Patent US4331401A successfully refreshed from Google Patents.
US4331401A
Expired / Lapsed
US
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Exposure control system for a photographic camera
Assignee: Fujinon Corp
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Filing: 1981-02-27
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Granted: 1982-05-25
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Expires: 2001-02-27
Abstract
Abstract In a photographic camera with an automatic exposure control system, a voltage obtained by a light measuring circuit with reference to a reference voltage based on a film speed is divided into 1/n and (n-1)/n of the voltage. The scene brightness is measured while the diaphragm provided before a photosensor of the light measuring circuit is stopped down until the output voltage of the light measuring circuit becomes equal to 1/n of the voltage. After the output voltage has become 1/n of the voltage, the diaphragm is held in its position and then the shutter speed is controlled according to the (n-1)/n voltage.
Inventors
- 👤 Saburo Numata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 10:06
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/087; G03B7/089
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
161 words
An exposure control system for a camera provided with an automatic exposure control means including a light measuring circuit having a photosensor and giving an output corresponding to scene brightness measured through an aperture located in front of the photosensor, a memory means for memorizing the output of said output, a film speed setting means, a voltage divider connected with the output of the memory means for dividing the output voltage of the memory means, an aperture control means connected with said memory means via said voltage divider and with said light measuring means for controlling the size of said aperture based on the difference between the output of the light measuring means and the output of the voltage divider, and a shutter speed control means connected with said voltage divider and said film speed setting means for controlling exposure time based on the difference between the output of the film speed setting means and the output of the voltage divider.
Claim 2
Dependent Claim
161 words
An exposure control system for a camera provided with an automatic exposure control means including a light measuring circuit having a photosensor and giving an output corresponding to scene brightness measured through an aperture located in front of the photosensor, a memory means for memorizing the output of said output, a film speed setting means, a voltage divider connected with the output of the memory means for dividing the output voltage of the memory means, an aperture control means connected with said memory means via said voltage divider and with said light measuring means for controlling the size of said aperture based on the difference between the output of the light measuring means and the output of the voltage divider, and a shutter speed control means connected with said voltage divider and said film speed setting means for controlling exposure time based on the difference between the output of the film speed setting means and the output of the voltage divider.
Claim 3
Dependent Claim
38 words
An exposure control system for a camera as defined in claim 1 wherein said voltage divider divides the output voltage of the memory means and the film speed setting means into 1/n and (n-1)/n of the output voltage.
Claim 4
Dependent Claim
42 words
An exposure control system for a camera as defined in claim 1 wherein said divider comprises a pair of resistors of the same resistance connected in series and connected between the output of said film speed setting means and said memory means.
References Cited (Backward Citations)
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Cited
US4090207A
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US4107707A
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US4174160A
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US4150889A
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US4146317A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-05-24 | 1985-11-23 | 1986-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-24 | 1989-11-23 | 1990-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-24 | 1993-11-23 | 1994-05-25 | $7700.00 | Window Closed / Lapsed |