Patent US3879138A successfully refreshed from Google Patents.
US3879138A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical light-measuring systems
Assignee: Yashica Co Ltd
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Filing: 1973-05-29
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Granted: 1975-04-22
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Expires: 1993-05-29
Abstract
Abstract An electrical light-measuring system capable of effectively measuring even relatively small amounts of light. A meter circuit is provided with an indicating meter which indicates the light intensity. This meter circuit is electrically connected with a current-amplifier circuit which controls the current of the meter circuit. This current-amplifier circuit has an input, and a constant-voltage circuit has an output, a photosensitive element being connected between the latter output and input for receiving the light which is to be measured. The meter circuit is capable of being adjusted for adjusting the relationship between the current which flows through the meter and the resistance of the photosensitive element.
Inventors
- 👤 Katsumi Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 12:31
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
161 words
In an electrical light-measuring system, meter circuit means including an indicating meter for indicating light intensity, current-amplifier circuit means electrically connected with said meter circuit means for controlling the current thereof, said current-amplifier circuit means having an input, constant voltage circuit means having an output, and photosensitive means for receiving the light which is to be measured, said photosensitive means being electrically connected between said output and input, said meter circuit including a series variable resistor connected in series with said indicating meter for varying the slope of the relationship between the resistance of said photosensitive means and the current which flows through said indicating meter, and a parallel variable resistor connected across the series connected series variable resistor and indicating meter in parallel therewith for changing the range of said relationship, said current-amplifier circuit means including a transistor having a base connected to said photosensitive means and an emitter connected in series with said series variable resistor and indicating meter.
Claim 2
Dependent Claim
161 words
In an electrical light-measuring system, meter circuit means including an indicating meter for indicating light intensity, current-amplifier circuit means electrically connected with said meter circuit means for controlling the current thereof, said current-amplifier circuit means having an input, constant voltage circuit means having an output, and photosensitive means for receiving the light which is to be measured, said photosensitive means being electrically connected between said output and input, said meter circuit including a series variable resistor connected in series with said indicating meter for varying the slope of the relationship between the resistance of said photosensitive means and the current which flows through said indicating meter, and a parallel variable resistor connected across the series connected series variable resistor and indicating meter in parallel therewith for changing the range of said relationship, said current-amplifier circuit means including a transistor having a base connected to said photosensitive means and an emitter connected in series with said series variable resistor and indicating meter.
Claim 3
Dependent Claim
161 words
In an electrical light-measuring system, meter circuit means including an indicating meter for indicating light intensity, current-amplifier circuit means electrically connected with said meter circuit means for controlling the current thereof, said current-amplifier circuit means having an input, constant voltage circuit means having an output, and photosensitive means for receiving the light which is to be measured, said photosensitive means being electrically connected between said output and input, said meter circuit including a series variable resistor connected in series with said indicating meter for varying the slope of the relationship between the resistance of said photosensitive means and the current which flows through said indicating meter, and a parallel variable resistor connected across the series connected series variable resistor and indicating meter in parallel therewith for changing the range of said relationship, said current-amplifier circuit means including a transistor having a base connected to said photosensitive means and an emitter connected in series with said series variable resistor and indicating meter.
Claim 4
Dependent Claim
161 words
In an electrical light-measuring system, meter circuit means including an indicating meter for indicating light intensity, current-amplifier circuit means electrically connected with said meter circuit means for controlling the current thereof, said current-amplifier circuit means having an input, constant voltage circuit means having an output, and photosensitive means for receiving the light which is to be measured, said photosensitive means being electrically connected between said output and input, said meter circuit including a series variable resistor connected in series with said indicating meter for varying the slope of the relationship between the resistance of said photosensitive means and the current which flows through said indicating meter, and a parallel variable resistor connected across the series connected series variable resistor and indicating meter in parallel therewith for changing the range of said relationship, said current-amplifier circuit means including a transistor having a base connected to said photosensitive means and an emitter connected in series with said series variable resistor and indicating meter.
Claim 5
Dependent Claim
39 words
The combination of claim 1 and wherein said constant voltage circuit means includes a constant voltage element and a voltage divider resistance connected in series and having therebetween a junction which forms said output connected to said photosensitive means.
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) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |