The Pros and Cons of Plasma TVs 
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Written by Mike Levy   
Thursday, 01 July 2004


AV Education on RHT

The Pros and Cons of Plasma TVs

Written by Michael Levy

Introduction
Audio/video product designers tend to be dreamers. When I was young, I would dream of a George Jetson-inspired day when you could just hang a picture on the wall and view a bright, clear, vivid moving image. Plasma TV has made that seemingly impossible dream real.

Believe it or not, plasma screen technology goes back to the ‘60s. It took advancements in chip design and miniaturization through the decades to make it commercially feasible. Growing up in that era, I could daydream of the concept, but somewhere in the back of my mind, I doubted it could really make it to the walls of my home. Now, people go every day to vendors ranging from CostCo to the best custom home theater designers to get a sexy, thin plasma-beaming HDTV in their living rooms.

Walking through the vast hallways of the Consumer Electronics Show (CES, as it is known in abbreviation) this past January in Las Vegas, I was amazed at how far plasmas had come in such a short period of time. There were new sets with brighter, more detailed and larger screens. LG Electronics had an 86-inch prototype on display, creating bright and detailed images in a well-lit room. Fujitsu, Sony, Panasonic, Faroudja, Runco, and Pioneer had screens as large as 60 inches.

These large electronic and glass canvasses now create images with gray scale, black level, color fidelity, detail and clarity in motion well ahead of their predecessors. Prices have also been dropping nicely as demand increases for thin HDTV, along with innovations in plasma manufacturing.

How a Plasma Works
Plasmas replace the cathode ray picture tube in a television with individual pixels that are addressed digitally. Each pixel consists of three glass-encased plasma bubbles, one each for the colors red, green, and blue. Inside the bubble is a plasma gas that emits x-rays when excited by an electrical charge. The bubbles are coated with a phosphor that emits light when hit with x-rays. A high voltage transistor is coupled to each bubble and it sparks the plasma as frequently as is necessary to create a particular brightness level.

The phosphors have a half-life like those in a standard television, so they degrade with time, but once they are operational they should remain so. So, like a normal color TV, the image is presented as dots that become invisible to the eye at a reasonable distance.

The Pros of Plasma Televisions
Plasma’s greatest strength is flexibility of use. You can put them almost anywhere as proven by the now-famous Philips ad where a young couple installs a plasma on the ceiling above their bed after a long battle to figure out which wall was best for their slick new TV. Other install tricks commonly used include hiding the connections for power and signal inside the wall, which make the plasma seem like it just floats in space.

If you can put a picture or painting on a specific wall in your home, you can usually put a plasma there. If you want to hide the screen away, there are slick new mechanisms from companies like Tech Art that will cover it with high-end artistic reproductions that roll away when you want to watch TV. Another company, Vantage Point, has created hardware called the UFO that allows you to creatively position the thin sets in ways that also allow you to move the set out of the way in a number of innovative configurations.

Plasmas work in a variety of lighting, and with a variety of sources. Most will accept everything from standard NTSC television to HDTV signals as resolute as 720p and 1080i. Many have DVI inputs for digital transmission of HDTV. The newest sets even have HDMI digital video connections, which is the MPAA-approved standard for digitally transmitting encrypted HDTV. Almost every plasma set has a battery of analog connections, including S-video, component and RGB.

Almost all plasmas, especially the larger sizes, are true 16x9 HDTV-capable sets that can reproduce a movie in the correct shape (also known as aspect ratio). Many plasmas now include video processors (known as “line doublers” years ago) in the form of chips from the likes of video manufacturers like Faroudja or Silicon Graphics, who aspire to be the Intel of the TV world. These video processors basically allow a user to take a lower resolution signal from a 480i TV show, recorded on your TiVo, for example, and upconvert it to a better-looking picture.
The Cons of Plasma Televisions
Plasma is not a perfect technology, and its weaknesses should be taken into account when deciding on a display. Plasma screens are fragile. They must be shipped standing up, and as they are mostly glass, they must be handled with extreme care. They are heavy, and the wall mounts must be properly set. They should never be installed where they could be knocked over or bumped into.

Plasma sets are power hungry because of the high voltages necessary to activate the actual plasma elements. The picture quality degrades with time due to phosphor wear, much as a traditional CRT TV set does. Also, the glass face reflects light in the room, somewhat degrading the image, as compared to the other flat panel technology, LCD.

How to Decide If Plasma Is Right For You?
When comparing the specifications of plasma displays, what is the most important factor? Is it the pixel count? Is it the brightness? Is it the contrast ratio? The answer is -- none of the above. As usual, the most important specifications are generally left out by most salespeople and even some manufacturers. What you really want to know about is black level, gray scale definition and digital processing. Often, the specifications don’t exist. Black level could be stated as an absolute value of light output when the image calls for black, and gray scale is sometimes stated in bits, such as 10 or 12, but the most important factor, digital processing, can only be judged by viewing moving images on the screen.

Video processing quality is very important to your day to day enjoyment of a plasma set. Poor processing will result in blurred images and/or strange dots and lines flashing onto the screen. Some sets now include excellent processing chip sets made by Faroudja, Silicon Graphics or DVDO. Video processors sense the difference between film and video-based material and react accordingly.

The pixel count, maximum brightness and contrast ratio are of secondary importance, albeit not according to most salesmen in the stores. While a higher pixel count is preferred (high definition has a minimum of 720 by 1280), it is meaningless if the processing either blurs the image or shows nasty digital artifacts. High brightness and contrast ratio are meaningless if the image shows artifacts due to a limited gray scale or has a high black level.

One solution is to buy a display that has very good fundamental parameters and match it with an external “native rate” processor from Faroudja, Silicon Image or other top video processing companies. The cost can be much higher, but the difference is amazing. Runco sells many of their plasmas exclusively with truly excellent video processors as part of their package.

The idea of using a good progressive source, like a progressive (i.e., video-processed) DVD player can really help on a plasma set-up. Interlaced sources playing film-based material are the hardest to process and adding a processor such as the I-scan from DVDO can greatly improve the image quality. The processing quality in both cases is much better than what is in most units. A topnotch AV dealer will demonstrate the difference a processor will make.
Conclusion
The beauty of this on-the-wall technology is how easily it integrates into rooms, ranging from dedicated theaters to studies to the most impressively decorated living rooms. Plasmas can nonchalantly lay waiting until called upon to turn your favorite room into an outrageous showplace of technology.

While on an ultimate scale, there are some other video technologies to consider before dropping major coin on a plasma, the overall strengths of the format and the picture quality level that plasma has now reached make it easy to understand why this is the hottest video technology since color TV.





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