Rain sensor/light sensor, function - GF54.21-P-4123-04SK
Function principle of rain sensor
Infrared light is radiated from the IR transmitter unit (2) and guided to the windshield (4) via the lens (1). The intensity of the light reflected at the windshield (4) is measured by the IR-receiver unit (3) which is located at the other end of the lens (1)
If the windshield in the area of the rain/light sensor is dry (picture A), then the light is almost completely reflected. The IR receiver (3) measures a high light intensity.
When the windshield (4) is wetted (picture B) in the area of the reflection surface, part of the light from the glass of the windshield (4) is scattered. This reduces the intensity of the reflected light. The IR receiver (3) measures a lower light intensity.
The light intensity measured by the IR receiver (3) is a measure for the quantity of water on the windshield (4) The smaller the measured intensity the larger the quantity of water on the windshield (4).
Function principle of light sensor
The light sensor measures the light intensity occurring 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).