| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance type moisture sensor capable of detecting an abnormality of a pair of electrodes, capable of distinguishing whether the abnormality is caused by disconnection of the electrode or by short-circuit between the electrodes, and capable of distinguishing between each abnormality and a power source non-supply state. SOLUTION: By installing a capacitance variable means in which a detection part 1 shows different values of the capacitance respectively among the normal state, a short-circuit time between electrodes 1a, 1a and a disconnection time of the electrode 1a, voltage levels outputted from a frequency-voltage conversion part 3 are different respectively among each state and the power source non- supply state, to thereby enable to judge which state is going on, without installing an electrode abnormality detection circuit separately.
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