Enhancement of the optical performances for the LED backlight systems with a novel dual lens-cap

Chang-Po Chao*, Lun De Liao, Chi Wei Chiu, Chien Yu Shen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A novel dual-cone-shaped side-emitting lens cap for High Brightness Light Emitting Diodes (HB-LEDs) is proposed for improving brightness and high uniformity of the direct LED backlight Units (BLUs) for large-sized LCD-TVs. Combining the designed lens cap with red, green and blue (RGB) chips on a Metal Core Printed Circuit Board (MCPCB), the LED module with the proposed cap is able to provide a compact white light source with unique features such as instant color variability and lower power usage, etc. The dual-cone-shaped of the proposed lens cap is designed to emit most of the light rays to the sides, only a small portion of light upward along the optical axis of the lens, providing a uniform luminance distribution and the high brightness on the backlight. In addition, a small reflective surface in semi-circular shape is designed and placed upon the proposed LED module about 10mm, the surfaces of which are attached with reflective films to increase the level of light mixing in the larger, global reflector optical box. With the structure of the LED module well designed, the LED backlight Module would be designed for the large-sized LCD-TV using the fewer number of LEDs to lead to lower power consumption. The results indeed identify the attributes of the BLU, which make it possible to achieve excellent backlight performance using a direct illumination approach from the light source of "Dual-Cone-Shaped Side-Emitting Lens Cap of LEDs.".

Original languageEnglish
Pages (from-to)132-137
Number of pages6
JournalKey Engineering Materials
Volume364-366 I
StatePublished - 11 Feb 2008


  • LED backlight
  • Lens cap
  • Optimal design

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