US2820688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital differential analyzer magnetic drum
Assignee: Northrop Grumman Corp
•
Filing: 1952-09-10
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Granted: 1958-01-21
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Expires: 1972-09-10
Abstract
No abstract record available.
Inventors
- 👤 Jr Everett D Philbrick
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:59
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/004; G11B27/00; G11B27/10; G11B27/19; G11B27/28; G11B27/32; G11B5/48
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1366617A
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US2439446A
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US2540406A
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US2540654A
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US2546829A
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US2605364A
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US2680785A
Cited
US2668879A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-01-20 | 1961-07-22 | 1962-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-01-20 | 1965-07-22 | 1966-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-01-20 | 1969-07-22 | 1970-01-21 | $7700.00 | Window Closed / Lapsed |