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Photocopy Machine

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What is Photocopy Machine?

A photocopy (also known as a photocopier or copy machine) is a machine that makes paper copies of documents and other visual images quickly and cheaply. Most current photocopy use a technology called xerography, a dry process that uses electrostatic charges on a light sensitive photoreceptor to first attract and then transfer toner particles onto paper in the form of an image. Heat, pressure or a combination of both is then used to fuse the toner onto the paper. (Photocopy can also use other technologies such as ink jet, but xerography is standard for office copying.) Earlier versions included the Gestetner stencil duplicator, invented by David Gestetner in 1881.

Photocopying is widely used in the business, education, and government sectors. While there have been predictions that photocopy 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 paper, 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, a fax machine, a scanner, and a computer network-connected printer into a multi-function printer. As of 2015, some high-end machines can copy and print in colour.

 

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History of Photocopy Machine:-

Chester Carlson, the inventor of photocopying, was originally a patent attorney, as well as a part-time researcher and inventor. His job at the patent office in New York required him to make a large number of copies of important papers. Carlson, who was arthritic, found this to be a painful and tedious process, this motivated him to conduct experiments with photo conductivity. Carlson used his kitchen for his "electrophotography" experiments, and, in 1938, he applied for a patent for the process. He made the first photocopy using a zinc plate covered with sulfur. The words "10-22-38 Astoria" were written on a microscope slide, 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 failed because the process was still underdeveloped. At the time, multiple copies were most commonly made at the point of document origination, using carbon paper 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, including IBM and General Electric—neither of which believed there was a significant market for copiers.

In 1944, the Battelle Memorial Institute, a non-profit organization in Columbus, 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 manufacturer and seller of photographic paper) approached Battelle to obtain a license to develop and market a copying machine based on this technology.

“Haloid called the new copier machines "Xerox Machines" and, in 1948, the word "Xerox" was trademarked. Haloid eventually changed its name to Xerox Corporation.

In 1949, Xerox Corporation introduced the first xerographic copier called the Model A. Xerox became so successful that, in North America, photocopying came to be popularly known as "Xeroxing.

During the 1960s and through the 1980s, Saving Corporation developed and sold a line of liquid-toner copiers that implemented a technology based on patents held by the company.

 

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How a Photocopy Machine work?

Charging: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of a photo conductive material. A photo conductor is a semiconductor that becomes conductive when exposed to light.

Exposure: A bright lamp illuminates the original document, and the white areas of the original document reflect the light onto the surface of the photo conductive 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.

Developing: The toner is 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 paper sticks to a balloon with a static charge.

Transfer: The resulting toner image on the surface of the drum is transferred from the drum onto a piece of paper with a higher negative charge than the drum.

Fusing: The toner is melted and bonded to the paper by heat and pressure rollers.

 

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