Unlike the CRT (Cathode Ray Tube), the LCDs (Liquid Crystal Display) are not able to produce light of its own. Thus it uses a backlight that provides illumination to it. Backlight provides illumination to the LCD from the back and side of the display panel. Backlight is generally used in small displays such as smartphones, LCD televisions, computer displays, wristwatches, etc.

For color screens, the LED backlighting comes under 2 categories. The first one is the RGB LED backlights and the second one is the white LED backlights.

• RGB LED backlights – The RGB LEDs are made up of red, blue and green LED which can be made to generate several color temperatures of white. RGB LED backlights are generally found in high display devices like HP EliteBook and HP DreamColor LP2480zx monitor. It has also found its use in Dell’s Studio series laptops. RGB LEDs are enabled to provide color gamut to screens. The 3 LED backlights can form a color spectrum that intently coordinates the color filters in the LCD pixels themselves. Using this technique, the filter passband is narrowed, as a result of which a narrow band of spectrum is allowed by each color component through the LCD. As there is a blockage of less amount of light, the efficiency of light is increased. In addition to that, the actual green, blue and red points can be displaced farther out such that more vivid colors can be formed by the display.

• White LED backlights – White LEDs are used frequently in the manufacture of desktop and notebook screens. A white LED is actually a blue LED with yellow phosphor to bring about the discharge of white light.

The LED backlights face several challenges as well. With the increase in the age of an LED, it's very hard to attain uniformity. As 3 different light sources are used i.e. red, green and blue, it means that with aging LED the white point of the display can get displaced at varied rates.  At higher temperature white LEDs faces blue shifts (from 3141K to 3222K for 10 degree Celsius to 80 degree Celsius). Power efficiency may also be kept as a point to note for LEDs.

To defend against the above-discussed challenges in white and RGB LED backlights, NDF Special Light Products has developed an LED technology known as 'advanced remote phosphor'. It uses blue pump LEDs in addition to a sheet having the printing of phosphorous luminescent materials. These are used in those LED applications that require a long life like Air Traffic Control displays, Cockpit display and medical displays.  The principle for this technology is similar to Quantum dots.

With time it is seen that notebook computer is using LED backlights at an immense rate. Since 2005 Sony is taking the help of LED backlights for its VAIO notebook. Asus, Apple, and Dell also made their own LED backlight notebooks by 2007. Today all screens of Apple use LED backlight, be it computer, laptops, etc.

Hope you liked the article on LED backlights. Brands that manufacture them are ELECTRONIC ASSEMBLY, Lumex and Newhaven Display. Make sure to follow them by the links as provided.

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