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.
1. A paper cutter comprising a base, a rail, a slide unit, a cutter seat and at least two blades, said base being provided with said rail for said slide unit to slide thereon, said cutter seat being rotatably coupled to said slide unit, said cutter seat being provided with said blades, and characterized by:
said cutter seat rotating around said rail and said slide unit comprising a one-way locking member, said cutter seat having ratchet teeth formed on a periphery thereof defining a plurality of locking edges for engagement with said locking member for one-way engagement of said locking member with one of said locking edges, said cutter seat being positioned with respect to said slide unit whereby turning said cutter seat rotationally in a first direction, permits said blades to be displaced to an exchangeable, and the plane including the rotational axes of said blades is perpendicular to said rail axis position; and,
a biasing element coupling said one-way locking member to said slide unit for providing an engagement force between said one way locking unit and one of said locking edges to prevent rotation of said cutter seat in a second direction rotationally opposite to said first direction.
2. The paper cutter, as recited in claim 1 , wherein said one-way locking member is a pawl, said pawl being urged by an elastic element towards one-way direction against one of said locking edges, by turning said cutter seat towards a reversed direction, said pawl being detached from said locking edge.