LEDs for backlights on LCD displays have several advantages depending on the implementation:
a) White LEDS
- Current efficiency of WHITE LEDS when coupled with the ability to better couple the light into the backlight will yield more efficient displays compared to flourescent at least in laptop size displays. Smaller CCFL tubes do not have the 100lumen/watt efficiency of their bigger cousins.
- Current lifetimes of LCD backlights are already in the 40-50K hour range, however, a very well implemented LED backlight could outlast this. As many LEDs will be used, you can eliminate the single point failure mechanisms.
b) RGB LEDS
- Extremely wide color gamut. When coupled with properly tuned phosphors, using RGB LEDS for a backlight gives you a color gamut well beyond white LED or CCFL backlit displays. Think redder reds, bluer blues, etc. ... better even than CRT. If you have not seen a well set up LCD with RGB backlight, you will be amazed at the difference.
- Perfect color....always and forever. Using feedback, you can continously tune the LED output to ensure every display is exactly the same today, and for the foreseeable future.
- The "holy" grail.... sequential color LCD displays. This is really the be all and end all. As opposed to using a display with a color matrix, you use a monochrome display and turn the LEDS on and off. This increases the amount of light the display passes by 3x or more. It also makes the actual display glass much cheaper as there are 1/3 the active parts since you only need one element per pixel, not three. Suddenly you have displays 3 times as efficient as today. This is just a matter of time as rise/fall times for LCD displays fall. I becomes practical around 2msec.
- Increased contrast ration, elimination of goasting. When you turn off an LCD pixel, it turns most of the way off quickly, the tails off at the end. With RGB LCD backlight, as it turns on/off quickly, you can turn the LED on for only a portion of every frame time, turning it off during that last decay of the LCD hence increasing contrast ratio. Phosphor based LEDS do not turn off fast enough to really make this possible, at least not with current phosphors.
Semiman