet members; a pushing unit that is formed like a plate and that abuts on a surface of the one of the sheet member and the bundle of the sheet members so as to push the one of the sheet member and the bundle of the sheet members into the folding unit; pressing plates that are provided to form a pair, that have convexly curved surfaces to face each other, and that form a crease at a center portion of the one of the sheet member and the bundle of the sheet members by interposing and pressing the one of the sheet member and the bundle of the sheet members having been pushed into the folding unit therebetween; a driving unit that performs a pressing operation and a press-releasing operation of the pair of the pressing plates; a moving unit that moves a pressing position of the pair of the pressing plates interposing the one of the sheet member and the bundle of the sheet members; and a control unit that controls the driving unit and the moving unit, wherein the control unit controls a moving speed of the pressing position moved by the moving unit.