Kamis, 02 Juni 2011

Reviews; Plasma vs LCD

It’s one of the questions we’re asked most oft en. No, not “Will you fi x this?” or “What’s the matter with Apple products?” This is a much bigger query, one we’ve hotly debated among ourselves, one that can divide friends and family. That’s right: LCD versus plasma. Which is the better display technology? While either will provide you with a picture, we know you want more than that. Having just weighed and debated this very question in order to pick out the best HDTV for the latest issue of Maximum Tech (on newsstands now), we figured we’d set the record straight here.

While early plasma screens often had a problem with burn-in, plasma manufacturers have found various ways to reduce the problem—using pixel orbiters to move a static image around slightly to reduce burn-in, using gray pillar boxes instead of black, and (in case of charge build-up) image-washing routines that can reset temporarily built-up charges. That’s not to say burn-in—and charge build-up, its less-temporary cousin—don’t still occur on plasma screens. We saw charge build-up in our testing of Samsung’s PN50C8000 plasma screen, but we didn’t notice any signs of burn-in in the Panasonic TC-P50VT25. On the other hand, the backlights in LCDs have been known to change a screen’s color spectrum over time—ultraviolet emissions from coldcathode fl uorescent lights can cause yellowing in the internal components, while the LEDs in more modern LCDs can age at different rates, causing uneven brightness. Fortunately for (some) LCD owners, the backlight can sometimes be replaced, giving the screen a new lease on life. Plasmas, because they use gases that deteriorate over time, don’t have the option of a replacement backlight. Either way, there’s no need for distress as most displays possess a half-life of 60,000 to 120,000 hours. Since eight hours a day would be only 3,000 hours per year, both formats start out with a decent expected shelf life.

In our recent side-by-side comparison of a plasma and LCD HDTV, we couldn’t help but notice that the colors on the LCD looked oversaturated next to the plasma screen—something that has been reproduced in other side-by-side tests where LCDs were seen to produce warmer, redder shades than plasmas.
In both types of displays, each pixel is comprised of red, green, and blue sub-pixel elements that work in conjunction to create millions of colors. In a plasma screen, each pixel is a little chamber that contains a tiny bit of charged plasma, which emits light that varies in color and intensity based on the voltage applied to the plasma cell, enabling precise brightness control. LCDs, on the other hand, reproduce colors by using polarized fi lters (in the form of liquid crystals) to block light from the backlight from reaching sub-pixels the screen won’t be showing, which is a more challenging way to produce accurate colors, since it works by subtraction rather than addition.

It’s well known that plasmas beat out LCDs when it comes to producing true, deep black—we’ve seen the proof during testing time and time again. Picture two fl ashlights. One is off. The other is on, but has a piece of black construction paper over the lamp. Which one will look darker? Since pixels in a plasma display are powered individually, a black pixel is “off”—it draws no power and emits no light. A “black” pixel on a CCFL LCD, on the other hand, remains “on”—the backlight is on, but the polarizing fi lter is blocking as much light as it can. Some light still leaks through, creating washed out, grayish blacks.
Newer LED-backlit LCDs can actually turn off portions of the display backlight, as well as automatically reduce backlighting on dark scenes, producing increasingly impressive black levels and contrast, but plasma screens still produce a better, darker black.

LCDs get the short end of the stick here, as they typically have poor offaxis viewing thanks to the polarized filters they contain, which cause black levels, color, and brightness to change when you move away from a front-and-center position. Testing done by Dr. Ray Soneira of DisplayMate (www.displaymate.com) showed noticeable picture degradation at +/- 10 degrees away from center on an LCD screen, while plasma screens performed significantly better, showing virtually no change while being viewed from +/- 45 degrees.

At the middle of the size range, the playing field is nearly level—below 42 inches or so, display prices for LCDs and plasma displays are within a few hundred dollars of each other. At the high end, though, plasmas become a better deal—the bigger the display size, the more likely you are to be able to get a plasma TV for less money than a same-size LED LCD. It’s worth noting that life span does play a part here, since some LCDs can get a new lease on life via a backlight replacement, while plasmas cannot, as the gases in them simply deplete and can’t be replaced. If you’re into getting the biggest bang for your buck and you want to go large, go plasma. At smaller screen sizes, though, LCDs are more competitive.

And the Winner Is...
Plasma TVs wound up the victor, and this Deathmatch proves why. Plasmas offer better blacks, more accurate colors, and a wider viewing angle. At larger sizes, they’re also the less expensive option—though potential burn-in and shorter life span are disadvantages. LCDs are definitely still in the race, especially given the trend toward LED backlighting, which removes some of the inherent disadvantages. For now, though, we’re all about plasma.

2 komentar:

nice review,, maybe I should try this someday :D

thank for the visit bro,,,
have a nice day

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