Racket and the like
AssigneeMassachusetts Institute of Technology
InventorYao T. Li
Life of this patent
Estimating the term…
Abstract
A racket having a primary frame and a secondary frame, the latter being disposed within and being secured to the primary frame. The secondary frame contains the string surface of the racket and is adapted to distribute forces in such a way that the "sweet spot" of the racket is much larger than in a conventional racket of the same size. Use of a secondary frame permits manufacturing economies not permitted by the more conventional design.
Claims17
A racket that comprises a primary frame attached to a handle and an oval-shaped interior opening, an oval-shaped secondary frame sized to fit in the interior opening of the primary frame, the secondary frame being a thin planar rim with an interior window and being rigid with respect to inwardly-directed forces in the plane of the rim,
- a plurality of strings secured in required tension by the secondary frame and disposed within said window to define a string surface within said window, and
- means coupling the secondary frame securely within the interior opening of the primary frame, to maintain planar stability of the secondary frame and to transmit orthogonally-directed forces upon the string surface to the primary frame, but not the tension forces of the strings, said tension forces being taken primarily by the secondary frame, said means coupling being a coupling system comprising elastomer means, said primary frame having an internal channel to receive the elastomer means, the peripheral edge of the planar rim that constitutes the secondary frame being securely held within the elastomer means, the plane of the rim being parallel to the string surface.
A racket as claimed in claim 7 wherein the elastomer member is bonded to both the primary frame and secondary frame.
A racket that comprises a primary frame attached to a handle and having an interior opening and an internal channel;
- a secondary frame having an interior window, said window being smaller than said interior opening, the secondary frame comprising a thin planar rim and being rigid in the bending mode for moments with axes normal to the plane of the rim;
- a coupling system comprising elastomer means disposed within the internal channel, the outer periphery of the thin planar rim being secured within the internal channel by the elastomer means, securing the secondary frame within the interior opening of the primary frame and concentrically with respect to said interior opening;
- and a plurality of strings secured in required tension by the secondary frame and disposed within said window to define a string surface within said window, the string surface being disposed parallel to the plane of the thin planar rim.
For use as part of a racket having a primary frame that comprises an interior opening, a secondary frame sized to fit in the interior opening of the primary frame, said secondary frame comprising two similarly-shaped thin rims and being rigid with respect to inwardly directed forces in the planes of the rims, each rim having a thickness dimension that is much less than its width dimension, and a plurality of strings secured in required tension by the secondary frame and disposed within said window to define a string surface within said window, the ends of the strings that form the string surface being secured between the two rims in the form of a sandwich structure, means being provided to secure the two rims together.
Dependencies are inferred from the claim text.