AV Education on RHT
The Pros and Cons of Plasma TVs
Written by Michael Levy
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.