The History of Plasma Display Panels

The History of Plasma Display Panels

I. IntroductionBy Jamie Hutchinson"For most of its time, it was a solution looking for a problem," says Larry Weber (BSEE '69, MSEE '71, PhD '75) of the technology he has dedicated his professional life to. Today that "solution"the amazing plasma display panel, invented at the University of Illinois in 1964seems to have finally found the problem (not to mention the goldmine) it always deserved: carrying high-definition television (HDTV) into millions of homes.

Weber's 60-inch plasma display, a prototype he developed for Matsushita (bearing the Panasonic label), combines the large size and superb resolution necessary for HDTV with the convenience of thinness. You can even hang it on your wall. In fact, one of these marvels hangs on the wall of Weber's upstate New York company, Plasmaco, an R & D arm of Matsushita. When you see it, you'll know why the Society for Information Display gave Weber its highest award in 2000 for his contributions to plasma displays.

And you'll begin to understand why the TV industry gave a 2002 Emmy award for technological achievement to the original U of I inventors of the plasma display: Weber's old teachers Donald Bitzer (BSEE '55, MSEE '56, PhD '60) and the late Gene Slottow (PhD '64), and their first graduate student, Robert Willson (PhD '66), whose name appears alongside those of Bitzer and Slottow on the original plasma display patent. Fujitsu, the leading manufacturer of plasma displays, also shared the award.

Weber, Fujitsu, and others are now clearing the final hurdle that separates plasma displays from long-term commercial viability: cost. With low-end models selling for about $3000half the price of two years agomanufacturers seem well on their way toward making plasma displays the ultimate solution to the problem of HDTV.

And yet, Bitzer and Slottow had a completely different problem in mind when they created the early displays at Illinois. For them, the plasma display was part of the solution to the problem of computer-based education. What's more, U.S. TV companies who early considered plasma as an alternative to the cathode ray tube soon dropped the idea. A few computer companies stuck with plasma until another flat-panel technology, liquid crystal, seized that market. Other than that, only military contracts sustained a small plasma display industry in the U.S., and so most U of I students who worked on the technology (including Willson) eventually had to find jobs in other areas. Meanwhile Japanese engineers, whose companies dispatched them for extended visits to Bitzer's lab, went home to an electronics industry that today dominates the development and manufacture of plasma displays.

What happened to the flat screen from the flatlands?II. Blue and Orange Beginnings

By Jamie HutchinsonBy 1963 Bitzer had demonstrated the success of his now-legendary automated teaching system, PLATO, within the limited, controlled environment of the Coordinated Science Laboratory. Bitzer and CSL director Daniel Alpert understood that putting PLATO in practice for large numbers of studentsin essence, transforming it from a classroom into a systemwould require more than replacing the ILLIAC I, a relic from the days of "big iron" that served as the original mainframe for PLATO's time-sharing network. A real-world PLATO would also eventually require a better way of visually mediating the exchange between computer and student.

At that time, almost all devices for interacting visually with computers were alphanumeric displays that could only render letters and numbers, not the graphics required for teaching and learning many subjects. Bitzer rigged a system using radar display tubes that could digitally read pictures and alphanumeric characters from ILLIAC I, then transmit the images by cable to TV terminals at each student station.

The earliest versions of PLATO used TV sets for the student terminals. ILLIAC digitally sent graphical and alphanumeric data to Raytheon double-electron-gun storage tubes, which were designed to display radar signals and transmit the displayed images. One electron gun would write the data from ILLIAC to the storage tube display, while the other rescanned that display in TV format for cable transmission to the student's TV terminal (shown above). Slides could also be scanned and added to the TV output. (D. L. Bitzer) The system worked well enough while PLATO was in a proof-of-concept phase. However, the constant refreshing of the image that is required in a cathode ray tube, while fine for TV, didn't lend itself well to the sustained display required for graphics. The tubes had no memory for holding an image, and the cheap computer memory that makes tubes suitable for graphics today was a dear resource in the 1960s. PLATO would require a better display for the long haul.

