Method and apparatus for making compensation for DC offset voltage generated in aplifying circuit in electromagnetic flowmeter
US4856345A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 12, 1988 |
| Grant date | Aug 15, 1989 |
| Priority date | — |
| Expiry date | Apr 12, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01F1/60
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In magnetic induction flow measurement in which a flow rate of a fluid is measured by a DC magnetic field having a periodically reversed polarity, an apparatus is used to compensate a DC offset voltage generated in an amplifying circuit in an electromagnetic flowmeter in which a signal voltage produced across electrodes is sampled and stored in each of a pair of sampling periods where the magnetic field takes a positive polarity and a negative polarity, respectively. A difference between the sampling values is formed as an output signal voltage. The signal voltage is sampled and stored in a compensation period following the pair of sampling periods to produce a compensation voltage to be superimposed onto the signal voltage, and compensation is made on the signal voltage by using the compensation voltage which is held until a succeeding compensation period. The apparatus includes: a pair of the electrodes provided on a tube through which an electrically conductive fluid flows; a differential amplifier to which the pair of electrodes are respectively connected through capacitors; an adder having two inputs one of which is connected to an output of the differential amplifier; an ampi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.