Rain and dirt sensor for motor vehicle windscreen - uses light source below or at inner side of pane and light measurer at top or outside

摘要

A rain a dirt sensor for the outside of a windscreen (10) includes a light source (16) a reflection surface (13) and a photo-detector (17). The latter are located on the inside of the screen, and light from the light source is reflected by a screen/air bordering surface. If the screen becomes dirty or wet, light is decoupled by a primary optical element and is coupled by a secondary optical element. The source and the detector are located to correspond with the appropriate points on a rotational ellipse. At least one of the optical elements is pref. made of an acrylic glass. ADVANTAGE - Large external detection surface.