Photocopier
A photocopier (also called copier or copy machine, and formerly Xerox machine, the
Commercial
Photocopying is widely used in the business, education, and government sectors. While there have been predictions that photocopiers will eventually become obsolete as information workers increase their use of digital document creation, storage, and distribution and rely less on distributing actual pieces of paper, as of 2015, photocopiers continue to be widely used. During the 1980s, a convergence began in some high-end machines towards what came to be called a multi-function printer: a device that combined the roles of a photocopier, a fax machine, a scanner, and a computer network-connected printer. 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. High-end color photocopiers capable of heavy-duty handling cycles and large-format printing remain a costly option found primarily in print and design shops.
History
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 manufacturer of photographic paper, approached Battelle to obtain a license to develop and market a copying machine based on this technology.[2]
Haloid felt that the word "electrophotography" was too complicated and did not have good
In 1949, Xerox Corporation introduced the first xerographic copier, called the Model A.
In the early 1950s,
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. A primary obstacle associated with the pre-xerographic copying technologies was the high cost of supplies: a Verifax print required supplies costing US$0.15 in 1969, while a Xerox print could be made for $0.03, including paper and labor. The coin-operated Photostat machines still found in some public libraries in the late 1960s made letter-size copies for $0.25 each, when the minimum wage for a US worker was $1.65 per hour; the Xerox machines that replaced them typically charged $0.10.
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. 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
Among the key advantages of photocopiers over earlier copying technologies is their ability:
- to use plain (untreated) office paper
- to implement duplex (two-sided) printing
- to scan several pages automatically with an ADF
- eventually, to sort and/or staple output
Color photocopiers
Colored toner became available in the 1940s, although full-color copiers were not commercially available until 1968, when
Digital technology
There is an increasing trend for new photocopiers to implement
A significant advantage of digital copier technology is "automatic digital collation". For example, when copying a set of 20 pages 20 times, a digital copier scans each page only once, then uses the stored information to produce 20 sets. In an analog copier, either each page is scanned 20 times (a total of 400 scans), making one set at a time, or 20 separate output trays are used for the 20 sets.
Low-end copiers also use
How it works (using xerography)
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- Charging: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of a photoconductive material. A photoconductor is a semiconductor that becomes conductive when exposed to light.[6]
- Exposure: A bright lamp illuminates the original document, and the white areas of the original document reflect the light onto the surface of the photoconductive drum. The drum areas that are exposed to light become conductive and therefore discharge to the ground. The drum area not exposed to light (those areas that correspond to black portions of the original document) remains negatively charged.
- Developing: The toner is positively charged. When it is applied to the drum to develop the image, it is attracted and sticks to the negatively charged areas (black areas), just as paper sticks to a balloon with a static charge.
- Transfer: The resulting toner image on the surface of the drum is transferred from the drum onto a piece of paper that has an even greater negative charge than the drum has.
- Fusing: The toner is melted and bonded to the paper by heat and pressure rollers.
A negative photocopy inverts the document's colors when creating a photocopy, resulting in letters that appear white on a black background instead of black on a white background. Negative photocopies of old or faded documents sometimes produce documents that have better focus and are easier to read and study.
Copyright issues
Photocopying material that is subject to
In certain countries, such as Canada, some universities pay royalties from each photocopy made at university copy machines and copy centers to copyright collectives out of the revenues from the photocopying, and these collectives distribute resulting funds to various scholarly publishers. In the United States, photocopied compilations of articles, handouts, graphics, and other information called readers often require texts for college classes. Either the instructor or the copy center is responsible for clearing copyright for every article in the reader, and attribution information must be clearly included in the reader.
Counterfeiting
To counter the risk of people using color copiers to create counterfeit copies of paper currency, some countries have incorporated anti-counterfeiting technologies into their currency. 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. Some photocopying machines contain special software that can prevent copying currency that has a special pattern.
Color copying also raises concerns regarding the copying and/or forging of other documents, such as driver's licenses and university degrees and transcripts. Some driver's licenses are made with embedded holograms so that a police officer can detect a fake copy. Some university and college transcripts have special anti-copying watermarks in the background. If a copy is made, the watermarks will become highly visible, which allows the recipient to determine that they have a copy rather than a genuine original transcript.
