US4141633A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure control device
Assignee: Pentax Corp
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Filing: 1977-10-26
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Granted: 1979-02-27
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Expires: 1997-10-26
Abstract
Abstract An automatic exposure control circuit for a camera is disclosed. The circuit is capable of automatically controlling the shutter speed when the diaphragm is manually set, and is capable of automatically controlling the diaphragm opening when the shutter speed is manually set. In both cases the same transducer is used for the manual diaphragm or shutter speed selection.
Inventors
- 👤 Naoyuki Uno
- 👤 Tetsuji Shono
- 👤 Fumio Urano
- 👤 Masahiro Kawasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:19
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/087
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
160 words
An exposure control device comprising: (a) an electromagnetic shutter speed control means, (b) an automatic diaphragm opening control means, (c) transducer means exclusively comprising: (1) a first transducer for developing a first voltage dependent upon scene brightness, (2) a second transducer for developing a second voltage dependent upon film speed, and (3) a third, dual purpose transducer for developing a third voltage and adapted to be controlled according to a manual setting of either shutter speed or diaphragm opening to provide said third voltage dependent thereon, and (d) circuit means selectably switchable between an automatic diaphragm opening control (EE) mode and an automatic shutter speed control (ES) mode and responsive to said first, second, and third voltages for developing a diaphragm opening control output when switched to said EE mode or a shutter speed control output when switched to said ES mode and for applying said output to said diaphragm opening control means or said shutter speed control means, respectively.
Claim 2
Dependent Claim
160 words
An exposure control device comprising: (a) an electromagnetic shutter speed control means, (b) an automatic diaphragm opening control means, (c) transducer means exclusively comprising: (1) a first transducer for developing a first voltage dependent upon scene brightness, (2) a second transducer for developing a second voltage dependent upon film speed, and (3) a third, dual purpose transducer for developing a third voltage and adapted to be controlled according to a manual setting of either shutter speed or diaphragm opening to provide said third voltage dependent thereon, and (d) circuit means selectably switchable between an automatic diaphragm opening control (EE) mode and an automatic shutter speed control (ES) mode and responsive to said first, second, and third voltages for developing a diaphragm opening control output when switched to said EE mode or a shutter speed control output when switched to said ES mode and for applying said output to said diaphragm opening control means or said shutter speed control means, respectively.
Claim 3
Dependent Claim
73 words
An automatic exposure control device as claimed in claim 1 wherein said circuit means comprises switch means for selectively selecting the EE and ES modes of operation, said switch means connecting said third voltage substantially directly to said electromagnetic shutter control means when positioned to select said EE mode, and connecting circuitry for combining said first, second and third voltages to said electromagnetic shutter control means when positioned to select said ES mode.
Claim 4
Dependent Claim
41 words
An automatic exposure control device as claimed in claim 1 further comprising an indicator means connected to said circuit, said indicator providing indications of diaphragm and shutter speed values when said circuit is switched into said EE and ES modes respectively.
Claim 5
Dependent Claim
44 words
An automatic exposure control device as claimed in claim 3 wherein said indicator is an ammeter and wherein said automatic diaphragm control means is connected to operate under control of the pointer of said ammeter when said circuit is switched into said EE mode.
Claim 6
Dependent Claim
80 words
An exposure control device as claimed in claim 1 wherein said first transducer means comprises a photodiode and a log compression transistor having its collector connected to said photodiode, whereby said first voltage is developed across the base-emitter circuit of said log compression transistor, and wherein said second transducer means comprises a variable resistor and a pair of series connected log compression diodes, all connected in series, whereby said second voltage is developed across said pair of log compression diodes.
Claim 7
Dependent Claim
43 words
An exposure control device as claimed in claim 1 wherein said third transducer means comprises a variable resistor connected in series with a pair of series connected log compression diodes, whereby said third voltage is developed across said pair of log compression diodes.
Claim 8
Dependent Claim
80 words
An exposure control device as claimed in claim 6 wherein said first transducer means comprises a photodiode and a log compression transistor having its collector connected to said photodiode, whereby said first voltage is developed across the base-emitter circuit of said log compression transistor, and wherein said second transducer means comprises a variable resistor and a pair of series connected log compression diodes, all connected in series, whereby said second voltage is developed across said pair of log compression diodes.
Claim 9
Dependent Claim
94 words
An exposure control device as claimed in claim 1 wherein said circuit comprises first and second mode selection switches, said first and second switches being connected in said circuit to connect to said electromagnetic shutter control means the sum of said first and second voltages minus said third voltage, when said switches are switched to their respective first positions, corresponding to the ES mode, and to connect to said electromagnetic shutter said third voltage minus a locally generated correction voltage when said switches are in their respective second positions corresponding to the EE mode.
Claim 10
Dependent Claim
81 words
An automatic exposure control device as claimed in claim 8 wherein said automatic shutter control means comprises, an electromagnet for holding a shutter in a fixed position, a time constant charge accumulation circuit for altering the energization of said electromagnet depending upon the charge stored therein, and an input circuit comprising a log expansion transistor having its collector connected to said time constant circuit, the case-emitter circuit of said transistor serving as the input terminals of said automatic shutter control means.
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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) | 1982-02-26 | 1982-08-28 | 1983-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-26 | 1986-08-28 | 1987-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-26 | 1990-08-28 | 1991-02-27 | $7700.00 | Window Closed / Lapsed |