Capacitive sensor for sensing the amount of material in a container
US6472887B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 2000 |
| Grant date | Oct 29, 2002 |
| Priority date | — |
| Expiry date | Nov 28, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F23/263
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
One embodiment of the invention is a capacitive sensor for sensing the amount of material in a container. This embodiment includes an oscillator that generates an oscillating signal. This oscillator includes an integrating amplifier that is formed by (1) an operational amplifier that has a low-impedance output and a virtually-grounded input, and (2) a capacitor that has a capacitance which depends on the amount of material in the container. The capacitor connects between the low impedance output and the virtually-grounded input of the operational amplifier In some embodiments, the operational amplifier includes a first amplifier and a second amplifier that are connected in series, with an output of the second amplifier fed back through the capacitor to the input of the first amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.