. London Hazards Centre. 2002. Archived fromthe original
. New York:Simon & SchusterISBN0-7432-5117-2.
In the early 1950s,Radio Corporation of America(RCA) introduced a variation on the process calledElectrox, whereby images are formed directly on specially coated and rendered with a toner dispersed in a liquid.
: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of aphotoconductivematerial. A photoconductor is asemiconductorthat becomes conductive when exposed to light.
Xerographic copier manucturers took advantage of a high perceived-value of the 1960s and early 1970s, and marketed that was specially designed for xerographic output. By the end of the 1970s, producers made xerographic runability one of the requirements for most of their office brands.
Colored toner became available in the 1950s, although full-color copiers were not commercially available until3Mreleased theColor-in-Colorcopier in 1968, which used adye sublimationprocess rather than conventional electrostatic technology. The first electrostatic color copier was released by Xerox (the 6500) in 1973. Color photocopying is a concern togovernments, as it cilitatesand other documents: for more information, seeCounterfeitingsection.
There is an increasing trend for new photocopiers to adoptdigitaltechnology, thus replacing the olderanalogtechnology. With digital copying, the copier effectively consists of an integratedscannerandlaser 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.
Before the widespread adoption of xerographic copiers, photo-direct copies produced by machines such asKodaks Verix were used. A primary obstacle associated with the pre-xerographic copying technologies was the high cost of supplies: a Verix print required supplies costing USD $0.15 in 1969, while a Xerox print could be made for USD $0.03 including and labor. The coin-operatedPhotostat machinesstill found in some public libraries in the late 1960s made letter-size copies for USD $0.25 each, at a time when the minimum wage for a US worker was USD $1.65 per hour; the Xerox machines that replaced them typically charged USD $0.10.
List of Printers Which Do or Do Not Display Tracking Dots. Electronic Frontier Foundation
Photocopying material that is subject tocopyright(such as books or scientific s) 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 ofir use(in the United States) oir dealing(in otherBerne Conventioncountries) allows copying for certain specified purposes.
Similar toforensic identificationoftypewriterscomputer printersand copiers can be traced by imperfections in their output. The mechanical tolerances of the toner and feed mechanisms causebanding, which can reveal information about the individual devices mechanical properties. It is often possible to identify the manucturer and brand, and, in some cases, the individual printer can be identified from a set of known printers by comparing their outputs.
Haloid felt that the word electrophotography was too complicated and did not have good recall value. After consulting a professor of classical language atOhio State University, Haloid and Carlson changed the name of the process toxerography, which was derived fromGreekwords that meant dry writing. Haloid called the new copier machines Xerox Machines and, in 1948, the word Xerox wastrademarked. Haloid eventually changed its name toXerox Corporation.
Jason Tuohey (2004-11-22).Government Uses Color Laser Printer Technology to Track Documents
Photocopier Hazards and a Conservation Case Study (notes 17,18)
Some devices sold as photocopiers have replaced the drum-based process withinkjetor transfer film technology.
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
: The toner is melted and bonded to the by heat and pressure rollers.
Concerns about emissions from photocopy machines have been expressed by some in connection with the use ofseleniumand emissions ofozoneand fumes from heated toner.
Chester Carlson, the inventor of photocopying, was originally apatent attorney, as well as a part-time researcher and inventor. His job at thepatent officeinNew Yorkrequired him to make a large number of copies of important s. Carlson, who wasarthritic, found this to be a painful and tedious process. This motivated him to conduct experiments with photo conductivity. Carlson used his kitchen for hiselectrophotographyexperiments, and, in 1938, he applied for a patent for the process. He made the first photocopy using azincplate covered withsulfur. The words 10-22-38 Astoria were written on amicroscopeslide, 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 iled because the process was still underdeveloped. At the time, multiple copies were most commonly made at the point of document origination, usingcarbon or manual 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, includingIBMandGeneral Electricneither of which believed there was a significant market for copiers.
In 1944, theBattelle Memorial Institute, a non-profit organization inColumbus, 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 manucturer and seller of photographic ) approached Battelle to obtain a license to develop and market a copying machine based on this technology.
Printer forensics to aid homeland security, tracing counterfeiters. 2004-10-12
) is amachinethat makescopies of documents and other visual images quickly and cheaply. Most current photocopiers use a technology called, a dry process that uses electrostatic charges on a light-sensitive photoreceptor to first attract and then transfer toner particles (a powder) onto in the form of an image. Heat, pressure or a combination of both is then used to fuse the toner onto the . (Copiers can also use other technologies such asink jet, but xerography is standard for office copying.) Earlier versions included theGestetnerstencil duplicator, invented byDavid Gestetnerin 1881.
