Patent US2501031A successfully refreshed from Google Patents.
US2501031A
Expired / Lapsed
US
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Magnetic field structure for dynamic loud-speakers and the like
Assignee: RCA Corp
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Filing: 1945-11-30
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Granted: 1950-03-21
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Expires: 1965-11-30
Abstract
No abstract record available.
Inventors
- 👤 David H Cunningham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:17
CPC Classifications
H; H04; H04R; H04R9/00; H04R9/02; H04R9/025
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1811367A
Cited
US1864809A
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US1991738A
Cited
GB389898A
Cited
GB412552A
Cited
US2029282A
Cited
US2174355A
Cited
US2312238A
Cited
GB552328A
Cited
US2395166A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-03-20 | 1953-09-19 | 1954-03-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-03-20 | 1957-09-19 | 1958-03-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-03-20 | 1961-09-19 | 1962-03-21 | $7700.00 | Window Closed / Lapsed |