Patent ID: 7524301

Claim:
A handle assembly for use in an instrument having bidirectional steering and a deflectable shaft, wherein upon being deflected in a first direction, the shaft generates a return force in an opposite second direction, and the shaft whereupon being deflected in the second direction generates a return force in the opposite first direction, the assembly comprising: a manually positionable control mechanism coupled to the shaft to selectively deflect the shaft in the first and second directions, the control mechanism including a slider displaceable along a linear path for causing the deflection of the shaft in the first and second directions; and a counterforce mechanism operably coupled to the slider, the counterforce mechanism including a biasing element to bias the slider in a direction opposite to the return force once the slider is moved from a neutral position in which the shaft is in a straightened position, the biasing element providing a variable biasing force to the slider to counter the variable return force generated as the shaft deflects due to movement of the slider from the neutral position to one of the first and second directions, wherein the biasing force is about equal to the return force so that the forces effectively offset one another and permit a user to more easily and progressively deflect the distal end.