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A photocopier (also called copier or copy machine, and formerly Xerox machine, the
generic trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or ...
) is a
machine A machine is a physical system that uses power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromol ...
that makes copies of documents and other visual images onto
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, Textile, rags, poaceae, grasses, Feces#Other uses, herbivore dung, or other vegetable sources in water. Once the water is dra ...
or
plastic film Plastic film is a thin continuous polymeric material. Thicker plastic material is often called a "sheet". These thin plastic membranes are used to separate areas or volumes, to hold items, to act as barriers, or as printable surfaces. Plast ...
quickly and cheaply. Most modern photocopiers use a technology called ''
xerography Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots , meaning "dry" and , meaning "writing"—to emphasize that unlike reproduction techniques then in use such as c ...
'', a dry process that uses
electrostatic Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word (), mean ...
charges on a light-sensitive photoreceptor to first attract and then transfer
toner Toner may refer to: * Toner (printing), a powder mixture used in laser printers and photocopiers * Toner (skin care), a water-based lotion, tonic, or wash designed to cleanse the skin in preparation for other skincare products * Hair toner, produ ...
particles (a powder) onto paper in the form of an image. The toner is then fused onto the paper using heat, pressure, or a combination of both. Copiers can also use other technologies, such as
inkjet Inkjet printing is a type of printer (computing), computer printing that recreates a digital image by propelling droplets of ink onto paper or plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range f ...
, but xerography is standard for office copying. Commercial
xerographic Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots , meaning "dry" and , meaning "writing"—to emphasize that unlike reproduction techniques then in use such as c ...
office photocopying gradually replaced copies made by verifax,
photostat The Photostat machine, or Photostat, was an early Photocopying, projection photocopier created in the 1900s (decade), decade of the 1900s by the Commercial Camera Company, which became the Photostat Corporation. The "Photostat" name, which was ori ...
,
carbon paper Carbon paper (originally carbonic paper) consists of sheets of paper that create one or more copies simultaneously with the creation of an original document when inscribed by a typewriter or ballpoint pen. The email term cc which means "carbon ...
,
mimeograph machine A mimeograph machine (often abbreviated to mimeo, sometimes called a stencil duplicator or stencil machine) is a low-cost duplicating machines, duplicating machine that works by forcing ink through a stencil onto paper. The process is called ...
s, and other
duplicating machines Duplicating machines were the predecessors of modern document-reproduction technology. They have now been replaced by digital duplicators, image scanner, scanners, laser printers, and photocopiers, but for many years they were the primary means o ...
. 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 An MFP (multi-function product/printer/peripheral), multi-functional, all-in-one (AIO), or multi-function device (MFD), is an office machine which incorporates the functionality of multiple devices in one, so as to have a smaller footprint in a ...
: a device that combined the roles of a photocopier, a
fax Fax (short for facsimile), sometimes called telecopying or telefax (short for telefacsimile), is the telephonic transmission of scanned printed material (both text and images), normally to a telephone number connected to a printer or other out ...
machine, a scanner, and a computer network-connected
printer Printer may refer to: Technology * Printer (publishing), a person * Printer (computing), a hardware device * Optical printer for motion picture films People * Nariman Printer (fl. c. 1940), Indian journalist and activist * James Printer (1640 ...
. 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

