US3776111A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic exposure determining device
Assignee: Nikon Corp
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Filing: 1972-11-17
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Granted: 1973-12-04
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Expires: 1992-11-17
Abstract
Abstract A motor driven automatic exposure determining device for a camera in which the motor is operated in forward or reverse direction from a single voltage source. In addition to driving an exposure control element, such as a shutter speed control mechanism or a diaphragm aperture control mechanism, the motor drives a variable impedance of a bridge circuit for balancing the bridge circuit. Another impedance of the bridge circuit is a photoelectric element responsive to light from the scene to be photographed. A transistor switching circuit, comprising four transistors, is employed to control the connection of the motor terminals to the terminals of the single voltage source by providing circuits for energizing the motor for forward or reverse rotation depending upon which of two pairs of the transistors is rendered conductive by a detecting transistor circuit responsive to bridge unbalance and to the direction of unbalance. By a unique interconnection of the detecting circuit and the switching circuit, a single transistor of the detecting circuit renders a pair of transistors of the switching circuit conductive simultaneously and with low power consumption.
Inventors
- 👤 O Maida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:08
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
274 words
An automatic exposure determining device, comprising a reversibly rotatable electric motor for setting an exposure factor in one sense or the opposite sense, depending upon the direction of rotation, to provide proper exposure, a voltage source for said motor, a switching circuit for connecting said motor to said voltage source for rotation of said motor in one direction or the opposite direction, said switching circuit comprising a first pair of switching transistors for connecting terminals of said motor to terminals of said voltage source when conductive and a second pair of switching transistors for reversely connecting said terminals of said motor to said terminals of said voltage source when conductive, means including a photosensitive element for producing a first output in response to a first exposure condition and for producing a second output in response to a second exposure condition, first transistor means connected to said first pair of switching transistors for rendering said first pair of switching transistors conductive in response to said first output, and second transistor means connected to said second pair of switching transistors for rendering said second pair of switching transistors conductive in response to said second output, said first transistor means comprising a first transistor having its emitter connected to the base of a switching transistor of said first pair and having its collector connected to the base of the other switching transistor of said first pair, and said second transistor means comprising a second transistor having its emitter connected to the base of a switching transistor of said second pair and having its collector connected to the base of the other switching transistor of said second pair.
Claim 2
Dependent Claim
274 words
An automatic exposure determining device, comprising a reversibly rotatable electric motor for setting an exposure factor in one sense or the opposite sense, depending upon the direction of rotation, to provide proper exposure, a voltage source for said motor, a switching circuit for connecting said motor to said voltage source for rotation of said motor in one direction or the opposite direction, said switching circuit comprising a first pair of switching transistors for connecting terminals of said motor to terminals of said voltage source when conductive and a second pair of switching transistors for reversely connecting said terminals of said motor to said terminals of said voltage source when conductive, means including a photosensitive element for producing a first output in response to a first exposure condition and for producing a second output in response to a second exposure condition, first transistor means connected to said first pair of switching transistors for rendering said first pair of switching transistors conductive in response to said first output, and second transistor means connected to said second pair of switching transistors for rendering said second pair of switching transistors conductive in response to said second output, said first transistor means comprising a first transistor having its emitter connected to the base of a switching transistor of said first pair and having its collector connected to the base of the other switching transistor of said first pair, and said second transistor means comprising a second transistor having its emitter connected to the base of a switching transistor of said second pair and having its collector connected to the base of the other switching transistor of said second pair.
Claim 3
Dependent Claim
81 words
A device in accordance with claim 1, wherein the switching transistors of the first pair are complementary types and the switching transistors of the second pair are complementary types, one of said motor terminals being connected to said terminals of said source through the emitter-collector paths of one switching transistor of each pair, respectively, and another of said motor terminals being connected to saiD terminals of said source through the emitter-collector paths of the other switching transistor of each pair, respectively.
Claim 4
Dependent Claim
46 words
A device in accordance with claim 2, wherein said first transistor is of the same type as the switching transistor to which its emitter is connected and wherein said second transistor is of the same type as the switching transistor to which its emitter is connected.
Claim 5
Dependent Claim
29 words
A device in accordance with claim 3, wherein the connections of the collectors of the first and second transistors to the bases of the switching transistors include series resistors.
Claim 6
Dependent Claim
76 words
A device in accordance with claim 4, wherein said means for producing said outputs comprises a bridge circuit and a pair of detecting transistors connected to output terminals of the bridge circuit for detecting unbalance of the bridge circuit in one direction or the other, respectively, and for rendering said first transistor or said second transistor conductive, said bridge circuit including said photosensitive element and including means connected to said motor for balancing the bridge circuit.
Claim 7
Dependent Claim
47 words
A device in accordance with claim 5, wherein said detecting transistors are complementary types having their bases connected to one of said output terminals, their emitters connected to another of said output terminals, and their collectors connected to the bases of said first and second transistors, respectively.
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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) | 1976-12-03 | 1977-06-04 | 1977-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-03 | 1981-06-04 | 1981-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-03 | 1985-06-04 | 1985-12-04 | $7700.00 | Window Closed / Lapsed |