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Patent US3421231A successfully refreshed from Google Patents.
US3421231A
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US
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Electrokinetic tutoring means
Assignee: Individual
•
Filing: 1967-01-06
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Granted: 1969-01-14
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Expires: 1987-01-06
Abstract
No abstract record available.
Inventors
- 👤 Patrick A Kane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:13
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06
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) | 1972-01-14 | 1972-07-15 | 1973-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-01-14 | 1976-07-15 | 1977-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-01-14 | 1980-07-15 | 1981-01-14 | $7700.00 | Window Closed / Lapsed |