| 摘要 |
A resistivity value measuring circuit comprises: a capacitor to accumulate charges; a switch to electrically connect a device to be measured such as a thermistor with the capacitor; a transistor to discharge the charges accumulated in the capacitor; and a measuring circuit to repetitively measuring the first time and the second time by performing the connecting operation by the switch. The first time corresponds to the period of time until the voltage of the capacitor which is accumulated by only a reference device as a constant resistivity becomes a predetermined value. The second time corresponds to the period of time until the voltage of the capacitor which is accumulated by the parallel connection of the reference device and the thermistor becomes the predetermined value. A measurement value of the thermistor and the ratio of the first and second times are made correspond on the basis of the result of the measurement of the measuring circuit. With this circuit, a resistivity value of the thermistor can be cheaply and accurately detected.
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