| 摘要 |
PURPOSE:To preclude the dew condensation and freezing of a humidity sensing element and to improve the reliability of a humidity sensing function through a former half period by warming up the humidity sending element by a heat generating body through a temperature sensing circuit when temperature drops. CONSTITUTION:If the temperature drops during the use of a circuit until the humidity sensing element which constitutes a humidity sensing circuit 1 enters a dew condensation state, a temperature deciding circuit 6 decides the temperature sensed by the temperature sensing circuit 5 and a heat-generating body driving circuit 4 operates to supply a current to the heat generating body 3 and warm up the humidity sensing element, thereby preventing its dew condensation and freezing. When the temperature rises until the temperature sensed by the circuit 5 rises above the discrimination temperature of the circuit 6, on the other hand, a delay timer circuit 7 connected to a discrimination output higher than the discrimination temperature of the circuit 6 operates a certain time later to reset an inhibiting circuit 2 connected to the output of the delay timer circuit 7, and consequently humidity detection and measurement which are stopped temporarily becomes possible to preclude the dew condensation and freezing of the humidity sensing element completely.
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