Plasma: the basics
People first started using plasma TVs as far back as 1997, at which time their hang-on-the-wall design was widely hailed as the holy grail of home entertainment.
Plasma pictures are made up of individual pixels, each one of which sits at the front of a tiny chamber filed with gas (a mixture of neon and xenon). At the front of each of these chambers are phosphors, at the rear of each chamber is an electrical source. This electrical source is used to ionise the chamber's gas generating unltraviolet light which excites the phosphors into glowing in the way required by the picture. There are three sub-pixels; red, green and blue - for each plasma dot, giving you a potentially emormous pallette of colours.
Why Buy Plasma?
Grey scale response / contrast - Plasma technology can deliver superior subleties - which means plasmas can generally give you more detail in dark picture areas.
Response Times - Response time is the amount of time, measured in milliseconds, that it takes for a pixel to go from inactive to active and back again. Athough the latest LCD screens have made big improvements in this area, plasma is still considerably better, so its picture quality generally suffers less.
Size - LCD is catching up, but it's still cheaper for manufacturers to use Plasma for really big screen sizes - certainly 42in and above - than it is for them to use LCD. On the other hand, plasma isn't really viable at sizes smaller than 32in.
Viewing Angle - LCD screens frequently boast viewing angles of anywhere upto 175 degrees. But our experience suggests that these figures are very optimistic, as LCD pictures start to lose lots of contrast and colour at angles much less than than those quoted. Pretty much all plasma screens, on the other hand, retain their quality upto around 160 degrees.
Colour Saturation - Plasma traditionally scores high here because of the way it blocks light, turning off pixels when they're not needed so that no stray light can dilute its coulours. With LCD there's always smoe stray light in the mechanism, which adds a greying influence to colours thus makes authentic tones more difficult to see.
LCD: the basics
Contrary to what you might think, LCD technology has been around longer than plasma. It's that plasma affinities with larger screen sizes gave it a head start over LCD, which has only recently started to conquer its size demons and break free of its traditional PC shackles. LCD TVs work like so. A liquid containing individually controlable crystals is suspended between two transparent panels, and when these crystals are activated by voltage , they align themselves so that they either allow a certain amount of light (produced by a fluorescent tube behind the panel) to pass through the panel, or else block it off. Both the lit and unlit crystals create visible pixels that together compose the final image on the screen.
Why Buy LCD?
Screen life - We've seen some industry claims that LCD can last twice as long as plasma (around 40 years at 4hrs a day versus 20 years at 4hrs of use a day). Even though we suspect that such claims show a distinct LCD bias on the part of the source, it does seem that LCD can last a bit longer than plasma.
No screenburn - Plasma screens are suspectible to something called screenburn, which occurs when a bright image, like the sky news logo, is displayed on screen for an extended period of time. The constant saturation 'tires' plasma's phosphors, leaving a permanent shadow of the bright image behind. LCD technology is pretty much immune to this problem.
Slimness - Because there is no need for gas filled or heavy glass fronts in a LCD screen, LCDs tend to be slimmer and lighter than plasmas.
Brightness - LCD technology can generally deliver brighter pictures than a plasma - though more brightness isn't automatically better if it is used to disguise a lack of contrast.
Power consumption - LCDs generally use less power than plasma TVs because they dont need to power hundreds of electrodes to stimulate phosphors.