Modified wide radiating lenses of the power-chip light emitting diodes (LEDs) for a direct-lit backlight unit of a liquid crystal display (LCD) are numerically investigated. To improve the optical properties of the backlight, the lens of the Golden DRAGON (R) ARGUS (R) LED, the cluster of LEDs, and the cluster arrangement for the 32-in bottom-lit backlight unit of a LCD are modified and verified by optical tracing simulation software. First, the central section shape is modified and analyzed to reduce the angular luminous intensity in the small angle range. The results show that the modifying lens method can effectively realize the aim. Then, several LEDs with the modified lenses are put in 32-in backlight. It is shown that the uniformity and efficiency of the new backlight are obviously better than the ones of the original type. (C) 2009 Elsevier GmbH. All rights reserved.
