| 摘要 |
PROBLEM TO BE SOLVED: To exactly set a reference voltage in the process producing flow rate pulses. SOLUTION: A flow rate measuring device 10 comprises sensors 50A, 50B for detecting the passage of a magnet 22 provided on a rotor 20 in response to the flow rate of a fluid to be measured; amplification circuits 60A, 60B for amplifying sensor signals outputted from the sensors 50A, 50B; waveform shaping circuits 70A, 70B for producing flow rate pulses from signals amplified in the amplification circuits 60A, 60B; and a control circuit 80 for calculating the flow rate by counting the flow rate pulses. The control circuit 80 outputs, when the potentials of the amplification circuits 60A, 60B are not at an L-level, an H-signal to an electronic volume 90; and adjusts when the amplification circuits 60A, 60B are not at an H-level, the electronic volume 90 by outputting an L-signal to the volume 90 so that the reference potentials of the amplification circuits 60A, 60B are changed and then the median value between the maximum value and the minimum value of the sensor signal becomes the reference potential of the amplification circuits 60A, 60B. COPYRIGHT: (C)2008,JPO&INPIT
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