As plasma TVs go gentle into that good night and big-screen OLED technology struggles with major birthing pains, we are faced with an immediate future where LCD is the only flat-panel TV technology for the mass market. Granted, plasma is not dead just yet: even though Panasonic is out of the picture, LG and Samsung will continue to sell plasma TVs this year. However, neither company's 2014 plasma offerings show any meaningful forward progress, with Samsung already backing away from plans to introduce a new high-end model this summer. The shift to Ultra HD sealed plasma's fate, as the higher resolution would be quite difficult to achieve on a plasma TV. OLED TVs are also a reality right now, but primarily at the 55-inch screen size and at a very high price point that takes the vast majority of shoppers out of the equation.
Like it or not, that leaves LCD. Many videophiles fall squarely in the "not" category and make LCD out to be the worst technology you could ever ask for, which is a bit of exaggeration. It is true that, in its most basic form, an LCD TV can't come anywhere close to plasma or OLED in overall picture quality. However, a number of key advancements in LCD technology have resulted in TVs that can perform at a very high level. Of course, you have to pay more - sometimes a lot more - to get these advancements in a top-shelf LCD, and perhaps that's the biggest downside to the demise of plasma, which could offer high performance at a more reasonable price than the LCD and especially the OLED camps can.
We have covered these LCD technology advancements in the past, but this seems like a good time for a refresher course. After many years of writing stories telling people how to choose between plasma and LCD, I guess it's now time to write a story about how to choose the right type of LCD for you, depending on what level of performance and what price point you seek.
Arguably the single most important decision you can make when selecting an LCD TV is the type of lighting method it employs. Unlike plasma and OLED technologies that are self-emitting (each pixel generates its own light), all LCD TVs require an external light source, and this "always on" light source is the reason early LCDs always struggled to compete with plasma in the important area of black-level performance.
For many years, the primary LCD light source was a cold cathode fluorescent lamp (CCFL), but now the industry has shifted to the use of LEDs. CCFL-based LCDs are growing increasingly rare; many LCD manufacturers have gotten rid of them entirely, but some continue to offer them at the very bottom of the price chain. CCFL-based LCDs are the least energy-efficient, they contain undesirable mercury, and they cannot be precisely controlled the way an LED-based LCD can.
In the LED realm, you have a choice of three different lighting methods. The best and most expensive method is the full-array LED backlight with zone dimming. As the name suggests, this method puts a lot of individual LEDs on a grid behind the LCD panel and divides them into zones. The brightness of each zone can be independently adjusted to suit the image being displayed. For instance, if the image is of a bright moon hanging in a dark sky, the LED zone(s) behind the moon will be brightly illuminated, while the rest of the zones can be completely turned off to reproduce a true black. This allows the image to have much better blacks and contrast than an LCD TV with an always-on backlight.
The drawback is, because the number of LEDs is not a 1:1 ratio with the number of pixels, this lighting method is not as precise as what you can get with self-illuminating plasma and OLED pixels. In the black area just around the bright object, you might notice a glowing or halo effect. The higher the number of dimmable zones the TV has, the more precise the dimming will be. Usually, the more dimmable zones the TV has, the more it will cost. As an example, Vizio will offer full-array LED backlighting in all of its LCD TVs this year; the entry-level E Series has only 18 dimmable zones, while the top-shelf Reference Series has 384 zones.
The second and most popular method over the past couple of years is the edge LED lighting method, in which the LEDs are placed only around the edge of the screen, and the light is directed inward to cover the entire screen area. This design allows for a much thinner, lighter cabinet and is the most energy-efficient. However, this method can also lead to noticeable problems with brightness uniformity around the screen. Put up an all-black test pattern or even just a generally dark image, and you can see that some areas of the screen are clearly brighter than others (some people call this clouding, as the image does indeed look cloudy). There is often obvious light bleed near the edges and corners of the screen.
The more expensive edge-lit LED TVs may include a form of zone dimming. Obviously, since the LEDs are located only around the edges, this dimming is even less precise than what you get in the top-shelf full-array LED models, but it can help minimize issues of brightness uniformity and light bleed. Frankly, I would never buy an edge-lit LED that lacks zone dimming, as I find brightness uniformity issues to be an absolute deal-breaker for movie watching. But, if you primarily watch brighter HDTV/game content and few movies, then you might choose to save money and get an edge-lit LED-based model without the dimming.
Finally, some LCD manufacturers use a lighting method called Direct LED, common in smaller-screen TVs and lower-priced large-screen models. Direct LED uses a backlight grid like the full-array approach, but it does not use as many LEDs and does not include the zone dimming. As a result, the picture may not be quite as bright, and the black level can't get as dark. Additionally, the cabinet design is usually a little thicker and heavier than the edge-lit approach. Still, screen uniformity can actually be much better, so it's not necessarily a worse choice to go with Direct LED over edge LED.
Continue on to Page 2 to learn about the Panel Type, Refresh Rate, and Other Factors . . .