Patent US2790253A successfully refreshed from Google Patents.
US2790253A
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US
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Filter demonstration device
Assignee: Cambridge Filter Corp
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Filing: 1953-07-30
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Granted: 1957-04-30
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Expires: 1973-07-30
Abstract
No abstract record available.
Inventors
- 👤 John L Ayer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:28
CPC Classifications
G; G09; G09B; G09B25/00; G09B25/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US1517144A
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US2079474A
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US2112304A
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US2184406A
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US2184433A
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US2228371A
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US2638688A
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US2613454A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1960-04-29 | 1960-10-29 | 1961-04-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1964-04-29 | 1964-10-29 | 1965-04-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1968-04-29 | 1968-10-29 | 1969-04-30 | $7700.00 | Window Closed / Lapsed |