Plasma vs. LCD: The State of the HDTV

The ongoing clash between plasma and LCD HDTVs (or rather, their owners) rivals classic tech wars such as Apple versus Microsoft and Nintendo versus Sega in its ability to destroy friendships and alienate loved ones. As with any good tech fight, however, the skirmishes that occur in review comments and home theater enthusiast forums across the Internet are typically characterized by fans exchanging glib one-liners (in this case, about black levels and refresh rates). And many of those one-liners haven't been updated since 2002.

Don't buy a new TV based on outdated information. Here's where plasma and LCD HDTVs stand today.

Blacks, Brightness, and LEDs

Panasonic's 42-inch TC-P42G25 plasma HDTV.
Traditionally, plasma displays have been able to produce higher contrast levels, meaning that their blacks are blacker and their whites are whiter than those of their LCD brethren. This point is particularly important for TV and movie enthusiasts, since you're not going to see too many dimly lit scenes watching Monday Night Football.

It shouldn't matter what you watch, though--in theory, since the human eye has more light-sensitive photoreceptors (rods) than color-sensitive photoreceptors (cones), we're drawn to displays with higher contrast ratios no matter what material we're watching.

The reason plasmas were able to achieve better blacks in the past was that they were better able to control how and where the display was lit than their LCD-based rivals, which used cold cathode fluorescent lamps (CCFL) behind the LCD layer to light the display and couldn't completely block that light out when displaying a black scene.

Enter the LED-backlit LCD, which has made a tremendous splash in the HDTV market over the past two years. LED-backlit LCD TVs have several advantages over CCFL-backlit LCDs: They're thinner, they use less power, and they generate less heat.

For movie buffs, however, the most important feature is "local dimming," which lets the TV selectively turn the LEDs on and off. When an LED-backlit LCD shows a dark scene, it can turn the lighting off in the black parts of the image while leaving the lighting on for the other parts, generating deeper blacks and better contrast.

Of course, how good your screen looks depends a lot on the room you watch it in. Plasmas typically looked best in pitch-black rooms, since the nature of plasma display technology requires a glass screen, which reflects more light than a matte LCD panel. That made plasmas perfect for home theater enthusiasts, but not so great for anyone who watches TV in a room with sunlight or in a mixed-use room where the lights have to stay on.

Sharp's LED-backlit LC-52LE820UN was very reflective in dim lighting.
Sharp's LED-backlit LC-52LE820UN was very reflective in dim lighting.
These days, however, some LED-backlit LCDs use glass panels combined with a glossy coating that makes them just as hard to see in a lit room as any plasma, and in the meantime plasma TV manufacturers have been working to improve their antireflective glass panels. As a result, we can't generalize quite so easily about the two TV technologies.

PCWorld conducts TV testing in a dimly lit room, and we found that the LED-backlit Sharp LC-52LE820UN was horribly reflective, while all three plasmas we tested at the same time (the Panasonic TC-P42G25 and TC-P46G25, plus the LG 50PK950) looked just fine.

The verdict: Plasma diehards may still insist that theirs is the superior technology, and LCD fans may hail LEDs as their savior. When it came down to blacks, viewing conditions, and contrast, though, we didn't find a significant difference between the two display types as a whole, just differences between individual models.

Plasma Burn-In

The 50-inch 50PK950 by LG.
The 50-inch 50PK950 by LG.
Early plasma sets had a problem with "burn-in," where a TV that had shown a static image (a heads-up display in a video game, for example) would continue to show a faint outline of that image after the display had changed to something else. The effect appeared because the phosphors in that part of the display would overheat and lose some luminosity, producing a shadow.

Strictly speaking, burn-in is still possible in modern plasma TVs. Today's plasmas, however, use less energy than those that first hit the market, which means it's harder to overload the phosphors and cause burn-in, especially if you're using the Home viewing mode instead of the Store mode.

Even in-store display models, which often show the same image for a while on the high-intensity Store display mode, almost never exhibit burn-in. You shouldn't have a problem playing games, but it's best to be safe and turn the TV off when you're not using it--your manufacturer's warranty generally doesn't cover burn-in issues.

The verdict: Burn-in isn't as big a deal as it used to be, but it can still crop up. Turn off your plasma set when you're not watching it, and you should be fine--or buy an LCD model to ensure that you won't get burned.

In Video: How to Fine-Tune Your HDTV

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