Giz Explains LCD TV Basics

Illustration for article titled Giz Explains LCD TV Basics

If you guessed that Giz Explains Plasma TV was just the first of several TV-technology explainers, you were right. Congratulations! You win... this week's installment: Giz Explains LCD TVs. The little panels are in your phone, on your desk and maybe you're looking at one for your home theater too. Here's the quick and dirty basics.


Alright, so LCD stands for liquid crystal display. (Again, we're keeping this kind of simple, for simplicity's sake.) Basically, the liquid crystal part is a gel that sits in front of a backlight or—in the case of older panels such as those found in Game Boys up till like 2003—a reflective panel. (Remember those crappy lighting accessories?) The gel is divided up into a bunch of separate pixels, which can be fired individually. Color LCDs are a bit more complicated, made up of red, blue and green subpixels which combine to create pixels with the full range of color. To throw one more bit of tech at ya, most LCDs at this point are thin-film transistor LCDs, so that the control layer is embedded within the panel itself instead of off to the side. This provides better image stability and other benefits.

One of the problems with LCDs, and why plasma has an advantage in showing blacks, is that the liquid crystal layer is not opaque, even when all of the pixels are closed. On most LCDs, the bright backlight is on when the TV is on, so that will always bleed through at least a bit. LED-backlit LCDs can light up just a part of the panel instead of the whole thing, to an extent minimizing the problem.

Besides the "dynamic" backlighting described above, LCD technology is constantly improving its contrast through various crazier schemes involving pixel twisting and other light-blocking techniques.

The other notorious LCD problem is moton blur. If you've been buying LCD monitors for the past few years, you'll notice that advertised response times have dropped precipitously, down to as little as 2ms on some gamer-friendly computer monitors, and 6ms on big ol' TVs, so there's less true blurring of the picture. LCDs can also reduce motion blur further by processing the image: High-end LCDs use 120Hz technology to essentially double the framerate of source video, tricking the eye into seeing less blur.


Some 120Hz LCDs achieve this by tossing in a black frame of "downtime," but other sets morph two frames into a third, middle image that sits somewhere between the original frame and the next. As you might suspect, this can result in a weird, uncanny super silkiness that some reviewers object to.


Other reasons home theater buffs pick plasma over LCD in serious showdowns are that LCD naturally produces a less uniform picture and can't be seen as well (in color or brightness or both) from wide angles. LCDs can produce great pictures, and will keep getting better (LED backlights FTW), but in sets 42 inches and above, it just can't quite touch plasma, despite the fact that its cheaper pricer point has given it an overwhelming marketshare on the HDTV front.


Sony, which pushes Bravia LCD and hasn't sold plasma sets in years, is sending signals that it will soon focus on OLED instead. OLED pretty much makes both LCD and plasma look sad. They still cost a billion dollars and are a few years away, but the day of the OLED will come. [Giz Explains]



@Canoehead: Lower power consumption was a major reason I went with LCD over plasma. I also keep it on a switch to stop standby power drain.

BTW, anyone else doing this feel that standby is a bunch of crap? It's supposed to make the TV turn on more quickly, but I swear my TV turns on as quickly from standby as it does from after I turn its switch back on. If there is a difference, it's a few seconds at most. Not enough to justify a constant drain.