Bitzer enlisted Willson, then a graduate assistant, and Slottow, then a research engineer, in the task of exploring how a matrix of discrete neon cells might be driven by a high-frequency ac current, using capacitors at each cell so that individual cells, or pixels, could be addressed. The big breakthrough came one summer evening as Bitzer and Slottow waited outside CSL for their wives to pick them up after work. They began discussing the project in terms of its barest essentials and realized that the simplest configuration would be to exploit the natural capacitance of the glass on either side of a panel, which could be done by placing electrodes on the outside of each cell, separating the driving current from the gas.

Next morning, the team set about building a new device. With Willson doing most of the handiwork, they ultrasonically drilled a hole fifteen thousandths of an inch wide into a thin glass slide, then sandwiched that slide between two others. They deposited thin-film gold electrodes on the outside surfaces to carry a high-voltage driving source. They sealed the sandwich with epoxy on three sides and glued it to a vacuum pump on the fourth, then pumped it clean and backfilled it with neon.

Power on. Blue.It was July 1964, and the first ac plasma display panel had been built. The panel's single cell operated on the fundamental rules that govern the millions of cells in one of today's panels.

A 4 x 4 pixel plasma display. Graduate student Brij Arora (MSEE '68, PhD '72) built the first multipixel display. "We could address the lines to write the character or erase it. It was a very exciting thing," recalled Arora. (D. L. Bitzer) After this initial success, the team learned that nitrogen from the air had leaked into their cell, accounting not only for its blue hue, but also for its good "memory margin"its property of remaining lit in the presence of a "sustain" voltage significantly lower than the "breakdown" voltage necessary to initiate the discharge. By 1967, the inventors had figured out how to achieve good memory margin using just neon, and they had developed the driving circuitry necessary to address a large array of pixels. (Alpert had kept Bitzer's research under his wing after becoming graduate college dean in the mid-1960s. After the move, Bitzer's lab was renamed the Computer-based Education Research Laboratory.) That year, they built a 16 x 16 panel that glowed orange, thanks to the purer neon mixture. PLATO screens and other plasma panels for years to come, here at the U of I and beyond, would radiate the same orange.

A 16 x 16 pixel "UI" display from 1967. (D. L. Bitzer)

In its "on" state, a plasma cell actually flickers thousands of times per second. Every time the ac sustain voltage reverses polarity, its corresponding field within the cell realigns with an alternating "wall voltage" emanating from the glass, creating a total cell voltage sufficient to ignite the discharge. A new wall voltage of opposite polarity then begins to build up until it cancels the cell voltage, extinguishing the discharge, and a new cycle begins.

III. Seeing green

By Jamie HutchinsonPatent attorney Nate Scarpelli (BSEE '58) was new to the Chicago law firm of Merriam Marshall Shapiro Klose when the firm assigned him the task of patenting PLATO, the plasma display, and other ideas for the U of I. The "Merriam" was Charles Merriam, who sat on the board of the U of I Foundation and was the driving force behind University Patents, originally set up within the Foundation to license U of I patents, but later spun-off into the publicly held University Patents, Inc. The push was on to commercialize U of I technologiesa new and controversial course for the century-old land grant institutionwith an eye toward building the university's endowment.

Although the first patent covering the fundamental operation and applications of the plasma display panel was not granted until 1971 ("one of the most complete applications I think I've ever done," recalls Scarpelli), U of I began collecting on the technology as early as 1967. That year U of I sold an exclusive license to the Owens-Illinois glass company, which would deliver the first commercial-grade "Digivue" displays for use in PLATO in 1971.

An Owens-Illinois "Digivue" panel with electronics exposed. (Owens-Illinois)IBM took an early interest as well, and the lure of Big Blue's prestige and deep pockets forced Merriam and Alpert into some ticklish negotiations between the two corporate players, with the happy result that U of I collected a million dollars from IBM in exchange for another license. That license would lead in 1983 to the IBM 3290 Information Panel, "the industry's first mass-produced, large-screen plasma display terminal for commercial use," according to an IBM advertisement.

