US5502299A
Expired / Lapsed
US
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Current ratio circuit for multi-color imaging
Assignee: Re Secured Networks LLC
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Filing: 1994-12-12
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Granted: 1996-03-26
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Expires: 2014-12-12
Abstract
Abstract An electronic circuit extracts a ratio of currents from two sources and provides an output that is a function of the current ratio. An embodiment of the circuit includes a source current that may be provided by a blue-green photodetector and a sinking current that may be provided by a red photodetector. The source current feeds the input of a current splitter formed by a pair of PFETs. A portion of the source current is fed from the current splitter to a current ratio extractor implemented in CMOS. The remaining portion of the current from the current splitter is fed to a node shared with the sinking current and a second input to the current ratio extractor. The current ratio extractor produces an output voltage that is a function of the ratio of the photodiode currents and is substantially independent of the total current. The output voltage provides color information that may be used in low-cost machine vision systems for tasks such as sorting objects based on color or detecting object boundaries while rejecting shadows and reflective glints.
Inventors
- 👤 David L. Standley
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:42
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/46; G01J3/50; G01J1/00; G01J1/42; G01J1/44; G01R; G01R19/00; G01R19/10
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
58 words
An electronic circuit, comprising: a first current source providing a source current; a second current source providing a sinking current; a current splitter connected to said first and second current sources; and means connected to said current splitter and said second current source for providing an output comprising a function of said source current and said sinking current.
Claim 2
Dependent Claim
58 words
An electronic circuit, comprising: a first current source providing a source current; a second current source providing a sinking current; a current splitter connected to said first and second current sources; and means connected to said current splitter and said second current source for providing an output comprising a function of said source current and said sinking current.
Claim 3
Dependent Claim
36 words
The electronic circuit of claim 1, wherein said first current source comprises a first photodetector sensitive to a first spectral region and said second current source comprises a second photodetector sensitive to a second spectral region.
Claim 4
Dependent Claim
36 words
The electronic circuit of claim 1, wherein said current splitter comprises a first FET connected between said first and second current sources and a second FET connected between said first current source and said output means.
Claim 5
Dependent Claim
59 words
The electronic circuit of claim 3, wherein said output means comprises a third FET connected between said second Flit and said second current source, a fourth FET connected to said second current source, a resistance means connected between the gates of said third and fourth FETs, and a voltage-controlled current source connected to the gate of said fourth FET.
Claim 6
Dependent Claim
51 words
The electronic circuit of claim 1, wherein said current splitter splits said first current into a first split current and a second split current, and said output means provides an output comprising a ratio of said first split current and a function of said sinking current and said second split current.
Claim 7
Dependent Claim
57 words
The electronic circuit of claim 1, wherein said source current comprises I 1 , said sinking current comprises I 2 , said first split current comprises k I 1 , said second split current comprises (1-k)I 1 , and said output means provides an output related to the ratio I 2 -(1-k)I 1 !/k I 1 .
Claim 8
Dependent Claim
89 words
An electronic circuit, comprising: a first current source providing a source current; a second current source providing a sinking current; a current splitter connected between said first and second current sources, said current splitter splitting said source current into a first split current and a second split current; a current ratio extractor connected to said current splitter and said second current source; and said current ratio extractor providing an output related to a ratio of said first split current and a function of said sinking and second split currents.
Claim 9
Dependent Claim
89 words
An electronic circuit, comprising: a first current source providing a source current; a second current source providing a sinking current; a current splitter connected between said first and second current sources, said current splitter splitting said source current into a first split current and a second split current; a current ratio extractor connected to said current splitter and said second current source; and said current ratio extractor providing an output related to a ratio of said first split current and a function of said sinking and second split currents.
Claim 10
Dependent Claim
36 words
The electronic circuit of claim 7, wherein said first current source comprises a first photodetector sensitive to a first spectral region and said second current source comprises a second photodetector sensitive to a second spectral region.
Claim 11
Dependent Claim
37 words
The electronic circuit of claim 7, wherein said current splitter comprises a first PFET connected between said first and second current sources and a second PFET connected between said first current source and said current ratio extractor.
Claim 12
Dependent Claim
60 words
The electronic circuit of claim 9, wherein said current ratio extractor comprises a first NFET connected between said second PFET and said second current source, a second NFET connected to said second current source, a resistance means connected between the gates of said first and second NFETs, and a voltage-controlled current source connected to the gate of said second NFET.
Claim 13
Dependent Claim
58 words
The electronic circuit of claim 7, wherein said source current comprises I 1 , said sinking current comprises I 2 , said first split current comprises k I 1 , said second split current comprises (1-k)I 1 , and said current ratio extractor provides an output related to the ratio I 2 -(1-k)I 1 !/k I 1 .
Claim 14
Dependent Claim
103 words
An electronic circuit for a machine vision system, comprising: a first photodetector sensitive to a first spectral region providing a source current; a second photodetector sensitive to a second spectral region providing a sinking current; a current splitter connected between said first and second photodetectors, said current splitter splitting said source current into a first split current and a second split current; a current ratio extractor connected to said current splitter and said second photodetector; and said current ratio extractor providing an output comprising a ratio of said first split current and a function of said sinking current and said second split current.
Claim 15
Dependent Claim
103 words
An electronic circuit for a machine vision system, comprising: a first photodetector sensitive to a first spectral region providing a source current; a second photodetector sensitive to a second spectral region providing a sinking current; a current splitter connected between said first and second photodetectors, said current splitter splitting said source current into a first split current and a second split current; a current ratio extractor connected to said current splitter and said second photodetector; and said current ratio extractor providing an output comprising a ratio of said first split current and a function of said sinking current and said second split current.
Claim 16
Dependent Claim
58 words
The electronic circuit of claim 12, wherein said source current comprises I 1 , said sinking current comprises I 2 , said first split current comprises k I 1 , said second split current comprises (1-k)I 1 , and said current ratio extractor provides an output related to the ratio I 2 -(1-k)I 1 !/k I 1 .
Claim 17
Dependent Claim
28 words
The electronic circuit of claim 13, wherein said first photodetector is sensitive to a blue-green spectral region and said second photodetector is sensitive to a red spectral region.
Claim 18
Dependent Claim
35 words
The electronic circuit of claim 13, wherein said current splitter comprises a first PFET connected between said first and second photodetectors and a second PFET connected between said first photodetector and said current ratio extractor.
Claim 19
Dependent Claim
58 words
The electronic circuit of claim 15, wherein said current ratio extractor comprises a first NFET connected between said second PFET and said second photodetector, a second NFET connected to said second photodetector, a resistance means connected between the gates of said first and second NFETs, and a voltage-controlled current source connected to the gate of said second NFET.
Claim 20
Dependent Claim
43 words
The electronic circuit of claim 16, wherein said voltage-controlled current source comprises a third PFET having a gate connected to said output and a fourth PFET connected to said third PFET and having a gate connected to the gate of said second PFET.
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) | 1999-03-26 | 1999-09-25 | 2000-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-03-26 | 2003-09-25 | 2004-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-03-26 | 2007-09-25 | 2008-03-26 | $7700.00 | Window Closed / Lapsed |