What Is a Rain Sensor for a Windshield

A rain sensor or rain switch switching device activated by rainfall. There are two main types of rain sensors. The first is a water saving device connected to an automatic irrigation system, which causes the system to shut down in case of rain. The second is a device used to protect the interior of a car from the rain and to support the automatic mode of the wipers. It is a small electronic device in the mirror. It automatically turns on the windshield as soon as it senses rain.

For our discussion, we focus on automotive sensors. In 1958, experimented Cadillac Motor Car Division of General Motors with a water-sensitive switch that triggered various electric motors to close the convertible top and raise the open windows in a specially built Eldora do Biarritz model in case of rain.

The first unit appears to have been used by General Motors for the same purpose. In a concept designated vehicle, Le Saber "and built seven years earlier in 1950-1951. For the 19,556 model year, Cadillac introduced again a car rain sensor, this time to automatically trigger the wipers adjust their speed and conditions.

The most common modern rain sensors are based on the principle of total internal reflection. An infrared light radiated by the 45-degree angle into the windshield from the inside. If the glass is wet, less light makes it back to the sensor and the wipers turn on.

In the past, automakers tried to remove the wipers or check their speed automatically. Some of the schemes involved the detection of vibrations caused by individual raindrops hit the windshield, which applies special coatings that do not fall through, or even the ultrasonic vibrating windshield to break up the drops so they do not need to be wiped out at all. But these systems are plagued by problems and never made it to production or were quickly disbanded, because they made more drivers than happy.

But a new type of wiper system has begun to appear on cars that are actually doing a good job of detecting the amount of water on the windshield wipers and controls. Such a system is made by TRW, Inc. TRW Inc. uses optical sensors to detect the moisture. The sensor is mounted in contact with the inside near the rearview mirror.