LCD vs. Plasma (Not that it matters…)

 

LCD or Plasma? Television prices have been steadily dropping for the last several years, and two basic types of TVs has emerged- LCD, or Liquid Crystal Display, and Plasma. The two technologies couldn't be more different, and each has its own strengths and weaknesses...

THE BOTTOM LINE Let me answer the most important question first. In my opinion, either type of TV will impress you. I've seen both and High Definition video on either display type is stunning. The BIG difference, generally speaking, is that below about 40" diagonal the LCDs are more affordable while above 40" the plasmas are a better price. So, if you'd rather forgo all the anguish of having to make the best choice, just top reading and go buy a TV- either kind. Go read *this* article to learn about important features to look for in a TV.

THE BASICS Pixels Before looking at the difference between the two technologies, you need to understand that modern television images are made of pixels. If you look at a TV image with a magnifying glass, you would see that the picture is made of small blocks or tiles that look a lot like a checker board. But instead of being only red and white, the pixels can be any color in the rainbow. Of course, color theory tells us with just red, green and blue light, any other color can be made.

Contrast Ratio   This is a number that tells how bright and dim a pixel can get. Its not something you normally notice until to look for it, but black on a TV isn't completely black. Because of manufacturing limitations, its really hard to turn a pixel (one square on the checkerboard) completely off. There's more on this later. Just remember this, the contrast ratio is really saying how "black" can a pixel be. Ultimately, a higher contrast ratio results in brighter looking colors and a generally more vivid looking image.

LCD LCD, or Liquid Crystal Display, TVs make a color by filtering the desired color. Imagine that the checkerboard is semi-transparent with a white light beneath the board, and that each square can change colors. That's how LCD works. Now, thinking of the LCD TV as a back-lit semi-transparent checkerboard, these are the problems. Currently, its just not possible to make each of the squares touch completely. There is a small gap running between all of them letting some of the white back-light shine through. That means a black screen isn't completely black. The small bit of light shining through sort of washes out colors, making them not quite as vibrant resulting in a lower contrast ratio. Second, the color of a square can't instantly change color. It takes some time, or at least more time than a plasma display. That means motion video can look blurred, but only a little. 5 years ago, it was noticeable, but not in modern LCD displays. Third, the image on an LCD is best when you're standing right in front. Further off to the side, the image isn't quite as good. The pixels that comprise an LCD image have gaps that let some light leak through, even when the pixel is off. This lowers the contrast ration of the image. On the other hand, LCD displays can be brighter and use less electricity than plasma. And, the newer "LED" LCD displays can adjust the brightness of small sections of the back-light to be brighter or dimmer to compensate for the gaps. This results in a higher effective contrast ratio, which should not be confused (though LCD manufacturers would like you to be) the contrast ratio. By compensating sections of the back-light brightness to the image, certain images will look much better, but not all. Think of the effective contrast ratio as your math exam after the grade has been curved. But think of contrast ratio as the original grade. One looks a little better than the other.

PLASMA Plasma TVs make a color by emitting the desired color. Imagine that the each square in the checkerboard is an individual light that can shine any color it wants. That's how Plasma works. Just like older "tube" type TVs, plasma TVs use glowing phosphorus powder and generally speaking they just don't glow as brightly as LCDs. Further, as you'd guess, with use the phosphorus degrades, shining a little less brightly. A phenomenon call burn-in occurs when certain parts of the screen are made to shine more brightly than others over a long period of time (it takes hours if not days). 5 years ago this was a problem if, for example, you played a video game on a plasma TV for several days at the time. Because certain parts of the game (like maybe a scoreboard) doesn't move, those pixels aren't being used randomly like the others and so will be used at a slightly different rate, and eventually it gets "burned in" to the screen. Its the same effect (though momentarily) your eyes have after looking at a bright light. The "image" of the light is temporarily sort of "burned" onto your retina, and everything you look at is imprinted by the light. But modern plasma displays simply don't have the burn-in problem any more. In addition, because plasma pixels can turn off and on so rapidly, there is less blurring with rapid motion video than on an LCD display. And, because the pixels on a plasma can turned more completely off, they have a higher contrast ratio.

BOTTOM LINE There are other minor differences I haven't discussed, and the web is full if articles that go into a lot of details, but I'm telling you, there's just not a lot of difference. Now, don't misunderstand. There are good and bad manufacturers thus good and bad TVs, but the underlying technology has been so well refined that the question of LCD or plasma just isn't important.