The Clickinks Blog | How does a Laser Printer Work?

How does a Laser Printer Work?

22. January 2011 06:00 by Danielle Bernhard in clickinks, drum unit, laser toner cartridges, laserjet, remanufactured toner  //  Tags:   //   Comments (0)
You may have a Laserjet printer, or have at least used one, but do you really know how a laser printer works?

In the beginning, the first printers attached to computers were impact printers, typically dot matrix. Everyone understood how these devices worked, as they functioned just like the electric typewriters of the time. A hard object struck an ink ribbon with enough force to transfer the ink onto the page. As technology evolved, along came the next generation, which included inkjet and laser printers. The inkjet printer works just like the name implies; an image is put on the paper by using microscopic jets of ink. The laser printer, on the other hand, is a bit of a mystery. How can a highly focused beam of light impart letters and images on a piece of paper? Is the laser inside my printer dangerous?

Following are the six key processes that happen inside a laser printer when you click print.

Charging: A charge roller (or corona wire in older machines) will project an electrostatic charge onto the photoreceptor. This is a revolving drum or belt which is capable of holding an electrostatic charge on its surface as long as it hasn't been exposed to wavelengths of electromagnetic radiation (and will be referred to as drum for the rest of this article).

Writing: A processor chip converts information for scanning onto the drum. The laser is aimed at a series of lenses and mirrors onto the drum. Lasers are used because they generate a coherent beam of light for a high degree of accuracy. Wherever the laser strikes the drum, it reverses the charge, thus creating a latent image on the surface.

Developing: The surface containing the latent image is exposed to toner, which is very fine particles of wax or plastic mixed with coloring agents. The charged toner particles are electrostatically attracted to the drum where the laser wrote the latent image.

Transferring: The drum is pressed or rolled over paper, transferring the image. Higher end machines use a positively charged transfer roller on the back-side of the paper to pull the toner from the photoreceptor to the paper.

Fusing: The paper passes through a fuser assembly, which has rollers that provide heat and pressure that bonds the toner to the paper.

Cleaning: When the print is complete, an electrically neutral rubber blade cleans any excess toner from the drum and deposits it into a waste reservoir, and a discharge lamp removes the remaining charge from the drum.

Each printer applies these steps in different ways. Most laser printers today actually use a linear array of light-emitting diodes to write the light on the drum. The toner is based on either wax or plastic, so that when the paper passes through the fuser assembly, the particles of toner melt. The paper may or may not be oppositely charged. The fuser can be an infrared oven, a heated pressure roller, or a xenon bulb. The warm up process that a laser printer goes through when power is initially applied to the printer consists mainly of heating the fuser element. Many printers have a toner-conservation mode which uses less toner but does yield prints with lower contrast. Color laser printers add colored toner in three additional, yet identical, processes.

So you now know that when you print that document, you are safe from a wayward laser beam melting a hole in your monitor and when it is time to get a replacement for that laser toner cartridge, you need to go to With your purchase of our remanufactured toner cartridges, you help reduce the amount of cartridges that are disposed of into landfills and save yourself money at the same time.

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