US3522665A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Teaching system
Assignee: Sprague Electric Co
•
Filing: 1967-12-12
•
Granted: 1970-08-04
•
Expires: 1987-12-12
Abstract
No abstract record available.
Inventors
- 👤 Charles G Kalt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:26
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06; G09B7/08
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2546666A
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US2724910A
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US2953859A
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US3057082A
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US3141244A
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US3177595A
Cited
US3187443A
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US3382588A
Cited
US3316660A
Cited
US3401470A
Cited
US3421231A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-08-03 | 1974-02-02 | 1974-08-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-08-03 | 1978-02-02 | 1978-08-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-08-03 | 1982-02-02 | 1982-08-04 | $7700.00 | Window Closed / Lapsed |