US4675596A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital fluid analyzer using capacitive sensing
Assignee: ZIDEX SYSTEMS A CORP OF
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Filing: 1984-09-10
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Granted: 1987-06-23
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Expires: 2004-09-10
Abstract
Abstract Apparatus for determining the dielectric constant of a fluid as a measure of possible contaminants therein. A reference fluid sample having a known dielectric constant is first placed in a capacitive dielectric sensor and then the fluid to be analyzed is placed in the sensor. By comparing the measured values, an indication is provided of the degree of contamination of the analyzed fluid.
Inventors
- 👤 Thomas Smith
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:45
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26; G01R27/2617; G01R27/2635; G01N; G01N27/00; G01N27/02; G01N27/22; G01N27/221
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
162 words
Apparatus for determining the amount of contamination in a fluid, comprising: a test cell sensor for receiving fluid samples, said test cell sensor including a capacitive element between whose plates a fluid sample is located when one of said samples is in said test cell; a voltage controlled RC oscillator circuit, said capacitive element in said sensor forming the capacitive portion of said RC oscillator circuit; a phase lock loop circuit producing an output signal which is a measure of the dielectric constant of the fluid sample in said test cell; and comparing means connected to said phase lock loop circuit for comparing said phase lock loop output signals to provide a measure of the difference in dielectric constants of the tested fluids, said difference being an indication of the degree of contamination of one of said fluids; said comparing means including sample and hold circuitry for storing a signal representing a measure of the dielectric constant of the first tested fluid.
Claim 2
Dependent Claim
162 words
Apparatus for determining the amount of contamination in a fluid, comprising: a test cell sensor for receiving fluid samples, said test cell sensor including a capacitive element between whose plates a fluid sample is located when one of said samples is in said test cell; a voltage controlled RC oscillator circuit, said capacitive element in said sensor forming the capacitive portion of said RC oscillator circuit; a phase lock loop circuit producing an output signal which is a measure of the dielectric constant of the fluid sample in said test cell; and comparing means connected to said phase lock loop circuit for comparing said phase lock loop output signals to provide a measure of the difference in dielectric constants of the tested fluids, said difference being an indication of the degree of contamination of one of said fluids; said comparing means including sample and hold circuitry for storing a signal representing a measure of the dielectric constant of the first tested fluid.
Claim 3
Dependent Claim
25 words
Apparatus in accordance with claim 1 in which said comparing means includes an analog-to-digital converter responsive to the output of said sample and hold circuitry.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-22 | 1990-12-22 | 1991-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-22 | 1994-12-22 | 1995-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-22 | 1998-12-22 | 1999-06-23 | $7700.00 | Window Closed / Lapsed |