History of the Photocopier
In 1937 Bulgarian physicist Georgi Nadjakov discovered that, when placed into an electric field and exposed to light, some dielectrics acquire permanent electric polarisation in the exposed areas. That polarisation persists in the dark and is destroyed in light. Chester Carlson, the inventor of photocopying, was originally a patent attorney, as well as a part-time researcher and inventor. His job at the patent office in New York required him to make a large number of copies of important papers. Carlson, who was arthritic, found this to be a painful and tedious process. As a result, he was motivated to conduct experiments with photoconductivity. Carlson used his kitchen for his "electrophotography" experiments, and, in 1938, he applied for a patent for the process. He made the first photocopy using a zinc plate covered with sulphur. The words "10-22-38 Astoria" were written on a microscope slide, which was placed on top of more sulphur and under a bright light. After the slide was removed, a mirror image of the words remained. Carlson tried to sell his invention to some companies, but, because the process was still underdeveloped, he failed. At the time, multiple copies were made using carbon paper or duplicating machines, and people did not see the need for an electronic machine. Between 1939 and 1944, Carlson was turned down by over 20 companies, including IBM and GE, neither of which believed there was a significant market for copiers.
In 1944, the Battelle Memorial Institute, a non-profit organization in Columbus, Ohio, contracted with Carlson to refine his new process. Over the next five years, the institute conducted experiments to improve the process of electrophotography. In 1947, Haloid Corporation (a small New York-based manufacturer and seller of photographic paper) approached Battelle to obtain a license to develop and market a copying machine based on this technology.
Haloid felt that the word "electrophotography" was too complicated and did not have good recall value. After consulting a professor of classical language at Ohio State University, Haloid and Carlson changed the name of the process to "Xerography," which was derived from Greek words that meant "dry writing." Haloid called the new copier machines "Xerox Machines" and, in 1948, the word Xerox was trademarked. Haloid eventually changed its name to Xerox Corporation.
In the early 1950s, RCA (Radio Corporation of America) 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.
In 1949, Xerox Corporation introduced the first xerographic copier called the Model A. Xerox became so successful that, in North America, photocopying came to be popularly known as "xeroxing." Xerox has actively fought to prevent "Xerox" from becoming a genericised trademark. While the word "Xerox" has appeared in some dictionaries as a synonym for photocopying, Xerox Corporation typically requests that such entries be modified, and that people not use the term "Xerox" in this way.
"Photostat" is an outdated term for a photocopy. Some languages include hybrid terms, such as the widely used Polish term kserokopia ("xerocopy"), even though relatively few photocopiers are of the Xerox brand.
Prior to the widespread adoption of xerographic copiers, photo-direct copies produced by machines such as Kodak's Verifax were used. A primary obstacle associated with the pre-xerographic copying technologies was the high cost of supplies: a Verifax print required supplies costing USD $0.15 in 1969, while a Xerox print could be made for USD $0.03 including paper and labour. At that time, Thermofax photocopying machines in libraries could make letter-sized copies for USD $0.25 or more (at a time when the minimum wage for a US worker was USD $1.65).
Xerographic copier manufacturers took advantage of a high perceived-value of the 1960s and early 1970s, and marketed paper that was "specially designed" for xerographic output. By the end of the 1970s, paper producers made xerographic "runability" one of the requirements for most of their office paper brands.
Some devices sold as photocopiers have replaced the drum-based process with inkjet or transfer film technology.
Among the key advantages of photocopiers over earlier copying technologies are their ability to do the following:
- to use plain (untreated) office paper
- to implement duplex (or two-sided) printing
- to sort and/or staple output
Coloured toner became available in the 1950s, although full-colour copiers were not commercially available until 3M released the colour-in-colour copier in 1968, which used a dye sublimation process rather than conventional electrostatic technology. The first electrostatic colour copier was released by Canon in 1973.
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Colour photocopying is a concern to governments, as it makes counterfeiting currency easier to accomplish. Some countries have introduced anti-counterfeiting technologies into their currency specifically to make it harder to use a colour photocopier for counterfeiting. These technologies include watermarks, microprinting, holograms, tiny security strips made of plastic (or other material), and ink that appears to change colour as the currency is viewed at an angle. Some photocopying machines contain special software that can prevent copying currency that contains a special pattern.
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In recent years, all new photocopiers have adopted digital technology, thus replacing the older analogue technology. With digital copying, the copier effectively consists of an integrated scanner and laser printer. 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 the process of printing them). Some digital copiers can function as high-speed scanners; such models typically offer the ability to send documents via email or to make them available on file servers.
A great advantage of digital copier technology is 'scan once print many'. When copying a set of twenty pages twenty times, for example, a digital copier scans each page only once then uses the stored information to produce twenty sets and released into the exit tray or finisher by digital offset for easy retrieval. In an analog copier, either each page is scanned twenty times (a total of 400 scans), making one set at a time, or twenty separate output trays are used for the twenty sets.