Research on light intensity distribution uniformity of dynamic speed limit signs based on dot matrix LED

Abstract

Aiming at the problem of uneven illuminance distribution of light source array on the surface of dot matrix LED dynamic speed limit sign. In this paper, the distribution threshold of single LED effective illumination value and the superposition distribution model of lattice light source illumination are established through the derivation of basic optical theory and the experimental test of grating aperture isolation method, and then the influence of the theoretical and measured distance between two LEDs on the illumination distribution uniformity of LED array light source is simulated and analyzed by using optical software Trace/Pro. The rectangular LED dot matrix and the 8-shaped LED dot matrix, which is a common element in the speed limit value of the dynamic speed limit sign, are simulated and analyzed with the established lamp bead spacing. The results show that the distance between two light beads plays a key role in the distribution uniformity of illumination. When the central distance between two light beads is 22 mm, the distribution uniformity of illuminance in the central area of the light source and the overlapping area of radiation light from two LED light beads reaches 95.2%, which meets the requirement that the unevenness of speed limit signs should not be greater than 10%.