| 摘要 |
PROBLEM TO BE SOLVED: To improve noise resistances and reduce an apparatus cost and man- hour for the assembly. SOLUTION: A first piezoelectric element detects a pressure change resulting from a vortex generated in a measurement object fluid, and outputs a first detection signal SA1 to a differential amplifying part 17 via a first electrode 23. A second piezoelectric element detects a pressure change resulting from a vortex generated in the measurement object fluid and outputs a second detection signal SA2 to the differential amplifying part 17 via a second electrode 24. Since the differential amplifying part 17 differentially amplifies the first detection signal SA1 and second detection signal SA2 by first charge voltage- converting circuits 31, 32 and outputs a flow rate detection signal SD, in-phase noises included in the first detection signal SA1 and second detection signal SA2 can be reduced easily. Accordingly, a stable measurement for a low flow rate is enabled. Moreover, since a conductor 25 for taking out a detection voltage from the first electrode 23 and second electrode 24 is not required to be a shield conductor, an apparatus cost and man-hour for assembly can be reduced.
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