Infrared soiling or icing indicator for vehicle windscreen - evaluates intensity-modulated IR beam reflected from windscreen to photodetector with daylight filter to initiate warning or activate e.g. windscreen cleaning.

摘要

The soiling indicator has an IR source (IRQ) directing a beam (DS) onto the windscreen, the reflected radiation (RS) received by a photodetector (PD) providing a corresp. electrical signal. The latter is evaluated to operate a warning and/or cleaning device. Pref. the beam provided by the IR source is subjected to intensity modulation, with a daylight filter (TLF) inserted in front of the photodetector, the detected modulation evaluated via a comparison and logic circuit. ADVANTAGE - Automatic cleaning, heating of windscreen or air conditioning.