How Do Laser Printers Work

Representing one of the most widely utilized pieces of equipment for printing, whether it’s in homes or offices, laser printers have brought the printing press of yore to households across the world.

What once was only achievable with the help of a contraption that’s as large as a smaller car can now be done just as efficiently (and much better) with a small device full of wires and color containers that can fit in a doctor’s bag.

Laser printers have, indeed, revolutionized the way people can get their hands on printed sheets of paper, and now the process from writing an article on a computer where it’s just a bunch of 0’s and 1’s to have a printed version of the text in front of you can be completed in a matter of minutes. (If you exclude the time necessary to write the text, of course.)

In this article, we are going to talk about how do laser printers work. To be precise, we’re going to describe what components these are made out of, as well as what happens ‘beneath the hood’, when you hit the ‘Print’ button on your keyboard. (Or, when you use your mouse to do the same thing – no one uses the print button on the keyboard anymore, it seems.)

Without further ado, here’s the deal.

What is a Laser Printer?

 laser printers working on table

If you want to learn what a laser printer is, simply looking at the name of the contraption itself can give you a clue as to what it is.

Laser printers are machines that print out images, documents, and whatever else that you can fit on a piece of paper. What makes laser printers different from other sorts of a printer is that they use lasers to imprint the ink onto the paper below it.

There are black-and-white laser printers and laser printers that can make images in color. The former ones are slowly but surely becoming less and less popular, so you’ll likely find a much greater variety of color printers out there, in case you need a printing machine and fancy buying one shortly.

Benefits of a Laser Printer

  • Fast Printing – One of the biggest reasons why people may choose a laser printer over an inkjet one would certainly be the speedy printing process. This is especially noticeable when it comes to printing large quantities of paper in a single go. (It takes a laser printer a bit longer to warm up than a regular inkjet model, but this is just when you turn it on the first time.)
  • Better for Text Only – While there is a slight advantage to using inkjet printers for prints with plenty of images, if it’s the only text that you want to print out, simply using a laser printer might be a better option. Also, if the text you’re printing has a small font or lots of details and tiny lines, laser printers are way better for this, too.
  • High-Volume Printing – In case you need to print a large number of pages in a single go, laser printing easily beats the vast majority of inkjet models. Also, since the toner cartridges cost less than inkjet models, replacing them when they do go out will be cheaper.
  • Better Value-for-Money Ratio – … unless you fancy printing image-rich sheets, then you would probably be better off simply going for an inkjet printer instead. That said, if you need a printer to print a lot of text and perhaps only a few images now and then, then going for a laser printer would probably be the best overall option.

Components of a Laser Printer

laser printer toner replacing


The purpose of a laser in a laser printer is to throw its light at particular types of the drum below it.

As this happens, the shape of the light thrown against this drum makes whatever shape the colors and ink underneath need to be to make the imprint of the image or text, or some other kind of document you’re printing.

At the same time as the ink hits all the right spots on paper, the area ‘affected’ by this process is evenly heated, so that the ink sticks to the paper. Other than the laser itself, together with the diode that produces the light, it’d be important to point out that there’s plenty of mirrors involved here, too.


If you’ve ever heard of how do laser printers work, you’ve certainly already heard of toners, too.

The thing with these contraptions is, the toner in a printer is a component that needs to be refilled after a while.

The more you’re using the printer to print out text, or especially pictures and other more complex, color-rich media, the sooner will the toner dry up, which then means you need to refill it.

Luckily for many people who use their laser printers, it is possible to recharge your filter cartridge yourself. Provided you take good care of the toner and change it regularly, you can rest assured that you will be able to use the printer itself for an indefinite amount of time.

Transfer Belt

… or, it could even be just a bunch of rollers, depending on the model of the printer.

The job of a transfer belt in a printer, as the name of this crucial laser printer part, suggests itself, is to transfer the paint from the entire system we’ve explained above, to the paper.

It moves the paper along the belt so that the laser can start ‘working’ on it and printing the design you want to print out on it.

As we mentioned in one of the paragraphs above, there is an alternative to these transfer belts, and they’re called rollers. These rollers are usually used for smaller printer models, that aren’t chunky enough to house an entire section in their housing.

Drum Unit

The ‘drum section’ of a laser printer features a pretty simple design.

