Photocopier
Most modern photocopiers use a technology called xerography, a dry process that uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles (a powder) onto paper in the form of an image.
Low-end machines that can copy and print in color have increasingly dominated the home-office market as their prices fell steadily during the 1990s.
His job at the patent office in New York required him to make a large number of copies of important papers.
At the time, multiple copies were most commonly made at the point of document origination, using carbon paper or manual duplicating machines.
In 1944, the Battelle Memorial Institute, a non-profit organization in Columbus, Ohio, contracted with Carlson to refine his new process.
In 1947, Haloid Corporation, a manufacturer of photographic paper, approached Battelle to obtain a license to develop and market a copying machine based on this technology.
After consulting a professor of classical language at Ohio State University, Haloid and Carlson changed the name of the process to xerography, a term, coined from Greek roots, that meant "dry writing."
In the early 1950s, Radio Corporation of America (RCA) introduced a variation on the process called Electrofax, whereby images are formed directly on specially coated paper and rendered with a toner dispersed in a liquid.
During the 1960s and through the 1980s, Savin Corporation developed and sold a line of liquid-toner copiers that implemented a technology based on patents held by the company.
Before the widespread adoption of xerographic copiers, photo-direct copies produced by machines such as Kodak's Verifax (based on a 1947 patent) were used.
Xerographic-copier manufacturers took advantage of the high perceived value copying had in the 1960s and early 1970s and marketed "specially designed" paper for xerographic output.
Among the key advantages of photocopiers over earlier copying technologies is their ability: In 1970, Paul Orfalea founded Kinko's retail chain, in Isla Vista, California.
In such urban areas, Kinko's became a place where a multitude of users could make their ideas "typed, designed and xeroxed, then transmitted by fax, computer disk and Federal Express.
This design has several advantages, such as automatic image-quality enhancement and the ability to "build jobs" (that is, to scan page images independently of printing them).
Some digital copiers can function as high-speed scanners; such models typically offer the ability to send documents via email or make them available on file servers.
In the United States, photocopied compilations of articles, handouts, graphics, and other information called readers often require texts for college classes.
These include watermarks, microprinting, holograms, tiny security strips made of plastic (or other material), and ink that appears to change color as the currency is viewed at an angle.
[15] Some high-quality color printers and copiers steganographically embed their identification code into the printed pages, as fine and almost invisible patterns of yellow dots.
[16][17] The Electronic Frontier Foundation (EFF) has investigated this issue[18] and documented how the Xerox DocuColor printer's serial number, as well as the date and time of the printout, are encoded in a repeating 8×15 dot pattern in the yellow channel.
