| 摘要 |
PURPOSE:To prevent the collection of moisture due to the delay of energization of a heater, by setting a reference voltage so that the reference voltage is high when there is no hydrophile property on a window pane and is low when the hydrophile property on the window pane rises. CONSTITUTION:The collection of moisture on the window pane is detected by a sensor 3. At that time, the resistance of the sensor falls. When there is no hydrophile property on the pane and moisture is collected on the pane to such an extent as to hardly affect the sight, only a low resistance variation can be expected. Therefore, if an input reference voltage for a voltage comparator 1c is set high, the comparator is surely inverted even with a slight resistance fluctuation of the sensor to energize the heater 2. When a certain time has elapsed, the moisture is removed by the heating of the heater 2 and the resistance of the sensor 3 returns to the original value. As a result, the voltage comparator 1c is inverted and the heater 2 is de- energized. At the same time, the input reference voltage for the voltage comparator 1c is changed into divided voltages by resistors 1b, 2b. |
