Light-emitting diode (LED) large-scale uniform rectangular illumination has a wide range of applications and is usually created by an irradiance superposition scheme. Abandoning the traditional method, we propose an approach to generate this illumination mode and enhance efficiency. With this method, an independent rectangular irradiance distribution is generated by each LED lens unit, and the large-scale illumination is obtained by arraying the irradiance distribution. Two slim direct-lit LED backlightings with a distance-height ratio of 3 were designed. An optical performance with irradiance nonuniformity less than 0.0228 and efficiency greater than 96% were obtained. Compared with the traditional methods, the efficiency is significantly enhanced and the number of the LED units is dramatically reduced by this new method.
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