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Chester Carlson

Chester Carlson

Chester Floyd Carlson
The Inventor of Xerograpgy

The xerographic process, which was invented by Chester Floyd Carlson in 1938 and developed and commercialized by the Xerox Corporation, is widely used to produce high-quality text and graphic images on paper.

Carlson originally called the process electrophotography. It’s based on two natural phenomena: that materials of opposite electrical charges attract and that some materials become better conductors of electricity when exposed to light. Carlson invented a six-step process to transfer an image from one surface to another using these phenomena.

First, a photoconductive surface is given a positive electrical charge. The photoconductive surface is then exposed to the image of a document. Because the illuminated sections (the non-image areas) become more conductive, the charge dissipates in the exposed areas. Negatively charged powder spread over the surface adheres through electrostatic attraction to the positively charged image areas. A piece of paper is placed over the powder image and then given a positive charge. The negatively charged powder is attracted to the paper as it is separated from the photoconductor. Finally, heat fuses the powder image to the paper, producing a copy of the original image.

US Patent 1944 for the machine shown

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