I'm Brian Cooley with a CNET FAQ.
Question: What is an LED LCD TV?
Answer: It's an LCD flat panel television whose picture screen is illuminated by light emitting diodes or LEDs instead of fluorescent tubes like in typical LCD sets.
What are the two types of LED LCD?
LED LCD televisions are either edge lit or local dimming.
Edge lit sets have an LED light source mounted all around the picture screen, left, right, top, and bottom, but not behind it.
They direct the light to the back of the picture via what are called light guides.
Local dimming sets have a full panel of LEDs behind the picture screen, positioned much like today's standard LCD fluorescent tubes.
What ar the pluses and minuses of each type?
Edge lit sets can be made dramatically thin.
This does nothing for the picture but it looks cool, and like all LED LCDs, they tend to use less energy in general.
On the downside, edge lit sets tend to show an image that is brighter around the edges, where the lights are, even if the image doesn't call for that.
Local dimming sets aren't as thin since they have to make room to sandwich a layer of LEDs behind the screen, but they have the advantage of local dimming.
That means different parts of the screen can be made darker or lighter depending on what the image calls for.
This can really help create a more accurate picture with deep black levels and colors that really pop, something plasmas have typically done the best.
Does LED technology improve off angle viewing?
All LCDs still tend to suffer from rather poor off angle viewing.
In other words, the image will get dim and unclear if you sit well off to one side.
This is just the nature of an LCD screen itself, not the light source behind it so LED illumination doesn't change things.
How about power consumption?
LED LCDs tend to use less power than even typical fluorescent LCD sets, and all LCDs tend to use less power than plasma sets.
The power consumption of all TVs, though, is improving notably thanks in part to new efficiency standards, but LED LCDs are probably your choice if low power consumption is your priority.
Oh, and if it is, make sure you turn it off at the plug when you're not using it.
What's the bottom line when I go TV shopping?
Well, consider an LED LCD
and know that when they're really good, they come very close to equaling the image of a good plasma, but also realize you're probably going to spend a few hundred dollars more for an LED LCD versus a conventional one, and if you want one of those super thin edge lit sets, know that there's a lot of innovation expected the next model year or two that will improve their evenness of lighting while maintaining a super slim case, so you might wanna hold off for a while, and the prices, they'll only come down.
For a complete take on LED LCD technology, read this piece from CNET's David Carnoy and David Katzmaier, and for full reviews of LED LCD sets, of course, check CNET's TV review section.
You'll find links to both at faq.cnet.com.
I'm Brian Cooley, thanks for watching.