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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 negatively charged cylindrical drum to define a differentially-charged image.〔(【引用サイトリンク】title=Laser Printer - Definition of laser printer by Merriam-Webster )〕 The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated in order to permanently fuse the text and/or imagery. As with digital photocopiers and multifunction/all-in-one inkjet printers, laser printers employ a xerographic printing process. However, laser printing differs from analog photocopiers in that the image is produced by the direct scanning of the medium across the printer's photoreceptor. This enables laser printing to copy images more quickly than most photocopiers. == History == In the 1960s, the Xerox Corporation held a dominant position in the photocopier market. In 1969, Gary Starkweather, who worked in Xerox's product development department, had the idea of using a laser beam to 'draw' an image of what was to be copied directly onto the copier drum. After transferring to the recently formed Palo Alto Research Center (Xerox PARC) in 1971, Starkweather adapted a Xerox 7000 copier to create SLOT (Scanned Laser Output Terminal). In 1972, Starkweather worked with Butler Lampson and Ronald Rider to add a control system and character generator, resulting in a printer called EARS (Ethernet, Alto Research character generator, Scanned laser output terminal) -- which later became the Xerox 9700 laser printer. The first commercial implementation of a laser printer was the IBM 3800 in 1976. It was designed for data centers, where it replaced line printers attached to mainframe computers. The IBM 3800 was used for high-volume printing on continuous stationery, and achieved speeds of 215 pages per minute (ppm), at a resolution of 240 dots per inch (dpi). Over 8,000 of these printers were sold. The Xerox 9700 was brought to market in 1977. Unlike the IBM 3800, the Xerox 9700 was not targeted to replace any particular existing printers; but, it did have limited support for the loading of fonts. The Xerox 9700 excelled at printing high-value documents on cut-sheet paper with varying content (e.g., insurance policies).〔 In 1979, inspired by the Xerox 9700's commercial success, Japanese camera and optics company, Canon, developed a low-cost, ''desktop'' laser printer: the Canon LBP-10. Canon then began work on a much-improved print engine, the Canon CX, resulting in the LBP-CX printer. Lacking experience in selling to computer users, Canon sought partnerships with three Silicon Valley companies: Diablo Data Systems (who turned them down), Hewlett-Packard (HP), and Apple Computer. The first laser printer designed for office use reached market in 1981: the Xerox Star 8010. The system used a desktop metaphor that was unsurpassed in commercial sales, until the Apple Macintosh. Although it was innovative, the Star workstation was a prohibitively expensive () system, affordable only to a fraction of the businesses and institutions at which it was targeted. The first laser printer intended for mass-market sales was the HP LaserJet, released in 1984; it used the Canon CX engine, controlled by HP software. The LaserJet was quickly followed by printers from Brother Industries, IBM, and others. First-generation machines had large photosensitive drums, of circumference greater than the loaded paper's length. Once faster-recovery coatings were developed, the drums could touch the paper multiple times in a pass, and therefore be smaller in diameter. In 1985, Apple introduced the LaserWriter (also based on the Canon CX engine),〔(【引用サイトリンク】title=TPW - CX Printers- Apple )〕 but used the newly released PostScript page-description language. Up until this point, each manufacturer used its own page-description language, making the supporting software complex and expensive. PostScript allowed the use of text, fonts, graphics, images, and color largely independent of the printer's brand or resolution. PageMaker, written by Aldus for the Macintosh and LaserWriter, was also released in 1985 and the combination became very popular for desktop publishing.〔〔 Laser printers brought exceptionally fast and high-quality text printing, with multiple fonts on a page, to the business and consumer markets. No other commonly-available printer during this era could also offer this combination of features. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Laser printing」の詳細全文を読む スポンサード リンク
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