Spring scissor blade
View Patent ↗An endoscopic scissor instrument includes an elongate hollow member, an actuator that moves axially through the hollow member, and first and second scissor blades with respective cutting surfaces. At least one of the scissor blades is rotatably coupled to the hollow member adjacent its distal end. At least one of the scissor blades includes a base supporting a resilient leaf-spring portion that includes a respective cutting edge. The resilient leaf-spring portion extends from the base in a cantilevered arrangement and generates a spring force acting on the respective cutting edge such that in a loaded state there is an automatic preload force imparted between the cutting edges of the scissor blades to maintain a consistent and continuous mating force between the two opposed sharpened cutting edges preferably over the complete range of rotational movement of the scissor blades.
1. A surgical instrument comprising:
an elongate hollow member having a proximal end and a distal end;
an actuator that moves axially through said hollow member;
first and second scissor blades rotatably coupled adjacent said distal end of said hollow member; and
said actuator coupled to at least one of said first and second scissor blades to provide rotational movement to at least one of said first and second scissor blades relative to one another in response to axial movement of said actuator so as to rotate said at least one of said first and second scissors blades,
wherein said first scissors blade includes a first feature with a first cutting edge,
wherein said second scissors blade includes a longitudinally extending rigid supporting base having a midline and a longitudinally extending lateral side offset relative to said midline, and immediately adjacent said base a resilient leaf-spring portion substantially thinner than said base having a deflectable second cutting edge that extends along a length of said leaf-spring portion,
said leaf-spring portion extending from said lateral side of said base in a cantilevered arrangement such that said leaf-spring portion is laterally offset from said midline of said base, and said leaf-spring portion extends from said lateral side of said base at a bias angle relative to said base, and
wherein as said at least one of said first and second scissors blades is rotated relative to the other between open and closed positions,
(i) said first and second cutting edges are brought into contact with each other at a contact point, said contact point moving along said length of said leaf spring portion as said first and second scissors blades are rotated, and said second cutting edge resiliently deflects against said first cutting edge at said contact point,
(ii) said bias angle of said leaf-spring portion relative to said base generates a lateral spring force in a direction transverse to a plane through which one of said first and second scissors blades is rotated relative to the other when said first and second blades are moved relative to each other between said open and closed positions and against said first feature of said first blade, and
(iii) said leaf-spring portion is flat when not subject to deflection.
2. A surgical instrument according to claim 1 , wherein:
said leaf-spring portion is formed discrete from said base and coupled to said base along said length of said base.
3. A surgical instrument according to claim 2 , wherein:
said leaf-spring portion is welded to said blade support.
4. A surgical instrument according to claim 1 , wherein:
said first scissors blade includes a longitudinally extending rigid supporting base and an immediately adjacent resilient, leaf-spring portion substantially thinner than said base, said leaf-spring portion forming said first feature, and said first cutting edge being deflectable, said leaf-spring portion extending from said base of said first scissors blade in a cantilevered arrangement along a length of said base, and longitudinally coextending with said base,
wherein said first and second cutting edges of said first and second scissors blades resiliently deflect about each other at said contact point.
5. A surgical instrument according to claim 1 , wherein:
said spring force being laterally generated maintains a consistent and continuous mating engagement of said first and second cutting edges as said at least one of said first and second scissors blades is rotated relative to the other between said open and closed positions.
6. A surgical instrument according to claim 1 , wherein:
said second cutting edge has a length less than 50 mm.
7. A surgical instrument according to claim 1 , wherein:
said resilient leaf-spring portion has a thickness between 0.05 mm and 0.5 mm.
8. A surgical instrument according to claim 1 , wherein:
said resilient leaf-spring portion has a tapered profile along its lengthwise dimension.
9. A surgical instrument according to claim 1 , wherein:
said elongate hollow member comprises a flexible tube or coil.
10. A surgical instrument according to claim 1 , wherein:
said resilient leaf-spring portion extends from said base at a relief angle relative to a rotational plane of said base of said second scissors blade.
11. A surgical instrument according to claim 1 , wherein:
said elongate hollow member defines a longitudinal axis,
at least one of said first and second scissor blades are rotatable relative to one another about a pivot axis by axial movement of said actuator, and
said flat leaf-spring portion extends in a plane transverse to both said pivot axis and said longitudinal axis.
12. A surgical instrument according to claim 1 , wherein:
at least one of said first and second scissors blades is rotatably coupled on a pivot axle, and said at least one of said first and second scissors blades includes a slot, a cam is coupled to a distal end of said actuator, and said cam is positioned in said slot, such that axial movement of said actuator causes said cam to ride in said slot and effects rotation of said at least one of said first and second scissors blades about said pivot axle.
13. A surgical instrument comprising:
an elongate hollow member having a proximal end and a distal end;
an actuator that moves axially through said hollow member;
first and second scissor blades rotatably coupled adjacent said distal end of said hollow member; and
said actuator coupled to at least one of said first and second scissor blades to provide rotational movement to at least one of said first and second scissor blades relative to one another in response to axial movement of said actuator,
wherein said first scissors blade includes a first feature with a first cutting edge,
wherein said second scissors blade includes a longitudinally extending rigid supporting base and a laterally offset, resilient leaf-spring portion substantially thinner than said base,
said leaf-spring portion extending from a lateral side of said base in a cantilevered arrangement along a length of said base, and longitudinally extending with said base,
said leaf-spring portion having a second cutting edge that extends along a length of said leaf-spring portion, and
said leaf spring portion extending from and immediately adjacent to said base at a bias angle relative to said base and transverse to a plane through which one of said first and second scissors blades is rotated relative to the other when said first and second blades are moved relative to each other between said open and closed positions to generate a lateral mating force between said first and second cutting edges at a contact point.