Rain sensor/light sensor, function - GF54.21-P-4123-04PQ
Function principle of rain sensor
Infrared light is beamed from the infrared transmitter unit (1) and is directed to the windshield (3). The intensity of light reflected at the windshield (3) is measured by the IR-receiver unit (2)
If the windshield (3) is dry in the area of the rain/light sensor (picture A), then the light is almost completely reflected and the IR-receiver unit (2) measures a high light intensity.
If the windshield (3) is wet in the area of the rain/light sensor (picture B), then part of the light is scattered out of the glass of the windshield (3). As a result the intensity of the reflected light reduces and the IR-receiver unit (2) measures a lower light intensity.
The light intensity measured by the IR receiver (2) is a measure for the quantity of water on the windshield (3) The lower the measured light intensity the greater the amount of water on the windshield (3).
Function principle of light sensor
The rain/light sensor measures the light intensity falling on it from outside.
The information is transmitted via the overhead control panel control unit to the Controller Area Network bus class B (interior) (CAN-B).