HDTV The Pros and Cons

HDTV - The Pros and Cons of Plasma, LCD and DLP HDTVs

HDTV expands consumer choices from the traditional CRT and rear projection. To these, now vastly improved, types it adds Plasma, LCD/LCoS and DLP. All have their strong points and drawbacks.

CRT

Traditional CRT (Cathode Ray Tube or 'direct view') works by shooting electrons at a screen. The electrons from the gun get pushed around by magnets, 'painting' the screen by illuminating lines of pixels (short for 'picture elements').

In the case of HDTV there are commonly 1,080 lines and the entire screen is formed from 1920 by 1280 pixels. There are lots of varieties, including those with only 720 lines and smaller numbers of pixels.

Newer HDTV-style CRT models offer the same great pictures - deep, sharp blacks, excellent contrast, even richer and more realistic looking color, along with the enhanced resolution of HDTV. Better resolution translates to a sharper picture.

Those traditional strengths come with some trade-offs. CRT tubes can only be made so thin before the edges of the picture become fuzzy. Though some current sets have shallow tubes, they are still deeper than flat panel TVs. Even shallow tubes are around 14" deep.

The largest screens are limited to about 38". And the larger the CRT, the heavier and bulkier they become. Most CRTs are at least 20" (51cm) deep and weigh up to 200lbs (91kg).

Plasma

One of the cleverest design ideas, plasma TVs produce an image by passing a current through a gas held between two glass screens. The electricity causes the gas to glow in a way similar to fluorescent tubes.

The screen size generally starts where CRTs leave off at 38", and can be as large as 62". Most are made in 'thin-profile' style, only a few inches deep. They're both lightweight and thin (relatively), making it possible to hang them on the wall. You can recreate the movie theater atmosphere and free up floor space.

But, though prices have fallen in the last year, they are still on the high side and quality is very mixed. Good sets will still cost upwards of $5,000 or more. Even then, contrast ratios (the difference between dark and light across the screen) are rarely as good as a high-quality CRT.

Newer models have less difficulty with burn-in. 'Burn-in' results when a static image, such as the broadcaster's logo, stays on the screen for long periods. The image then never fades. Still, consumers need to be wary.

Nevertheless, spend enough and you'll get one of the most spectacular pictures available in a large screen.

LCD/LCoS

Liquid Crystal Display (or Liquid Crystal on Silicon) TVs operate much the way a laptop or flat-panel computer monitor screen does. It passes current through a series of rectangles.

Most TVs, though, suffer from the same problems as monitors. Blacks aren't black enough, contrast isn't high enough and viewing is generally limited to a smaller angle than other types.

But in the more costly models, most of these problems have been overcome to a large degree. Picture quality can be outstanding and they don't suffer from burn-in problems.

DLP

Digital Light Processing is a rear-projection technology that - in most commercial sets today - ranges in size from 40" to 80". They frequently have replaceable lamps and offer excellent picture quality in a flat-panel arrangement.

They are often less costly than other HD sets and (with the micro-projector type) don't suffer from burn-in problems.

Fortunately for those considering an HDTV purchase, prices have fallen over the last year and continue on a downward trend. But don't wait too long. By Feb 17, 2009 all broadcasters will discontinue analog (standard TV) broadcasts and switch completely to digital. Sometime before that happens, prices are likely to spike.

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