Chester F. Carlson

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Chester F. Carlson

The American inventor Chester F. Carlson (1906-1968) invented the process of xerography which became the basis for the operation of the office copying machines first introduced by the Xerox Corporation in 1959.

Chester Floyd Carlson was born on February 8, 1906, in Seattle, Washington. Illness and poverty in his family forced him to become his parent's main financial support while he was in his teens. Despite these responsibilities and handicaps. Carlson worked his way through college, graduating with a Bachelor of Science degree in physics from California Institute of Technology in 1930.

After trying in vain to gain employment as a physicist in California he left for New York City, where the P. R. Mallory Company, an electrical manufacturing firm, offered him a position in its patent department. This job proved to be of crucial importance to Carlson's career as an inventor in two ways. First, he was introduced to patent law and procedures; second, the need to duplicate patent drawings and specifications made him aware of the inadequacies of the existing photostat process for copying documents.

Carlson stayed at Mallory until 1945, eventually becoming head of the patent department.

While working at Mallory, Carlson attended New York Law School at night, receiving his law degree in 1939. One year later he was admitted to the New York bar. At the same time he conducted research on a duplication process that would produce clean copies quickly without using the chemical solutions, film, and printing paper necessary for photographic reproduction.

Carlson began his search for an alternative process by reading the available literature on printing, photography, and various copying technologies. His study convinced him that in some yet unspecified manner it might be possible to duplicate documents by making use of photoconductivity. He decided that wet-process photography must be replaced by the dry techniques of what he called "electrophotography."

Using the little amount of money he possessed, Carlson bought chemicals and equipment and turned his New York apartment into a laboratory (1934). Unable to devote full time to this work, Carlson hired an unemployed German physicist and engineer named Otto Kornei to help him. Carlson and Kornei, limited to a research budget of $10.00 a month, were able in October 1938 to make the first electrophotographic copy. It read simply "10-22-38 Astoria."

This copy was produced by a primitive, but innovative, method that formed the foundation for Carlson's subsequent research and for the industry that grew out of it. First, a rabbit's fur or cotton cloth was rubbed vigorously over the surface of a metal plate coated with a layer of sulfur. The rubbing charged the plate with static electricity. The charged plate was then placed beneath a piece of glass upon which was inked the material to be copied. Metal plate and glass were next exposed to a bright light source for a few seconds. This exposure caused the sulfur coating to lose its charge in varying degrees depending upon how much light reached its surface. In effect, the intense illumination produced an invisible electrostatic image of the material being copied. This image could be made visible by dusting an electroscopic powder on the plate. The powder was attracted to the areas which had been less intensely illuminated. In order to make the fragile powder image permanent, Carlson carefully pressed a piece of wax-coated paper over the prepared plate. The powder adhered to, and fixed upon, the surface of the waxed paper.

Although there obviously remained much to be done in improving the new dry-copying technique—which came to be called "xerography"—Carlson applied for key patents on the process (1939, 1940). Carlson had neither the money, laboratory facilities, nor mechanical talent to transform his experiments into a working copy machine ready for public use. Therefore, in 1944 he reached an agreement with the Battelle Memorial Institute, a nonprofit industrial research laboratory, to develop his invention beyond its first stages. Three years later the Haloid Company of Rochester, New York, undertook the final conversion of xerography into a commercial product. Haloid, which became Haloid-Xerox and then Xerox, publicly demonstrated xerography in 1948 and offered the first Xerox copying machines for sale in 1959.

As xerography became a complex technical and business venture Carlson withdrew from active involvement with it, except for serving as a consultant to the Xerox Corporation. By 1945 his invention brought him sufficient financial security so that he could retire from Mallory. Royalties from his xerography patents made Carlson a multi-millionaire, and in later life he engaged in many philanthropic endeavors.

Further Reading

For Carlson's life and work, and the commercial development of xerography, see John H. Dessauer, My Years With Xerox: The Billions Nobody Wanted (1971). The technical side of xerography is treated in John H. Dessauer and Harold E. Clark (editors), Xerography and Related Processes (London, 1965). □