More LCD TVs are now using LED backlights; last year LEDs were used mostly on high-priced TVs. These so-called LED TVs aren't a new, better type of TV, though ads imply that. They're LCD TVs that use LED backlights instead of fluorescent ones. When well implemented, LED lighting can contribute to deeper blacks, better contrast, a slimmer profile, and lower energy use. Some manufacturers are selling only LED models, especially in larger sizes, so you might have less choice in conventionally backlit sets.
Most of the new LED-based sets we're seeing now use edge-LED backlights, with LEDs around the perimeter of the screen and special diffusers that spread the light across the entire panel. Edge LEDs allow LCD TVs to be very thin. They're also very energy-efficient, resulting in the lowest power consumption of TVs we've tested.
We're finding fewer new TVs with full-array LED backlights across the entire panel and a feature called local dimming. Local dimming allows for variable brightness in a scene, with dimmer lighting behind dark sections of an image and brighter lighting in other areas, an attempt to improve perceived contrast.
On the TVs we've tested, local dimming is often very effective, resulting in better contrast and deeper black levels. For example, the newer Vizio XVT LCD TVs with TruLED backlights have produced some of the best black levels we've seen on an LCD, almost as good as the better plasma sets. We've tested a few edge LEDs with local dimming, but we haven't found it to be very effective on those sets.
Consider an LCD TV with a full-array backlight and local dimming if you want deeper blacks and better contrast and you're willing to pay more. If you want those attributes without a high price tag, consider a plasma TV instead. And don't rule out conventional LCDs, which can do just as well as LED-based sets, and usually at a lower price. If you want the thinnest TV and lowest power consumption available, opt for an edge-LED set. New TVs might combine the advantages of full-array and edge-lit LEDs: LG Electronics has announced a new type of full-array LED backlight with lights placed on a thin film, allowing for a very thin profile, along with local dimming.