US2539077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Teaching device
Assignee: Individual
•
Filing: 1946-08-31
•
Granted: 1951-01-23
•
Expires: 1966-08-31
Abstract
No abstract record available.
Inventors
- 👤 Barbara J Hawkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 07:01
CPC Classifications
G; G09; G09B; G09B7/00; G09B7/06; G09B7/066
Claims Analysis
Total Claims: 0
No claims parsed yet. Click Sync Now above to re-index claims from Google Patents.
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) | 1954-01-22 | 1954-07-24 | 1955-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1958-01-22 | 1958-07-24 | 1959-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1962-01-22 | 1962-07-24 | 1963-01-23 | $7700.00 | Window Closed / Lapsed |