An apparatus for operating a windshield wiper having an automatic wiper control. The apparatus is provided with a rain sensor having a light-emitting transmitter and a receiver that responds to the emitted light by emitting a sensor signal, and an evaluation device for the sensor signal....http://www.google.se/patents/US5847654?utm_source=gb-gplus-sharePatent US5847654 - Device for operating a windshield wiper
