| 摘要 |
PROBLEM TO BE SOLVED: To provide a liquid concentration measuring device capable of removing an influence of a leak resistance generated between detection electrodes, when measuring a liquid concentration. SOLUTION: This device has a constitution including a first oscillation part 20 and a second oscillation part 25, and switches sw1, sw2 are switched by pulsing waves having two different frequencies f1, f2. When one switch sw1 is switched on and the other switch sw2 is switched off, the detection electrode 41 is charged. Conversely, when one switch sw1 is switched off and the other switch sw2 is switched on, the charged detection electrode 41 is discharged. The difference between each output voltage V(f1), V(f2) of an operation amplifier 43 acquired by such charge/discharge is taken. Besides, each switch sw1, sw2 is controlled exclusively by using the same logic circuit. COPYRIGHT: (C)2010,JPO&INPIT
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