Plasma TV Systems
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 colours 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 colours Plasma displays can produce any colour 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 colours. The negative to Plasma displays are that they cannot get as bright as LCD displays, and all of that plasma gas means that the displays can get very hot if they are showing a lot of white. So they do not melt, most displays turn down the brightness as they show more white (called white falloff). This means that if you are watching TV in a brightly lit room they will be more difficult to view, so if you show a lot of white screens (such as PowerPoint presentations, or documentaries on polar bears), they will look paler than their LCD cousins. 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.
Plasma TVs are much smaller than their rear projection cousins. And because they create the light in the image in the panel itself, they usually have better viewing angles than LCD displays.
Due to the more difficult construction of Plasma displays, they have generally been relegated to larger, more expensive TV sized. 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.