Heat is then momentarily applied to fuse the ink particles to the paper. A sheet of copy paper is passed close to the drum, and a positive electric charge under the sheet attracts the negatively charged ink particles, resulting in the transfer of the image to the copy paper. Light passed through the document to be copied, or reflected from its surface, reaches the selenium surface, onto which negatively charged particles of ink (i.e., the toner) are sprayed, forming an image of the document on the drum. Xerography typically uses an aluminum drum coated with a layer of selenium. When the light is removed, their mobility falls. The chemical element selenium, for example, is a poor electrical conductor, but when light is absorbed by some of its electrons and a voltage is applied, these electrons are able to pass more freely from one atom to another. The basis of the process is photoconductivity, an increase in the ability of certain substances to allow an electric current to flow through them when struck by light. Xerography, which involves the application of electrostatic charges and heat, is extremely versatile and can be employed to produce copies of all kinds of written, printed, and graphic matter. Carlson in 1937, the process did not become available for commercial use until 1950. The method most widely used by modern office copiers is called xerography (from the Greek words meaning “dry writing”). SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!Ĭopier, also called photocopier, copy machine, photocopy machine, copier machine, or photocopying machine, a device for producing copies of text or graphic material by the use of light, heat, chemicals, or electrostatic charges.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians. #COLLATE DEFINITION WHEN COPYING HOW TO#COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today.Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.From tech to household and wellness products. This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.
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