Chester Carlson Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington. Carlson invented electrophotography (now xerography, meaning "dry writing"), producing a dry ...
(1906–1968), the inventor of photocopying, was originally a
patent attorney A patent attorney is an attorney who has the specialized qualifications necessary for representing clients in obtaining patents and acting in all matters and procedures relating to patent law and practice, such as filing patent applications and o ...
, as well as a part-time researcher and inventor. His job at the
patent office A patent office is a governmental or intergovernmental organization which controls the issue of patents. In other words, "patent offices are government bodies that may grant a patent or reject the patent application based on whether the applicati ...
in
New York New York most commonly refers to: * New York (state), a state in the northeastern United States * New York City, the most populous city in the United States, located in the state of New York New York may also refer to: Places United Kingdom * ...
required him to make a large number of copies of important papers. Carlson, who was arthritic, found this a painful and tedious process. This motivated him to conduct experiments with photoconductivity. Carlson used his kitchen for his "
electrophotography Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots , meaning "dry" and , meaning "writing"—to emphasize that unlike reproduction techniques then in use such as c ...
" experiments, and, in 1938, he applied for a patent for the process. He made the first photocopy using a
zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...
plate covered with
sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...
. The words "10-22-38 Astoria" were written on a
microscope A microscope () is a laboratory equipment, laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic ...
slide, which was placed on top of more sulfur 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 failed because the process was still underdeveloped. At the time, multiple copies were most commonly made at the point of document origination, using
carbon paper Carbon paper (originally carbonic paper) consists of sheets of paper that create one or more copies simultaneously with the creation of an original document when inscribed by a typewriter or ballpoint pen. The email term cc which means "carbon ...
or manual
duplicating machines Duplicating machines were the predecessors of modern document-reproduction technology. They have now been replaced by digital duplicators, image scanner, scanners, laser printers, and photocopiers, but for many years they were the primary means o ...
. People did not see the need for an electronic copier. Between 1939 and 1944, Carlson was turned down by over 20 companies, including
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
and
General Electric General Electric Company (GE) was an American Multinational corporation, multinational Conglomerate (company), conglomerate founded in 1892, incorporated in the New York (state), state of New York and headquartered in Boston. Over the year ...
—neither of which believed there was a significant market for copiers. In 1944, the
Battelle Memorial Institute Battelle Memorial Institute (or simply Battelle) is an American private nonprofit applied science and technology development company headquartered in Columbus, Ohio. History The institute was founded in 1929 by Gordon Battelle. Originall ...
, a non-profit organization in
Columbus, Ohio Columbus (, ) is the List of capitals in the United States, capital and List of cities in Ohio, most populous city of the U.S. state of Ohio. With a 2020 United States census, 2020 census population of 905,748, it is the List of United States ...
, 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. 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 The Ohio State University (Ohio State or OSU) is a public university, public Land-grant university, land-grant research university in Columbus, Ohio, United States. A member of the University System of Ohio, it was founded in 1870. It is one ...
, Haloid and Carlson changed the name of the process to ''
xerography Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots , meaning "dry" and , meaning "writing"—to emphasize that unlike reproduction techniques then in use such as c ...
'', a term, coined from
Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...
roots, that meant "dry writing." Haloid called the new copier machines "Xerox Machines" and, in 1948, the term ''Xerox'' was
trademarked A trademark (also written trade mark or trade-mark) is a form of intellectual property that consists of a word, phrase, symbol, design, or a combination that identifies a product or service from a particular source and distinguishes it from ot ...
. Haloid eventually became
Xerox Corporation Xerox Holdings Corporation (, ) is an American corporation that sells print and digital document products and services in more than 160 countries. Xerox was the pioneer of the photocopier market, beginning with the introduction of the Xerox ...
in 1961. In 1949, Xerox Corporation introduced the first xerographic copier, called the Model A. Seeing off computing-leader
IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...
in the office-copying market, 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
genericized trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or ...
. While the word ''Xerox'' has appeared in some dictionaries as a synonym for photocopying, Xerox Corporation typically requests such entries be modified, and discourages use of the term ''Xerox'' in this way. In the early 1950s,
Radio Corporation of America RCA Corporation was a major American electronics company, which was founded in 1919 as the Radio Corporation of America. It was initially a patent pool, patent trust owned by General Electric (GE), Westinghouse Electric Corporation, Westinghou ...
(RCA) introduced a variation on the process called
Electrofax {{Unreferenced, date=December 2009 An electrofax was a type of fax. It involved electrostatic printer (computing), printer and copier technology, where an image was formed directly on the paper, instead of first on a drum, then transferred to paper ...
, 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 The Eastman Kodak Company, referred to simply as Kodak (), is an American public company that produces various products related to its historic basis in film photography. The company is headquartered in Rochester, New York, and is incorporated i ...
'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
brand A brand is a name, term, design, symbol or any other feature that distinguishes one seller's goods or service from those of other sellers. Brands are used in business, marketing, and advertising for recognition and, importantly, to create and ...
s. Some devices sold as photocopiers have replaced the drum-based process with
inkjet Inkjet printing is a type of printer (computing), computer printing that recreates a digital image by propelling droplets of ink onto paper or plastic substrates. Inkjet printers were the most commonly used type of printer in 2008, and range f ...
or transfer-film technology. 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 In 1970, Paul Orfalea founded Kinko's retail chain, in Isla Vista, California. Starting with a single copier that year, this copy service chain would expand to over 1,000 locations around the world. By the 1980s, Kinko's operated 24 hours a day, 7 days a week, with customers using the copy center for academic and business work as well as personal publishing and advertising. By the 1990s, Kinko's had 700 locations around the United States, with 5 in Manhattan. 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". Kate Eichhorn, in ''Adjusted Margin: Xerography, Art, and Activism in the Late Twentieth Century'', notes that during this period (1970s through 1990s) the copy machine played "an especially notable role in the era's punk, street art, and DIY movements." FedEx purchased the Kinko's chain in 2004, and its services were incorporated into the name
FedEx Office FedEx Office Print & Ship Services Inc. (doing business as FedEx Office; formerly FedEx Kinko's, and earlier simply Kinko's) is an American retail chain that provides an outlet for FedEx Express and FedEx Ground (including Home Delivery) shippin ...
in 2008.


