Patent US3620143A successfully refreshed from Google Patents.
US3620143A
Expired / Lapsed
US
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Automatic exposure control system with fast linear response
Assignee: Polaroid Corp
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Filing: 1968-12-16
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Granted: 1971-11-16
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Expires: 1988-12-16
Abstract
Abstract AN AUTOMATIC EXPOSURE CONTROL SYSTEM FOR REGULATING ONE OR MORE VARIABLE PHOTOGRAPHIC EXPOSURE PARAMETERS. THE LIGHT LEVELS OF A SCENE ARE EVALUATED USING ONE OR MORE PHOTOYOLTAIC CELLS. THE CELLS ARE OPERATED IN A CURRENT MODE THROUGH USE OF AN OPERATIONAL AMPLIFIER HAVING AN INPUT CIRCUIT WHICH INCORPORATES A CAPACITIVE FEEDBACK PATH. WITH THE SYSTEM, A HIGHLY RESPONSIVE LINEAR OUTPUT REPRESENTATIVE OF SCENE LIGHT LEVELS IS DERIVED FOR USE IN CONTROLLING AN EXPOSURE.
Inventors
- 👤 John P Burgarella
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:36
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/34; H03F3/343; H03F3/347; G; G01; G01J; G01J1/00; G01J1/42; G01J1/4209; G01J1/4214; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/087; H03F1/00; H03F1/34; H03F3/45; H03F3/45071; H03F3/70
Claims Analysis
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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) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |