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Patent US2497770A successfully refreshed from Google Patents.
US2497770A
Expired / Lapsed
US
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Transistor-microphone
Assignee: AT&T Inc
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Filing: 1948-12-29
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Granted: 1950-02-14
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Expires: 1968-12-29
Abstract
No abstract record available.
Inventors
- 👤 Robert L Hanson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:02
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/04; H04; H04R; H04R23/00; H04R23/006
Claims Analysis
Total Claims: 0
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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) | 1953-02-13 | 1953-08-15 | 1954-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-02-13 | 1957-08-15 | 1958-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-02-13 | 1961-08-15 | 1962-02-14 | $7700.00 | Window Closed / Lapsed |