US3723014A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photoelectric light measuring device
Assignee: Minolta Co Ltd
•
Filing: 1971-04-13
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Granted: 1973-03-27
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Expires: 1991-04-13
Abstract
Abstract In a photoelectric light measuring device, a photoelectric transducer, such as photoconductive cell, is connected in series with a transistor, so that the logarithm of incident light on the cell can be graduated uniformly on an ordinary ammeter having a linear current-deflection characteristic, thereby enabling easy reading and affording a simple mechanism in a photometer or an automatic shutter speed control system, without adverse temperature dependency of the indication.
Inventors
- 👤 Y Nanba
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 09:14
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4209; G01J1/4214; G01J1/44
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
85 words
A photoelectric light measuring device comprising: a photoelectric transducer, a transistor for logarithmic conversion having its collector connected to said photoelectric transducer, and an amplifier for feeding output current to a load, said load providing an output representative of the amount of Light received by said photoelectric transducer, said amplifier having an input terminal to receive a control signal connected to the connection point between said photoelectric transducer and said transistor and an output terminal connected to the base of said transistor through an impedance.
Claim 2
Dependent Claim
85 words
A photoelectric light measuring device comprising: a photoelectric transducer, a transistor for logarithmic conversion having its collector connected to said photoelectric transducer, and an amplifier for feeding output current to a load, said load providing an output representative of the amount of Light received by said photoelectric transducer, said amplifier having an input terminal to receive a control signal connected to the connection point between said photoelectric transducer and said transistor and an output terminal connected to the base of said transistor through an impedance.
Claim 3
Dependent Claim
61 words
A photoelectric light measuring device as defined in claim 1, which further comprises a second transistor for compensation of the temperature dependency of said first transistor connected to the first transistor so that the collector-emitter voltage of the second transistor becomes substantially equal to the base-emitter voltage of the first transistor, said first and second transistors having substantially the same characteristics.
Claim 4
Dependent Claim
25 words
A photoelectric light measuring device as defined in claim 1, which further comprises, as said load for said amplifier, an ammeter for indicating exposure quantity.
Claim 5
Dependent Claim
25 words
A photoelectric light measuring device as defined in claim 4, which further comprises, as said load for said amplifier, an ammeter for indicating exposure quantity.
Claim 6
Dependent Claim
61 words
A photoelectric light measuring device as defined in claim 3, wherein said ammeter has a primary coil and a secondary coil on a moving coil frame, the secondary coil being electromagnetically coupled to the primary coil connected in the output circuit of said amplifier and being connected between the collector of the second transistor and the base of the first transistor.
Claim 7
Dependent Claim
95 words
A photoelectric measuring device as defined in claim 5, wherein said ammeter contains an over-range limit switch consisting of fixed upper and lower limit contacts and a moving contact mechanically linked to said coil frame, and upper and lower over-range indication lamps, one end of each of said lamps being respectively connected to the upper limit contact and the lower limit contact and the other end of each of said lamps being connected in common to one end of an electric source, said moving contact being connected to the other end of the electric source.
Claim 8
Dependent Claim
61 words
A photoelectric light measuring device as defined in claim 4, wherein said ammeter has a primary coil and a secondary coil on a moving coil frame, the secondary coil being electromagnetically coupled to the primary coil connected in the output circuit of said amplifier, and being connected between the collector of said second transistor and the base of said first transistor.
Claim 9
Dependent Claim
61 words
A photoelectric light measuring device as defined in claim 4, wherein said ammeter has a primary coil and a secondary coil on a moving coil frame, the secondary coil being electromagnetically coupled to the primary coil connected in the output circuit of said amplifier and being connected between the collector of the second transistor and the base of the first transistor.
Claim 10
Dependent Claim
95 words
A photoelectric measuring device as defined in claim 8, wherein said ammeter contains an over-range limit switch consisting of fixed upper and lower limit contacts and a moving contact mechanically linked to said coil frame, and upper and lower over-range indication lamps, one end of each of said lamps being respectively connected to the upper limit contact and the lower limit contact and the other end of each of said lamps being connected in common to one end of an electric source, said moving contact being connected to the other end of the electric source.
References Cited (Backward Citations)
US2406716A
Cited
US3518438A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |