Patent Application
20200237072
The invention relates to a nail clipper for clipping the fingernails or toenails of human beings in a manner that makes it easier to clip tough nails and to control where the cutting edges are positioned prior to clipping and remain positioned during the clipping. The user actuates the invention's clipping operation by applying pressure between the thumb and forefinger directly above and below the clipper's cutting edges, and with their other fingers cradling the underside of the clipper, such that there is no resultant force that might cause the cutting edges to move from the desired position for cutting the user's nail.
Various nail clippers have been provided that all perform the basic clipping operation. They are primarily comprised of the cutting arm springs joined together at one end and having slightly separated and opposing cutting edges on their other end. Some of these designs are U.S. Pat. No. 5,226,849 and D. 392,419. The current invention employs a modified first lever which is relatively shorter than the first lever in prior art common nail clipper designs, and which first bends upwardly at a more extreme angle than in prior art common nail clipper designs and then curves downwardly before straightening out so that its end is largely parallel to the cutting arm springs of the nail clipper. This first lever is also designed to hold a small roller at its free end so that the roller touches the underside of a second lever and rolls along its underside between the two side walls of the downward U-shaped channel of said second lever. The second lever arm pivots on a hinge that is integrated and attached to both cutting arm springs at the end opposite their cutting edges. The addition of the second lever arm assembly, along with the modified first lever and its integrated roller, together result in the current invention's improved usability and increased cutting force provided by a continuously increasing mechanical advantage and differentiate it from the prior art. U.S. Pat. No. 4,176,449 employs a similar design which envelops an unmodified common nail clipper of prior art in a two part hinged apparatus that includes a second lever arm to press down on the lever of the enveloped common nail clipper of prior art. The device described in U.S. Pat. No. 4,176,449 uses a second lever with a U-shaped cross-section that engages with a first lever but does not include a roller on the first lever that would provide for smoother use, as the current invention provides. This design requires the hinge point for the second lever to be considerably further away from the nail clipper's cutting edges than the ends of a common nail clipper's cutting arms are so that the angle at which the common nail clipper's lever hits the second lever is acute enough to allow it to slide along the second lever as the second lever is rotated towards the clipper's cutting edges during use. This device requires a second clamping bar to be riveted to the end of the common nail clipper to extend the common nail clipper's cutting arms so that the longer second lever can be hinged to the clamping bar at the end farthest from the common nail clipper's cutting edges. This results in a device that is considerably longer than a common nail clipper which violates one of the goals of the current invention. Further, this invention also differs from the current invention in that it is not an integrated part of the nail clipper, which reduces aesthetic beauty and could result in the invention clamp loosening and separating from the nail clipper during use.
Another of these designs is U.S. Pat. No. 8,578,612, by the same inventor as the current invention, which is largely similar to the current invention except for the location of the roller. U.S. Pat. No. 8,578,612 includes a roller on the second lever and a hollow backside to the second lever that allows the first lever to pass through the second lever during use. The problem with this design is the mechanical advantage, and resulting clipper cutting force, is reduced as the roller on the second lever moves forward on the first lever as they are both pressed down during use. This results in an effectively shorter first lever with a lower mechanical advantage at the end of a clipping action versus at the beginning. The current invention allows the user to create more force at the end of a clipping action without increasing the force applied to the first lever, thereby making it easier to complete the clip, or cutting, of the nail. In the current invention the second lever acts as a class 2 lever with the load, or resistance, applied by the roller on the first lever and the roller moving towards the fulcrum during use, which reduces the length of the load arm with no change to the length of the effort arm, thereby increasing the mechanical advantage and the force against the roller mounted on the first lever.
Alternate prior art function using a scissors-like action that closes the cutting edges. Some of these designs are relevant as their goal is similar to the current invention. These designs, covered by U.S. Pat. No. 741,709 and D629,161 S, add a lever arm to the scissors-like design that allows the user to apply pressure close to the location of the cutting edges in a manner similar to the current invention. While this design is similar to the current invention in that they share the goal of allowing the user to apply force close to the cutting action, the scissors-like cutting action is different from the current invention's cutting action.
Traditional fingernail and toenail clippers require a user to apply pressure to the clipper's levers/handles at the end opposite the cutting edges. The current invention reverses this to allow the user to apply force close to the cutting edges, thereby making the tool more ergonomically correct and easier to use. The current invention takes the traditional nail clipper design and adds a second lever arm assembly that rotates on a pivot point attached to the edge of the cutter arms at the end opposite the cutting edges. The additional lever arm assembly is shaped such that when pushed down by the user it will push down on the roller mounted on the clipper's other lever arm which causes the cutting edges to close together with ever increasing force to clip the nail.
Referring now to the drawings the user presses downward on what has heretofore been referred to as the second lever, 3 in
In
In the preferred embodiment of the invention, the user moves the second lever, 3, towards the clipper cutting arms, 1, the roller, 5, mounted on the first lever, 2, and secured to the first lever with the shaft pin, 2b, moves along the second lever's underside back surface, 3b, in a direction from the free end towards the hinged end of the second lever, 3. As the roller moves closer to the hinged end of the second lever, 3, the effective lever effort to load length ratio increases thereby applying more force against the roller, 5, for a constant force applied by the user when executing a nail clipping action.
