An imaging drum is a cylindrical part of a laser printer that transfers toner, images and text onto paper after a laser imprints the words or images onto the drum. It is also known as an imaging unit, an image drum, a drum unit or a photoreceptor drum.
Imaging drums are designed to print thousands of pages. This number varies depending on the printer. When printed pages include black spots or lighter-than-normal lines and images, the imaging drum needs to be replaced. Some printers include imaging drums with toner cartridges, but many printers have separate toner and imaging drum units.