US3587421A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric exposure meter
Assignee: Nikon Corp
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Filing: 1968-07-10
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Granted: 1971-06-28
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Expires: 1988-07-10
Abstract
Abstract AN ELECTRONIC EXPOSURE METER IS DISCLOSED THAT PROVIDES AN INDICATION OF THE AMOUNT OF OVER AND UNDEREXPOSURE WITH A MATCHED POINTER TYPE OF METER. THIS IS ACCOMPLISHED BY CONNECTING A METER ACROSS ONE DIAGONAL OF A BRIDGE CIRCUIT TO SENSE THE BALANCE THEREOF. THE BRIDGE CIRCUIT GENERALLY COMPRISES A PHTOCONDUCTOR AND A DIODE SERIES CONNECTED ACROSS A POWER SOURCE, A VARIABLE RESISTOR AND A SECOND DIODE, ALSO SERIES CONNECTED ACROSS THE CURRENT SOURCE AND IN PARALLEL WITH THE FIRST SERIES CIRCUIT, AND THE METER CONNECTED BETWEEN THE JUNCTIONS OF THE SERIES CIRCUITS.
Inventors
- 👤 Shigeo Ono
- 👤 Ichiro Hamaguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:13
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G03; G03B; G03B7/00; G03B7/04
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) | 1974-06-27 | 1974-12-27 | 1975-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-27 | 1978-12-27 | 1979-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-27 | 1982-12-27 | 1983-06-28 | $7700.00 | Window Closed / Lapsed |