US3889276A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic shutter control device for cameras
Assignee: Cosina Co Ltd
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Filing: 1974-01-02
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Granted: 1975-06-10
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Expires: 1994-01-02
Abstract
Abstract Electronic shutter control device comprising a light measuring means for measuring light through the objective lens, a memorizing means and a shutter control circuit for controlling exposure time of a shutter movable between its opening position and closing position. The light measuring means measures light from an object to be photographed and passing through the objective lens before and after shutter opening. When a first light-receiving element is in the center of the image plane, it gives relatively great weight to the measurement of the light from the center of the field. Thereafter, the first lightreceiving element moves to the side of the image plane and the second light-receiving element together with the first lightreceiving element in the moved position give relatively great weight to the measurement of the light from the periphery of the field. Either average light measuring or center light measuring can be selectively effected. The object brightness before shutter opening memorized in the memorizing means in addition to the object brightness after the opening of the shutter is delivered to the shutter control circuit, and thus the exposure time is controlled.
Inventors
- 👤 Osamu Shirai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:19
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
144 words
In an electronic shutter coNtrol device having a shutter movable between opened and closed positions, and a shutter controlling circuit that automatically controls exposure time depending on the brightness of an object to be photographed; the improvement comprising light measuring means for measuring the brightness of light from an object that enters through the objective lens, said light measuring means measuring the light incident to the central portion of the image plane before the shutter is opened and measuring the light incident to the peripheral portion of the image plane after the shutter is opened, means to weight the information obtained by said measuring means, memorizing means to memorize said weighted information, and means for supplying to said shutter controlling circuit the information memorized in said memorizing means before the shutter is opened, in overlapping relation with the information after the shutter is opened.
Claim 2
Dependent Claim
144 words
In an electronic shutter coNtrol device having a shutter movable between opened and closed positions, and a shutter controlling circuit that automatically controls exposure time depending on the brightness of an object to be photographed; the improvement comprising light measuring means for measuring the brightness of light from an object that enters through the objective lens, said light measuring means measuring the light incident to the central portion of the image plane before the shutter is opened and measuring the light incident to the peripheral portion of the image plane after the shutter is opened, means to weight the information obtained by said measuring means, memorizing means to memorize said weighted information, and means for supplying to said shutter controlling circuit the information memorized in said memorizing means before the shutter is opened, in overlapping relation with the information after the shutter is opened.
Claim 3
Dependent Claim
85 words
A device as claimed in claim 1, said light measuring means comprising first and second light receiving elements, said first light receiving element being disposed in the path of light from a reflective mirror to an eyepiece of a finder to measure the light entering the central portion of the image plane before the shutter is opened, said second light receiving element being fixed relative to said mirror to measure the light entering the peripheral portion of the image plane after the shutter is opened.
Claim 4
Dependent Claim
135 words
A device as claimed in claim 1, said light measuring means comprising first and second light receiving elements, said first light receiving element being disposed behind a reflective mirror to measure the light entering the central portion of the image plane before the shutter is opened, said first element being mounted for movement to one side of said mirror prior to the opening of the shutter to a position to measure the light entering the peripheral portion of the image plane after the shutter is opened, said second light receiving element being fixed relative to said mirror to measure light entering the peripheral portion of the image plane after the shutter is opened at a position symmetrical to the position to which that first element has moved relative to the optical axis of the mirror.
Claim 5
Dependent Claim
213 words
In an electronic shutter control device having a shutter movable between opened and closed positions, and a shutter controlling circuit that automatically controls exposure time depending on the brightness of an object to be photographed; the improvement comprising a first light receiving element disposed behind a reflective mirror to measure light entering the central portion of the image plane through the objective lens, said first element being movable to one side of said mirror to open the shutter and to measure light entering the peripheral portion of the image plane after the shutter is opened, a second light receiving element fixed at a position symmetrical to the position to which said first element has moved relative to the optical axis to measure light entering the peripheral portion of the image plane after the shutter is opened, an amplifier for amplifying the outputs of said first and second light receiving elements, weighting means comprising at least two resistances connected to an output terminal of said amplifier, a memorizing capacitor connected at the junction of said two resistances to memorize weighted information before the shutter opens, and means for applying a voltage between the terminals of said memorizing capacitor in addition to the potential at said junction of said resistances after the shutter is opened.
Claim 6
Dependent Claim
213 words
In an electronic shutter control device having a shutter movable between opened and closed positions, and a shutter controlling circuit that automatically controls exposure time depending on the brightness of an object to be photographed; the improvement comprising a first light receiving element disposed behind a reflective mirror to measure light entering the central portion of the image plane through the objective lens, said first element being movable to one side of said mirror to open the shutter and to measure light entering the peripheral portion of the image plane after the shutter is opened, a second light receiving element fixed at a position symmetrical to the position to which said first element has moved relative to the optical axis to measure light entering the peripheral portion of the image plane after the shutter is opened, an amplifier for amplifying the outputs of said first and second light receiving elements, weighting means comprising at least two resistances connected to an output terminal of said amplifier, a memorizing capacitor connected at the junction of said two resistances to memorize weighted information before the shutter opens, and means for applying a voltage between the terminals of said memorizing capacitor in addition to the potential at said junction of said resistances after the shutter is opened.
Claim 7
Dependent Claim
50 words
A device as claimed in claim 4, said weighting means comprising means to adjust the ratio of values of said two resistances thereby to adjust said weighting, whereby the light measuring of said central portion and the average light measuring of said central and peripheral portions may be selectively effected.
Claim 8
Dependent Claim
97 words
A device as claimed in claim 4, and a crank lever movable in association with a film winding operation from a first posItion to a second position, a spring member for urging said crank lever from said second position to said first position, a slide lever connected to said crank lever and supporting said first element, a guide groove for guiding an extension protruding from said slide lever, a hook lever for locking said crank lever in said second position, and an intermediate lever for actuating the lock lever in association with the movement of said mirror.
References Cited (Backward Citations)
US3498193A
Cited
US3682057A
Cited
US3698302A
Cited
US3691917A
Cited
US3690241A
Cited
US3731604A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |