Patent US1981999A successfully refreshed from Google Patents.
US1981999A
Expired / Lapsed
US
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Optical telephone system
Assignee: AT&T Inc
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Filing: 1932-08-20
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Granted: 1934-11-27
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Expires: 1952-08-20
Abstract
No abstract record available.
Inventors
- 👤 Norman R French
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:12
CPC Classifications
G; G02; G02B; G02B5/00; G02B6/00; G02B6/10; G02B6/24; G02B6/26; G02B6/28; G02B6/293; G02B6/29371; G02B6/29373; H; H01; H01P; H01P3/00; H01P3/20; H04; H04B; H04B10/00; H04B10/25; H04B10/2589; G02B6/35; G02B6/351; G02B6/3512; G02B6/353; G02B6/354; G02B6/3544; G02B6/3548; G02B6/3552; G02B6/3564; G02B6/3568; G02B6/3572
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) | 1937-11-26 | 1938-05-28 | 1938-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1941-11-26 | 1942-05-28 | 1942-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1945-11-26 | 1946-05-28 | 1946-11-27 | $7700.00 | Window Closed / Lapsed |