Created as a replacement for CRT and rear projection TVs, plasma technology was the first flat-panel display to be sold to the public. Plasma TVs found much success in the mid to late 90s, and their superiority over LCDs allowed them to dominate the flat-screen market until the 2000s, when LCD technology finally began to catch up. Today, they have lost the market share to LCDs, but plasmas are certainly not to be overlooked when shopping for your next TV.
How it works:
In a plasma display, gases (helium, neon, xenon) are stored in thousands of tiny phosphor-coated cells (the same phosphor material used in a CRT). A dielectric layer containing electrodes in placed both in front and behind the cells. This gas-electrode system is sandwiched between two glass plates. When the electrodes are charged, the gases stored inside creates plasma, which emits ultra-violet light. Ultra-violet light is invisible to the naked eye, but it causes the phosphor to create visible colored light.
50" Panasonic Plasma TC-P50G25
So how is the colored light controlled? Each pixel on a plasma display is divided into three different gas cells, one red, one blue, and one green (the primary colors). By controlling the pulse of current flowing, the brightness and color output can be controlled, allowing other colors to be created.
Great Black Levels
The biggest advantage that plasma TVs have over other TVs is their ability to completely block out light. On an LCD screen, the light source is always on, so it much be filtered to achieve black. This works, but it usually gives a bluish hue from the glowing light. On a plasma screen, the pixels are only illuminated when gases inside are electrically charged. This means that each pixel can be turned off completely, allowing for near-perfect black levels. Because of this, plasma displays are great for dark scenes, such as those in horror or space movies.
High Contrast Ratio
Since the light emitted through a plasma television can be completely cut off, this allows them to reach darker colors, thus giving them an incredibly high contrast ratio.
Great Viewing Angle
Unlike backlit LCDs and rear projection TVs, a plasma display's screen is lighted by its phosphor coating on the other side, which means that each pixel has its own light source. This gives a plasma displays not only a great horizontal viewing angle, but a great vertical viewing angle as well, which many LCDs lack.
Plasma displays have much better response compared to LCDs, which results in no noticeable motion blur. Many of today's LCDs have implemented methods of improving this with 120Hz refresh rate technology, and some have lowered their response times to 2ms. However, they still lag in response compared to plasma TVs.
Plasma TVs have an incredibly long lifespan, with most models rated at about 60,000 hours. Current models (2008 and newer), such as those from Panasonic and Samsung, have a life expectancy of 100,000 hours. If you were to watch television 6 hours a day, that's almost 46 years! Plasmas do lose their brightness over time, which will be explained in the disadvantages section.
Big screen for low price
To stay competitive with LCDs, the prices of plasma tvs have dropped drastically since 2007. Today, a top-of-the-line plasma model can be purchased at retail price for a little more than half the price of an LCD with of similar quality. For larger models (55" and bigger), there is an even greater difference. For example, Samsung's 65" LCD, model LN65B650 retails for $5,999.99, while their 63" Plasma only costs 3,599.99. Not a bad deal for only 2" less.
Placing a static image on a plasma screen can result in burn-in, which leaves a ghost of the image on the screen. While burn-in can often be fixed by placing an image on a solid white screen, LCDs are still a much better choice if you're looking for a flat screen TV that doubles as a monitor.
Loss of Quality Over Time
Even though plasma displays last for quite a while, they do lose quality after a while. Over time, the gases stored inside a plasma television will dissipate, reducing causing the screen to become dimmer. This process begins from the moment you turn the television on, but will not be noticeable for a long time. On a typical plasma made today, after about 100,000 hours, the screen will have faded to half its original brightness. The average user, who watches TV 4-6 hours a day, usually won't notice a difference in brightness until after about 10 years.
Problems at High Altitudes
If you live in an area with high elevation, you may want to think twice before purchasing a Plasma television. As elevation increases, pressure decreases. At a certain elevation, this has a negative effect on the gas cells inside a plasma, causing it to expand and operate improperly. Most manufacturers will state their TV's maximum elevation. Here's the ones that I could find:
NEC: 9,180 feet
Panasonic: 7,800 feet
Pioneer: 7,500 feet
Samsung: 6,500 feet
These numbers are much higher than older models which had problems at altitudes above 6,000 feet, but there are still areas which exceed these recommendations. More than likely, if you're living in an area unsuitable for operating a plasma television, your local electronics store is already aware, and won't carry plasma televisions, anyway.
Plasmas have a highly reflective glass screen which will reflect bright light, causing a nasty glare if placed at the wrong angle. Some plasma displays have anti-glare screens, but usually sacrifice color quality due to the much more dull screen. When shopping for a new flat-screen, if you are considering a plasma, be sure to consider its placement.
Plasma TVs may no longer be the king of the hill when it comes to flat-screens, but with their beautiful picture output and relatively low cost, they are still the best bang-for-your-buck display.