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Patent US3528181A successfully refreshed from Google Patents.
US3528181A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Teaching machines
Assignee: Structural Communication Systems Ltd
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Filing: 1967-01-25
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Granted: 1970-09-15
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Expires: 1987-01-25
Abstract
No abstract record available.
Inventors
- 👤 Robert Stanley Arbon
- 👤 John Godolphin Bennett
- 👤 Colin Douglas Bright
- 👤 Anthony Malcolm Hodgson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 21:56
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06; G09B7/08
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-09-14 | 1974-03-16 | 1974-09-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-09-14 | 1978-03-16 | 1978-09-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-09-14 | 1982-03-16 | 1982-09-15 | $7700.00 | Window Closed / Lapsed |