Patent attributes
An ultrasonic clamp coagulator apparatus is disclosed including a housing including an actuator, an outer tube, an ultrasonic waveguide, an ultrasonically actuated blade, a clamp member pivotable with respect to the blade, and a force limiting mechanism including a first compression spring having a first spring constant, positioned between the actuator and the clamp arm, and a second compression spring having a second spring constant less than the first spring constant. The first compression spring transfers a force at a first rate as a function of a motion of the actuator to pivotably move the clamp member toward the blade. The second compression spring transfers a force as a function of the tissue thickness positioned between the clamp member and the blade. At least one of the first and second compression springs is pre-compressed to provide a preload less than the respective spring constant.
