xerography (zərŏg`rəfē'), also called electrophotography, method of dry photocopying in which the image is transferred by using the attractive forces of electric charges. A beam of light, usually from a laser, is made to strike the original material, e.g., a white page with black lettering. Light rays are reflected off the white areas onto a photosensitive plate over which electric charges have been spread. Charges are neutralized from the areas struck by the rays. Since no light rays are reflected from the lettering, charges are retained on the plate in areas corresponding to the lettered areas of the original. A plastic powder called toner is introduced that sticks to the charged areas. A sheet of paper is then passed between the plate and another charged object that draws the powder from the plate to the paper, forming an image of the original; the powder is fused to the paper with heat. The process has image resolution that is sufficient for printed or written materials, and certain pictorial materials are fairly well reproduced. As the image on the drum is a projected one rather than one made by contact printing, it is possible to produce a copy that is smaller or larger than the original. Variations of the xerographic process are used in such devices as computer laser printers laser printer, a computer printer that produces high-resolution output by means of a process that is similar to photocopying . In place of reflected light from an image (as is used in xerography ), a laser printer uses data sent from a computer to turn a laser beam
..... Click the link for more information. and plain-paper facsimile facsimile (făksĭm`əlē) or fax,
..... Click the link for more information. machines.
Image-forming process that relies on a photoconductive substance whose electrical resistance decreases when light falls on it. Xerography is the basis of the most widely used document-copying machines (see photocopier). The process was invented in the 1930s by U.S. physicist Chester F. Carlson (1906–1968) and developed in the 1940s and '50s by Xerox Corp. (then called Haloid). Light passing through or reflected from a document reaches a selenium-coated drum surface onto which negatively charged particles of ink (toner) are sprayed, forming an image of the document on the drum. As a sheet of paper is passed close to the drum, a positive electric charge under the sheet attracts the negatively charged ink particles, transferring the image to the copy paper. Heat briefly applied fuses the ink particles to the paper. The first commercially successful xerographic copier was introduced in 1959.
..... Click the link for more information. and plain-paper facsimile facsimile (făksĭm`əlē) or fax,
..... Click the link for more information. machines.
Bibliography
See study by D. Owen (2004).
xerography
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Light shining on the item to be copied is reflected off a mirror, through a lens, and off a second …
(credit: © Merriam-Webster Inc.)
xerography
See electrophotographic.
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