Patent US3769775B1 successfully refreshed from Google Patents.
US3523409A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Portable air filter
Assignee: Individual
•
Filing: 1968-08-26
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Granted: 1970-08-11
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Expires: 1988-08-26
Abstract
No abstract record available.
Inventors
- 👤 Werner A Paterson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:56
CPC Classifications
B; B01; B01D; B01D46/00; B01D46/10; B01D46/12; F; F24; F24F; F24F13/00; F24F13/28
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US3126428A
Cited
US1596950A
Cited
US2232375A
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US2808124A
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US2873908A
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US3077825A
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US3080695A
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US3148956A
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US3223393A
Cited
US3348365A
Cited
US3406530A
Cited
US3375640A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-08-10 | 1974-02-09 | 1974-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-08-10 | 1978-02-09 | 1978-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-08-10 | 1982-02-09 | 1982-08-11 | $7700.00 | Window Closed / Lapsed |