New Headlamp Bulbs for Higher Peripheral Visibility and Reduced Discomfort Glare

Recent studies [2,3,4] have shown that with increase of the blue spectral content in the peripheral part of a headlamp beam pattern the visibility during night is also increased, especially at low ambient illumination. On the other hand several studies [2,5,8] have shown that the blue spectral content of a headlamp, although having no significant influence on disability glare, nevertheless increases discomfort glare for the opposing traffic. It follows that the effect of color can positively be used to both increase visibility and reduce discomfort glare if (for right-hand traffic) it provides a maximum amount of blue spectral content in the right peripheral region and a minimum amount of blue spectral content in the left peripheral region, while still lying within SAE white. Special light sources, to be used in conventional headlamps, have been developed to form such optimized beam patterns. The technology and optical properties of these light sources are presented, color measurements of representative headlamp beam patterns using these light sources are shown and their benefits regarding visibility for the driver and reduction of discomfort glare are deduced.