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Patent US2491631A successfully refreshed from Google Patents.
US2491631A
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US
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Method of making spark gaps
Assignee: Duracell Inc USA
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Filing: 1945-03-10
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Granted: 1949-12-20
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Expires: 1965-03-10
Abstract
No abstract record available.
Inventors
- 👤 Alexander C Wall
- 👤 Herbert E Oles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:28
CPC Classifications
H; H01; H01T; H01T21/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US405124A
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US2304927A
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US876899A
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US1281309A
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US1452275A
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US2177502A
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US2297492A
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US2222093A
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US2402119A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1952-12-19 | 1953-06-20 | 1953-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1956-12-19 | 1957-06-20 | 1957-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1960-12-19 | 1961-06-20 | 1961-12-20 | $7700.00 | Window Closed / Lapsed |