Function of rain sensor - GF82.30-P-4103-02S
Function principle
Infrared light is radiated from the infrared transmitter (2) through the lens (1) to the windshield (4). The intensity of the light reflected at the windshield is measured by the IR receiver (3) which is located at the other end of the lens.
- Windshield is dry (figure A)
If the windshield is dry in the vicinity of the rain sensor, almost all of the light is reflected: the IR receiver (3) measures high light intensity.
- Windshield is wet (figure B)
If the windshield is wet in the area of the reflection surface a portion of the light escapes from the windshield glass. This reduces the intensity of the reflected light, the IR receiver unit (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).
Reading out rain sensor
The rain sensor is connected to the class B Controller Area Network bus (interior) (CAN-B) via the overhead control panel control module as an interface. The front left SAM control unit transmits a request via CAN-B to the rain sensor, which notifies the front left SAM control unit of the current quantity of water in response to each request.