Xerography is Invented by Chester Carlson

It took Carlson 15 years to establish the basic principles of electrophotography, and he patented his developments every step along the way.

He filed his first preliminary patent application on October 18, 1937. His early experiments, conducted with sulphur in his apartment kitchen, were smoky and smelly and he was soon encouraged to find another place. At about the same time, he developed arthritis of the spine, like his father. He pressed on with his experiments, however, in addition to his law school studies and his regular job.

To make things easier, he hired Otto Kornei, an immigrant physicist from Austria who had fled the Nazi regime there. They set up their laboratory in a back room of a house in Astoria, Queens, New York City.

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 handkerchief to apply an electrostatic charge, then laid the slide on the zinc 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, melting the wax off, and had their first near-perfect duplicate. After repeating the experiment several times, they celebrated by going out to lunch.

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.