| 摘要 |
PURPOSE:To obtain an inexpensive sensor circuit having a long lifetime by providing an analog switch in parallel to a humidity sensor to control the voltage impressed to the sensor. CONSTITUTION:The AC voltage of a sine wave, etc. is impressed to a humidity sensor 3 from an oscillation circuit 2 via a resistance 4. Then the humidity detection voltage is obtained at a juncture 20 and supplied to a comparator 8 to be compared with the voltage value given from a variable resistor 10 for set humidity. Thus a signal of H or L level is obtained. This obtained signal is supplied to a controller 12 to control the working of an air conditioner, etc. Then an analog switch 13 is connected in parallel to the sensor 3 and then turned off by the controller 12 when the humidity is measured. Thus the output voltage of the circuit 2 is impressed to the sensor 3. In such a way, the lifetime of the humidity sensor circuit 3 can be increased since the voltage is impressed to the circuit 3 only when the switch 13 is off. |
