Both television technologies use discrete picture elements to form an image. The cells in a plasma television contain an inert gas that is trapped between two glass plates. At the rear is an electromagnetic exciter, which heats the gas until it ionizes and emits UV radiation. A phosphor coating on the front plate glows with the appropriate colour. Liquid crystals are diodes that darken when an electrical voltage is applied. Picture elements are placed behind a coloured filter and a control voltage is used to change their level of darkness, from transparent to fully opaque. Light is provided by a bulb mounted behind a diffuser. Both technologoes can experience cell failures. Cells burn out in plasma displays or become 'stuck' in LCD displays. Both respond fairly slowly to rapid changes in image content. Both have poorer contrast ratios than CRTs. Plasma displays may be more fragile than LCDs and they consume more power. LCD displays tend to have larger picture cells, which may make the image appear 'coarse' on close viewing. The bulbs in an LCD display will age and fail and some are quite expensive. Flourescent bulbs are often used nowadays, but they emit light at very specific frequencies - they are not evenly white - and this can cause the colour balance to be incorrect. (This is same problem that occurs when taking photographs under flourescent light.)

Plasma Now, LCDs Later At the moment, vendors of large LCDs simply can't compete on price. It's also because plasma screens don't have the response-time issues that make LCDs less than optimal for moving images such as video or games. The principal drawback of previous-generation plasma screens--the tendency of stationary images to burn in and produce permanent ghosting--has diminished greatly in newer products. NEC, for example, has developed technology to deal with the problem by moving stationary pixels just enough to prevent such burn-in, Giazzon says. But LCDs have some advantages over plasma, Giazzon adds. If you're contemplating a home entertainment setup involving a PC--perhaps running Windows XP Media Center Edition--or other activities involving text as well as graphics, you'll get a crisper, brighter image from an LCD. LCD TVs weigh 10 to 15 percent less than plasmas of comparable size. They often look better in daylight than plasmas, though Steudle concedes that plasmas have a brightness advantage at night. As for response time, Steudle says that it will drop from today's 25 milliseconds (and in newer units, 16 milliseconds), to less than 5 milliseconds in 2004. Stanford Resources' Dash expects LCD TV sales to grow tremendously over the next few years, to 9 million in 2005 and to over 18 million in 2006. But while larger-format LCD TVs will increase in popularity in the second half of the decade, she doesn't anticipate that they will kill off plasmas. http://www.pcworld.com/news/article/0,aid,107907,00.asp

Outward appearances are definitely deceiving when it comes to LCD and Plasma televisions. Although both types of televisions are flat and thin, they employ different technology in an attempt to deliver similar results. Plasma TV Overview Plasma television technology is based loosely on the fluorescent light bulb. The display itself consists of cells. Within each cell two glass panels are separated by a narrow gap in which neon-xenon gas is injected and sealed in plasma form during the manufacturing process. The gas is electrically charged at specific intervals when the Plasma set is in use. The charged gas then strikes red, green, and blue phosphors, thus creating a television image. Each group of red, green, and blue phosphors is called a pixel (picture element). Although Plasma television technology eliminate the need for the bulky picture tube and electron beam scanning of traditional televisions, because it still employs the burning of phosphors to generate an image, Plasma televisions still suffer from some of the drawbacks of traditional televisions, such as heat generation and screen-burn of static images. LCD televisions, on the other hand, use a different technology (see also question #1 for this same explanation). Basically, LCD panels are made of two layers of transparent material, which are polarized, and are "glued" together. One of the layers is coated with a special polymer that holds the individual liquid crystals. Current is then passed through individual crystals, which allow the crystals to pass or block light to create images. LCD crystals do not produce their own light, so an external light source, such as florescent bulb is needed for the image created by the LCD to become visible to the viewer. Unlike standard CRT and Plasma televisions, since there are no phosphors that light up, less power is need for operation and the light source in an LCD television generates less heat than a Plasma or traditional television. Also, because of the nature of LCD technology, there is no radiation emitted from the screen itself. Plasma vs LCD The ADVANTAGES of Plasma over LCD are: 1. Larger screen size availability. 2. Better contrast ratio and ability to render deeper blacks. 3. Better color accuracy and saturation. 4. Better motion tracking (little or no motion lag in fast moving images). The DISADVANTAGES of Plasma vs LCD include: 1. Plasma TVs are more susceptible to burn-in of static images. 2. Plasma TVs generate more heat than LCDs, due to the need to light of phosphors to create the images. 3. Does not perform as well at higher altitudes. 4. Shorter display life span (about 30,000 hours or 8 hrs of viewing a day for 9 years) than LCD. However, screen life span is improving to as high as 60,000 hours. due to technology improvements. LCD television ADVANTAGES over Plasma include: 1. No burn-in of static images. 2. Cooler running temperature. 3. No high altitude use issues. 4. Increased image brightness over Plasma. 5. Longer display life (about 60,000 hours - at which time all you may need to do is replace the light source, not the entire set). This can vary according other environmental and use factors. 6. Lighter weight (when comparing same screen sizeds) than Plasma counterparts. DISADVANTAGES of LCD vs Plasma televisions include: 1. Lower contrast ratio, not as good rendering deep blacks. 2. Not as good at tracking motion (fast moving objects may exhibit lag artifacts) - However, this is improving. 3. Not as common in large screen sizes above 42-inches (although the number is growing). 4. Although LCD televisions do not suffer from burn-in susceptibility, it is possible that individual pixels on an LCD televisions can burn out, causing small, visible, black or white dots to appear on the screen. Individual pixels cannot be repaired, the whole screen would need to be replaced at that point, if the individual pixel burnout becomes annoying to you. 5. LCD televisions are typically more expensive than equivalent-sized Plasma televisions, especially when comparing EDTV Plasmas to HDTV-LCD Televisions. http://hometheater.about.com/od/lcdtvfaqs/f/lcdfaq2.htm

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