Patent US3606530A successfully refreshed from Google Patents.
US3606530A
Expired / Lapsed
US
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Focus maintaining device
Assignee: Bell and Howell Co
•
Filing: 1969-09-23
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Granted: 1971-09-20
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Expires: 1989-09-23
Abstract
Abstract A FOCUS MAINTAINING A FILM PROJECTOR THAT MAINTAINS FOCUS BY ALTERING THE POSITION OF A REFLECTING SURFACE IN A FOLDED PROJECTION SYSTEM.
Inventors
- 👤 Edward J Hennessy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:48
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/40; G03; G03B; G03B21/00; G03B21/14; G03B21/53
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-19 | 1975-03-21 | 1975-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-19 | 1979-03-21 | 1979-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-19 | 1983-03-21 | 1983-09-20 | $7700.00 | Window Closed / Lapsed |