"LED TVs": 10 things you need to knowWe've written articles in the past explaining various TV technologies, including the differences between 720p and 1080p and 120Hz and 240Hz LCD TVs. But with Samsung, LG, Sony, and other manufacturers pushing so-called "LED TVs" these days, it's high time that I--with an assist from our resident video guru David Katzmaier--sort through all the marketing mumbo jumbo and provide some insight into just what an LED-lit TV is. Not that only Samsung calls its TV LED TVs, but that is a bit of a misnomer. Here goes.
 Local dimming LED backlights can dim or turn off individually as needed. The type of backlighting can impact how deep a shade of black a TV can produce. All current LED-based LCDs with rear-placed, "full-array" LED backlighting--except the new Sharp LC-LE700M series--feature a technology called "local dimming". With local dimming, specific areas of the backlight can be dimmed or brightened when different areas of the picture get darker or brighter. With fluorescent backlighting and edgelit LED backlighting, by contrast, the entire backlight dims or brightens at once, if at all. Being able to dim specific quadrants helps reduce the amount of light that leaks through to darkened pixels, and the end result is blacks that appear darker and more realistic. Since black levels are crucial to contrast ratio, the deeper the blacks, the more the picture--and colors--appear to pop. Also, the image as a whole will seem crisper. A great example of local dimming done right is Samsung's Series-9, which is one of the best-performing TVs we've ever tested. One downside to local dimming is an effect called "blooming", where brighter areas bleed into darker ones and lighten adjacent black levels. This effect varies widely from model to model. The incidence of blooming is directly related to how many local dimming LED elements ("dimmable zones") are behind the screen, but some manufacturers won't divulge that information. Blooming isn't an issue on other kinds of displays, including edgelit models. 4. Edgelit TVs are really thin, but uniformity suffers As I said, the key benefit to an edgelit LED backlighting scheme is that manufacturers can make thinner TVs. However, the downside is that the backlighting isn't quite as uniform. With edgelit displays, if you put a white image up, you might notice that the outer edges of the screen appear brighter or "hotter". Also, when you put up an all-black image, the edges of the screen will appear lighter (grayer). 5. LED backlighting of either variety doesn't improve LCD's poor off-angle viewing One of the big downsides to LCD TVs is that the picture degrades if you're sitting off to the side or the TV is placed too high or low, based on your eye level. LED backlighting doesn't change any of this and, in some cases, may actually make things worse. The Samsung Series-9, for example, currently offers the best black levels of any LCD we've seen--so long as you're sitting in the sweet spot, with the middle of the screen between your eyes. But move a few feet to the left or right and you'll notice the picture doesn't look as good. Why is this so apparent? Well, the problem is you're starting with such a good picture, you're more apt to notice the difference when you move to the side or stand up and gaze down at the TV. With a TV picture that doesn't look as good to begin with, the difference doesn't appear as stark when you move off axis. Make sense? Tags: Light-emitting Diode, Samsung Electronics Co. Ltd., LED-lit TV, Edgelit TV, TV |
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I think the title of this should be "LED Edge lit/Backlit TVs" 10 things you need to know"
Oct 13, 2009 20:24
Plasma just looks better and is cheaper. We are all are not stock brokers!
The Samsung PN63B550 63" Plasma is a great television to watch streaming content!
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Oct 24, 2009 05:34
