Schematic Overview of the Xerographic Photocopying Process

By using a cylinder to carry the photosensor, automatic processing was enabled. In 1960 the automatic photocopier was created and many millions have since been manufactured. The same process is used in microform printers and computer output laser or LED printers. 

The steps of the process are described here as applied on a cylinder, as a photocopier. Some variants are considered within the chapter. Every step of the process has its own design. 

A metal cylinder is mounted to rotate about a horizontal axis. This is called the drum. The end-to-end dimension is the width of print to be produced plus a generous tolerance. The drum in the copiers originally developed by Xerox Corporation was manufactured with a surface coating of amorphous selenium (more recently, ceramic or organic 

The drum rotates at the speed of paper output. One revolution passes the drum surface through the following steps  

Step 1 Charging. An electrostatic charge is uniformly distributed over the surface of the drum in the dark by a corona-producing device correctly called a screened corotron or scorotron for short. How well the drum is charged depends on several variables. The most important are listed here  

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