Yu-Cheng CHANG^1*, Chung-Jen OU², Yu-Sheng TSAI¹, and Fuh-Shyang JUANG¹

¹Institute of Electro-Optical and Materials Science, National Formosa University, Huwei Township, Yunlin County 632, Taiwan
²Department of Electrical Engineering, Hsiuping Institute of Technology, Dali City, Taichung County 412, Taiwan

(Received June 17, 2008; Accepted March 13, 2009)

Light emitting diode (LED) has more advantages compared with a traditional incandescent light bulb and a fluorescent lamp, such as small size, low quantity of heat, long life, low power consumption, fast response, plain packaging and ease of develop ment of a frivolous short product. A methodology is proposed to improve the uniformity of the LED illumination system. As a light source in a backlight unit (BLU), the requirement for optical characteristics of a LED is different from highly directional conventional ones. New diffused-type LEDs need to be developed to fulfill the requirement of the BLU industry. A non-spherical lens is designed to optimize uniformity, and a great improvement in uniformity from 28.4 to 64% is demonstrated. In the future, it may used in an LED display to improve the unevenness of illumination.

Key words: light emitting diode, lens design, simulation, LED lens, uniformity

^*E-mail address: r2498@ms53.hinet.net