Color Laser Printers--How Do They Work?

Color laser printers have become affordable for the average home user.  Many home users have no idea how such a printer works its magic.  If you are in the market for a laser printer, it might help in the process if you are familiar with part of the technology.  A color laser printer is a printer that has the ability to produce rapid high quality graphics and text on plain paper. An image is produced by directly scanning an image using a laser beam transversely through the photoreceptor of the printer. Laser printers employ a printing process that is similar to digital multifunctional printers, MFPs and photocopiers with a difference to analog photocopiers. The name ‘laser printer’ is used because of its nature to use a laser beam in most, if not all, of its essential operations. Its speed also differentiates this printer from the other printers and also because of its high and accurate rendering capability. A good example could be the ability to create a hundred colored pages within a minute and even a higher number, 200, of non-colored pages also within a minute.

How does a color laser printer work?

Well, you click “print” and it works, right?  For most of us that is all we need to know or would care to know. But, in reality, it helps you in the purchase process to have an understanding of the unit if you are going to be buying a laser printer for the office network or shelling out a decent amount of cash.  Whether it is a HP, Epson, Cannon or Dell laser printer it works the same way, positive charges and negative charges. The old saying actually applies, opposites attract.

 

Understanding what is consisted in the printer can help one understand how it works. It has a layer assembly which has 6 major components. There is the image processor that has its own memory which stores converted text data to raster images for processing and printing. There is the charged corona or roller wire, a toner that is negatively charged, a photosensitive drum that resembles a conveyor-like contraption, a fuser assembly and lastly and also vital, the laser assembly.

A laser printer uses the light beam from a laser to control the placement of electric charges on a photoconductor surface. A photoconductor is a material that only conducts electricity when exposed to light, so that charges can move through the photoconductor only when the laser beam hits it. The printer uses a corona discharge to place charges on the darkened photoconductor and then uses the laser beam to remove charges from certain places. The end result is a pattern of electric charges that's an image of the final print. The toner particles, which are made of black plastic, are given an electric charge so that they cling to the charge image on the photoconductor. This pattern of toner particles is then transferred to electrically charged paper and fused to that paper with heat and pressure.

The same basic printing process is used in both xerographic copiers  and laser or led printers.  (The copiers you see in an office environment are Xerographic copiers and first became known when Xerox entered into the market with their copier.)  In all cases, a charge image is formed on the surface of a photoconductor and this pattern of electric charge attracts a pattern of colored plastic powder. The powder is then transferred to paper and melted or pressed into the paper's surface to form a permanent print.

A laser printing process starts with the memorizing of a pattern in which the laser is going to “cut” the desired image(s). A corona wire or primary charge roller gives a negative electrical charge to all of the ions on the surface of a rotating drum unit. The laser then cuts the predetermined pattern into the charged ions by neutralizing them. These cuts will eventually become letters, words, etc. Electrically charged toner then fills in the cuts made by the laser. As the drum continues to rotate the toner is then pressed onto a sheet of paper. The paper then passes through a heated roller, which bonds the toner to the paper. After cleaning excess toner off the page, your printed sheet is complete.

A drum unit is a device inside a laser printer that creates print on the paper. It is electrically charged and discharged for every new sheet of paper it prints.

 

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