Capacitive pressure transducer system
US4987782A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Oct 3, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01L9/125
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A capacitive ratioing oscillator circuit utilizing a prior art pressure capsule, but through modification of the state variable oscillator circuit achieves a digital output which varies with the square root of the capacitance ratio C35 C.sub.p /C.sub.r. In this sensor the dielectric constant of the pressure media is measured in time with the pressure difference measurement. The oscillator includes a differentiator-inventor step herein each of capacitors C.sub.r and C.sub.p are connected to a common point and resistors are connected in parallel with each of said capacitors and with the common point connected to the inverting terminal of a first operational amplifier, a feedback line is connected from the output of the operational amplifier to the second resistor opposite the common point, first and second integrator circuits are connected to the output of said operational amplifier, a limit circuit is connected across the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit to the input of the inverter stage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.