Function

Function principle
An infrared light beam is radiated by the infrared transmitter unit (2) and focused on the window (4) by the lens (1). If the window is dry in the area of the rain sensor (B38) the light is reflected almost completely (A). An IR receiver unit (3) is located at the other end of the lens which measures the percentage of light reflected. When the windshield in the area of the reflection surface is moist a portion of the light escapes from the glass (B). With increasing moisture the percentage of reflected light decreases The rain sensor measures this percentage and transmits the reading via the CAN bus on request. The rain sensor (B38) is connected to the overhead control panel control module (N70) by the CAN bus. The signal acquisition and actuation module (SAM) (N10/1) transmits a request to the rain sensor (B38) via the CAN bus and the rain sensor indicates to the SAM the momentary quantity of moisture each time a request is received.