The drum unit transfers toner into paper is the simple answer to the question "What is a drum unit?"
The drum unit has a photosensitive roller. It builds up a negative charge.
The laser printer then lasers the image to be printed into the roller with positive ions.
The toner powder from the cartridge is then attracted to the positive ions in the roller.
When the paper rolls against the roller's surface, the toner is transferred to the paper.
An electric charge then melts and fuses the toner powder into paper with heat.
Article is closed for comments.