US3843880A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Illumination-to-voltage conversion apparatus
Assignee: Minolta Co Ltd
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Filing: 1973-10-31
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Granted: 1974-10-22
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Expires: 1993-10-31
Abstract
Abstract A high signal-to-noise ratio (S/N) is obtainable in an apparatus for transforming luminous intensity into a voltage which is in exact inverse proportion to the luminous intensity. The apparatus is constituted by connecting a first controlling means t1 for current controlling in series to a photoconductive element Rp having non-linear characteristic of Rp K.E , where Rp is resistance, E is luminous intensity and K and gamma are constants, and by connecting a second controlling means t2 so as to receive a voltage Vp across both ends of the photoconductive element Rp and to give a signal, which is approximately proportional to Vp 1 , of said first controlling means t1, which controls the current Ip of the photoconductive element Rp to be approximately proportional to the value E 1, and as a result causes the voltage Vp to be approximately in inverse proportion to the luminous intensity E.
Inventors
- 👤 K Tsuchiyasu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:51
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
127 words
Illumination-to-voltage conversion apparatus comprising: a direct current source, a photoconductive element having a resistance proportional to the - Alpha th power of the received luminous intensity, first controlling means connected in series with said photoconductive element across said direct current source for controlling the current flowing through said photoconductive element, second controlling means connected to receive as an input signal the voltage appearing across both ends of said photoconductive element and producing an output signal for controlling said first controlling means to regulate the current through said photoconductive element to be approximately proportional to the 1 - gamma th power of said voltage appearing across said photoconductive element, and a means for taking out as an output signal the voltage across both ends of the photoconductive element.
Claim 2
Dependent Claim
127 words
Illumination-to-voltage conversion apparatus comprising: a direct current source, a photoconductive element having a resistance proportional to the - Alpha th power of the received luminous intensity, first controlling means connected in series with said photoconductive element across said direct current source for controlling the current flowing through said photoconductive element, second controlling means connected to receive as an input signal the voltage appearing across both ends of said photoconductive element and producing an output signal for controlling said first controlling means to regulate the current through said photoconductive element to be approximately proportional to the 1 - gamma th power of said voltage appearing across said photoconductive element, and a means for taking out as an output signal the voltage across both ends of the photoconductive element.
Claim 3
Dependent Claim
40 words
The apparatus of claim 1 wherein said second controlling means has a characteristic to produce an output signal represented by b + d . log (X + r) for an input signal X, wherein b, d and r are constants.
Claim 4
Dependent Claim
94 words
The apparatus of claim 1 wherein said first controlling means comprises a first transistor having a collector electrode which is connected to said photoconductive element, said second controlling means comprising at least one second transistor having a collector electrode which is connected in series to at least one diode for logarithmic transformation and a variable resistor, the base and emitter electrodes of said first transistor being connected across the series combination of said diode and said variable resistor, and the base and emitter electrodes of said second transistor being connected across said photoconductive element.
Claim 5
Dependent Claim
55 words
The apparatus of claim 3, further including a third transistor connected in series with said photoconductive element, the base and emitter electrodes of said second transistor being connected across the series combination of said photoconductive element and said third transistor, the base electrode of said third transistor being connected to a source of reference voltage.
Claim 6
Dependent Claim
30 words
The apparatus of claim 4 wherein said second controlling means comprises two second transistors connected in series in a Darlington configuration and connected in series with at least two diodes.
Claim 7
Dependent Claim
20 words
The apparatus of claim 5 wherein said source of reference voltage comprises a potentiometer connected across said direct current source.
References Cited (Backward Citations)
US3194968A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |