Patent ID: 8499647

Claim:
An electromagnetic flow meter comprising: a magnetic excitation coil arranged so that the direction in which the magnetic field thereof is produced is perpendicular to the direction of flow of a fluid flowing within a measuring tube; a magnetic excitation device providing an AC magnetic excitation current to the magnetic excitation coil; a pair of electrodes disposed within the measuring tube perpendicular to the direction of flow of the fluid flowing within the measuring tube and to the direction of the magnetic field produced by the magnetic excitation coil; a detector detecting an AC flow rate signal that includes a signal EMF produced between the electrodes; an amplifier amplifying the AC flow rate signal detected by the detector; a sampler sampling the AC flow rate signal that has been amplified by the amplifier, to produce a DC flow rate signal; an A/D converter converting into a digital signal the DC flow rate signal from the sampler; and a noise eliminator eliminating a noise component included in the DC flow rate signal to the A/D converter is provided between the sampler and the A/D converter, and comprising: a noise component extractor extracting only a noise component included in the DC flow rate signal from the sampler; and an output device outputting, as a DC flow rate signal to the A/D converter, the difference between a first input signal and a second input signal, where the DC flow rate signal from the sampler is defined as the first input signal and the noise component extracted by the noise component extractor is defined as the second input signal.