US2547259A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Educational device
Assignee: Individual
•
Filing: 1948-02-03
•
Granted: 1951-04-03
•
Expires: 1968-02-03
Abstract
No abstract record available.
Inventors
- 👤 Henry A Engelhardt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:54
CPC Classifications
G; G09; G09B; G09B17/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US281112A
Cited
US296900A
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US723022A
Cited
US1026809A
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US1110434A
Cited
US1559665A
Cited
US1891414A
Cited
US2149363A
Cited
US2129834A
Cited
US2474447A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1954-04-02 | 1954-10-02 | 1955-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-04-02 | 1958-10-02 | 1959-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-04-02 | 1962-10-02 | 1963-04-03 | $7700.00 | Window Closed / Lapsed |