Color photocopiers

Colored toner became available in the 1940s, although full-color copiers were not commercially available until 1968, when 3M released the ''Color-in-Color'' copier, which used a
dye sublimation Dye-sublimation printing (or dye-sub printing) is a term that covers several distinct digital computer printing techniques that involve using heat to transfer dye onto a substrate. The sublimation name was first applied because the dye was ...
process rather than conventional electrostatic technology. Xerox introduced the first electrostatic color-copier (the 6500) in 1973. Color photocopying is a concern to
government A government is the system or group of people governing an organized community, generally a State (polity), state. In the case of its broad associative definition, government normally consists of legislature, executive (government), execu ...
s, as it facilitates
counterfeiting A counterfeit is a fake or unauthorized replica of a genuine product, such as money, documents, designer items, or other valuable goods. Counterfeiting generally involves creating an imitation of a genuine item that closely resembles the original ...
currency A currency is a standardization of money in any form, in use or circulation as a medium of exchange, for example banknotes and coins. A more general definition is that a currency is a ''system of money'' in common use within a specific envi ...
and other documents: for more information, see .


Digital technology

There is an increasing trend for new photocopiers to implement digital technology, thereby replacing the older analog technology. With digital copying, the copier effectively consists of an integrated scanner and
laser printer Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a Electric charge, negatively charged cylinder call ...
. 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. A significant advantage of digital copier technology is "automatic digital
collation Collation is the assembly of written information into a standard order. Many systems of collation are based on numerical order or alphabetical order, or extensions and combinations thereof. Collation is a fundamental element of most office fi ...
". 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 digital technology, but tend to consist of a standard PC scanner coupled to an inkjet or low-end laser printer, which are far slower than their counterparts in high-end copiers. However, low-end scanner-inkjets can provide color copying at a lower upfront purchase-price but a much higher cost per copy. Combined digital scanner/printers sometimes have built-in fax machines and can be classified as one type of
multifunction printer An MFP (multi-function product/printer/peripheral), multi-functional, all-in-one (AIO), or multi-function device (MFD), is an office machine which incorporates the functionality of multiple devices in one, so as to have a smaller footprint in a ...
.


How it works (using xerography)

