Patent US3993551A successfully refreshed from Google Patents.
US1628987A
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US
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Thermionic device and method of evacuating the same
Assignee: AT&T Inc
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Filing: 1920-09-24
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Granted: 1927-05-17
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Expires: 1940-09-24
Abstract
No abstract record available.
Inventors
- 👤 Robert W King
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:12
CPC Classifications
H; H01; H01J; H01J7/00; H01J7/14; H01J7/18; H01J7/186; H01J19/00; H01J19/28; H01J2893/00; H01J2893/0001; H01J2893/0012; H01J2893/0013
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) | 1930-05-16 | 1930-11-15 | 1931-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1934-05-16 | 1934-11-15 | 1935-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1938-05-16 | 1938-11-15 | 1939-05-17 | $7700.00 | Window Closed / Lapsed |