Novel Lens Design and Experimental Verification for High Efficiency Direct Type Backlight Module of LCD-TVs
A novel cone-shaped lens for Light Emitting Diodes (LED) is proposed for the application of direct type backlight module. The direct type LED backlight module is usually implemented for large size LCD-TVs with the superiority of better color performance, fast on/off switchings for lighting, etc. However, the light output efficiency is about 50％ due to the loss for light to pass through the diffuser plate. The diffuser plate is originally applied to raise uniformity of the display but somehow decrease efficiency of light source to display. To provide alternative solution, this study proposes a novel coneshaped lens to replace the low light-efficiency diffuser plate to improve the light output efficiency and simultaneously maintain the satisfactory uniformity. The cone-shaped lens is coated as minor on the outside surface to reflect the light emitting from the LED below the cone as shown in Hg. 1 (a). This reflection leads the light from LED to the side of the optical axis, not along with it, and avoids bright spellings on the backlight directly, as shown in Fig. 1(b). The geometry of the cone shape is optimized for providing better uniformity in the system, and the corresponding topology, spacing and pitch of the LED, is also analyzed for improving the brightness uniformity. The commercial software, TracePro, is applied for preliminary validation for 37 backlight module. It shows a 15％ brightness improvement by using lens instead of diffuser plate and satisfactory uniformity as shown in Fig. 2. Finally, a prototype of LED backlight module with the designed lens and preferred spacing is built to verify the simulation results. The experimental results show good agreement with simulations.
Chi-Wei Chiu Chien-Yu Shen Paul C. -P. Chao
Department of Electrical and Control Engineering, National Chiao Tung University, Hsinchu 300, Taiwa Department of Mechanical Engineering, Chung Yuan Christian University, Chung Li 320, Taiwan, China
国际会议
上海
英文
303-304
2007-03-12（万方平台首次上网日期，不代表论文的发表时间）