| 摘要 |
<p>PURPOSE:To apply an optical sensor to both of automatic lighting of a headlight and control of an air conditioner in an automobile by changing the gain of an amplifier in accordance with the output of a photodetector. CONSTITUTION:A photo diode 1 is arranged on a dashboard of the automobile and receives the external light through a front glass. The resistance value of a current feedback resistance 4 is set to several hundreds kOMEGA - 1MOMEGA, and an optical current flows through the resistance 4 when the quantity of incident light is small, and the optical sensor has high sensitivity to the quantity of incident light. Meanwhile, when the quantity of incident light is increased, the output voltage of a current amplifier 2 is increased; and when this voltage exceeds the operating voltage of a Zener diode 6, the resistance value of the Zener diode 6 is quickly reduced and it is made practically conductive at last. The resistance value of a current feedback resistances 5 is set to several kOMEGA, and the optical current flows to the resistance 5 when the Zener diode 6 is made conductive, and the optical sensor is linearly operated even for the large quantity of incident light.</p> |
