Wide-Angle Non-Imaging Illumination Lens Arrayable for Close Planar Targets

摘要

An illumination lens for hemispherically emitting light emitting diodes is disclosed that produces a circular illumination pattern of wide extent on a relatively close target. Exemplary applications are in commercial refrigerator-case lighting and in LED backlights for liquid crystal displays. This illumination lens is designed to be installed in arrays, such that the multiple patterns overlap to sum up to a nearly uniform illumination pattern. The individual lens produces an illumination ramp which monotonically declines to zero at or close to the location of the adjacent lens in the array. Design methods are disclosed whereby this illumination ramp is translated into a source-image size function that is the basis for generating any particular lens. Preferred embodiments include a cusp at the center of the outer surface. Design methods are disclosed for numerically generating the lens surfaces for any particular combination of array spacing and target distance.