| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a liquid concentration measurement apparatus for eliminating an effect due to a leakage resistance generated between a detection electrode when a liquid concentration is measured. Ž<P>SOLUTION: A constitution is provided with first and second oscillation sections 20, 25. Switches sw1, sw2 are switched by pulses at two different frequency f1, f2. If one switch sw1 is turned on and the other switch sw2 is turned off, an operational amplifier 43 is operated so as to cause potentials at an non-inverting input terminal and an inverting input terminal to be the same, and the detection electrode 41 is charged. Conversely, If one switch sw1 is turned off and the other switch sw2 is turned on, the detection electrode 41 is discharged since a positive side of the detection electrode 41 is grounded. A difference between output voltages V(f1), V(f2) of the operational amplifier 43 obtained by charging and discharging the detection electrode 41 is found. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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