How a Laser Printer works

Laser Printers are amazing pieces of equipment but how do they work? Let's take a quick look at the internals of a Laser Printer and see how they manage to actually print.

It all starts with a laser beam which projects the required image to be printed onto an electrically charged cylinder known as a "Drum Unit". The Drum Unit is a rotating selenium cylinder with photoconductive properties.

Due to the photoconductive properties of the drum unit the areas on the drum which have not been exposed to the laser become conductive. This is when the toner (ink in powdered form) comes into play. The areas which are not hit by the laser beam now attract the toner powder to stick while the laser charged areas actually repel the toner powder. This is how the required image is initially formed.

 Next the paper is dragged over the drum unit and the toner powder gets transferred directly onto the paper just the same as a paint roller would transfer paint onto a wall. At this stage the toner is still in powder form and it needs to get bonded to the paper.

A mono laser printer only uses a single drum where as a colour laser uses individual drums for each colour. The overall operation is the same except that with colour each toner and drum has to perform this sequence individually.

The final stage in laser printing is the "Fuser" which actually heats up the toner powder on the paper at very high temperatures and then bonds it onto the paper. No doubt most people have felt the warmth of the pages which come out of a laser printer and now you will know why that occurs.

Although the above is a very basic overview of a Laser printers workings I hope that it has taken away some of the mystery of how they actually produce a printed image.

As most people are aware the laser printer actually evolved from the old "Xerox" Photocopiers. These used very similar technology but it wasnt untill 1976 that IBM released the first commercial laser printer onto the market. Laser printers have now become very popular for both small business and even home use. This has mainly been due to their relatively low cost and their ability to print at high speeds and to produce a very high quality image.

How a Laser Printer Works Video

If you are like me and you find it easier to visualize the workings of a laser printer then feast your eyes on the following video.

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Laser Printer Maintenance

A laser printer unlike an inkjet printer requires maintenance after printing anywhere from 20,00 to 50,000 pages depending on the actual printer model. The procedure for maintenance is to thoroughly clean the entire internals of the printer with compressed air and clean or replace the paper rollers.

The paper rollers have a thick rubber covering, which over time deteriorates and eventually gets covered with an oily film. The oily film comes off of the paper which is constantly moving over the rollers surface and leaving a dirty, oily film. The paper rollers can be cleaned with a moist lint-free cloth or a cleaning fluid which aids in restoring the grip of the rubber covering.

The fuser heating rollers require that the oil be replaced or refilled after a few hundred thousand printed pages. The laser printer compared to other types of printers is quite expensive to maintain especially a colour laser printer as they have four drum units and four sets of paper rollers compared to the mono lasers single drum and set of paper rollers.