#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 Photoconductivity is an optical and electrical phenomenon in which a material becomes more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiation. W ...
material. A photoconductor is a
semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...
that becomes conductive when exposed to light. #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 Toner may refer to: * Toner (printing), a powder mixture used in laser printers and photocopiers * Toner (skin care), a water-based lotion, tonic, or wash designed to cleanse the skin in preparation for other skincare products * Hair toner, produ ...
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
copyright A copyright is a type of intellectual property that gives its owner the exclusive legal right to copy, distribute, adapt, display, and perform a creative work, usually for a limited time. The creative work may be in a literary, artistic, ...
(such as books or scientific papers) is subject to restrictions in most countries. This is common practice, as the cost of purchasing a book for the sake of one article or a few pages can be excessive. The principle of
fair use Fair use is a Legal doctrine, doctrine in United States law that permits limited use of copyrighted material without having to first acquire permission from the copyright holder. Fair use is one of the limitations to copyright intended to bal ...
(in the United States) or
fair dealing Fair dealing is a limitation and exception to the exclusive rights granted by copyright law to the author of a creative work. Fair dealing is found in many of the common law jurisdictions of the Commonwealth of Nations. Fair dealing is an e ...
(in other Berne Convention countries) allows copying for certain specified purposes. In certain countries, such as Canada, some
universities A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...
pay royalties from each photocopy made at university copy machines and copy centers to
copyright collective A copyright collective (also known as a copyright society, copyright collecting agency, licensing agency or copyright collecting society or collective management organization) is a non-governmental body created by copyright law or private agreeme ...
s 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 A counterfeit is a fake or unauthorized replica of a genuine product, such as money, documents, designer items, or other valuable goods. Counterfeiting generally involves creating an imitation of a genuine item that closely resembles the original ...
copies of paper currency, some countries have incorporated anti-counterfeiting technologies into their currency. These include watermarks, microprinting,
hologram Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interf ...
s, 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 Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...
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
watermark A watermark is an identifying image or pattern in paper that appears as various shades of lightness/darkness when viewed by transmitted light (or when viewed by reflected light, atop a dark background), caused by thickness or density variations i ...
s 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
ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...
is a concern. In the early days of photocopiers, the sensitizing light source was filtered green to match the optimal sensitivity of the photoconductive surface. This filtering conveniently removed all ultraviolet. Currently, a variety of light sources are used. As
glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...
transmits ultraviolet rays between 325 and 400 nanometers, copiers with ultraviolet-producing lights such as fluorescent,
tungsten Tungsten (also called wolfram) is a chemical element; it has symbol W and atomic number 74. It is a metal found naturally on Earth almost exclusively in compounds with other elements. It was identified as a distinct element in 1781 and first ...
halogen, or
xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...
flash, expose documents to some ultraviolet. Concerns about emissions from photocopy machines have been expressed by some in connection with the use of
selenium Selenium is a chemical element; it has symbol (chemistry), symbol Se and atomic number 34. It has various physical appearances, including a brick-red powder, a vitreous black solid, and a grey metallic-looking form. It seldom occurs in this elem ...
and emissions of
ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...
and fumes from heated toner.


Forensic identification

Similar to
forensic identification Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts". Hu ...
of
typewriters A typewriter is a Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...
,
computer printer A printer is a peripheral machine which makes a durable representation of graphics or text, usually on paper. While most output is human-readable, bar code printers are an example of an expanded use for printers. Different types of printer ...
s and copiers can be traced by imperfections in their output. The mechanical tolerances of the toner and paper feed mechanisms cause banding, which can reveal information about the individual device's mechanical properties. It is often possible to identify the manufacturer and brand, and, in some cases, the individual printer can be identified from a set of known printers by comparing their outputs. 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 Xerox Holdings Corporation (, ) is an American corporation that sells print and electronic document, digital document products and services in more than 160 countries. Xerox was the pioneer of the photocopier market, beginning with the introduc ...
and
Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the material accepted as officially written by an author or an ascribed author * Literary canon, an accepted body of works considered as high culture ** Western canon, th ...
as companies doing this. The
Electronic Frontier Foundation The Electronic Frontier Foundation (EFF) is an American international non-profit digital rights group based in San Francisco, California. It was founded in 1990 to promote Internet civil liberties. It provides funds for legal defense in court, ...
(EFF) has investigated this issue 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. The EFF also reports that the US government has asked these companies to implement such a tracking scheme, so that
counterfeit A counterfeit is a fake or unauthorized replica of a genuine product, such as money, documents, designer items, or other valuable goods. Counterfeiting generally involves creating an imitation of a genuine item that closely resembles the original ...
ing can be traced. The EFF has filed a
Freedom of Information Act Freedom of Information Act may refer to the following legislations in different jurisdictions which mandate the national government to disclose certain data to the general public upon request: * Freedom of Information Act (United States) of 1966 * F ...
request in order to look into privacy implications of this tracking.


Wet photocopying

Photocopying, using liquid developer, was developed by Ken Metcalfe and Bob Wright of Defence Standards Laboratory in
Adelaide Adelaide ( , ; ) is the list of Australian capital cities, capital and most populous city of South Australia, as well as the list of cities in Australia by population, fifth-most populous city in Australia. The name "Adelaide" may refer to ei ...
in 1952. Photocopying, using liquid developer, was used in 1967. Images from 'wet photocopying' do not last as long as dry toner images, but this is not due to acidity.


See also


References


Further reading

* R. Schaffert: ''Electrophotography''.
Focal Press Focal Press is a publisher of creative and applied media books and it is an imprint of Routledge/Taylor & Francis. Company history The firm was founded in London in 1938 by Andor Kraszna-Krausz, a Hungarian photographer who migrated to England ...
, 1975 * {{Authority control American inventions Office equipment Printing processes Products introduced in 1949 Computer peripherals Articles containing video clips Forgery Copying