| 摘要 |
PURPOSE:To control the indoor humidity even at the time of an abnormal condition by changing over a humidity detecting element to a setting impedance element when the abnormal condition that the humidity detecting element does not execute a sensor function is obtained. CONSTITUTION:When a humidity detecting element 10 comes to be an abnormal condition which cannot execute a sensor function and a detecting value Vf to appear at the output side of a humidity detecting circuit 8 is higher than an upper limit setting value Vr1, the output side of the first comparator 141 of the first detecting circuit 24 is changed from an H level to an L level, at the output side of an or circuit 23, an abnormal detecting signal (H level signal) appears, and the signal is inputted to a switch driving circuit 28. For such a reason, a transistor 32 of the switch driving circuit 28 is turned on, a relaying coil 23 is excited, and a moving piece 9 of a changing-over switch 17 is changed over from a normally closed contact point 18 side to a normally opened contact point 21 side. For such a reason, the humidity detecting element 10 linked at an amplifier circuit 9 of the humidity detecting circuit 8 is changed over to a setting impedance element 7.
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