The study of LED uniform lightguide for liquid crystal display backlight applications

A conventional backlight unit (BLU) is used to as the light module to present uniform light of liquid crystal display (LCD). In general, cold cathode fluorescent lamp (CCFL) is utilized to be the light Source of BLU. The light emitting diode (LED) is now considered well known as a promising device for solid state lighting. It has the advantages of long durability, no mercury substance and good endurance of heavy impact. To satisfy the market demands of the thin-film liquid crystal display (LCD) and the green product, the LED is applied to as the light Source to make display thinner, lighter, no Hg containing. In this research, the LED uniform lightguide is demonstrated because it enables the point-like light to distribute propagating-light line pattern successfully. By optimizing the size and the radian of the device, the designed LED uniform lightguide can achieve the output efficiency more than 85%, and its illuminative uniformity is improved about 85%. Thus, the LED uniform lightguide not only can decrease the number of LED to save the space, but also enhance the optical efficiency. In the future, a novel LED uniform module could make displays thinner and lighter for backlight system applications.