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.”
The need for a quick, satisfactory copying machine that could be used right in the office seemed very apparent to me—there seemed such a crying need for it—such a desirable thing if it could be obtained. So I set out to think of how one could be made.
Carlson knew that several major corporations were researching ways of copying paper. The Haloid Company had the Photostat, which it licensed to Eastman Kodak, the photography giant. However, these companies were researching along photographic lines, and their solutions required special chemicals and papers. The Photostat, for instance, was essentially a photograph of the document being copied.
Selényi’s article described a way of transmitting and printing facsimiles of printed images using a beam of directed ions directed onto a rotating drum of insulating material. The ions would create an electrostatic charge on the drum. A fine powder could then be dusted upon the drum; the powder would stick to the parts of the drum that had been charged, much as a balloon will stick to a static-charged stocking.
To this point, Carlson’s apartment-kitchen experiments in constructing a copying machine had involved trying to generate an electric current in the original piece of paper using light. Selényi’s article convinced Carlson to instead 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. This approach would give his invention an advantage over the Photostat, which could create only a photographic negative of the original.
On October 22, 1938, they had their historic breakthrough. Kornei wrote the words “10.-22.-38 ASTORIA.” in India ink on a glass microscope slide. The Austrian 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. After repeating the experiment to be sure it worked, Carlson celebrated by taking Kornei out for a modest lunch.
The road to Carlson’s success—or that for xerography’s success—had been long and filled with failure. He was turned down for funding by more than twenty companies between 1939 and 1944. He tried for some time to sell the invention to International Business Machines (IBM), the great vendor of office equipment, but no one at the company saw merit in the concept—it is not clear that anyone at IBM even ‘understood’ the concept. His next-to-last attempt to garner the interest—and funds—he needed to commercialize the physics was a meeting with the Department of the Navy. The Navy had a specific interest in the production of dry copies, but they did not “see” what Carlson saw.
On October 6, 1942, the Patent Office issued Carlson’s patent on electrophotography.