| 摘要 |
PROBLEM TO BE SOLVED: To easily confirm a detection condition of a flow rate in a detecting part. SOLUTION: A transmission element 111 transmits an ultrasonic wave, and a reception element 112 receives the ultrasonic wave from the transmission element 111. An output signal from the reception element 112 is amplified, and a phase comparator 140 outputs a voltage corresponding to a phase difference, based on a high-frequency signal generated by a high-frequency signal oscillator 120 and an output signal from a high-frequency signal amplifier 130. A low-frequency signal amplifier 150 amplifies the output voltage from the phase comparator 140, a comparator 160 compares an output signal from the low-frequency signal amplifier 150 with a reference voltage to output a pulse for indicating a comparison result. A frequency divider 170 divides the output pulse. A decoder 180 decodes an output signal from the frequency divider 170 to light luminescent parts 81-84 of a flow indicator LU in order, by a green color. COPYRIGHT: (C)2005,JPO&NCIPI
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