How It All Started

Selenium is an element that is essential for good health and also has a peculiar and useful electrical property. Wiloughby Smith (chief engineer at the Telegraph Construction and Maintenance Company in Britain) began testing selenium as possible material for use in telegraph cables. He was puzzled to find that bars made of selenium did not give consistent results when their conductivity was measured. Smith discovered that different light conditions affected the ability of selenium to conduct. Chester Carloson (an American Inventor) used this unique property of selenium in the first photocopier machine, which he patented in 1942.


How It Works

A photocopier uses electrostatic charge to produce a copy.

The original copy is placed onto a sheet of glass.

The image of the page is projected onto a positively charged drum.

The drum has a coating that conducts electricity when light falls on it.

Parts of the drum which are lit by the projected image lose their electrostatic charge when they start to conduct.

The black toner is negatively charged.

This toner is attracted to the positively charged parts of the drum.

The drum rotates and rolls against a piece of copier paper.

The toner is transferred from the drum to the paper making a black and white image of the original.

Finally, the paper is heated, which makes the toner stil to it ("fixing" the image)


Copiers: A Playful Look at How They Work

THe parts of a photocopier


"Uses Of Electrostatics." Bitesize. BBC, 2011. Web. 20 Feb. 2013.


"Electrostatic Charge." Gcisscience. Web. 20 Feb. 2013.


"Copiers: A Playful Look at How They Work." Youtube.com. Web. 20 Feb. 2013.


Blake, Leesa, Michael Mazza, Alex Mills, Frank Mustoe, Jim Ross, Thomas Stiff. "Photocopiers, Laser Printers, and Scanners." On Science 9. 2009. Print.

"Parts of a Photocopier." EHow. Web. 20 Feb. 2013.