In SEAT models the rain sensor interval function regulates the wiping frequency automatically depending on the rain intensity. The sensor is housed in the base of the interior mirror. It consists of several infrared light emitting diodes and a centrally-placed photodiode. The light emitted by the light emitting diodes is reflected from the windscreen to the photo sensor. The more water droplets there are on the windscreen, the less light the sensor receives.
This information is forwarded to an electronic control system that adjusts the wiping frequency of the wipers accordingly. In addition the sensitivity of the sensor can be individually adjusted via a selector switch. The rain sensor is designed so that neither minor damage, dirt nor aging of the windscreen affect its functioning.
The rain sensor's advantages are convenience and safety. The driver can concentrate fully on the traffic situation without having to readjust the wiper frequency. This is definitely a significant gain in safety in the case of sudden visual obstructions, such as when overtaking trucks on wet roads.
