US3477142A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple choice teaching device
Assignee: TEACHING MACHINES Inc
•
Filing: 1967-07-17
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Granted: 1969-11-11
•
Expires: 1987-07-17
Abstract
No abstract record available.
Inventors
- 👤 Dudley E Cornell
- 👤 Robert A O'connell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:54
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US3100352A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-11-10 | 1973-05-12 | 1973-11-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-11-10 | 1977-05-12 | 1977-11-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-11-10 | 1981-05-12 | 1981-11-11 | $7700.00 | Window Closed / Lapsed |