US3531920A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter
Assignee: Cambridge Filter Corp
•
Filing: 1968-09-16
•
Granted: 1970-10-06
•
Expires: 1988-09-16
Abstract
No abstract record available.
Inventors
- 👤 Charles G Hart
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:19
CPC Classifications
F; F24; F24F; F24F13/00; F24F13/28; B; B01; B01D; B01D46/00
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2569243A
Cited
US2654440A
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US2936855A
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US3025964A
Cited
US3058594A
Cited
US3258900A
Cited
US3392843A
Cited
US3397518A
Cited
US3410062A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-10-05 | 1974-04-06 | 1974-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-10-05 | 1978-04-06 | 1978-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-10-05 | 1982-04-06 | 1982-10-06 | $7700.00 | Window Closed / Lapsed |