Patent US3928860A successfully refreshed from Google Patents.
US3928860A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure control circuit for photographic camera
Assignee: Fujinon Corp
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Filing: 1975-02-21
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Granted: 1975-12-23
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Expires: 1995-02-21
Abstract
Abstract A balancing capacitor or capacitors are connected with the input and/or the output of an operational amplifier of an electric shutter control circuit of a photographic camera. The balancing capacitor is connected between the input of the operational amplifier and a power supply or the ground. The balancing capacitor may be connected between the output of the operational amplifier and the power supply. The capacitor connected between the output of the amplifier and the power supply also serves to partly precharge a memorizing capacitor before the operation of the circuit, and is cut from the supply when the circuit is put into operation. In a variation of the invention, the operational amplifier is connected with balancing capacitors at both the input and output terminals of the amplifier.
Inventors
- 👤 Saburo Numata
- 👤 Shinichiro Fujino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 19:42
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
226 words
An exposure control circuit for a photographic camera including a photo senser, an operational amplifier operatively connected between a power supply and ground and with the photo senser to amplify the input voltage thereof determined by the resistance of the photo senser which represents the light value from the subject to be photographed, a memorizing capacitor connected with the output of the operational amplifier and switching means for disconnecting the photo senser from the operational amplifier in response to the opening of the shutter of the camera and connecting the memorizing capacitor to a shutter closing means which operates to close the shutter when the input voltage of the switching means reaches a predetermined level whereby the time until the shutter closing means is energized is controlled in accordance with the value of illumination incident upon the photo senser, characterized in that at least one of the input terminal and the output terminal of the operational amplifier has a balancing capacitor having one side connected therewith, the other side of said balancing capacitor being connected to said power supply so as to effect a balance in capacitance between the input from the photo senser to the operational amplifier and the output of the operational amplifier, whereby the input voltage of the operational amplifier is instantly raised up to the operating voltage upon energization of the circuit.
Claim 2
Dependent Claim
226 words
An exposure control circuit for a photographic camera including a photo senser, an operational amplifier operatively connected between a power supply and ground and with the photo senser to amplify the input voltage thereof determined by the resistance of the photo senser which represents the light value from the subject to be photographed, a memorizing capacitor connected with the output of the operational amplifier and switching means for disconnecting the photo senser from the operational amplifier in response to the opening of the shutter of the camera and connecting the memorizing capacitor to a shutter closing means which operates to close the shutter when the input voltage of the switching means reaches a predetermined level whereby the time until the shutter closing means is energized is controlled in accordance with the value of illumination incident upon the photo senser, characterized in that at least one of the input terminal and the output terminal of the operational amplifier has a balancing capacitor having one side connected therewith, the other side of said balancing capacitor being connected to said power supply so as to effect a balance in capacitance between the input from the photo senser to the operational amplifier and the output of the operational amplifier, whereby the input voltage of the operational amplifier is instantly raised up to the operating voltage upon energization of the circuit.
Claim 3
Dependent Claim
35 words
An exposure control circuit for a photographic camera as defined in claim 1 wherein said balancing capacitor is a capacitor connected between the input of the operational amplifier and the power supply of the amplifier.
Claim 4
Dependent Claim
34 words
An exposure control circuit for a photographic camera as defined in claim 1 wherein said balancing capacitor is a capacitor connected between the power supply of the amplifier and the output of the amplifier.
Claim 5
Dependent Claim
48 words
An exposure control circuit for a photographic camera as defined in claim 3 wherein a normally closed switch is connected between the power supply and said capacitor between the output and the power supply, said switch being opened in response to release of the shutter of the camera.
Claim 6
Dependent Claim
26 words
An exposure control circuit for a photographic camera as defined in claim 4 further comprising an additional balancing capacitor connected with the input of the amplifier.
Claim 7
Dependent Claim
31 words
An exposure control circuit for a photographic camera as defined in claim 5 wherein said additional balancing capacitor is connected between the input and the power supply of the operational amplifier.
Claim 8
Dependent Claim
30 words
An exposure control circuit for a photographic camera as defined in claim 5 wherein said additional balancing capacitor is connected between the input of the operational amplifier and the ground.
Claim 9
Dependent Claim
225 words
An exposure control circuit for a photographic camera including a photo senser, an operational amplifier operatively connected between a power supply and ground and with the photo senser to amplify the input voltage thereof determined by the resistance of the photo senser which represents the light value from the subject to be photographed, a memorizing capacitor connected with the output of the operational amplifier and switching means for disconnecting the photo senser from the operational amplifier in response to the opening of the shutter of the camera and connecting the memorizing capacitor to a shutter closing means which operates to close the shutter when the input voltage of the switching means reaches a predetermined level whereby the time until the shutter closing means is energized is controlled in accordance with the value of illumination incident upon the photo senser, characterized in that at least one of the input terminal and the output terminal of the operational amplifier has a balancing capacitor having one side connected therewith, the other side of said balancing capacitor being connected to said ground so as to effect a balance in capacitance between the input from the photo senser to the operational amplifier and the output of the operational amplifier, whereby the input voltage of the operational amplifier is instantly raised up to the operating voltage upon energization of the circuit.
Claim 10
Dependent Claim
225 words
An exposure control circuit for a photographic camera including a photo senser, an operational amplifier operatively connected between a power supply and ground and with the photo senser to amplify the input voltage thereof determined by the resistance of the photo senser which represents the light value from the subject to be photographed, a memorizing capacitor connected with the output of the operational amplifier and switching means for disconnecting the photo senser from the operational amplifier in response to the opening of the shutter of the camera and connecting the memorizing capacitor to a shutter closing means which operates to close the shutter when the input voltage of the switching means reaches a predetermined level whereby the time until the shutter closing means is energized is controlled in accordance with the value of illumination incident upon the photo senser, characterized in that at least one of the input terminal and the output terminal of the operational amplifier has a balancing capacitor having one side connected therewith, the other side of said balancing capacitor being connected to said ground so as to effect a balance in capacitance between the input from the photo senser to the operational amplifier and the output of the operational amplifier, whereby the input voltage of the operational amplifier is instantly raised up to the operating voltage upon energization of the circuit.
Claim 11
Dependent Claim
31 words
An exposure control circuit for a photographic camera as defined in claim 8 wherein said balancing capacitor is a capacitor connected between the input of the operational amplifier and the ground.
Claim 12
Dependent Claim
32 words
An exposure control circuit for a photographic camera as defined in claim 9 further comprising a capacitor connected between the input of the operational amplifier and the power supply of the 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) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |