Grey bars help Plasma and CRT's (both direct view and rear projection style) due to the technology they are based on is susceptible to burn-in, or image persistence. LCD and DLP (digital light processing) sets are not susceptible to burn-in.
For the past 3-4 years, Plasma televisions have had logic added into the system that is responsible for drawing the picture. The logic adds some randomization to the way the screen is drawn so that no display groupings are used excessively more than others. It's a fairly complex system that helps to dramatically reduce the instances of burn in. They also will often have an option in the system that allows a user to run a "clear burn-in" process. Basically a process that lights all the pixels at a set intensity for a specific amount of time to even everything out.
Yes, Plasma screens wear out and when they eventually do (about 15-20 years out typically) there is no way to repair them. DLP's have bulbs that burn out, but can be replaced. They also have other systems that wear out, but can be replaced as long as someone will make the parts. LCD screens have back lights that will fail, and are not typically user serviceable though they may be serviced by techs. A back light should last a good many years.
For most people, any of the products will last long enough for them. Plasmas have better black levels, though their brightness is much less than a LCD can achieve, thus they work best in areas of medium to low light. LCD's continue to evolve in an effort to improve black levels, but still can't beat a good Plasma. But LCD's can put out a very bright light, and thus work quite well in brightly lit environments.
Neither is necessarily better than the other. And both will display a nice HDTV picture and look best when not stretching a picture to fit the screen size.
For the past 3-4 years, Plasma televisions have had logic added into the system that is responsible for drawing the picture. The logic adds some randomization to the way the screen is drawn so that no display groupings are used excessively more than others. It's a fairly complex system that helps to dramatically reduce the instances of burn in. They also will often have an option in the system that allows a user to run a "clear burn-in" process. Basically a process that lights all the pixels at a set intensity for a specific amount of time to even everything out.
Yes, Plasma screens wear out and when they eventually do (about 15-20 years out typically) there is no way to repair them. DLP's have bulbs that burn out, but can be replaced. They also have other systems that wear out, but can be replaced as long as someone will make the parts. LCD screens have back lights that will fail, and are not typically user serviceable though they may be serviced by techs. A back light should last a good many years.
For most people, any of the products will last long enough for them. Plasmas have better black levels, though their brightness is much less than a LCD can achieve, thus they work best in areas of medium to low light. LCD's continue to evolve in an effort to improve black levels, but still can't beat a good Plasma. But LCD's can put out a very bright light, and thus work quite well in brightly lit environments.
Neither is necessarily better than the other. And both will display a nice HDTV picture and look best when not stretching a picture to fit the screen size.
