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.

How we select a TV at ENCO Electronics

There are numerous brands of TVs out there to choose from, and many of them are good.  But our methods of choosing a TV are all based in how TVs work.  So, to begin with, lets break a TV down into the important parts.  And for those of you who get a little squeamish when someone cracks open a nice TV, don't worry, I'll keep this simple.  The movie or sports show we see playing on a TV basically get to the TV from one of two places- your living room (DVD player, Blu-Ray, etc.) or the cable company.  Once inside the TV, the video must be processed fast to fit the screen and its characteristics.  Finally, there must be a way to control the TV- and there's way more to control than you might think.

CABLE AND LOCAL BROADCAST TV In order to display cable and off-air signals they must be converted with a tuner.  If you will be using a cable box, it will handle the task of converting the signals to something viewable.  Otherwise the TV must have a tuner.  The type of tuner gets a little complicated, but what we look for is a TV with a high-quality tuner, which you'll find in most name-brand TVs.

Before June 12, 2009, off-air signals could be broken down into just two groups or formats- analog (old) and digital (new).  At that time, local broadcasters transmitted both types.  The analog format has been around for decades and is what we grew up on.  It carries less information than the new digital format.  You could say that analog offered fewer "megapixels" than digital.  But as of June 12, 2009 all analog broadcasts have ceased.

VIDEO PLAYERS AND GAMES To understand video content from DVD, Blu-Ray, Vudu, AppleTV, Wii, XBOX, etc., you'll need a little background on audio and video formats.  Here again, there are both audio and video signals that are analog and digital.  And though there are a number of formats, we select a TV that can handle at least these video formats- composite, component and HDMI.  Depending on the application, more than one of each may be necessary.  And depending on the application, it may be important for the TV to have analog stereo, optical audio and coaxial digital audio inputs, as well as analog stereo output.

As I mentioned, the application the TV is going to be used in will determine  the number and type of inputs and outputs necessary.  In what you might call a "stand alone" application where you'll want just the TV and a few sources, but no surround sound, you'll want a TV with enough inputs for each source you want.  Most of the new non-game sources (like Blu-Ray, DirecTV, Dish Network and cable boxes) have HDMI outputs, which can handle up to 1080p.  On the other hand, most video games still offer component video.

What is analog and digital?  For anyone technically minded, there are numerous resources on the internet that deal in-depth with analog and digital concepts.  But for the rest, think of it this way.  An analog signal is kind of like two friends chatting while a digital signal is more like two lawyers negotiating a contract (but being friendly about it).  Both are communicating but the lawyers are being much more precise.  Digital signals leave no room for ambiguity.  Why haven't we always used digital if its so much better? you may ask.  The reason is that, until recently, the technology simply hasn't been available to cheaply employ digital signaling.  Further, digital signals can be compressed, so that much more information can fit into the same space.  That single ability, for digital data to be compressed, makes High Definition video possible.

Composite, Component and HDMI video?  Composite- this format uses a single wire (almost always with yellow ends) to carry basic, low resolution video.  Think VCR. Component- this format uses three wires (red, green and blue) to carry HD video up to 1080i.  Most modern games offer this format.  Think DVD and Blu-Ray. HDMI- this format uses a highly custom cable to carry digital audio and video up to 1080p.  HDMI offers the ability to encode (scramble) video making it impossible to make copies.  We hate it, but the movie studios love it.

VIDEO PROCESSING A very advanced video processor inside the TV has to manipulate the video into signals suitable for the TV screen.  A bunch of factors, including whether the display is plasma or LCD (which determines the pixel response time, tendency for burn-in, color temperature, etc.), how many pixels comprise the screen, minuscule color characteristics of the screen (sometimes each pixel!) and on and on.  This is where your money is really being spent.  A cheap processor can introduce flicker, blurring, bland colors, mosaics, jaggies, etc.  But a good processor can really make an HD picture so vivid and clear it seems to pop off the screen.  We look for TVs with great processors.  Here again, better quality manufacturers usually employ high quality processors.

THE SCREEN See *this* article for an in-depth look at plasma vs. LCD.  The resolution of the screen is important.  Generally speaking, the more pixels or dots used to make the video image, the more clear it can be.  What is resolution?  Think of it this way, image Leonardo da Vinci painting the Sistine Chapel with a great big paint brush.  That's low resolution.  Just as the size of the brush limits how detailed da Vinci can work, the size of the pixels determines how precisely an image can be displayed.

CONTROL All the other characteristics I've mentioned are generally not an issue if you use upper-end equipment.  However, even the really good TV manufacturers often fall surprisingly short when it comes to control.  Now, by control I mean turning the TV off and on, changing channels, and picking a source.  I know that's a short list and sounds so basic that it should even be considered.  Again, its beyond the scope of this article to go into a lot of details, so I'll give just one example of how important control can be. Frequently, a TV is used in conjunction with other equipment like Blu-Ray players, surround receivers, etc.  And unless you're a glutton for punishment, you want to be able to control all that gear from one simple, easy-to-use remote or color touch panel (we've got lots of those available), and NOT from five.  And one of the most important functions you'll need on that remote is the ability to turn everything on and off.  "So what?" you may ask. If you think about it, there are two ways to turn a TV on and off.  One way is with a button that, when you press it, the TV turns on; press it again and it turns off; press it again and it turns on... you get the idea.  That's known as a "toggle" function, and is horrible on an all-in-one remote- I'll explain shortly.  The other way to turn a TV off and on is with two buttons.  One button turns the TV on.  Once the TV is on, pressing this button again does nothing because the TV is already on.  The other button turns the TV off.  And again, once the TV is off, pressing this button again does nothing.  This is known as a "discrete" function. Now, imagine a surround system with a TV that offers just a toggle function, and you want to turn the system off.  You press the power button on the remote, but the TV misses the signal (yes, it happens occasionally).  Now, everything is off, but the TV is still on.  You press the power button again, now the TV is off but everything else is on.  Press the button again, and the TV turns on but everything else is off.  Its all very, very frustrating.  But, if the TV has discrete power functions, but missed the signal, just press the off button again.  All the equipment is now off.  Discrete codes make life much easier, and that's just one of the things we look for.  The point is this, all other things being equal, the gear really has to work.  It has to be easy to use.

CONCLUSION A lot goes into choosing the right TV.