| 摘要 |
PROBLEM TO BE SOLVED: To absorb variations of a source voltage and a thermistor and improve measurement accuracy by connecting a tuning variable resistor which can select a resistance value approximate to a high-temperature resistance characteristic of the thermistor, and the thermistor in series. SOLUTION: A tuning variable resistor 6 is connected in series to a thermistor 2 in an RC oscillation circuit 1 using the thermistor 2 and a capacitor 3 as an element determining an oscillation frequency. The tuning variable resistor 6 can select a resistance value approximate to a high-temperature resistance characteristic of the thermistor 2, selecting and adjusting during a tuning process so that a temperature value of an object to be measure which is maintained at a constant high temperature agrees with an operated display value of a signal-processing circuit 5 when the temperature is measured. Accordingly, variations of a source voltage and the thermistor 2 in a high-temperature ambience are absorbed at the same time. An error in the display value in the high- temperature ambience, e.g. 200 deg.C or higher can be restricted to be considerably small. |
