Motor vehicle lighting controlled by test beam reflectometry - involves evaluation of distance and density of fog for main or dipped headlamp and rfog-lamp switching

摘要

A laser (2) emits a test beam (1) with a wavelength of about 900 nm in the near infrared region, into a patch of fog (3) from which the reflection (4) is measured by a receiver (5) in the vehicle. The propagation time and the intensity of the reflection (4) are evaluated to obtain an estimate of fog density. To prevent dazzle of the driver, the headlamps and fog lamps are switched automatically in daytime or night-time driving. USE/ADVANTAGE - In variable fog, correct mode of lighting by main or dipped beams and fog lamps is selected automatically.