Most people use an invention that was invented seventy years ago every day and few realize it or even think about. The invention has become such an integral part of the every day workings of offices, schools and universities that many people cannot even think of life without it. Xerographic printing machine is the very formal name for your average, everyday photocopier. That large bulky machine that always seems to run out of toner at the worst possible times, consistently seems to have a paper jam and that makes that really distressing sound whenever it works. People use these machines and Xerographic paper every day but few people realize how incredible the process is.

Xerography is the process that photocopiers use and a man named Chester Carlson discovered it in 1938. The word comes from two Greek words, xeros that means ‘dry’ and graphos that means ‘writing’. That is exactly what a xerographic printer does. It writes things onto xerographic paper without the use of ink or other liquids. Aside from photocopiers, the process is used in laser printers and many other digital printing mediums. It is used in an amazingly great number of processes and businesses and few people actually realize just how prevalent it is in the world.

The process of xerographic printing involved a horizontal cylinder that is known as the drum and that is coated with amorphous selenium. This compound can hold an electrostatic charge in darkness but releases the charge when exposed to light. The drum is the center of the xerographic printing process. The first step is for the drum to be given an electrostatic charge. Light is passed through the page to be copied. Where there is text or image the light does not pass through and where there is nothing, light will pass through. The light releases the electrostatic charge and the drum is left with a positive image of what needs to be copied. Toner – which is actually a mixture of carbon and iron filings – are attracted to the charge on the drum and adhere to the areas of the xerographic paper where there is a charge.

Paper that has been oppositely charged passes over the drum and the toner particles are attracted to the paper. The charge on the paper is neutralized and released from the drum. Using heat or pressure, the toner is then fused to the paper making the image a lasting impression on the paper or medium it is printing on. Finally the electrostatic charge on the drum is released and any leftover toner compound is cleaned off and discarded. One page has been printed with the xerographic technique.

It is amazing that such an involved process happens so quickly! Each time a stack of papers are copied this process occurs without anyone even realizing it. Thanks to xerographic paper and printing, making copies is quick and easy. As technology improves the process is refined and it is sure to become even better as time goes on. Well, at least until something better comes along.