| 摘要 |
PROBLEM TO BE SOLVED: To realize a pH meter which does not require a maintenance operation and which can be miniaturized easily by a method wherein the pH meter is provided with a circuit which controls the potential of a liquid-potential detection electrode to a constant voltage and with a circuit which measures the pH concentration of a solution to be measured. SOLUTION: The output of a pH electrode 100a is connected to the input terminal, on one side, of a pH measuring circuit 10, and a liquid-potential detection electrode 102 is connected to the input terminal, on the other side, of the circuit 10 and to the terminal, on one side, of a potential stabilization circuit 11. In addition, the output of a potential stabilization electrode 103 is connected to the terminal, on the other side, of the circuit 11. The electrode 100a, the electrode 102 and the electrode 103 are installed inside a solution 9 to be measured. The circuit 11 supplies a current to the electrode 102 via the circuit 11. The circuit 11 is controlled, a constant potential is generated at the electrode 102, and the circuit 10 uses the constant potential as a reference. Thereby, a pH concentration can be measured on the basis of the output of the electrode 100a. In addition, the output current of the circuit 11 is suspended temporarily, and a resistance component can be corrected on the basis of a potential difference of whether the output current exists or not. |
