Chester Carlson and Xerography

Early printing machine, by Johann Bernhard Basedow

Early printing machine, by Johann Bernhard Basedow

On September 19, 1968, American physicist, inventor, and patent attorney Chester F. Carlson passed away. He is best known for having invented the process of electrophotography, which produced a dry copy rather than a wet copy, as was produced by the mimeograph process. Carlson’s process was subsequently renamed xerography, a term that literally means “dry writing.”

It is believed that when Chester Carlson was about ten years old, he created a newspaper called This and That, created by hand and circulated among his friends with a routing list. During his high school years, Carlson worked for a local printer where he attempted to typeset and publish a magazine himself, with the target group of science-minded students. Chester Carlson attended Riverside Junior College and there also began as a chemistry major, switching to physics later on. In 1930Carlson earned his Bachelor of Science degree in Physics from Caltech.

At Bell Telephone Laboratories in New York City, Carlson began working as a research engineer and later transferred to the patent department as an assistant to one of the company’s patent attorneys. At Bell Labs, Chester Carlson noted more than 400 ideas and kept his enthusiasm for printing. Back then, copies in the department were made by typists who retyped the application completely, using carbon paper to make multiple copies at once. So called duplicating machibes were available, but a master copy had to be prepared first, making it a time and money expensive process. Chester Carlson wanted to develop a copying machine that was more efficient and did not require further intermediate steps.

During the 1930s,  Chester Carlson began studying law. He had to copy books at the New York Public Library because he could not afford them. There, Carlson was inspired by an article by Hungarian physicist Pál Selényi in an obscure German scientific journal, that showed him a way to obtain his dream ‘copy’ machine. Carlson began experimenting and at first, his attempts resulted in explosions and really bad smells. The first preliminary patent application was filed in October 1937. Inspired by Selényi’s paper, Chester Carlson to use light to remove the static charge from a uniformly-ionized photoconductor. As no light would reflect from the black marks on the paper, those areas would remain charged on the photoconductor, and would therefore retain the fine powder. He could then transfer the powder to a fresh sheet of paper, resulting in a duplicate of the original.

In 1938, Carlson and Otto Kornei (who had previously joined the experiments) prepared a zinc plate with a sulfur coating, darkened the room, rubbed the sulfur surface with a cotton handkerchief to apply an electrostatic charge, then laid the slide on the plate, exposing it to a bright, incandescent light. They removed the slide, sprinkled lycopodium powder to the sulfur surface, softly blew the excess away, and transferred the image to a sheet of wax paper. They heated the paper, softening the wax so the lycopodium would adhere to it, and had the world’s first xerographic copy. They repeated the experiment and Chester Carlson was astonished while Kornei was so disappointed that he discontinued his work on the problem. Also investors did not understand Carlson’s work while others did simply not believe in the product. Still, in 1942, the Patent Office issued Carlson’s patent on electrophotography.

In 1945, Chester Carlson presented his ideas before the Battelle Memorial Institute in Columbus, Ohio with success. From then on, he was supported in his further reaseach and marketing. One year later, Battelle, Carlson, and the Haloid company  signed the first agreement to license electrophotography for a commercial product.  When Haloid intended to make public announcements about electrophotography to retain its claims to the technology, the term ‘electrophotography’ bothered them. In 1948, ten years to the day after that first microscope slide was copied, the Haloid Company made the first public announcement of xerography.  The first device, the XeroX Model A Copier, became the first commercial photocopier. Unfortunately, the process was still manual and the machine was quite hard to use. Further, competitors on the market like Kodak and 3M began selling their own copying devices. Kodak’s Verifax device was also substantially more expensive and larger than Haloid’s.

The Rank Organisation also began investing and marketing the product. By 1958, Haloid was renamed to Haloid Xerox, accepting that xerography was now the company’s main line of business. The Xerox 914 model was probably the first device recognizable as a modern photocopier. It allowed an operator to place an original on a sheet of glass, press a button, and receive a copy on plain paper. Xerox 914 entered the market in 1959 and was very successful. Two years later, the company changed its name to Xerox Corporation.

At yovisto you can learn more about the Future of Digital Print in a lecture by Dan Clancy at MIT.

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