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Patent US2188940A successfully refreshed from Google Patents.
US2188940A
Expired / Lapsed
US
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Electron discharge device
Assignee: AT&T Inc
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Filing: 1937-12-02
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Granted: 1940-02-06
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Expires: 1957-12-02
Abstract
No abstract record available.
Inventors
- 👤 Benjamin A Diggory
- 👤 Gordon K Teal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:56
CPC Classifications
H; H01; H01J; H01J9/00; H01J9/02; H01J9/12; H01J19/00; H01J19/28; H01J19/30; H01J2893/00; H01J2893/0001; H01J2893/0012; H01J2893/0019
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) | 1943-02-05 | 1943-08-07 | 1944-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-02-05 | 1947-08-07 | 1948-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-02-05 | 1951-08-07 | 1952-02-06 | $7700.00 | Window Closed / Lapsed |