US2627932A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic filter for microphones
Assignee: RCA Corp
•
Filing: 1947-01-30
•
Granted: 1953-02-10
•
Expires: 1967-01-30
Abstract
No abstract record available.
Inventors
- 👤 John E Volkmann
- 👤 Maxim L Graham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:12
CPC Classifications
H; H04; H04R; H04R1/00; H04R1/08
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US1399083A
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US1474100A
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US1678842A
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US1836777A
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US2162270A
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US2196342A
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US2224974A
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US2325688A
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US2404877A
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US2518805A
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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) | 1956-02-10 | 1956-08-11 | 1957-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1960-02-10 | 1960-08-11 | 1961-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1964-02-10 | 1964-08-11 | 1965-02-10 | $7700.00 | Window Closed / Lapsed |