Optimized Design Of Bottom-Lit LED Liquid Crystal Display

LED liquid crystal display is that the new light source LED substitutes the traditionallight source CCFL (Cold Cathode Fluorescent Lamp) in display’s backlight module. Underthe situation of shortage of energy, the LED display with environmental protection and energysaving has become the trend of low-carbon green lifestyle. Secondary optics to LED can bemade duo to its small volume which can enhance the brightness obviously and low down thecost of production of LED display. Besides, the traditional LED display has the drawbacks thedeferred reaction and liquid crystal’s light leak which will influence the LED display’sdisplaying the fast witching pictures and reduce the contrast ratio.The size of traditional light source-CCFL is so big that we can not treat it as a point lightsource. For this reason we can not obtain accurate optical design and dynamic backlighttechnology for the traditional backlight. With the advantage of small size of LED and uniformdistribution in backlight module, we can obtain accurate optical design and local dimmingtechnology to improve the display capabilities.In this paper, we designed a type of second optical-freeform lens for display’s LED withnonimaging optics which will improve the brightness two times. When the brightness isenhanced, the number of LEDs can be reduced which will low down the cost of production ofLED display. We make modeling for LED backlight module which second optical lens arepositioned on LEDs by Lighttools and fabricate a19inch LED backlight sample. Through thesimulation results and experiment results, we find that the second optical lens can enhance thebrightness greatly and the utilization efficiency of optical energy.Besides, owing to complexity of existing local dimming technology algorithm, we putforward our new local dimming algorithm. This new algorithm will reduce the complexityand the difference between original picture and the processed picture by local dimmingtechnology is very small. The new local dimming algorithm will reduce the complexity ofdesigning electronic circuit and minimize the computing time which will improve visualperception.