Everyone understands the basic principles behind how an inkjet printer works – the printer sprays the page with minute amounts of ink, in the required combination to recreate the desired colour. It does this until your image is recreated on paper. There’s more to it than that, of course, but that is the essence of what is going on.

Laser printers are more complex, however. The process involved in getting what’s on your computer screen to your printer is really quite ingenious!

laser printer diagram

The secret to how laser printers work is static electricity. A component called the drum is given a positive electrostatic charge via electrical current; a small laser then draws the needed images onto the drum, creating what is called an electrostatic image – sort of a negative image where the background is negatively charged and the foreground – the images you want printed – are positively charged.

Toner is then sprayed onto the drum – with a positive charge, the toner clings to the negatively charged areas of the drum. The image is then ready to be transferred to a sheet of paper. The sheet of paper itself is then given a negative charge – stronger than the one on the drum – so that the toner is pulled away from the drum. As the sheet of paper rolls along the drum it is discharged – otherwise it would cling to the drum itself!

Next for the paper is a trip through the fuser – basically two hot rollers – which melts the toner onto the page, fixing the image. Paper is always warm coming out of a laser printer, and that is why. After each sheet the drum is discharged by a bright light called the discharge lamp, and the entire surface again given a positive charge, ready for the next image.

And that’s about it! It’s a simplified version of the full process, of course, but nonetheless shows how complex the steps are to get your image printed onto paper. When servicing your own laser printer, you’ll note that some feature separate drum units and toner cartridges, while others have a combined drum/toner cartridge assembly. If you’re not sure which type of cartridge your printer takes, contact us and we’d be glad to let you know!