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LCD TelevisionsLCD displays use an array of liquid crystal elements to create the image; a backlight creates the light, and the display uses the liquid crystal elements to control how much light passes through tor each the viewer. LCD technology is cheap to manufacture and is relatively energy efficient, making it very popular in HDTVs and other display devices such as computer monitors and cell phone displays.The display passes an electrical signal to each liquid crystal on the LCD display that controls how much light can pass through it, thus controlling the brightness. Each liquid crystal elements can be individually controlled, and color is produced by using filters on the individual liquid crystals. LCD televisions group three elements (for red, green and blue) together to form a singl pixel. By moderating how much light is allowed through each of these three liquid crystals, any one of the pixels can produce any color in the spectrum. There are various negatives to LCD displays. One of the problems is that it takes a certain amount of time for each individual liquid crystal to change the amount of light that is let through. This can result in ghosting on the display as the crystals lag behind the image, especially in fast action sequences that change quickly. Another problem with LCDs is viewing angle. Each liquid crystal can be thought of as a small pipe that lets light through from the backlight. As the viewer moves off from right in front of the display, less light reaches them. Other technologies, like Plasma, create the light closer to the screen, with the result that the light exits the pipe at a wider angle than an LCD allows. LCD displays also have trouble producing blacks as deeply as other technologies like Plasma. This is because the backlight on the LCD is always on, so some light always escapes even when the individual pixels are showing black. Some manufacturers are attempting to address this issue by using multiple backlights and dimming them selectively, but because the number of backlights is nowhere close to the total number of pixels this local dimming is imprecise. LCD dispays do have several benefits, for example they are not susceptible to the phenomenon known as burn-in where a "ghost" of an image can remain on the display even after it has been changed. This makes LCDs a good choice if you are going to be displaying a static image for an extended period of time. LCD displays are also capable of producing a very bright image, especiallly compared to Plasma televisions. Finally LCD televisions are relatively inexpensive to produce, something that has vaulted them to a dominant position in the HDTV market.
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