Corioliz type mass flowmeter having isolation form external vibration

Abstract

A first sample hold circuit or S/H, for holding an amplitude value at a predetermined phase of pipe vibration waveform, detected by both sensors and, a second S/H for re-holding the value at the predetermined phase, a comparator for comparing second S/H output with a set value, an differential amplifier for amplifying a difference value thus obtained, and an exciter circuit for increasing and decreasing the vibration amplitude of the pipe responsive to this amplified difference value are provided so as not to cause any change in exciting frequency characteristic, even when outside vibrations are added to the pipe. The present invention enables oscillation waveform to be less distorted and a more stable operation to be achieved even when responsibility, relative to outside vibrations, is increased.