The reason it’s so simple is that it doesn’t have to move in contrast to the little robot arm-looking thingy, so its design needn’t be too complicated. What’s more, many manufacturers keep it as simple as possible also for reasons of production costs as well as the subsequent maintenance.

Drums are typically green in color and they can sometimes be inbuilt by a laser printer, while the other times they can be made to be detachable.

Another thing worth mentioning here is that these drum units can receive either a positive electric charge or a negative one.

Fuser Unit

Last but not least, we have the so-called ‘fuser unit’.

The reason this part of how do laser printers work has received such a futuristic name is that it literally ‘fuses’ the paint and the paper.

The way this happens is because this fuser unit gets heated up and then the heat instantly melts the color powder (or black & white powder), which is the moment when that the thing you wanted to print outstays stuck to the paper below.

How Do Laser Printers Work

laser printer working Infographic

Button-Pushing & Data

The very first step of any printing process starts with the device that the printer is attached to.

Of course, there are standalone printers out there, but they are considerably more expensive than regular ones how do laser printers work used in homes and offices, so we won’t discuss those models here.

Let’s say you wanted to print a text you recently wrote about sea turtles. You format the text to your liking, add the image of a sea turtle, let’s say, and then click print.

What then happens is that the computer will ‘communicate’ with the printer to send over the data you want. At this point, the printer will give you information about how much ink it has left and what the printing time is likely to be.

Warming Up

As we mentioned earlier, there is a part of a laser printer called ‘the drum’.

This piece of work is charged with the negative static charge, so it can receive the positive charge of the passing laser when it heats up. (Meaning, when the drum heats up.)

Now, to facilitate this process (and to make it possible in the first place), a piece of wire called ‘the corona wire’ gets heated up first.

Now, while the warmup stage of printing doesn’t take long to complete, you still have to wait a little bit for it to be over so that the rest of the process can take place.

The Drum Begins to Roll

… and it receives a positive charge along the way.

The way this works is that the drum receives positive charge fairly quickly as it heats up, so the rolling gives the motion necessary for the application of the laser and of the paint to the paper to take place.

Sometimes, there is a separate roller for all four different colors in a laser printer – cyan, magenta, black, and yellow.

The next stage will involve the laser, which will react with the roller as it’s moving about the printer.

Laser Activation

Once the drum has been heated up sufficiently, the laser will turn on, and the printing process can begin.

The way all of this works is that there is a row of mirrors along with the drum roll, which will reflect the light signal sent by the laser onto the paper that passes between them.

We mentioned earlier that the drum roll is positively activated.

Well, the laser and its other parts are negatively activated, so when the laser comes in contact with the drum, the two charges will attract to each other, thus making the ink stick to the drum better.

Toner Charge

The toner charges, as well as a hopper, are both located next to the drum, which is, as you already know – negatively charged.

The job of these two is to release the ink onto the roller so that it can attach the ink to the paper. This process is made possible because of the whole positive/negative charge thing, which means that only the spots where the text or images of different shades are – are getting pointed at by the laser, which is then where the ink will be imprinted.

If it wasn’t for this charge, either the entirety of the paper would be black (because all colors mashed together would give black), or there would be no color on the paper whatsoever.

Transfer Belt Rolls the Paper

… and as it’s doing so it’s giving it a positive charge along the way, too.

You see, even the paper needs to be charged in a certain way to ensure the printing process will be smooth without blemishes or other potential problems with the distribution of ink.

It is very important to always place the paper at a correct angle in the feeding tray, otherwise, you run the risk of it getting stuck somewhere along the transfer belt.

If this happens, then you might be forced to open the printed casing and remove the trouble-making paper altogether.

Toner is Applied to the Page

The way toner is applied to the page is using the hot roller rolling over it to ‘seal the deal’.

As the ink connects to the paper below it thanks to the fact that the ink and the paper are charged differently with static electricity, the roller is there to connect them physically.

After the roller is doing its job and rolling the paper slowly towards the exit of the printer, you will start seeing the emerging text, image, or whatever else you may have going on the paper. Once the roller completes the rolling process, then you will have a paper that’s ready to use.

All in all, how do laser printers work are contraptions that can be a lifesaver if you want to be able to print out texts and other media in the comfort of your home. The great thing about them is that changing the cartridges is a piece of cake, so provided you take good care of the rest of your printer, you can rest assured you will be able to use it for a long time, indeed.

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