Force-limiting control member for endoscopic instruments and endoscopic instruments incorporating same

Abstract

A force-limiting control member for an endoscopic instrument is a flexible wire having a proximal and a distal end, wherein a portion of the wire is bent into a sinusoidal or coiled shape to form a spring portion of the control member. An endoscopic instrument incorporating the force-limiting control member includes a flexible coil having a proximal and a distal end, a pair of forceps jaws mounted for rotation on a clevis which is coupled to the distal end of the coil, and a proximal handle coupled to the proximal end of the coil. The proximal handle has a spring biased lever coupled to it in a manner which limits the throw of the lever to a preselected distance. The force-limiting control member extends through the coil and is coupled at its distal end to the forceps jaws and at its proximal end to the actuating member. The spring portion of the control member which preferably resides inside the handle and is free to expand as the actuating member is moved from its spring biased first position to its throw limited second position. The spring portion of the control member is formed to have a spring constant such that when the actuation member is in its second throw limited position, the spring portion is expanded to a length which causes it to exert a predetermined force without exceeding its elastic limit. This is advantageously accomplished by pre-stressing the spring.

Dependencies are inferred from the claim text.