Patent US3974509A successfully refreshed from Google Patents.
US3974509A
Expired / Lapsed
US
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Automatic exposure control circuit for a camera
Assignee: Panasonic Holdings Corp
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Filing: 1974-10-29
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Granted: 1976-08-10
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Expires: 1994-10-29
Abstract
Abstract An automatic exposure control circuit for a camera or the like includes a memory circuit comprising a series connection of a capacitor and an impedance element connected to an input of a high input impedance circuit to enable the measurement of the amount of mean light during photography under a fluorescent lamp.
Inventors
- 👤 Yuji Tsuda
- 👤 Junji Kajiwara
- 👤 Shigekazu Komori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:04
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
151 words
An automatic exposure control circuit for a camera having a shutter including a rear curtain comprising a photoelectric transducer element having a fast response to light for detecting the brightness of an object, an amplifier circuit for amplifying the output of said transducer element, a differential amplifier for amplifying the output of said amplifier, a store switch connected between the output of said amplifier and an input of said differential amplifier, a charging capacitor charged by an output of said differential amplifier for determining the speed of said shutter, a trigger switch connected in parallel with said charging capacitor, a comparator for detecting the output of said charging capacitor, an electromagnetic coil for controlling said shutter rear curtain in response to the output of said comparator, and a memory circuit having a series connection consisting of a store capacitor and a resistor connected between two input terminals of said differential amplifier.
Claim 2
Dependent Claim
151 words
An automatic exposure control circuit for a camera having a shutter including a rear curtain comprising a photoelectric transducer element having a fast response to light for detecting the brightness of an object, an amplifier circuit for amplifying the output of said transducer element, a differential amplifier for amplifying the output of said amplifier, a store switch connected between the output of said amplifier and an input of said differential amplifier, a charging capacitor charged by an output of said differential amplifier for determining the speed of said shutter, a trigger switch connected in parallel with said charging capacitor, a comparator for detecting the output of said charging capacitor, an electromagnetic coil for controlling said shutter rear curtain in response to the output of said comparator, and a memory circuit having a series connection consisting of a store capacitor and a resistor connected between two input terminals of said differential amplifier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |