Patent US2021920A successfully refreshed from Google Patents.
US2021920A
Expired / Lapsed
US
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Control circuits
Assignee: AT&T Inc
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Filing: 1935-01-15
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Granted: 1935-11-26
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Expires: 1955-01-15
Abstract
No abstract record available.
Inventors
- 👤 Andrew C Norwine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:57
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/62; H04B1/64
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1938-11-25 | 1939-05-27 | 1939-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1942-11-25 | 1943-05-27 | 1943-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1946-11-25 | 1947-05-27 | 1947-11-26 | $7700.00 | Window Closed / Lapsed |