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Preh has been developing sensors for a wide variety of applications in passenger cars and commercial vehicles since the 1980s.
In addition to the proven sensors for brake pad wear, these also include sensors for fanless measurement of the interior temperature and sensors for preventing windshield fogging. Preh sensors can be offered as a stand-alone solution, or according to customer requirements in combination with other sensors.
For many years, vehicles have been equipped with a convenient automatic function for light control. Once the switch has been set to "A", the head and taillights are automatically activated when dusk falls or the vehicle enters a tunnel - a clear gain in comfort.
This convenience function can become problematic when dense foggy conditions prevail, because the system for controlling the driving lights cannot detect fog. In fact, during the day there is even a risk that the fog will be classified as "daylight" and the driving lights will be switched off accordingly. Although the current state of the art requires manual intervention by the driver, many drivers are not aware of this. This is why, when fog is approaching, it is often found that vehicles have their driving lights switched off. In this case, the front daytime running lights are still working, but the rear lights, which are all the more important in fog, are off.
This is precisely where Preh's visibility range sensor comes in. This optoelectronic system, consisting of a transmitter and receiver, detects the light intensity scattered back by the water droplets in the fog and also uses pulsed light to compensate for interference. It completely eliminates the need for manual intervention by the driver, since emerging fog is detected at an early stage and the headlights, fog lights and rear fog lights are switched on or off accordingly. The sensor is preferably placed in the area behind the windshield that is covered by the windshield wiper. Extensive test drives conducted in numerous countries and under a wide range of weather conditions have proven the reliability of the visibility range sensor, which Preh has developed
