The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 15, 1989
Filed:
Apr. 12, 1988
Tutomu Mochizuki, Okazaki, JP;
Aichi Tokei Denki Co., Ltd, Nagoya, JP;
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 ampifier having an input connected to an output of the adder; an integration circuit having a resistor, a resistor and a capacitor and an operational amplifier; and a switch inserted between the amplifier and the integration circuit for sampling the signal voltage in the sampling period.