| 摘要 |
<p>Disclosed is a signal processing device which is always capable of measurement with constant precision, even if the temperature of the fluid to be measured changes, if the fluid to be measured becomes contaminated with bubbles, or if the fluid to be measured has rapidly changed from a gas to a liquid, and which can carry out phase and density measurement with low computational complexity. In a coriolis flow meter at least one or a pair of flow tubes which constitute a flow tube for measurement are driven by a drive device to operate a vibrator, and the flow tubes are alternately driven, and vibrated, thus the phase difference and/or the vibration frequency proportional to the coriolis force acting on the flow tubes is detected by means of a speed sensor or an acceleration sensor which is a vibration detection sensor, and the mass flow rate and/or the density of the liquid to be measured can be obtained. The coriolis flow meter is formed from: a transmitter (90) which transmits and outputs a frequency signal which can be modulated; and a frequency conversion unit (85) which performs an addition (or a subtraction) on the input frequency as detected by the speed sensor or the acceleration sensor, and the output frequency (Fx) of the transmitter (90), and performs a frequency conversion, then performs frequency shift so that the post-frequency conversion frequency value is always constant.</p> |
