System for indicating a condition of material
US5088325A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 11, 1991 |
| Grant date | Feb 18, 1992 |
| Priority date | — |
| Expiry date | Feb 11, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/266
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system for indicating level of material in a vessel as a function of material capacitance includes a capacitance probe adapted to be positioned so as to be responsive to variations in capacitance as a function of material level in the vessel. Detection circuitry is responsive to capacitance at the probe and to a reference signal for indicating material level, and includes facility for selectively adjusting sensitivity of the detection circuitry to material capacitance so as to adapt the system for materials of differing capacitance characteristics. Calibration circuitry for establishing the reference signal includes facility for varying operating characteristics of the detection circuitry during a calibration mode of operation independent of material level so as to calibrate the detection circuitry to capacitance at the probe. The detection circuitry is responsive to a comparison between the reference signal and capacitance at the probe for indicating when the circuitry is out of calibration, and is coupled to the sensitivity adjustment for varying such comparison as a function of the differing material capacitance characteristics.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.