Patent US3880040A successfully refreshed from Google Patents.
US3880040A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sound board for stringed instrument
Assignee: Kaman Music Corp
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Filing: 1974-10-16
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Granted: 1975-04-29
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Expires: 1994-10-16
Abstract
Abstract A multiple ply sound board for the top of the hollow body portion of a guitar has inner and outer plies of oriented graphite fiber material, and one or more medial plies of wood. The high stiffness to weight ratio of the graphite fiber plies permits the overall thickness of the sound board to be reduced in thickness compared to a conventional wood wound board.
Inventors
- 👤 Charles H Kaman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:56
CPC Classifications
G; G10; G10D; G10D3/00; G10D3/22
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
99 words
In a stringed musical instrument of the type having a hollow body portion and a neck with strings extending from the outer end of the neck to a bridge located on the body, the improvement comprising: a. a sound board for said body portion, and supporting said bridge thereon, b. said sound board including inner and outer plies which are made from graphite fibers embedded in a resin matrix, and at least one medial ply between said inner and outer plies made from a material having a modulus of elasticity and a density generally similar to that of wood.
Claim 2
Dependent Claim
99 words
In a stringed musical instrument of the type having a hollow body portion and a neck with strings extending from the outer end of the neck to a bridge located on the body, the improvement comprising: a. a sound board for said body portion, and supporting said bridge thereon, b. said sound board including inner and outer plies which are made from graphite fibers embedded in a resin matrix, and at least one medial ply between said inner and outer plies made from a material having a modulus of elasticity and a density generally similar to that of wood.
Claim 3
Dependent Claim
28 words
A sound board of the type defined in claim 1 wherein the combined thickness of said inner and outer graphite fiber plies is no more than 0.02 inches.
Claim 4
Dependent Claim
44 words
A sound board of the type defined in claim 1 further characterized by at least one bracing member cemented to the inner graphite fiber ply, and a reinforcing layer of graphite fiber material adhered to at least the exposed side of said bracing member.
Claim 5
Dependent Claim
29 words
A sound board of the type defined in claim 1 wherein a majority of said graphite fibers are oriented in generally parallel relationship with respect to the instrument''s strings.
Claim 6
Dependent Claim
39 words
A sound board of the type defined in claim 4 wherein said inner and outer graphite fiber plies have a combined thickness which is less than one-half that of the combined thickness of all plies in the sounding board.
Claim 7
Dependent Claim
54 words
A sound board of the type defined in claim 5 wherein said at least one medial ply is fabricated from a material with a modulus of approximately 1.5 X 106 pounds per square inch, said inner and outer graphite fiber plies having a modulus of at least 10 times that of said medial ply.
Claim 8
Dependent Claim
42 words
A sound board of the type defined in claim 3 wherein said combined thickness of said plies in said sound board is approximately 0.05 inches, and wherein said combined thickness of said inner and outer graphite fiber plies is approximately 0.01 inches.
Claim 9
Dependent Claim
37 words
A sound board of the type defined in claim 7 wherein said inner and outer plies are bonded to said medial ply by a thin film of epoxy adhesive provided on both sides of said medial ply.
Claim 10
Dependent Claim
62 words
A sound board of the type defined in claim 7 wherein a single medial ply is provided between said inner and outer plies, said medial ply being fabricated from wood with a modulus of approximately 1.5 X 106 pounds per square inch, said inner and outer graphite fiber plies having a modulus of at least 10 times that of said medial ply.
Claim 11
Dependent Claim
42 words
A sound board of the type defined in claim 9 wherein said single wood medial ply comprises a single layer having its grain oriented generally obliquely with respect to the longitudinal direction of said graphite fibers in said inner and outer plies.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-28 | 1978-10-28 | 1979-04-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-28 | 1982-10-28 | 1983-04-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-28 | 1986-10-28 | 1987-04-29 | $7700.00 | Window Closed / Lapsed |