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Xerox Seeks Erasable Form of Paper for CopiersJohn Markoff - The New York TimesPALO ALTO, Calif., Nov. 21 — During the 1970s, researchers at Xerox’s Palo Alto Research Center explored a software technique called "garbage collection" used for recycling computer memory. The technique allowed the automatic reuse of blocks of memory that were storing unused programs and data.
Today an anthropologist at the center, Brinda Dalal, has become a self-styled "garbologist" to assist in a joint effort with chemists at the Xerox Research Center of Canada to develop an "erasable paper" system. The goal is to recycle paper documents produced by the company’s copiers — potentially an unlimited number of times.
What she has discovered is a notable change in the role of paper in modern offices, where it is increasingly used as a medium of display rather than storage. Documents are stored on central servers and personal computers and printed only as needed; for meetings, editing or reviewing information.
The pieces of paper spewed from copiers frequently end up back in the recycling bin on the same day they are printed, she noted.
Of the 1,200 pages the average office worker prints per month, 44.5 percent are for daily use — assignments, drafts or e-mail. In her research, scouring the waste produced by office workers, she found that 21 percent of black-and-white copier documents were returned to the recycling bin on the same day they were produced.
"We were surprised by our results," she said. "Nobody looks at the ephemeral information going through people’s waste baskets."
Her research is part of a three-year-old technology development effort to design an add-on system for an office copier to produce "transient documents" that can be easily reused. The researchers now have a prototype system that will produce documents on a specially coated paper with a light yellow tint. Currently, the process works without toner and produces a low-resolution document that appears to be printed with purple ink.
The printed information on the document "disappears" within 16 hours. The documents can be reused more quickly by simply placing them in the copier paper tray. The researchers said that individual pieces of paper had been printed on up to 50 times, and the only current limit in the process appears to be paper life.
"People really like paper," said Eric J. Shrader, a computer scientist who is area manager for printing systems at the Hardware Systems Laboratory of the research center, which is known as PARC. "They like the way it feels."
The project is still very much in a laboratory phase, he said. The researchers are still trying to refine the process, both to increase contrast and to extend control over the lifespan of the print process.
During the 1990s, the Japanese office equipment maker Ricoh developed a commercial system that made it possible to remove toner from paper to make recycling possible, he said. It was possible to recycle individual pieces of paper up to 10 times, according to Ricoh, but that system is no longer commercially available.
Xerox has not yet decided whether it will commercialize its technology, Mr. Shrader said, but the goal is to create a system where the specially coated paper costs between two and three times standard copier paper, making the total cost of the system substantially less than conventional paper when paper is reused repeatedly.
The company said the precise nature of the technology was proprietary and that Xerox had applied for a number of related patents covering the invention. The researchers describe the invention as being based on compounds that can change color when they absorb a certain wavelength of light, but can then gradually revert to their original appearance. The compounds currently self-erase in about 16 to 24 hours, or can be erased immediately when heated.
The challenge Xerox faces is to find a market for a new paper printing technology in an era when information is increasingly being viewed and read on electronic displays of all types.
For example, PARC itself has done extensive research on the idea of "electronic paper." Its researchers separately developed an "electronic reusable paper" system called Gyricon. A Gyricon sheet is a thin layer of transparent plastic composed of small beads similar to toner particles. The beads are "bichromal," with light and dark sides. When a voltage is applied at different positions on the sheet, the beads rotate to create an image. Xerox tried unsuccessfully to commercialize the technology.
The Sony Reader, introduced this year, is based on a similar technology developed by the E Ink Corporation of Cambridge, Mass.
"I worry that this would be like coming out with Super 8 just before the video camera," said Paul Saffo, a Silicon Valley researcher who has been a consultant to Xerox. "This would have been a bigger deal 10 years ago. These days there’s so much getting read online I wonder if time hasn’t passed this by."
