| 摘要 |
PROBLEM TO BE SOLVED: To measure a mass flow rate in high accuracy and in high sensitivity by offsetting time errors generated by drift and the like in circuit constituting elements. SOLUTION: The approximate since-wave signal having the phase difference in proportion to Coriolis force is converted into the sine-wave signal cleared of the drift component with analog-signal processing circuits 2 and 2' having the drift-component filtering function. From a pair of the sine-waves signals, N (N>1) pieces of (T+ΔT) pules and (T-ΔT) pulses are charged and discharged in one measuring time by a comparator/gate circuit 4 and a charging/ discharging circuit 5, and the difference is obtained. The time difference of 2NΔT is computed. In this time difference, the drift components generated on the circuits are included. Therefore, a switching circuit 3 is provided between the analog-signal processing circuits 2 and 2' and the compactor/gate circuit 4. The circuits are switched at every one measuring time, and the time errors caused by the drift and the like are perfectly offset.
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