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Wednesday, February 28, 2007

Up until about a decade ago it was really easy to select a television set. That's because there was only a limited number of technologies to choose from. There was basically the cathode ray tube which functions by firing electrons through a vacuum and onto a screen that turns them into light of different colors, thus creating a television picture made out of pixels. Only a decade or two ago, the cathode ray tube was the only real option and with it you didn't even have to decide whether you wanted black and white or color, because black and white had already been phased out. That left screen size as the only consideration, and that was largely determined by your budget. Now, in the twentieth century, the cathode ray tube is still in existence (although in all likelihood it will be phased out by the end of the current decade), but it's joined by a wide variety of other television technologies that make the act of choosing a television set much more complicated than it used to be. Now, in addition to the cathode ray tube there are essentially two kinds of TV sets: flat screens and projection screens.

Flat screen TV's are the most popular and stylish television sets available these days. They consist primarily of Plasma screen TV's and LCD screen TV's. Plasma screen TV's are made up of microscopic pockets of gas- one pocket for each pixel- that emit light at different wavelengths when an electrical current is applied to them. The color of light that they emit is determined by the voltage applied to the gas pocket. Plasma screens tend to have incredibly intense color and don't have an upper physical limit on the size of a screen that can be constructed, but don't look as good in higher ambient light levels, tend to wear out faster than other technologies, consume a lot of energy, and tend to make a buzzing sound at altitudes in excess of six thousand feet.

LCD screens are the other leading flat screen technology. LCD screens consist of a transparent film of electro-reactive crystals overlaying a bank of fluorescent lights. When an electrical current is applied to the crystals they change shape in different ways that filter the light behind them. Different colors of the light are allowed through depending on the shape of the crystal. LCD displays are less expensive than Plasma screens, energy efficient, good for displaying computer desktops, but tend to blur fast moving images because of delays in the time needed for the crystals to react and have an upper physical limit in size.

Projection screens can use LCD technology or DLP technology. In the case of LCD projection screen televisions, the image is produced just like a flat screen image, but is then projected onto a larger screen by back lighting. LCD projection screens have the benefits and detractions of a flat screen LCD display, but have fallen out of favor because of their bulk. DLP screens are known for incredible range of colors and don't have the blurring problems of LCD screens, but are also extremely bulky.

Hopefully this article provides good general background on various types of newer television technologies.

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