March 9, 1999

NC State Engineer Is Original Inventor of Plasma Screens

Serious television viewers have recently added several items to their wish list of television viewing technology--High Definition Television (HDTV) and the flat-panel plasma screen. The high tech pair represent the state-of-the-art in television viewing, yet the plasma screen, which is the recommended device for viewing HDTV, was co-invented by an NC State University engineering professor more than 25 years ago.

Dr. Donald Bitzer, Distinguished University Research Professor of Computer Science at NC State University, and Dr. H. Gene Slottow invented the plasma screen in the early 1960s while on the faculty at the University of Illinois at Urbana-Champlain. Bitzer and Slottow originally invented the plasma screen as an educational device to aid students working in front of computers in a student-based teaching project. Unlike cathode ray tube screens, such as the ones in televisions and computer monitors, the plasma screens have memory and do not have to refresh the image by rescanning. As a result, plasma screens do not flicker -- video flicker causes eye strain and can cause headaches and fatigue in people who watch television or work in front of computer screens for long periods.

"The original idea came as part of an education project I was working on at Illinois," says Bitzer. "We actually figured out how to make these screens in about 15 minutes while waiting for our wives to come pick us up. The education project and plasma displays are still being used around the world."

As a result of their brief conversation in the 1960s, plasma screens are on the market today. The screens are mostly produced in Japan, and numerous companies were formed to produce the parts and equipment needed to manufacture them. In Asia during the 1970s, plasma screens appeared mostly in monochromatic versions as information screens in public transportation and on checkout displays. Their use as television viewing devices, though predicted in the 1960s and 1970s, has only recently been realized. This is due in part to the cost of each screen. Although they are now mass produced, each screen can cost between $3,000 and $8,000.

Now, thirty years after inventing plasma screens, Bitzer has written an article on the history of their development. The article will appear in the April issue of Information Display, a magazine for the Society for Information Display.

In his office, Bitzer keeps the original prototypes of the plasma screen--some as small as one inch square.

"The basic principle has not changed, but the manufacturing has changed over the years," says Bitzer. "For example, manufacturers use sandblasters to mass produce the panels now. The glass is coated in a pattern with a chemical that resists the sand, and then the uncoated areas are sandblasted away to create the grooves for the gases."

The picture is created by exciting gases trapped in grooves sandwiched between glass plates, making the image seen on plasma screens brighter, clearer and more accurate than the picture seen on traditional cathode ray picture tubes. The lack of distortion in plasma screens makes them the perfect viewing technology for the recent HDTV revolution in television broadcasting and for the new digital video disc (DVD) technology.

"In fact, the signal that is sent to a traditional television set has to be processed to compensate for the distortion included in the cathode ray tube. With plasma screens, that alteration has to be removed, and a linear signal is used," says Bitzer. "There is no distortion."

Although they are less expensive than flat-panel plasma screens, traditional cathode ray picture tubes are very limiting in their capabilities. To create a larger display on a cathode ray screen, the length of the vacuum tube must be increased, which greatly increases the depth in proportion to screen size. The typical 19-inch television set is almost 2 feet deep (from back to front) whereas a plasma screen of twice that size can be as thin as 2 inches, making it the most versatile of displays available on the market.

"The only restriction on the size of a plasma screen is finding an oven and other processing equipment big enough to enclose the screen," says Bitzer.

Plasma screens enhance the quality, or actually more fully display the improved quality, of the image provided by high definition television signals, says Bitzer. It's like the difference between listening to a recording on a cassette tape and a digital compact disc.

Bitzer predicts that the cost of the displays will come down as the manufacturing technology advances to support mass production of the large plasma screens for television viewing and the demand for the screens increases with the rise in availability of HDTV broadcasts.

"These screens are the very best way to view television and videos," says Bitzer.

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