Patent ID: 7346989

Claim:
A lock-type disposal safe scalpel, comprising: a blade, a handle and a sheath, said blade being fixedly attached to a front end of the handle, said sheath being fit over the front end of the handle and coupled to the handle with a sliding mechanism and a positioning mechanism so that the blade is changeable between an exposed position where the blade extends outside through an opening at the front end of the sheath and a hidden position where the blade is hidden inside the sheath; said positioning mechanism having a button, a locking block, a protective locking recess, an operative locking recess and a sliding groove; said sliding groove being longitudinally provided on the handle, and the protective locking recess and the operative locking recess being provided on the front and back end of the sliding groove, respectively, the button and the locking block being configured to be associated with plastic arms which extend from the front and back side of the sheath, respectively, the button pressing against the locking block so that the locking block is transferable between a position at the protective locking recess and another position at the operative locking recess; and a deadlock recess being provided on the front end of the protective locking recess of the sliding groove, and being provided with a hindering mechanism so as to prevent the locking block from disengaging therefrom, whereby the scalpel is brought into a deadlocked state; wherein said hindering mechanism being formed by a side surface of the deadlock recess at the side of the protective locking recess, and the bottom of the side surface being configured to be higher than a position where the locking block is disengaged so that the locking block cannot be disengaged by the operation of the button.