Traffic signal lamp illuminated by light emitting diodes

摘要

A traffic signal lamp includes a plurality of light emitting diodes and two lens sets. A first lens set has an entrance surface comprising a plurality of convex cylindrical surfaces running in a vertical direction and an exit surface comprising a plurality of slanted surface segments running in a horizontal direction. A second lens set has an entrance surface comprising a plurality of elongated concave cylindrical surfaces running in the vertical direction and an convex exit surface having a small curvature. The first lens set collimates light in the horizontal direction and limits light in a viewing angle in the vertical direction. The second lens set redistributes light uniformly in a viewing angle in the horizontal direction.