LED Televisions Explained

LED TV Information

TV manufacturers have started to use LEDs as a method of providing backlighting in televisions rather than cold cathode fluorescent lamps (CCFL) that have been used in LCD TVs up to this point. Televisions that use this method of back lighting have been marketed as LED TVs. It is important to point out the use of LEDs in LED TV is to provide a backlight for LCD based televisions and not as the method of producing the images displayed on screen as is the case with OLED and true LED displays.

There are a couple of ways that LEDs are used to provide backlighting for LCD TVs, these are commonly referred to as edge-lit or back-lit configurations. As the names suggests edge-lit involves the positioning of the LED around the edges of the LCD panels and back lit utilizes the LED behind the LCD panel. Edge-lit TVs incorporate a light diffusing panel behind the LCD display to deflect the light emitted from the side LEDs out through the front of the LCD panel, whereas with back-lighting the light takes a direct path and is emitted directly through the LCD panel.

The types of LEDs used in lighting the LCD panel come in two variations, either white LEDs or RGB LEDs (red, green, blue). RGB LEDs produce better colour gamut than white LEDs do (where colour gamut refers to the subset of colors which can be accurately represented). This is because RGB LEDs produce a purer more complete white light than white LEDs do. Typically white LEDs are used in edge-lit displays where both white and RGB LEDs can be used in back-lit displays.

Edge-lit LED TVs have the benefit that that they can be designed and manufactured to be very slim. This is because LEDs are far smaller when compared to the CCFL lamps that they replace. Samsung and Sony both have super slim televisions on the market, Samsung’s television measure in at 2.5cm thick and Sony’s at just under 1cm.

Back-lit LED televisions have other attractive characteristics associated with them. Where RGB LEDs are used, greater color gamut is possible. In real terms, to the viewer this means the color reproduction is much improved enhancing the images displayed on screen to produce a more immersive viewing experience.

Also with back-lit configurations local dimming of LEDs is possible. This means LEDs can be individually switched on or off to produce dark black areas. This is not possible with edge-lit LED displays where the LEDs are either all on or off (this was also a problem with the use of CCFL lamps in LCD TVs). The benefit of back-lit TVs and local dimming is that truly high contrast ratios can be achieved (a comparison between the darkest black and brightest white that can be reproduced on screen). Edge-lit TVs can produce images that are either all dark black or all bright white, but not produce images that are both at the same time.

A benefit of the use of LEDs in both types of configurations is in relation to energy efficiency. The power consumption of LEDs is less than CCFL-LCD and plasma televisions. If the manufacturers are to be believed then LEDs use up to 50% less power than the equivalent plasma models or 40% when compared with the equivalent CCFL based LCD models. LED TVs can also be expected to have longer lives and improved reliability because LEDs are more reliable and durable than CCFLs.

It would be unbalanced not to mention all the benefits of LED TVs without mentioning the down side which is price. LED TVs and particularly back-lit LED TVs come at a premium price which is to be expected. This is a situation which is constantly improving with popularity and competition driving down the cost of LED TV.