Choosing Plasma TV or LCD TV

30 April 2007 No Comment

OK, so you know nearly everything there is to know about HDTV. Before you choose which model is right for you, though, there’s just one more question that needs to be answered: do you choose a Plasma model or an LCD model? Well, again, the choice isn’t easy, but here are some of the things you need to look out for when making your decision.

Plasma vs LCD technologies

Samsung Plasma HDTV
A Plasma TV (above) uses a matrix of tiny gas plasma cells that emit light of varying colour when a charge is passed through them. In contrast, an LCD TV (below) uses liquid crystals squeezed between two glass plates, which again emit light of varying colour when an electrical charge is passed through them.
Samsung LCD HDTV
Both technologies, therefore, rely on similar principles (pass a charge through a pixel to display the appropriate colour in the appropriate place), and although the resultant TVs look similar as you can see from these pics, the different types of material used (gas plasma versus liquid crystal) lead to quite different operating characteristics.

Viewing Angle

Most plasma TVs offer viewing angles of up to 160 degrees, whereas LCD TVs offer 175 degrees. However, this difference, in practice, is negligible, and both technologies are improving all the time.

Screen Refresh rate

This is extremely important. A low screen refresh rate will not be able to display fast moving images correctly, with the result that each image will leave a ghost-like trail behind it. This is bad enough when viewing TV, but unbearable when playing games. Generally speaking, Plasma TVs have a refresh rate equivalent to standard CRT TVs, and so don’t suffer form this problem. LCD TVs, however, used to suffer alarmingly from it, but the situation is changing now. Look for a refresh rate between 5ms – 15ms: anything higher will produce poor results.

Burn in

Certain items on screen may persist in the same place for long periods of time. The logo of the channel you’re watching, for example (what’s known as ‘furniture’!), or the score of the football match, or even the dashboard of a driving game.

Because these images persist in the same place, the pixels that display this image have to maintain the same intensity without change for long periods of time. After a while, the pixels effectively weaken, and will display a ghost-like rendering of the image even when it’s no longer being displayed.

This is known as burn-in, and used to be the bane of the Plasma TV owner. Happily, it’s not such a problem these days, as technologies such as ‘pixel orbitor’ have resolved it. Always best to check that your shiny new Plasma TV comes with such technology before buying it, though.

LCDs have never suffered from burn-in issues, as they were designed originally for PC monitors (which, as a rule, display mostly static images). However, they can suffer from stuck pixels, which is where a pixel retains one colour and refuses to change. This is less of a problem with more expensive models, though (you gets what you pays for!).

If you’re looking play video games on your new HDTV, it’s best to stick with LCD, as games can still cause burn-in on Plasma TVs.

Contrast and Brightness

One of the things that gives HDTV its clarity is contrast – the difference between pure black and pure white (and all the shades in between, of course). A higher contrast ratio will make the image appear almost 3D in character, with super-vivid images seemingly jumping out of the screen at you. The result is what some people have called looking through a window, rather than at a TV screen.

Traditionally, Plasma TVs had the edge here, as a TV can’t produce a black pixel: it simply passes no electrical charge through it. Thus, the black of a pixel is dependent upon how much light leaks through it. With Plasma TV, there is no light, whereas with LCD, there is always the ambient light from the backlit nature of the technology.

However, in practice, LCDs may just have the edge, as Plasma TVs have a glass surface that reflects light – and as it’s the absence of light that renders a black pixel, and light seemingly coming from the pixel will make it appear grey instead.

In general, both technologies should produce exceptional results, but CNet recommends Plasma for true home theater (and assuming you turn the lights off!). When it comes to choosing the spec, you should look for high contrast ratios – 15,000:1 and above is exceptional, but 10,000 still brings superb results.

Lifespan

LCDs tend to last longer than Plasma TVs. The typical death-spiral of both types of technology is that the screen will get less and less bright over time, until it becomes too annoying to watch comfortably (and you’ll certainly lose all the detail you spent your hard cash on to see in the first place).

That said, both technologies are making enormous improvements, and although LCD TVs have a half-life (i.e. the length of time before its brightness is half that at what it was when you bought it) of some 60,000 hours, Plasma TVs have a half-life of 30-60,000 hours. Pound for pound, an LCD TV will always last longer than a similarly-priced Plasma TV. However, to put this into perspective, your average CRT TV will last for 25,000 hours, and 30,000 hours is still on average over 16 years of use!

Screen Size

Plasma TVs tend to range from between 32 – 63 inches, with super-huge (and super-expensive) models weighing in over 100 inches of viewable pleasure. In contrast, LCD TVs range from between 13 – 43 inches, and although you can get LCD TVs that are bigger than 100 inches, they’re rare and even more expensive than they’re Plasma counterparts.

However, the size of Plasma TVs seems to have peaked, while LCD TVs keep on increasing (and decreasing) in size, so it may be that LCD TVs will catch up with and eventually overtake Plasma TVs in the size stakes.

Resolution

Resolution is the number of pixels available on the screen. In order to enjoy full HDTV, you’ll need at least 1280 x 720 pixels (even higher if you want to watch 1080i/p pictures in their native resolution). Most 50 inch and up Plasmas, and nearly all 26 inch and up LCD TVs offer this resolution, but it’s worth checking for before buying your HDTV, just to make sure (after all, there’s no point in buying an HDTV if you can’t actually watch proper HDTV on it!)

Cost

Ah, the most important factor of all! Which technology offers the better value? This used to be Plasma TVs, with LCD TVs being significantly more expensive than a similarly-sized Plasma model. However, increasing competition has changed all this, and now both technologies are roughly comparable.

That said, Plasmas are still cheaper for bigger screens, but take into account the fact that shipping an Plasma TV is more expensive than shipping an LCD TV, as Plasmas are more fragile, and hence need more sophisticated handling.

Note also that Plasmas are much heavier than LCD TVs, and so may need specialist installation, particularly if you want to hang a big Plasma screen on the wall.

Keep an eye on this, though, as the competition isn’t over yet (not by a long way!), meaning that both types of technology will shift in price significantly over the coming years.

 
  1. 1). HDTV Formats and Resolutions
  2. 2). HDTV Connections – from HDMI to Composite Video
  3. 3). HDTV Sources – Hi-Def DVD players, Games Consoles, Cable and Internet
  4. 4). HDTV Aspect Ratios – Hi-Def DVD players, Games Consoles, Cable and Internet
  5. 5). HDTV Plasma TVs vs HDTV LCD TV – which is best?
  6. 6). HDTV Info Summary
 

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