Patent US3484950A successfully refreshed from Google Patents.
US3484950A
Expired / Lapsed
US
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Teaching machine
Assignee: Educational Testing Service
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Filing: 1968-06-12
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Granted: 1969-12-23
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Expires: 1988-06-12
Abstract
No abstract record available.
Inventors
- 👤 Robert Serrell
- 👤 Frederick R Kling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:39
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06; G09B7/08
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2514578A
Cited
US2787669A
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US3294924A
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US3141243A
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US3194895A
Cited
US3383781A
Cited
US3269033A
Cited
US3395464A
Cited
US3408749A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-12-22 | 1973-06-23 | 1973-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-12-22 | 1977-06-23 | 1977-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-12-22 | 1981-06-23 | 1981-12-23 | $7700.00 | Window Closed / Lapsed |