Mr Liquid Crystal

The First TN patent

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Jim L. Fergason Ilixco

The twisted nematic device fascinated Jim, Ted, Sardari and Tom and when they worked on it, they didn’t think about who invented what. Instead they felt the device had a life of its own. They all knew that Jim had the idea for it and that most of what they worked on originated with him, but they didn’t think of the device as Jim’s because he didn’t encourage that kind of thinking. It was fun to explore the device and discover its capabilities.

But after observing the first TN devices, Jim knew that he had discovered something genuinely new and scientifically significant. It was time to assign authorship. He and Tom sat down in the 141 East Main Street office to discuss what they had that was patentable and how to write the disclosures. Jim felt that Tom should be the sole inventor of the Videsonic because he had discovered it all by himself. He didn’t like the practice at Westinghouse where some of the managers habitually added their names to the patent disclosures by their scientists, even though the managers had not worked on or contributed to the invention. He also felt that if patents with “extra” names were challenged in court, testimony would be a problem because opposing attorneys could examine people who would not be able to explain their contribution, how the invention worked, and how it was developed.

However, the idea for the TN invention was Jim’s so Jim was listed as the sole inventor. Jim sent a disclosure documenting his invention to Ilixco’s patent attorney, Tom Murray, in September, 1970. Jim had met Murray when Murray worked as an outside counsel at Westinghouse. Murray’s partner John Linkhauer, a chemical engineer and expert on chemistry-related patents, undertook the actual patent work. He promised to write and submit the U.S. TN-LCD patent application by October. Jim also applied for patents for the turbine blade testing technique, with him and Tom listed as co-inventors.

Jim then turned his attention back to how the company might use the twisted nematic device. This was 1970, when digital integrated circuits were popular. Tom was interested in logic devices and proposed that TN cells might be used in series to perform ‘optical’ logic functions. They even created a term, Optilogic, to describe these devices and used it on a data sheet. The Optilogic idea was impractical because electronic circuits were much faster and easier to use, but Ilixco spent several months experimenting with making Optilogic devices, and learned more about the TN effect from them. Jim was willing to explore new ideas, even if seemingly impractical, just to increase his knowledge of fundamental phenomena.

In October, Jim learned that John Linkhauer had not filed the TN-LCD patent disclosure. Linkhauer promised to submit it soon. But in December, 1970, Jim found out that Linkhauer still hadn’t filed the disclosure. From then on, Murray did Jim’s patent work himself. He filed Jim’s U.S. application on February 9, 1971.

Expert Fields Effect Cells

Expert Fields Effect Cells

After spending a few minutes savoring his invention, Jim walked briskly to his office. Halfway down the hallway, he hopped up, tapped his heels together and shouted, “Eureka!”

What was it about the collapsing twist that excited him? The ability of nematic liquid crystals to freely rotate is an important concept to understanding how the twist collapses. The mechanism of collapse was one of Jim’s key conceptual insights into how a twisted nematic device would behave.

In the absence of an electric field, the TN-LCD deformation consists of pure twist. When a field is applied, the first change occurs in the middle of the layer where the director begins to tilt toward normal orientation. This causes a small degree of splay which is projected into the regions above and below the middle and causes bend deformation and a structure similar to the bend-splay balance in Figure b.

As the field increases the center swings though a substantial portion of 90° and reaches a threshold at which the twist cannot be sustained because it is able to release stress by freely rotating around the axis of the director. The twist unwinds and the TN-LCD closes. The twist does not unwind completely unless the voltage is very high. A portion of it remains.

Splay, bend and twist can be thought of as “springs” that attract each molecule to the molecules around it, but are not attached to points on them. The molecules are free to move in three directions, oscillate around their centers and spin. The director(s) that represent the structures formed by splay, bend and twist can also be thought of as having some of the properties of a spring: the structures resist distortion by external forces but removal of these forces cause the structures to “snap back.” Like a spring, the forces of these elastic constants store energy.

Figure c represents free rotation which means that there is no resistance to rotation around the axis of the director. If the structures represented in figures a and b were rotated there would be slight resistance, due to the twist elastic constant. After released, the structures would snap back to their original configuration. However, if the structure in Figure c was rotated, there would be no resistance and the structures would not snap back.

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KSU art student Marci Murray

Life magazine makes liquid crystals, and Jim, famous

Life hit the newsstands on January 12, 1968. It sold for 35 cents. The movie “Bonnie and Clyde” had been released in 1967 with actress Faye Dunaway playing the part of the outlaw Bonnie Parker, and Life had a photograph of Dunaway, in costume, on the cover. But a photograph in the article on liquid crystals was so dramatic it stole the show. Now famous in liquid crystal circles, the photo showed a woman’s bare back (the model was KSU art student Marci Murray) vividly colored in green, blue, orange and black. Murray’s back had been coated with blackening material and then cholesteric liquid crystals. The vivid color patterns on her skin surface indicated the temperatures of the underlying tissue.

Groskinsky also included an illustration of a large, liquid crystal-based signage display developed by Xerox but built along the lines of technology Jim had pioneered at Westinghouse. This display development preceded that of the dynamic scattering mode display work that was later announced by RCA.

The article had the catchy title “The Chameleon Chemical: an oddity called liquid crystals proves to be of colorful use to doctors and scientists.” It began, “James L. Fergason, associate director of KSU’s Liquid Crystal Institute, is credited with the first practical use of cholesteric liquids for temperature measurement and the first use of cholesteric liquid crystal analysis and information display.” The entire article was about Jim’s research. Glenn Brown was not mentioned once.

Life magazine was then the most popular photographic magazine in the U.S., with millions of readers. Groskinsky had not told Jim that he was going to feature him as the lead liquid crystal researcher at LCI, and it seemed to be a major accomplishment for both Jim and LCI. In a letter dated January 15, 1968, Glenn wrote the following about Jim to Kent State University President Robert White, “I shall comment on personnel first. The salary adjustment for Jim Fergason is based on his fine contributions to Kent State. Our annual report reflects his attractiveness as a speaker on the subject of liquid crystals. He is a consultant to a couple of industries and receives many telephone calls from governmental and industrial laboratories seeking his counsel on research in the field of liquid crystals.” The letter continued, “As you recall, he [Jim] received mention in the January 12 issue of Life magazine. Jim is a very important person in the success of our Institute.”

LCD Feature on Jeopardy

“Jim was the Thomas Edison of liquid crystals.”

Dr. Beth Cunningham

“To have a career as an inventor, an open mind is an absolute must.”

Jim Fergason

“Bringing a new invention to market is a full-contact sport.” 

Jim Fergason

“That is the essence of science: Ask an impertinent question, and you are on the way to a pertinent answer.”

Jacob Bronowski