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US4096382A
Expired / Lapsed
US
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Photo-current log-compression circuit
Assignee: Fujinon Corp
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Filing: 1977-02-09
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Granted: 1978-06-20
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Expires: 1997-02-09
Abstract
Abstract A photoelectric current log-compression circuit includes a log-conversion diode, a photodiode and an operational amplifier for log-compression. In the negative feedback circuit of the operational amplifier is inserted a thermistor to control the amplification degree of the operational amplifier according to the current flowing through the log-conversion diode. Further, a forward voltage of a temperature compensating diode biased with a constant current is applied to the reference voltage of the operational amplifier.
Inventors
- 👤 Saburo Numata
- 👤 Shinichiro Okazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:25
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3084; G; G06; G06G; G06G7/00; G06G7/12; G06G7/24; H01; H01J; H01J40/00; H01J40/02; H01J40/14; H03G7/00; H03G7/001
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
126 words
A photoelectric current log-compression circuit comprising: a reference voltage source and a constant current source, an operational amplifier, a log-conversion diode connected to a non-inversion input terminal of said operational amplifier, a photodetector connected between the non-inversion input terminal and an inversion input terminal of the operational amplifier, a temperature compensating element which changes the resistance thereof inserted in a negative feedback circuit of the operational amplifier to control the amplification degree, and a temperature compensating diode connected between said sources and biased with a predetermined current therefrom, said log-conversion diode being connected between the operational amplifier and a connecting point between said constant current source and said temperature compensating diode whereby a forward voltage of the temperature compensating diode is applied to the operational amplifier.
Claim 2
Dependent Claim
126 words
A photoelectric current log-compression circuit comprising: a reference voltage source and a constant current source, an operational amplifier, a log-conversion diode connected to a non-inversion input terminal of said operational amplifier, a photodetector connected between the non-inversion input terminal and an inversion input terminal of the operational amplifier, a temperature compensating element which changes the resistance thereof inserted in a negative feedback circuit of the operational amplifier to control the amplification degree, and a temperature compensating diode connected between said sources and biased with a predetermined current therefrom, said log-conversion diode being connected between the operational amplifier and a connecting point between said constant current source and said temperature compensating diode whereby a forward voltage of the temperature compensating diode is applied to the operational amplifier.
Claim 3
Dependent Claim
18 words
A photoelectric current log-compression circuit as defined in claim 1 wherein said temperature compensating element is a thermistor.
Claim 4
Dependent Claim
23 words
A photoelectric current log-compression circuit as defined in claim 1 wherein a buffer is connected between the log-conversion diode and said connecting point.
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) | 1981-06-19 | 1981-12-19 | 1982-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-19 | 1985-12-19 | 1986-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-19 | 1989-12-19 | 1990-06-20 | $7700.00 | Window Closed / Lapsed |