Patent US4185822A successfully refreshed from Google Patents.
US4185822A
Expired / Lapsed
US
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Racket and the like
Assignee: Massachusetts Institute of Technology
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Filing: 1978-02-06
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Granted: 1980-01-29
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Expires: 1998-02-06
Abstract
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.
Inventors
- 👤 Yao T. Li
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 03:47
CPC Classifications
A; A63; A63B; A63B49/00; A63B49/02; A63B49/038; A63B49/028
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
188 words
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.
Claim 2
Dependent Claim
188 words
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.
Claim 3
Dependent Claim
25 words
A racket as claimed in claim 1 in which the secondary frame is thin enough to localize forces orthogonal to the plane of the rim.
Claim 4
Dependent Claim
24 words
A racket as claimed in claim 1 in which the thickness of the thin planar rim is much less than the width dimension thereof.
Claim 5
Dependent Claim
44 words
A racket as claimed in claim 1 wherein a plurality of holes are provided in the planar rim that constitutes the secondary frame to receive the strings which are strung through the holes to provide the string surface in the form of a mesh.
Claim 6
Dependent Claim
20 words
A racket as claimed in claim 4 in which the holes have rounded edges coated with a low friction coating.
Claim 7
Dependent Claim
60 words
A racket as claimed in claim 1 wherein the elastomer means comprises at least one elastomer member that fits within the channel along the whole length of the channel and has an inwardly facing slot along said length to receive the secondary frame which is compressed within said slot in order to transmit the orthogonally-directed forces to the primary frame.
Claim 8
Dependent Claim
21 words
A racket as claimed in claim 7 wherein the elastomer member is bonded to both the primary frame and secondary frame.
Claim 9
Dependent Claim
39 words
A racket as claimed in claim 1 wherein the elastomer means comprises two facing elastomer members with a slot therebetween to receive the peripheral edge of the planar rim and to secure the planar rim within the internal channel.
Claim 10
Dependent Claim
27 words
A racket as claimed in claim 1 wherein the coupling system comprises an undulating spring member that fits within the channel and secures the secondary frame therein.
Claim 11
Dependent Claim
49 words
A racket as claimed in claim 1 wherein the elastomer means comprises an elastomer strip at each side of the thin rim, each strip extending the whole length of the internal channel and being compressed therein between the thin rim and the primary frame and being adhered to each.
Claim 12
Dependent Claim
63 words
A racket as claimed in claim 1 wherein the cross dimensions of the internal channel are just slightly less than the thickness of the secondary frame to form a slot along the length of the channel, the planar rim that constitutes the secondary frame being fitted into the slot which holds it in compression to transmit the orthogonally-directed forces to the primary frame.
Claim 13
Dependent Claim
15 words
A racket as claimed in claim 1 wherein the elastomer means comprises a pneumatic tube.
Claim 14
Dependent Claim
18 words
A racket as claimed in claim 1 in which the primary frame is a tubular, thin wall structure.
Claim 15
Dependent Claim
51 words
A racket as claimed in claim 1 wherein the secondary frame comprises two similarly-shaped closed-loop thin rims and wherein the ends of the strings that form the string surface are secured between the two rims in the form of a sandwich structure, means being provided to secure the two rims together.
Claim 16
Dependent Claim
30 words
A racket as claimed in claim 14 wherein the two rims are held together by an adhesive which maintains tension on the string and transmits said tension to the rims.
Claim 17
Dependent Claim
150 words
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.
Claim 18
Dependent Claim
150 words
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.
Claim 19
Dependent Claim
125 words
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.
Claim 20
Dependent Claim
125 words
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.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-01-28 | 1983-07-30 | 1984-01-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-01-28 | 1987-07-30 | 1988-01-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-01-28 | 1991-07-30 | 1992-01-29 | $7700.00 | Window Closed / Lapsed |