Thursday, November 11, 2010

The Truth Behind LED TVs


Is it actually worth the high price or is it better to wait ?







LED backlighting in TVs has been a real boon for end users, while manufactures have been able to create stunningly slim televisions. It also keeps the environmentalists happy since there is no mercury used in LED backlit TVs there by giving you a greener product. We tested quite a few LED based LCD TVs in the past and the difference in power consumption is certainly visible while still maintaining a good brightness level.
The problem with the term "LED backlit LCD" is that it's a bit too long, which does not look good in advertisements and posters. Manufacturers have conveniently eliminated LCD and simply highlight "LED", duping customers into thinking they are LED TVs, which they clearly aren't. Today we'll have a look at the different types of LED LCD TVs currently available that offer improved picture quality over the other or even traditional LCD TVs.
All LED Backlit TVs are not created equal
The first thing that you should know is that not all LED LCD TVs are created equal. Just because the TV may have a sticker that says "LED" on it does not mean you'll get the same performance as the flagship model. Stop and think for a moment, if companies used the same technologies in their high-end and low-end products, no one would look at the higher end models, right?

There are predominantly two types of LED backlighting technologies; Edge-lit LEDs and Full array LEDs. The first batch of LED TVs that came out in 2009 were based on this technology and was first showcased by Samsung. Today you'll find everyone using this technology in their "cheaper" LED LCD TVs. Edge-lit typically means the LEDs are placed around the edge, which allow companies to make slimmer TVs. There are no major advantages in this type of LED LCD over conventional LCDs when it comes to picture quality. In fact there are many uniformity issues with edge-lit LEDs, like certain areas of the TV tend to be brighter than others, which we noticed when we reviewed the Sony ZX1. This is cheaper to produce than Full array LED LCDs, since they use a fewer number of LEDs.
The other technology that can be found on most of high-end TVs of today is Full array LEDs. As the name suggests, there is a full array of LEDs (see pic) sitting behind the LCD panel. This obviously gives you a more even backlighting with little or no uniformity issues. Mid-range to high end models typically have this sort of backlighting, like the Samsung UNC6500 series. In terms of picture quality, there is no real perceptible difference when compared to an LCD. The only advantage here is lower power consumption and again a slimmer profile. The latest crop of LED LCD TVs feature Local Dimming LED technology, which changes the game altogether.


What is Local Dimming LEDs?

LG was the first to push out this technology in India and today almost all major brands have Local Dimming (LD) in their flagship models. LD on Full array LED TVs give you the better picture quality compared to the LD on Edge-lit TVs, which was introduced this year in the Samsung UNC8000 series and LG LE5500 series. The LEDs used here are similar to the Full array models except that the array is broken into different zones and the LEDs in each zone can be dimmed or brightened depending on the scene at hand.

This gives you very good black levels that rival plasmas, since the LEDs in the dark areas can be completely turned off. There is a little catch here though. The side effect of this is a slight blooming effect noticed up close when a brighter image appears suddenly over a dark background. This happens because when displaying a dark background, the LEDs in that area are mostly off and when a bright object suddenly comes into that area, the LED's light up to full brightness and then dim down to the current selected picture mode. This happens very quickly and isn't very noticeable when watching a movie, but if you connect a PC to it with a static background, it's visible.     
Despite this, these TV's are capable of delivering the best picture quality among LCD TVs.
Commercial true LED TVs don't exist yet

How would one define a LED TV? It's when a single LED is responsible for illuminating a single pixel on the screen, which is when you could do away with the LCD panel altogether. Today's high-end LED LCD TVs pack in around 1500 LEDs and a typical full HD panel will have around 2 million pixels. So in order for a TV to be classified as a true LED TV, we would have to have 2 million LEDs powering individual pixels, which is simply not possible today, and probably won't be commercially viable for some time.
So you see, no matter how companies try to spin and twist words and create fancy slogans, if a TV uses an LCD panel, it's still an LCD TV and not a LED TV. Sony and LG clearly mention this on their site as LED LCD TV, but Samsung seem to have conveniently dropped the "LCD" from all of their LED TVs, which would easily fool the misinformed.
Aren't LED backlit TV's supposed to be cheap?

Technically LEDs should be cheaper to produce compared to CCFL based LCDs, but our guess is that manufacturers seem to be cashing in on the hype and buzz generated by none other than them. Everybody wants a slimmer TV for easier installation, more bragging rights, etc. and we seemed to have conditioned ourselves into thinking the extra price is justified.
Another reason for LED LCDs being expensive could very well be the manufacturing process not being that mature as yet compared to LCDs.
It's probably cheaper to manufacture an LCD, since this technology has been around for a while now and manufacturing units are more wide spread as compared to LED LCDs, which just started hitting selves a year back.
What the Future holds

In the next three to five years we should be able to see a considerable drop in prices as we adopt newer technology for cheaper and better LED LCD TVs. QD Vision is a company that claims to have developed a breakthrough technology called Quantum dots based on nano technology that is capable of delivering up to 40% more power efficiency and a color gamut over 100% of the NTSC spectrum. This is achievable due to the use of nano sized semiconductor crystals capable of emitting pure red, green and blue light.
You should see this technology hitting LED LCD models of 2011, which isn't far away. If you were on the fence on getting an LED LCD TV then we'd say get the one with Local Dimming LEDs if you can afford it, or else simply stick with a cheaper LCD TV, as the color reproduction will be better than the "cheaper" Edge-lit models. Better still, if you have a well functioning CRT at home, stick with that and take the plunge maybe next year when prices go down south.


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