How Photocopiers Work

Corona Wires

The corona wire uses static electricity to coat both the photoreceptive drum and the copy paper with a layer of positively charged ions.
Photo courtesy Xerox

For a photocopier to work, a field of positive charges must be generated on the surface of both the drum and the copy paper. These tasks are accomplished by the corona wires. These wires are subjected to a high voltage, which they subsequently transfer to the drum and paper in the form of static electricity.

One of these wires is stretched parallel to the drum surface and charges the photoconductive surface with positive ions, and the other wire is positioned to coat the paper's surface as the paper shoots by on its way to the drum.