Method and apparatus for detecting a dry/wet state of a dual exposed thermistor bead liquid level sensor
US6662650B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 9, 2002 |
| Grant date | Dec 16, 2003 |
| Priority date | — |
| Expiry date | Dec 14, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/247
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of detecting a dry/wet state of a dual thermistor bead sensor over a wide operating temperature range comprises the steps of: conducting first and second predetermined currents through one and another of the thermistor beads of the sensor, respectively, the second predetermined current being substantially less than the first predetermined current; measuring a first voltage across the one thermistor bead in response to the first predetermined current and generating a first signal representative thereof; measuring a second voltage across the other thermistor bead in response to the second predetermined current and generating a second signal representative thereof; modifying the second signal by an offset and gain to generate a third signal; and detecting the dry/wet state of the sensor over the wide operating temperature range based on the first and third signals. The first predetermined current is conducted through the one thermistor bead at an average current which renders the one thermistor bead a sense thermistor bead, and the second predetermined current is conducted through the other thermistor bead at an average current which renders the other thermistor bead a refere…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.