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RSSTulsa World
By Tulsa World, Okla.
Jul. 16--With HDTV rapidly gaining acceptance, what will happen to TVs that operate in standard definition?
Congress has mandated that all stations begin broadcasting over the air in digital high-definition by next year and cease broadcasting old-style analog programming by February 2009. After that, digital will be the only standard.
However, the change won't necessarily render all old TVs useless. ATSC tuners, or converter boxes that can translate digital broadcasts to analog, are already available.
Joe Chronister, a Magnolia pro sales associate at Best Buy Co., said his store sells only one brand of tuner, priced at $229.
"It's almost more cost-effective to buy a new TV with a built-in tuner at this point, though the price has dropped from $279 at last Christmas," he said.
Officials at Cox Communications Inc., Dish Network and DirecTV said their companies can provide receivers to allow older TVs to receive digital signals.
Customers with Cox's largest programming package already have digital receivers, said Cox spokeswoman Christine Martin.
Older televisions with the boxes won't display wide-screen or HD-quality visuals because the TVs are not capable of showing them. However, the picture quality will be comparable to current analog broadcasts.
In fact, many non-HDTV televisions sold today can receive digital broadcasts without the need for a converter box. Chronister said standard-definition televisions equipped with a digital tuner can receive HD signals, though the picture quality is not as sharp.
Currently, all new standard-definition TVs that are 27 inches or above carry digital tuners, while smaller TVs lack them, he said.
Liquid Crystal Display (LCD): LCD is used in everything from monochrome calculators to HDTVs. Thousands of tiny red, green and blue liquid crystal pixels are placed between panels of polarized glass and lighted from behind. Electrical current causes the crystals to untwist to varying degrees and allow controlled levels of light to pass through the pixel. Again, the tiny colored dots blend in our perception and form the picture. The display size is often limited by the sheer number of pixels and transistors -- a high percentage of transistors fail on the assembly line and add to the price.
Cathode ray tube (CRT): This technology is used in the vast majority of older televisions. A heated filament inside a vacuum, or cathode, emits beams of electrons that hits the back of the screen. Once hit, phosphor on the inside of the screen will glow in the form of tiny red, green or blue dots, or pixels, which blend when seen from a distance to form a picture. CRTs tend to top out at 32 inches because their weight and depth becomes too great at larger sizes.
Plasma: Thousands of tiny red, green and blue pixel cells filled with xenon and neon gas are placed next to a grid of electrodes. The electrodes knock electrons loose from the gas, causing them to emit photons of energy that light the phosphor within the pixels. Plasma screens aren't just the flattest of HDTVs -- they're relatively easier to manufacture at larger sizes.
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Source: www.howstuffworks.com
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Copyright (c) 2006, Tulsa World, Okla.
Distributed by McClatchy-Tribune Business News.
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