How it Works
Charging: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of a photoconductive material. A photoconductor is a semiconductor that becomes conductive when exposed to light.
Exposure: A bright lamp light up the original document, and the white areas of the original document reflect the light onto the surface of the photoconductive drum. The region of the drum that is bare to light become conductive and therefore release to ground. The regions of the drum not exposed to light remain negatively charged. The result is a latent electrical image on the surface of the drum.
Developing: The toner is positively charged. When it is applied to the drum to develop the image, it is attracted and sticks to the areas that are negatively charged (black areas), just as paper sticks to a toy balloon with a static charge.
Transfer: The resultant toner image on the surface of the drum is conveying from the drum onto a piece of paper with a higher negative charge than the drum.
Fusing: The toner is melted and bonded to the paper by heat and pressure rollers.