i****a
发帖数: 36252 | 1 http://reviews.cnet.com/led-tvs-review-10-things-you-need-to-kn
LED TVs: 10 things you need to know
I'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 TV is. Here goes.
1. An LED TV is not a new kind of TV.
2.There are two LED backlight configurations | G****y
发帖数: 305 | 2 thanks a lot. This is very helpful. | i****a
发帖数: 36252 | 3 http://reviews.cnet.com/2795-6482_7-399.html
LED TVs compared: Local dimming, edge-lit, and full array
If you thought all LED TVs were created equal, you're underestimating the
power of confusion as a marketing tool. In their continuing efforts to
compete against the picture quality advantages of plasma-based flat-panel
TVs, makers of LCDs TVs have introduced numerous new technologies. The most
successful in our opinion is full-array LED backlighting with local dimming.
When you see the words "LED TV" in an ad, it definitely refers to an LCD TV
with an LED backlight, but what type of LED backlight and how it's
configured make all the difference.
Below we've gathered reviews of six different "LED TVs" that provide
examples of all four LED backlight configurations, but first we'll provide a
bit of context. All LCD-based TVs rely on a backlight of some kind to
illuminate the liquid-crystal panel itself. The most common use fluorescent
backlights, known as CCFL, but a growing number feature LED backlights
instead. LEDs use somewhat less power, can enable thinner flat-panel
cabinets, and--crucially for TV makers--provide a great excuse to charge
more money. But make no mistake: despite the misleading marketing, LED TVs
are just LCD TVs with fancy backlights.
Unfortunately for TV shoppers, the confusion just increases from there. To
help cut through the clutter we're going to lengthen our descriptions beyond
the "LED TV" shorthand, and tell you how picture quality generally compares
with standard LCD. More details are available in our LED TVs: 10 things you
need to know companion piece as well as the individual reviews.
Full-array without local dimming: The rarest of the bunch but the most
familiar in concept. These models are just like standard LCD-based TVs aside
from the fact that the CCFL backlight is replaced by LEDs. The "full-array"
means that the LEDs themselves are arranged behind the entire LCD panel,
not just along the edge.
Picture quality impact: No difference compared with standard LCD.
Example below: Sharp LC-46LE700UN (a 2009 model; we'll review the 2011 LC-
70LE732U soon).
Edge-lit without local dimming: The most common today. Chances are if you
see an "LED TV" advertised, it's this variety, which was first widely
introduced by Samsung in 2009, then imitated in the last two years by just
about everyone else. It's characterized by thin cabinet designs--around just
an inch or even less in depth--that lead to decreased weight in shipping
and wall-mounting, along with increased bragging rights (although we fail to
see much practical appeal versus a standard, 3-to-5-inch-deep flat-panel TV
). Unlike full-array models, the LEDs on these sets are arranged only along
the edge of the LCD panel, and can illuminate the center and other areas of
the screen using so-called "light guides."
Picture quality impact: No major advantage over standard LCD, and can have
even more uniformity problems, such as brighter edges compared with the
middle.
Example below: Samsung UND6400 series
Full-array with local dimming: The original and still the best. There are
exceptions, but in general, TVs with this LED backlight configuration are
the best-performing LCDs you can buy. They're similar to full-array models,
but the individual zones of LEDs can be dimmed or brightened independently.
Picture quality impact: Can have significantly better black levels and
uniformity than normal LCD, but will also exhibit "blooming," or stray
illumination, to some extent.
Examples below: Vizio XVT3 series, Sony XBR-HX929 series
Edge-lit with local dimming: A hybrid currently available on select models
from Samsung, LG, and Sony. The idea is to allow some dimming of the screen
in independent areas without having to place LEDs behind the LCD panel, just
along the edge.
Picture quality impact: In our tests of the TVs here, the Samsung achieved
darker back levels than the best nondimming edge-lit model (the UND6400),
and the LG matched it, but neither matched the picture quality of full-array
with local dimming and both exhibited more blooming. | i****a
发帖数: 36252 | 4 that's why I hate watching movies on 120Hz/240Hz TV with anti-jegger and
with local dimming features.
good ol' 60Hz without the fancy marketing gimmick is still the best
screens
to watch movies on... until the next generation TVs comes out without
those issues |
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