A Night-Vision-Compatible LED Backlight For Liquid Crystal Display

Night vision compatible （NVC）LED backlight technology is very important in thespecial display field of the special display such as airborne LCD. The crucial issue is howto reduce the infrared leakage of the backlight without affecting its color gamut under thenight vision working condition, and provide higher brightness for LCD under directsunlight condition.This these describes a NVC LED backlight technology for LCD. The main content ofthis article includes: Firstly, it introduces the implementation and present research situationof home and abroad of the NVC technology, and presents the significance and content ofthe research projects. Secondly, the theoretical design and optical simulation for NVcompatible LED backlight system were completed based on the LED backlight theory ofthe LCD, and the LCD color gamut was estimated. Thirdly, the whole system architecturedesign and the circuitry design were completed according to the theoretical design andsimulation results，such as the schematic diagram and the PCB of the Back Light Unit(BLU)and driver circuit. Fourthly, system software module was designed based on the Quartus II9.0software development platform, and the NVC LED backlight was realized through jointdebugging of system. Finally, the NVC LED backlight system was tested and the resultswere analyzed. It could prove that the NVC design meet the requirement that zero infraredleak in night mode and providing higher brightness and wider gamut.The main achievement of this article presents a design method of NVC LED backlightsystem that not only reaches high luminance, but also performs a wide color gamut. Thebacklight consists of red(R), green (G), blue (B) and amber (A) LEDs without a NVC filter.During daytimes, RGBA LEDs are simultaneously turned on simultaneously, providinghigher brightness and wider color gamut. When working in the night mode, the red LEDsare turned off. To compensate the absence of red lights, the amber LEDs are turned on.After measurement, the backlight provides the promising characteristic of wide color gamut.It provides experience and platform for a further study of the NVC LED backlight for LCD.