| 摘要 |
PROBLEM TO BE SOLVED: To provide a flowmeter which realizes high-precision flow measurement which is not practically influenced by slurry noises and fluctuations caused by the frequency of each commercial power source, is comparatively inexpensive, and can be used by commercial power sources of both 50 Hz and 60 Hz. SOLUTION: A band-attenuation filter 4 is arranged in a stage rearer than a sample and hold portion 3, and frequency components of fluctuations contained in a DC flow signal 13 whose DC potential changes according to the flow velocity of a fluid, i.e., frequency components (f) being components of frequencies|m<SB>1</SB>fex±n<SB>1</SB>fac<SB>1</SB>|which are the differences between a frequency of an integer m<SB>1</SB>times as high as an exciting frequency fex and a frequency of an integer n<SB>1</SB>times as high as the frequency fac<SB>1</SB>(50 Hz) of a commercial power source and components of frequencies|m<SB>2</SB>fex±n<SB>2</SB>fac<SB>2</SB>|, which are the differences between a frequency of an integer m<SB>2</SB>times as high as the exciting frequency fex, and a frequency of an integer n<SB>2</SB>time as high as the frequency fac<SB>2</SB>(60 Hz) of a commercial power source, are attenuated. COPYRIGHT: (C)2004,JPO
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