US2530745A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transistor microphone with conductive grains
Assignee: AT&T Inc
•
Filing: 1948-12-10
•
Granted: 1950-11-21
•
Expires: 1968-12-10
Abstract
No abstract record available.
Inventors
- 👤 Jr Robert L Wallace
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:22
CPC Classifications
H; H04; H04R; H04R23/00; H04R23/006; H03; H03F; H03F3/00; H03F3/04; H10; H10D; H10D99/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1105066A
Cited
US920425A
Cited
US1534148A
Cited
US1745175A
Cited
US2444218A
Cited
US2347098A
Cited
US2353162A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1953-11-20 | 1954-05-22 | 1954-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1957-11-20 | 1958-05-22 | 1958-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1961-11-20 | 1962-05-22 | 1962-11-21 | $7700.00 | Window Closed / Lapsed |