Control system for a capacitive level sensor
US4347741A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 17, 1980 |
| Grant date | Sep 7, 1982 |
| Priority date | — |
| Expiry date | Jul 17, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/263
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitive system for sensing the level of material includes a conductive member electrically connected to ground potential, a probe including a sensing element arranged to establish a capacitance between the sensing element and conductive member which is determined by the level of the material and a shielding element interposed between the conductive member and the sensing element to form an electrically neutral zone therebetween to thereby reduce the effect of a conductive buildup of the material on the probe on the capacitance between the conductive member and the sensing element, and a first circuit electrically connected to the sensing and shielding elements for applying generally the same electrical potential to both the sensing and shielding elements, the first circuit having an output which varies in response to a change in the capacitance between the conductive member and the sensing element. A device for measuring an electrical characteristic of the shielding element which is related to the conductivity of the buildup of material on the probe is electrically connected to a second circuit which, through a feedback loop connected to the first circuit, automatically adjust…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.