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Read the fine print
By Richard Silberman
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When industry experts heard about Roentgen the latest high-resolution display unit being developed by IBM, they responded with enthusiasm, but predicted that it couldn't be mass-produced for at least ten years.
They projected that it would take at least that long to develop adequate manufacturing tools and to prepare factories to commercially produce the display, which features a groundbreaking 22-inch screen with 200 pixels per inch (ppi). Building a unit with such exceptionally high resolution in the lab was one thing, but manufacturing it on a broad scale was quite another.
But IBM researchers had been developing the world's clearest computer display as a commercially viable unit all along. Unlike some research projects, which remain in the prototype stage for long periods of time, this new display technology was always intended for mass production. The team deliberately designed their prototype to be built on existing factory lines so their display could hit the market swiftly. This mentality is common to storage and memory, but it's relatively new for display technology.
"The goal from the beginning of this project has been not just to make one or two, but to make thousands," explains Robert Wisnieff, manager of IBM's advanced display technology laboratory and the head of the Roentgen project. Wisnieff and his team accomplished this goal by focusing as much attention on the tools used to manufacture the display as on the display itself.
IBM's display assembly facility in Yasu, Japan became their laboratory. The facility was originally built to manufacture notebook displays with 12.1 inch screens and 82 ppi — a far cry from the revolutionary new display that Wisnieff's team was trying to produce. They studied and monitored the factory tools and then tested each display unit as it rolled off the line. By testing the end product, they could determine how well the assembly line was performing and make minute adjustments that would yield increasingly higher resolution.
Using innovative testing procedures and factory control software developed by IBM, the researchers fine-tuned the manufacturing process and pushed the assembly line to a remarkably high performance level. Among the key testing devices used in the project were an "array tester" and a "front of screen" tester. The array tester analyzed the millions of transistors on the back plane of each display unit, and the front of screen tester scrutinized the front of each display for "bad pixels, streakiness, and haziness," according to Wisnieff. This methodology allowed the team to determine the performance of each display pixel-by-pixel. "We write to every pixel in the display a fixed charge and then we go back and read that charge back out of that pixel. By varying the writing and holding conditions we can test whether or not that pixel will perform properly." Over a period of two years, the researchers adjusted their prototype accordingly to maximize the assembly line's capabilities.
The constant testing, which was conducted by IBM development and manufacturing engineers in Japan, produced an outstanding picture of the Yasu factory's performance. The data from the tests indicated how changing a variable in each individual tool — as well as adjusting the assembly line sequence as a whole — affected the unit at the end of the line. As Wisnieff puts it, "We took an assembly line that was built to manufacture notebook computers and found ways to maximize and even transcend its original capabilities."
Work on the 200 ppi display began in 1998, but researchers had actually been monitoring the tools at the Yasu factory since 1991. By 1998, they had seven years' worth of testing data to use in developing their prototype — detailed information on how to maximize the performance of each individual tool.
The team's foresight in addressing large-scale production issues at such an early stage in the product's development was unique. Moreover, their experience refining the factory's tools and processes will continue to serve as a guide for future projects. As the display grows from a high-end niche product to a more mainstream item, factories all over the world will be able to shift into production quickly and efficiently.
The techniques developed at the Yasu factory can be easily transferred to other factories. According to Wisnieff, every display factory has the same basic tools, which can be fine-tuned to deliver extraordinary performance. "In principal, all the factories that have been built can be adapted to do this," says Wisnieff. "Others could be taught to do what we've done, which is what we were hoping for."
Richard Silberman is a freelance writer who lives in New York City.