In 1949, Xerox Corporation introduced the first xerographic copier called the Model A.Xerox became so successful that, inNorth America, photocopying came to be popularly known as xeroxing. Xerox has actively fought to prevent Xerox from becoming agenericized 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. Some languages include hybrid terms, such as the widely usedPolishtermkserokopia(xerocopy), even though relatively few photocopiers are of the Xerox brand.
This page was last edited on 19 April 2018, at 15:55.
Low-end copiers also usedigitaltechnology, but tend to consist of a standard PC scanner coupled to an inkjet or low-end laser printer, both of which are r slower than their counterparts in high-end copiers. However, low-end scanner-inkjets can provide color copying at a lower purchase price but with a much higher cost per copy. The cost of electronics is such that combined scanner-printers sometimes have built-in x machines. (SeeMultifunction printer.)
In certain countries, such asCanada, someuniversitiespay royalties from each photocopy made at university copy machines and copy centers tocopyright collectivesout 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 calledreadersare often required 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.
During the 1960s and through the 1980s,Savin Corporationdeveloped and sold a line of liquid-toner copiers that implemented a technology based on patents held by the company.
Some high-quality color printers and copierssteganographicallyembed their identification code into the printed pages, as fine and almost invisible patterns of yellow dots. Some sources identifyXeroxandCanonas companies doing this.TheElectronic Frontier Foundation(EFF) has investigated this issueand documented how the Xerox DocuColor printers serial number, as well as the date and time of the printout, are encoded in a repeating 815 dot pattern in the yellow channel.EFFis 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 thatcounterfeitingcan be traced. The EFF has filed aFreedom of Information Actrequest in order to look into privacy implications of this tracking.
A negative photocopy inverts the colors of the document 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 ded documents sometimes produce documents which have better focus and are easier to read and study.
Wilbert de Vries (2004-10-26).Dutch track counterfeits via printer serial numbers
: The resulting toner image on the suce of the drum is transferred from the drum onto a piece of with a higher negative charge than the drum.
Schematic overview of the xerographic photocopying process (step 1-4)
Among the key advantages of photocopiers over earlier copying technologies are their ability:
A great advantage of digital copier technology is automatic digitalcollation. 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), one set at a time, or 20 separate output trays are used for the 20 sets.
Health and Safety Representatives Handbook. [National Association of Schoolmasters Union of Women Teachers (NASUWT)]. July 27, 2009. Archived fromthe original
Exposure toultraviolet lightis a concern. In the early days of photocopiers, the sensitizing light source was filtered green to match the optimal sensitivity of the photoconductive suce. This filtering conveniently removed all ultraviolet.Currently, a variety of light sources are used. Asglasstransmits ultraviolet rays between 325 and 400 nanometers, copiers with ultraviolet-producing lights such as fluorescent,tungstenhalogen, orxenonflash, expose documents to some ultraviolet.
Color copying also raises concerns regarding the copying and/or forging of other documents as well, such as drivers licenses and university degrees and transcripts. Some drivers licenses are made with embedded holograms so that a police officer can detect a ke copy. Some university and college transcripts have special anti-copyingwatermarksin 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.
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 , as of 2015, photocopiers continue to be widely used. In the 2010s, there is a convergence in some high-end machines between the roles of a photocopier, axmachine, ascanner, and a computer network-connectedprinterinto amulti-function printer. Lower-end machines that can copy and print in color have increasingly dominated the home-office market as their prices fell steadily through 2017. Higher-end color photocopiers capable of handling heavy duty cycles and large-format printing remain a costlier specialty for print and design shops.
To counter the risk of people using color copiers to createcounterfeitcopies of 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 specialsoftwarethat can prevent copying currency that contains aspecial pattern.
: Thetoneris positively charged. When it is applied to the drum to develop the image, it is attracted and sticks to the areas that are negatively charged (black areas), just as sticks to a balloon with a static charge.
: A bright lamp illuminates the original document, and the white areas of the original document reflect the light onto the suce of the photoconductive drum. The areas of the drum that are exposed to light become conductive and therefore discharge to the ground. The area of the drum not exposed to light (those areas that correspond to black portions of the original document) remains negatively charged.
Is Your Printer Spying On You?. Electronic Frontier Foundation
Commercial xerographic office photocopying was introduced byXeroxin 1959,and it gradually replaced copies made by Verix,Photostatcarbon mimeograph machines, and otherduplicating machines.Photoco photocopier toner pier