Patent ID: 7322110

Claim:
A knife comprising an elongated housing having a forward end adapted to enable a blade to extend therethrough and a rear end including a handle portion, a blade seat at least partially retained in said housing and movable between a retracted position and an extended position, said blade seat being adapted to hold at least one detachable blade, a trigger actuator attached to said blade seat and mounted to said housing nearby said handle portion, said trigger actuator movable from a first position where the blade seat is in said retracted position to a second position where said blade seat is in said extended position, a linkage assemblage at least partially within the housing and connected between the trigger actuator and the blade seat that moves the blade seat into the extended and retracted positions, said linkage assemblage including a return mechanism that normally returns the blade seat to the retracted position, the linkage assemblage including first, second, and third arms, each arm having first and second opposite ends, wherein: the first end of the first arm is rotatably pinned to the trigger actuator, the second end of the first arm is rotatably pinned to the second arm; the second arm is rotatably pinned to the housing; the first end of the third arm is rotatably pinned to the blade seat; and the second end of the third arm is rotatably pinned to the second arm.