TV companies including RCA, Zenith, and General Electric took notice of early press reports about plasma displays as potential "hang-on-the-wall" TVs. Some took out licenses, but they all sent visitors to see what was happening at CERL. Zenith provided the phosphors for Edward Stredde's (BSEE '66, MSEE '68) master's work on a multicolor plasma display.

Early press reports prophesied plasma's potential as a new TV display technology. This article from the Minneapolis Star pointed out the role of Minneapolis-based Control Data Corporation in PLATO. A CDC computer replaced ILLIAC as the PLATO mainframe, and the company bought limited rights to the PLATO name in the late 1960s. (Minneapolis Star) After finishing his PhD in 1975 with a dissertation on the discharge dynamics of plasma displays, Weber joined the CERL staff and began consulting to U.S. companies interested in such commercial applications of the Illinois technology.

Another CERL alum, Roger Johnson (BSEE '65, MSEE '66, PhD '70) joined the ECE faculty in 1971 and found his consulting home in the Pentagon and its contractors, which included Magnavox, Science Applications International (now SAIC), and the Owens-Illinois spin-off Photonics Systems. Johnson would leave his faculty post in 1977 and spend the next 25 years at SAIC developing flat displays and mobile workstations. In 1982, the company manufactured its "Plasmascope" displays for controlling ground-launched cruise missiles. The displays were "nuclear hardened" to withstand the radioactive environment of a nuclear war. Similar displays went into the Trident nuclear attack submarine and the "Doomsday Plane"officially known as the Advanced Airborne Command Post, a Boeing 747 outfitted to control U.S. forces in a nuclear war. Photonics and Magnavox collaborated on the largest plasma displays of the time, status boards used by the Air Force to monitor air operations.

Japanese companies were among the first to take out licenses and begin their own plasma display research, enjoying the support and encouragement of NHK, the government broadcasting system that had advocated HDTV as early as the 1960s. Among the prominent Japanese engineers who visited CERL to study plasma displays was Heiji Uchiike, now of Saga University. Uchiike spent a year at CERL in the early days of the plasma display and has gone on to train many of the top plasma engineers in Japan. Japanese companies who sent visitors to CERL, many of them staying for extended periods, include Fujitsu, Hitachi, Matsushita, Sony, NEC, and even NHK. These companies, especially Fujitsu, have made important developments based on the fundamental ideas that came out of Illinois.

Bitzer noted that the Japanese also saw plasma as an answer to the problem of displaying their Kanji script, something the Western alphanumeric computer displays of the early 1960s could not do. So plasma panels became widely used in Japan for cash registers, meters, and public signs.

The transparency of the monochrome plasma displays allowed slides to be superimposed on images read from the computer.

Infrared light-emitting diodes on the perimeter of a PLATO "smart" plasma screen could sense the position of a finger. Bitzer summed up the functionality of the PLATO stations: "It spoke, it recordedif you were teaching a foreign language, you could hear your own voice. It had touch, it had rear projected images, and graphics. You just had to like orange a lot for the graphics." (D. L. Bitzer)

IV. In the red

By Jamie HutchinsonOwens-Illinois had sunk millions into manufacturing plasma displays when it gave up on the business and sold its plasma division in the 1970s. U.S. TV companies didn't last long after they came to understand the investment it would take to make plasma competitive with cathode ray tubes. Computer companies stuck it out until 1987, when IBM became the last major U.S. company to dump its commercial plasma display business. That left only the Pentagon to sustain a small but very lucrative plasma display industry in the U.S.

Weber had derived most of his income from consulting on the commercial side, so there wasn't a lot left to do when IBM closed its plasma manufacturing plant in Kingston, NY. Except perhaps to join forces with three former IBM executives, buy the used equipment from the plant (88 trailer truckloads of it), haul it to an old apple juice factory in nearby Highland, and hang up a shingle. Which is exactly what he did.

Plasmaco was also a U of I project in technology commercialization. Weber remained on the CERL staff while serving as chief technical officer of the company, and many Plasmaco staff visited CERL for training. The university licensed Plasmaco to use its plasma technology, which now included energy-efficient driving circuitry developed by Weber himself. (Every plasma TV on the market now incorporates Weber's contributions, which are the subject of an ongoing legal dispute between U of I and Fujitsu.)

