Electrophotography is a type of dry photocopying method used to create copies of a picture using an electrostatic charge, similar to static electricity. Chester Carlson invented the technique in 1938 and called it electrophotography. Later the term changed to xerography, formed from the Greek words "xeros" and "-graphia," which translate to "dry writing." At the time of Carlson's invention, all photocopying processes needed liquid chemicals to work. Though the original invention took a long time and involved manual labor to operate, it involved no liquid substances and was a great advance in technology.
To create the image without the liquid chemicals, a machine using electrophotography creates static electricity to charge the image and transfer the picture onto a blank sheet of paper. Electrophotography is commonly used in photocopying machines and certain printers, such as LED and laser printers. The copying procedure happens in less than a minute but goes through a five step process each time.
First the drum, a type of metal cylinder located inside the machine, becomes charged with electricity. Different charges are given to the drum depending on the type of copy being made and the type of image the copy is taken from. After the drum charges, a bright light shines across the image and copies areas of light and dark onto the charged drum. Charged toner is attracted to the particles on the drum and covers the drum, creating a copy of the original image.
After these first three stages, the process moves on to the transfer phase. A piece of paper passes across the drum to capture the image. Both electrostatic energy and a certain amount of pressure cause the toner to transfer onto the paper and create a detailed copy of the original picture. In the final stage, the particles lose their charge, and heat, pressure, or both are used to ensure the image adheres to the paper. The user then receives the copied image.
The original machines that used electrophotography involved several steps, each which required the user to perform a task to move the process along. It took nearly 20 years for a breakthrough to occur that gave the world a fully automated copier. The first automatic copier put onto the market for sale was created by Haloid/Xerox, the company that later went on to become the popular brand Xerox and gained a reputation for its sales of printers and copiers along with other common office equipment.
