| 摘要 |
A circuit arrangement for an opto-electrical dirt sensor which detects foreign bodies on a transparent pane is highly reliable. To increase the reliability, the supply voltage for a reflected light barrier is increased and the operating point of the phototransistor of the reflected light barrier is stabilized by a suitable control circuit. The signal from the dirt sensor is evaluated, in particular for motor vehicle head lamps. The signal portions due to incident foreign light or to the vehicle's own head lamp are also evaluated. |