Weber (left) took the Illinois technology to Plasmaco and used it to bring in business. Here he shows off a transparent screen with moving graphics at a 1988 convention. (L. Weber) In 1990, Weber moved to New York and assumed full-time duties at the new company, which scraped by producing monochrome plasma computer displays until 1993. But by that time, liquid crystal displays had achieved color and conquered the market. Plasmaco now faced foreclosure, and the company's investors shook up the top management, making Weber president and CEO and forcing him to fire half his staff. "Things got very ugly with all the creditors that were after us," recalled Weber. "The sheriff was knocking at my door because we couldn't even show up for court. The lawyers wouldn't represent us because we hadn't paid them."

Weber convinced a banker to lend him $80,000 for components to begin developing a color display. By the last day of a 1994 industry convention in San Jose, CA, he was able to rig a static display of colored stripes that impressed people with its brightness and contrast ratio. Weber then began a joint development program with Matsushita, which bought Plasmaco in 1996 for $26 million, leaving Weber in his position as president. Weber hired his old student Bill Schindler (MSEE '82) to manage Plasmaco's 60-inch prototype project, unveiled in 1999 and widely agreed to have the best contrast ratio in the industry.

Weber hired his old student Bill Schindler (right) to head up Plasmaco's 60-inch prototype project. Weber and Schindler are pictured here at Plasmaco headquarters in Highland, NY, along with one of their 60-inch prototype displays. (J. Hutchinson) V. Isn't that beautiful?

By Jamie HutchinsonIf you sit 10 feet away from a 36-inch regular TV, Weber explains, you can't tell the difference between a normal picture and the high-definition standard toward which the TV industry is moving. You could widen the cathode ray tubethe venerable device that gave TV its nickname "The Tube"to the 60 or more inches required to see a one-millimeter pixel at 10 feet. But the tube can't get wider without getting deeper, so you would have to knock out a door and use a forklift to get a big one into your living room. Projection systems have spatial limitations of their own caused by the placement of the projector and screen, and they require a dark room for good results. Liquid crystal displays have the advantage of thinness (that's why they are great for laptops), but they are not as bright as plasma displays, they can't yet be made as wide, and their pictures disappear when viewed from the side.

That's why Japanese companies like Matsushita and Fujitsu are finally in a position to see the payoff for their long commitment to plasma display panels. Weber does see the possibility of future U.S.-based manufacturing of plasma displays. But the companies will be Japanese, looking to move production closer to the growing U.S. market for their products.

Johnson is more optimistic about U.S. leadership in the further development of plasma displays. Now retired from SAIC, he has gone back to running his old consulting company, which is incorporated in Illinois. Johnson believes Illinois can have "a second round at the plate, and maybe hit the ball again." He is interested in partnering with current ECE faculty and students who are conducting research relevant to plasma displays. For example, Professor Kevin Kim's lab is perfecting "microspheres" that may be useful for evenly depositing materials in plasma display manufacturing. Phil Krein developed an energy-saving power supply for plasma displays. And Mark Kushner developed software for simulating the physical dynamics of plasma cells. Johnson would also like to organize a seminar series on flat-panel displays at U of I.

"The press kept telling me that I was wrong, that it was going to be the future television," recalled Bitzer. "But that was not my heart. My heart was the education." Bitzer must now concede that the press was right, but he can still point to Weber's 60-inch wonder with all the pride of a new grandfather: "Did you ever see a display like that? Isn't that beautiful?"

Bitzer (right) and his old student Robert Willson were reunited at the Emmy scientific and technological awards dinner in New York City on October 2, 2002. Bitzer retired from the ECE faculty in 1989 and is now on the computer science faculty at North Carolina State University. Willson is a systems engineer at Analex Corporation and a part-time minister.H. Gene Slottow, 1921-1986. ECE head Richard Blahut and Professor Tim Trick accepted Slottow's Emmy in New York and then presented it to Slottow's widow, Irene, at a ceremony in Urbana. Mrs. Slottow has donated the Emmy to the ECE department.