Patent US3520072A successfully refreshed from Google Patents.
US3520072A
Expired / Lapsed
US
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Assignee: Individual
•
Filing: 1967-12-13
•
Granted: 1970-07-14
•
Expires: 1987-12-13
Abstract
No abstract record available.
Inventors
- 👤 Frank Greenwood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:58
CPC Classifications
G; G09; G09B; G09B17/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US471653A
Cited
US2899756A
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US760384A
Cited
GB215168A
Cited
US1728805A
Cited
GB434491A
Cited
US2055159A
Cited
US2129834A
Cited
US2584601A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-07-13 | 1974-01-12 | 1974-07-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-07-13 | 1978-01-12 | 1978-07-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-07-13 | 1982-01-12 | 1982-07-14 | $7700.00 | Window Closed / Lapsed |