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US3538686A
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US
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Self-sealing and self-holding filter frame
Assignee: Individual
•
Filing: 1968-10-21
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Granted: 1970-11-10
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Expires: 1988-10-21
Abstract
No abstract record available.
Inventors
- 👤 Louis Schwab
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:28
CPC Classifications
B; B01; B01D; B01D46/00; B01D46/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
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US2418371A
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US2596806A
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US2752002A
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US3023839A
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US2976796A
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US2964127A
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US2995206A
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US3252274A
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US3309848A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-11-09 | 1974-05-11 | 1974-11-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-11-09 | 1978-05-11 | 1978-11-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-11-09 | 1982-05-11 | 1982-11-10 | $7700.00 | Window Closed / Lapsed |