Imagine your car is a laser printer. 

Under the hood, is a ingenious combination of photosensitive parts, lasers, electrically charged ink, and heating units. All of these work together to produce that incredibly crisp, warm print within seconds.To print any document, the toner needs to be transferred to the paper, creating your image on the paper. That’s why it’s sometimes called an imaging drum.The drum is a cylinder, often teal, green, or maroon-colored, positioned very close to your toner cartridge. It transfers the image from toner to paper. 

A drum unit and a toner cartridge work in synergy. These two parts only exist in Laser printers – InkJet doesn’t use this technology.   

Printing drums and toner cartridges are often placed together in a plastic shell.. 

In other models, the drum and the toner are housed separately. 

When you click “print” on your computer, your printer uses a laser to “draw” the document on the imaging drum. When the laser beam touches the surface of the drum, the exposed parts get a neutral electric charge. The rest of the drum – where the whites on your paper should be – are left untouched. 

In turn, the neutral charge on the drum attracts negatively charged toner particles. The unexposed parts of the drum repel toner, so the toner powder only sticks to laser-exposed parts of the drum. 

As the drum rotates, it carries ink particles and transfers them to paper. Then, the paper goes over the fuser unit that warms it up, making ink stick to the paper for good and giving you that joy of warm and crisp fresh prints. 

Once your document is out of the printer, the drum is refreshed and ready for a new printing task. Leftover toner particles are cycled back to the toner cartridge – which is one of the reasons why laser printer toner lasts longer than inkjet ink.