Health issues
Exposure to
Concerns about emissions from photocopy machines have been expressed by some in connection with the use of selenium and emissions of ozone and fumes from heated toner.[8][9]
Forensic identification
Similar to
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. Some sources identify Xerox and Canon as companies doing this.[11][12] The Electronic Frontier Foundation (EFF) has investigated this issue[13] 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. EFF is working to reverse engineer additional printers.[14] The EFF also reports that the US government has asked these companies to implement such a tracking scheme, so that counterfeiting can be traced. The EFF has filed a Freedom of Information Act request in order to look into privacy implications of this tracking.[15]
Wet photocopying
Photocopying, using liquid developer, was developed by Ken Metcalfe and Bob Wright of
Photocopying, using liquid developer, was used in 1967.[18][19][20]
"Images from 'wet photocopying' do not last as long as dry toner images, but this is not due to acidity."[21]
See also
- Gestetner
- Heliography
- IBM Copier Family
- List of duplicating processes
- Print Audit
- Reprography
- Risograph
- Scanography
- Thermochromatic ink
- Thermofax
- Xerox art
- Xerox 914
References
- ^ "The Story of Xerography" (PDF). Xerox Corporation. Archived from the original (PDF) on 25 January 2021. Retrieved 28 September 2017.
- ^ "The Story of Xerography" (PDF). Xerox Corporation. Archived from the original (PDF) on 25 January 2021. Retrieved 28 September 2017.
- ^ "Xerox history: 1940s". Archived from the original on 28 September 2017. Retrieved 28 September 2017.
- ^ Greenwald, John (1983-07-11). "The Colossus That Works". TIME. Archived from the original on 2008-05-14. Retrieved 2019-05-18.
IBM stumbled badly when it set out to produce an office copier in the 1970s.
- ^ "Xerox". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.) - generic use recorded from 1966 onward.
- ^ "Encarta definition of 'photoconductor'". Archived from the original on 2008-12-11. Retrieved 2009-11-20.
- ^ a b "Photocopier Hazards and a Conservation Case Study (notes 17,18)". 1998. Archived from the original on 2009-04-13. Retrieved 2009-11-20.
- ^ "Photocopier and Laser Printer Hazards" (PDF). London Hazards Centre. 2002. Archived from the original (PDF) on 2010-04-01. Retrieved 2009-11-20.
- ^ "Health and Safety Representatives' Handbook". [National Association of Schoolmasters Union of Women Teachers (NASUWT)]. July 27, 2009. Archived from the original (PDF) on July 19, 2011. Retrieved April 30, 2011.
- ^ "Printer forensics to aid homeland security, tracing counterfeiters". 2004-10-12. Archived from the original on 2011-05-17. Retrieved 2009-11-20.
- ^ Jason Tuohey (2004-11-22). "Government Uses Color Laser Printer Technology to Track Documents". Archived from the original on 2009-01-25. Retrieved 2009-11-20.
- ^ Wilbert de Vries (2004-10-26). "Dutch track counterfeits via printer serial numbers". Archived from the original on 2022-11-10. Retrieved 2009-11-20.
- ^ "Is Your Printer Spying On You?". Electronic Frontier Foundation. Archived from the original on 2008-11-22. Retrieved 2009-11-20.
- ^ "List of Printers Which Do or Do Not Display Tracking Dots". Electronic Frontier Foundation. 19 September 2007. Archived from the original on 2008-12-05. Retrieved 2009-11-20.
- ^ "Printers". Electronic Frontier Foundation. Archived from the original on 2008-11-22. Retrieved 2014-05-03.
- ^ "Wet xero/photocopying developed by Ken Metcalfe and Bob Wright at 1952 Defence laboratory in Adelaide". AdelaideAZ. Archived from the original on 7 September 2022. Retrieved 23 April 2022.
- ^ "Aussie connection to digital's next frontier". Sprinter. 28 June 2012. Archived from the original on 7 September 2022. Retrieved 23 April 2022.
- ^ Nix, George F. (26 December 1967). "US3360258 Photocopy paper package". US patent. Archived from the original on 23 April 2022. Retrieved 23 April 2022.
- ^ "Comparison of Volatile Organic Compounds from Processed Paper..." (PDF). Air Infiltration and Ventilation Centre. Archived (PDF) from the original on 1 July 2022. Retrieved 23 April 2022.
Sonnino et al., 1983) and wet photocopying machines (Grot et al., 1991; Tsuchiya, 1988; Tsuchiya and Stewart, 1990; Walkinshaw et al., 1987). The.
- ISBN 978-0-8422-0255-8.
- ^ Atwood, Cathy; Gullick, Michael (February 1990). "Reviewed: Paper Preservation: Conservation Techniques and Methodology. 1988". Abbey Newsletter. American Institute for Conservation. Archived from the original on 7 September 2022. Retrieved 23 April 2022.
Volume 14; Number 1; Feb 1990;
Further reading
- R. Schaffert: Electrophotography. Focal Press, 1975
- Owen, David (August 2004). Copies in Seconds : How a Lone Inventor and an Unknown Company Created the Biggest Communication Breakthrough Since Gutenberg: Chester Carlson and the Birth of the Xerox Machine. New York: ISBN 0-7432-5117-2.