US3733984A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure control systems for single reflex cameras having a detachable housing
Assignee: Minolta Co Ltd
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Filing: 1972-07-03
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Granted: 1973-05-22
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Expires: 1992-07-03
Abstract
Abstract In a single lens reflex camera, an exposure control system for a photographic camera is so constructed that a housing having a pentagonal prism therein is attachable to and detachable from the camera body. A detecting circuit for detecting the brightness of an object through the objective lens in an exposure control circuit and a memory circuit are built-in to the housing and a portion of the circuitry thereof is made as an integrated circuit. In the camera body a portion of the switching circuit for controlling the exposure of an electric shutter using the output of the detecting circuit as one input is built-in as an integrated circuit. The mounting of the pentagonal prism housing onto the camera body causes the terminals of the detecting and memory circuit and the terminals of the switching circuit to connect with one another.
Inventors
- 👤 K Yata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:15
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083; G03B19/00; G03B19/02; G03B19/12
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
274 words
An exposure control system for a single lens reflex camera comprising: a camera body including reflecting means movable between a viewing position and a picture taking position; a housing attachable to said camera body and including: a light receptive element for generating a signal in accordance with the incident light thereon; said reflecting means reflecting light passing through the objective lens of the camera to said light receptive element and a viewfinder in said viewing position; means for detecting said signal and generating an output signal; means for storing said output signal; an integrated circuit comprising elements from said means for detecting and said means for storing, said integrated circuit including first terminals; and non-integrated circuitry including the other elements from said means for detecting and said means for storing and having second terminals; and at least one of said second terminals connecting with at least one of said first terminals; said camera body further including: a circuit for manually setting exposure time; switching means for changing between manual and automatic timeexposure settings and connected to one of said first terminals connected to said means for storing; switching circuit means connected to said means for switching; means actuated by said switching circuit means for terminating exposure; a second integrated circuit including elements of said circuit for manually setting exposure time and said switching circuit means, said second integrated circuit including third terminals; and second non-integrated circuitry including the other elements of said mEans for manually setting exposure time and said switching circuit means, and including fourth terminals, and at least one of said fourth terminals connecting with at least one of said third terminals.
Claim 2
Dependent Claim
274 words
An exposure control system for a single lens reflex camera comprising: a camera body including reflecting means movable between a viewing position and a picture taking position; a housing attachable to said camera body and including: a light receptive element for generating a signal in accordance with the incident light thereon; said reflecting means reflecting light passing through the objective lens of the camera to said light receptive element and a viewfinder in said viewing position; means for detecting said signal and generating an output signal; means for storing said output signal; an integrated circuit comprising elements from said means for detecting and said means for storing, said integrated circuit including first terminals; and non-integrated circuitry including the other elements from said means for detecting and said means for storing and having second terminals; and at least one of said second terminals connecting with at least one of said first terminals; said camera body further including: a circuit for manually setting exposure time; switching means for changing between manual and automatic timeexposure settings and connected to one of said first terminals connected to said means for storing; switching circuit means connected to said means for switching; means actuated by said switching circuit means for terminating exposure; a second integrated circuit including elements of said circuit for manually setting exposure time and said switching circuit means, said second integrated circuit including third terminals; and second non-integrated circuitry including the other elements of said mEans for manually setting exposure time and said switching circuit means, and including fourth terminals, and at least one of said fourth terminals connecting with at least one of said third terminals.
Claim 3
Dependent Claim
40 words
An exposure control system for a single lens reflex camera as in claim 1 wherein with said housing attached to said camera body connections are established between said first and said second terminals, and said third and said fourth terminals.
Claim 4
Dependent Claim
229 words
An exposure control system for a single lens reflex camera as in claim 2 wherein: said means for detecting includes means for generating constant current, a first transistor, a first resistance connected in series with said light receptive element, a divided resistance connected in parallel with said light receptive element and said first resistance and interconnecting said means for generating constant current with the collector of said first transistor, the base of said first transistor is connected to the junction of said divided resistance, a variable resistance connected to the emitter of said first transistor and having a resistance varying in accordance with the sensitivity of the film and the diaphragm aperture setting, and an output terminal connected to the junction of said light receptive element and said first resistance; said means for storing includes a capacitor, a first normally closed switch interconnecting said capacitor with said output signal, said first switch is opened prior to the movement of said movable means from said viewing position to said picture taking position with the camera release operation; and whereby the variation in the voltage produced by said output signal from a one volt variation across said variable resistance is the same variation in the voltage produced by said output signal from a one volt variation produced by the light radiation on the light receiving plane of said light receptive element.
Claim 5
Dependent Claim
119 words
An exposure control system for a single lens reflex camera as in claim 2 wherein said camera includes opening and closing curtains cocked in overlapping relationship and wherein said camera body further includes: a constant time delay circuit including a series connected second resistance and second capacitor, the junction between said resistance and said second capacitor is connected to the output of said switching circuit means; a second transistor having a base connected to the junction of said resistance and said second capacitor, said means for terminating exposure is driven by said second transistor; and said second resistance is set at a value whereby the error in exposure time introduced by said overlapped opening and closing curtains is compensated.
Claim 6
Dependent Claim
57 words
An exposure control system for a single lens reflex camera as in claim 2 wherein either one of said first and second terminals, and said third and fourth terminals is a flexible contact element; and the other of said first and second terminals, and said third and fourth terminals is printed on a flexible insulating base plate.
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) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |