Surgical instrument end effector articulation drive with pinion and opposing racks

1. An apparatus, comprising:

(a) a body; and

(b) a shaft assembly in communication with the body; wherein the shaft assembly comprises:

(i) an end effector having an articulation joint;

(ii) a first cam gear rotatably positioned within the shaft assembly,

(iii) a second cam gear in communication with the end effector at the articulation joint, and

(iv) a lock bar distally biased to lock against the second cam gear, wherein the first cam gear is rotatable through a first range of motion to unlock the lock bar relative to the second cam gear, wherein the first cam gear is rotatable through a second range of motion to rotate the end effector at the articulation joint, wherein the lock bar comprises a lock tooth, wherein the second cam gear comprises second cam teeth, wherein the lock bar is shaped to complement the shape of the second cam teeth.

2. The apparatus of claim 1 , wherein the first cam gear comprises a plurality of cam wings configured to urge rotation of the second cam gear.

3. The apparatus of claim 2 , wherein the second cam gear comprises a plurality of bosses configured to engage the plurality of cam wings.

4. The apparatus of claim 1 , further comprising an articulation knob in communication with a first arm and a second arm, wherein the first arm and the second arm are in opposing communication with the first cam gear, wherein the articulation knob is configured to rotate to effectuate opposing motion of the first arm and the second arm.

5. The apparatus of claim 1 , wherein the second cam teeth comprise straight walls.

6. The apparatus of claim 1 , wherein the first cam gear comprises first cam teeth, wherein the first cam teeth have a rounded shape.

7. The apparatus of claim 1 , wherein the first cam gear comprises first cam teeth, wherein the second cam gear comprises second cam teeth, wherein the lock tooth is positionable between the first cam teeth and the second cam teeth.

8. The apparatus of claim 7 , wherein the lock tooth is configured to snap into a position between the first cam teeth and the second cam teeth, wherein the lock tooth is operable to produce an audible click when the lock tooth snaps into the position between the first cam teeth and the second cam teeth.

9. The apparatus of claim 7 , wherein the lock tooth is configured to snap into a position between the first cam teeth and the second cam teeth, wherein the lock tooth is operable to produce a tactile feedback click when the lock tooth snaps into the position between the first cam teeth and the second cam teeth.

10. The apparatus of claim 1 , wherein the first cam gear comprises cam wings, wherein the second cam gear comprises bosses, wherein the cam wings and the bosses are positionable such that a gap is maintained between the cam wings and the bosses.

11. The apparatus of claim 1 , wherein the first cam gear and the second cam gear are coaxially aligned with a pivot axis, wherein the pivot axis is perpendicular to the end effector.

12. The apparatus of claim 1 , wherein the second cam gear comprises second cam teeth having parallel sides, wherein the lock bar comprises a lock tooth having parallel sides, wherein the parallel sides of the lock tooth are configured to engage the parallel sides of the second cam teeth to thereby prevent rotation of the second cam gear.

13. The apparatus of claim 1 , wherein the lock bar comprises at least one laterally extending boss configured to prevent the distal movement of the lock bar beyond a predetermined point.

14. The apparatus of claim 1 , further comprising a spring in communication with the lock bar, wherein the spring is operable to distally bias the lock bar.