US2838853A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Chalkboard having curved writing surface
Assignee: Rohm and Haas Co
•
Filing: 1956-07-03
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Granted: 1958-06-17
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Expires: 1976-07-03
Abstract
No abstract record available.
Inventors
- 👤 Batzdorff Alfred
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:23
CPC Classifications
B; B43; B43L; B43L1/00; B43L1/04; B43L1/06
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) | 1961-06-16 | 1961-12-16 | 1962-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-06-16 | 1965-12-16 | 1966-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-06-16 | 1969-12-16 | 1970-06-17 | $7700.00 | Window Closed / Lapsed |