Plasma

Plasma HDTVs have generally been a more expensive technology than LCD displays,
but this gap is shrinking. Plasmas offer benefits like darker blacks
and more accurate colors over LCD displays, but are generally not as
bright and have their own set of issues.

Plasma displays are made up of many small cells that are filled with
gas, typically neon and xenon. High voltage electrical impulses are
used to excite this gas, which produces the state called Plasma from
which the displays derive their name. As a plasma is produced, it
releases electrons that then excite phosphor materials that line the
cell, which produce the red, green and blue lights that are used to
create an image. Three cells, one for red, green and blue, are grouped
together to form a single pixel on the display. By modulating the
electrical impulse to produce brighter or dimmer combinations of these
three colors Plasma displays can produce any color in the visible
spectrum.

Because they lack the backlights that LCD displays use, Plasmas are
able to produce much deeper blacks and a higher contrast between the
darkest black and brightest white. This also helps them produce more
accurate colors. The negative to Plasma displays are that they cannot
get as bright as LCD displays, and they use a lot of power. The two are
related, for example if you are looking at an all white display on a
Plasma you’ll notice the brightness drops significantly, this is
because the television has reached it’s maximum power draw and is thus
unable to produce the maximum level of brightness across the entire
screen, a phenomenon known as White Falloff. Plasma displays are also
susceptible to  burn-in: if a static image is left on the display
for long periods of time, it can result in a “ghost” effect as the
burned in image remains visible even after the display has switched to
another image.

Due to the more difficult construction of Plasma displays, they have
generally been relagated to larger, more expensive HDTVs.  But as
costs have come down, we are beginning to see smaller Plasma displays
and they have become more competitive with LCD displays in that market.