Light Emitting Diode, or LED backlight is the most popular backlighting for small and medium LCDs. The advantages of LED backlighting are its low cost, long life, immunity to vibration, low operational voltage, and precise control over its intensity. The main drawback is it does require more power that most of the other methods, and this is a major drawback if the LCD size is large enough. LED backlights come in a variety of colors, with yellow-green being the most common, and now white is becoming cost effective and very popular. LED backlights offer a longer operating life - 50,000 hours minimum - and are brighter than ELPs. Being a solid state device, they are configured to operate with typically a +5VDC power (and optionally 12VDC power), so they do not require an inverter. The LED backlight has two basic configurations; Array and edge lit. In both types the LEDs are the light source that are focused into a diffuser that distributes the light evenly behind the viewing area. In Array lit configuration there are many LEDs mounted uniformly behind the display, it offers more uniform and brighter lighting and consumes more power. In Edge lit configuration, the LEDs are mounted to on side (typically the top) focused edge on into the diffuser, it offers a thinner package and consumes less power.
What does LEDs have over any other backlighting source? The three most important concerns any Notebook designer has to resolve are power, even lighting , and weight. LEDs beat all other solutions hands down. Power equals heat and power reduces battery life time between charges. LEDs are a cool light source, the lamination to heat ratio is even better that that of fluorescent lighting. As a result LEDs provide more light per watt. LEDs are chips. They are small and can be placed in a matrix pattern behind the panel to deliver an even uniform field of light across the entire viewing surface of the panel. Other sources like bulbs and tubes will generate hot spots (where the light is brighter) and producing an even field of light to the panel can be tricky and costly. Once again, LEDs are chips. Small and light weight. LEDs are the winners today and will remain so for some time to come.
LEDs are dominating the market, and we haven't even seen its full potential yet.
