US Patent 7357057 Paper cutter

A paper cutter includes a base with a rail secured thereon, a slide unit, a cutter seat and at least two blades. The base is provided with the rail for the slide unit to slide thereon. The cutter seat is pivotally connected to the slide unit. The cutter seat is provided with the blades. The slide unit further comprises a one-way locking member therein. The cutter seat comprises locking edges corresponding to the locking member for one-way engagement of the locking member with one of the locking edges. The cutter seat is positioned with respect to the slide unit. By turning the cutter seat towards a reversed direction, the blades are exchangeable. The one-way locking member is a pawl. The pawl is urged by an elastic member towards one-way direction to engage with the locking edge.