| 摘要 |
PROBLEM TO BE SOLVED: To improve use convenience even when a resistance temperature coefficient of a thermistor is large, by setting a plurality of thermistors of different resistance values which can be switched and connected so that the resistance values are changed in accordance with a temperature change. SOLUTION: A temperature-detecting part includes a substrate 11, a first thermistor 12 and a second thermistor 13. The thermistors 12, 13 are formed in different shapes, and therefore show different resistance values. For instance, at a low temperature side from -20 deg.C to 28 deg.C, the thermistor 12 is selected by a switch means, while at a high temperature side from 28 deg.C to 100 deg.C, the thermistor 13 is selected. In this manner, even when the temperature changes from -20 deg.C to 100 deg.C, the resistance value is within a range of approximately 1-25kΩ. Even when a range of the temperature used is enlarged, the thermistors 12, 13 are properly switched and connected depending on the temperature used, so that the thermistor fit to the temperature used is selected. A constant of a signal-processing circuit is never changed, and an increase/a decrease of noises is eliminated.
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