Color shift of head lamps for automotive lighting over lifetime

Abstract

The color shift of head lamps for automotive lighting over lifetime was investigated. For that purpose a combination of emission spectroscopy and thermography was used to determine spectra, color data and the cold-spot temperature. There are changes in the lamp behavior over lifetime with a visible blue shift until 500 h and a reversal afterwards. The cold-spot temperature is nearly constant until 1000 h and then increases slowly. The different behavior of Sc und Na partial pressure with increasing lifetime leads to a change of the spectral output of the lamp and therefore of the color appearance over lifetime.

A review on light-emitting diode based automotive headlamps

“…Thus as the time goes by, its performances potentially occur degradations and even catastrophic failures, socalled the reliability issue and lifetime, of which the oxidizing of electrical connections [79], freezing on front lens, color shift [80,81], lumen depreciation [82], unstable output or no light output are typical phenomena. The reliability means the probability to repair or replacement, while lifetime is the time length of service.…”