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US3420424A
Expired / Lapsed
US
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Concave-surfaced vacuum controlled air film
Assignee: International Business Machines Corp
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Filing: 1966-01-10
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Granted: 1969-01-07
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Expires: 1986-01-10
Abstract
No abstract record available.
Inventors
- 👤 Raymond A Barbeau
- 👤 Kelly B Day Jr
- 👤 James A Weidenhammer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 12:54
CPC Classifications
G; G11; G11B; G11B15/00; G11B15/60; G11B15/66; G11B15/67; G11B15/671; F; F15; F15B; F15B21/00; G06; G06K; G06K17/00; G11B15/61
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) | 1972-01-07 | 1972-07-08 | 1973-01-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-01-07 | 1976-07-08 | 1977-01-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-01-07 | 1980-07-08 | 1981-01-07 | $7700.00 | Window Closed / Lapsed |