A photocopier (or copier) is a machine that makes paper copies of documents and other visual images quickly and cheaply. Most current photocopiers use a technology called xerography, a dry process using heat. (Copiers can also use other output technologies such as ink jet, but xerography is standard for office copying.)
Xerographic office photocopying was introduced by Xerox in the 1960s, and over the following 20 years it gradually replaced copies made by Verifax, Photostat, carbon paper, mimeograph machines, and other duplicating machines. The prevalence of its use is one of the factors that prevented the development of the paperless office heralded early in the digital revolution.
Photocopying is widely used in business, education, and government. There have been many predictions that photocopiers will eventually become obsolete as information workers continue to increase their digital document creation and distribution, and rely less on distributing actual pieces of paper.
Colored toner became available in the 1950s, although full-color copiers were not commercially available until 3M released the Color-in-Color copier in 1968, which used a dye sublimation process rather than conventional electrostatic technology. The first electrostatic color copier was released by Canon in 1973.
Color photocopying is a concern to governments, as it facilitates counterfeiting currency. Some countries have incorporated anti-counterfeiting technologies into their currency specifically to make it harder to use a color photocopier for counterfeiting. These technologies 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 contains a special pattern.
In recent years[when?], all new photocopiers have adopted digital technology, thus replacing the older analog 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 "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 digital technology, but tend to consist of a standard PC scanner coupled to an inkjet or low-end laser printer, both of which are far slower than their counterparts in high-end copiers. However, low-end scanner-inkjets can provide color copying at a far lower cost than can a traditional color copier. The cost of electronics is such that combined scanner-printers sometimes have built-in fax machines. (See Multifunction printer.)
