Laser Printers

Its more than just putting paper in a machine!

The Basic Principle

The laser printer uses a principle called Electrostatics. This is when an electrical charge builds up in an insulated object. ( The main component of the printer is the photoreceptor, which is a revolving drum. This is made out of a very conductive material that is discharged by light protons.

How it works?

When the sheet of paper is placed in the laser printer, the drum is given a positive charge. A laser then fires a charged beam onto a mirror which captures the image and reflects it off the drum. As the drum is revolving it writes by shining the laser on the drum in certain spots, changing the electrical charge. The drum is then coated with a positively charged toner, as the paper is being drawn towards it. The toner comes from the toner cartridge which contains a rotating, magnetic cylinder. Toner contains plastic resin materials, and iron oxide. These materials make it attract to a magnetic cylinder and this cylinder then presents it to the drum as it passes by. ( The toner takes the same charge as the cylinder. As the passes the cylinder, the toner ignore the areas with the same charge. It then jumps to the areas with lesser charge and that is what makes the toner stick to the drum. ( Now that the image is on the drum in toner as the positively charged paper passes by the toner jumps from the drum onto the paper because they are oppositely charged. The image is now on the paper but not secure. In order to melt the toner onto the paper, the paper is rolled through heat rollers melting the toner onto the paper. This is why the paper is still hot when it comes out of the printer.
How a laser printer works

How it uses electrostatics?

The drum inside of the printer has a strong positive charge which is drawn upon by a negative laser. Then the drum is rolled through toner which is kept so the ink will stick to the sections that are currently negatively charged, causing an image to appear on the drum. ( The paper has a positive charge so it attracts the negatively charged toner from the drum and that is how the image appears.

Evolution of the laser printer


Harris,Tom. How laser printers work. 14 March 2007. 13 February 2013.

How does a laser printer work. 13 February 2013.

Salmon,Paul. How does a laser printer work. 13 February 2013.

By Nicolas Fan