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March 2006

This chapter is from the book

SATURDAY/SUNDAY: MARCH 11/12, 2006

THIS WEEK’S FOCUS: Choosing a Big-Screen TV

LCD FLAT-SCREEN DISPLAYS

If you’re worried about plasma burn-in, consider an LCD flat-panel display instead. LCD technology—which is the same technology used for flat-panel computer displays—doesn’t suffer from any burn-in or ghosting and is becoming a viable alternative to other display technologies.

Like a plasma display, a flat-panel LCD display uses transmissive light technology. A typical LCD display contains hundreds of thousands of individual pixels; each pixel has three subpixels with red, green, and blue color filters.

Every pixel in an LCD display contains a liquid crystal suspension sandwiched between two panels of polarized glass or plastic. The panels are polarized at right angles to each other. With no voltage applied, the individual liquid crystals are naturally twisted; light passes straight through the liquid crystal layer and the pixel appears to be transparent. When electric current is applied to an LCD pixel, the individual liquid crystals untwist and align in the same direction, which changes the angle of the light passing through the liquid crystal layer. The result is that no light passes through this pixel, making it darker than surrounding pixels. By varying the voltage applied to each pixel, the brightness of each individual pixel (and color subpixel) is thus controlled, resulting in a pattern of bright and dark pixels that creates the overall picture.

In addition to the benefit of not having a burn-in problem, LCD displays are also lighter and use less energy than comparable plasma displays. On the downside, LCD displays are still a little more expensive than plasmas (although that’s changing), and have slightly lower contrast and black levels.

ON THIS DAY: LUDDITE RIOTS (1811)

On March 11, 1811, the Luddite riots began in Nottingham, England. The riots started when a group of disaffected laborers attacked a factory, destroying the machines they feared would replace them. The term Luddite has since come to symbolize those who are opposed to all technological change.

BLOG OF THE WEEK: HOME THEATER BLOG

Keep abreast of all the latest developments in the home theater field at the Home Theater Blog. Check it out at http://www.hometheaterblog.com.

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