How Printers Work – WYSIWYG

WYSIWYG – what’s that?! Well, you pronounce it "whiz-e-wig", and it’s an acronym used in the image duplication industry. It stands for What You See Is What You Get. What it refers to is the principle of perfect reproduction – you want to be able to reproduce exactly what you print or copy. This has always been the goal of printing technologists – to get the perfect reproduction.

And how does that work, you say? That’s what we’re going to describe to you here. We’ll leave out the complicated technology and explain to you in simple layman’s terms just how printers work. Copy?

A tale of two technologies

There are two distinct printing technologies – laser and inkjet. Both of these incorporate non-impact printing. Actually, there is a third one – dot matrix – but that’s not used as much today – mostly for draft-quality printing. All these technologies have one thing in common – the printed image is created by a series of dots. The difference is the method by which these dots are created. First, we’ll look briefly at how dot matrix printers work.

For those of you who know what a typewriter is, you can easily relate to how a dot matrix printer works. If you don’t know what a typewriter is, ask your parents. It‘s just a matter of an ink-saturated hammer striking a piece of paper. The hammer (or pin, in the case of a dot matrix printer), represents one particular character.

Dot matrix and laser printers use the principles of electrophotography, which we’ll explain in more detail below. Dot matrix printers have magnetized printheads. The printheads consist of a series of pins, which are continuously under pressure, being pushed forward by springs attached to the print wire. The magnet holds the pins back. A charge is given to a coil, wrapped around the print wire, which takes away the power of the electromagnet, and allows the spring to jump forward onto the paper. Think of it like a slingshot, which is drawn back and ready to be released. As soon as you release the power holding back the slingshot, it flies forward – it’s the same action.

Laser printers – built for speed

Laser printers are the fastest and most popular printers on the market today. They produce extremely high quality images – some near photo quality. Let’s take a closer look at how they do that.

As we mentioned, laser printers use electrophotography, or an electrophotostatic process, to form images on paper. The basis of the principles involved here is the science of atoms – oppositely-charged atoms are attracted to each other, so opposite static electricity fields cling together. It’s hard to imagine that this has anything to do with printing, but in actuality, this is precisely what makes laser printers work.

Inside the laser printer is a drum, or photoreceptor. It’s made of highly photoconductive material that reacts to light, and is electrically charged by the corona wire. As the drum turns, a laser beam shines on it, discharging specific areas. This pattern of discharged areas is ultimately what determines the images that’ll be printed.

The next step is to coat this pattern with a fine black powder called toner. The toner has been given a positive charge, which allows it to stick just to the pattern, and not the rest of the area. The pattern of toner is then attracted magnetically onto the paper, which is passing the drum on a belt. Then the paper is discharged, which releases it from the drum.

Now that the image or pattern is on the paper, we have to make sure it stays there. That’s done by heated rollers, called the fuser, which melt the toner particles right into the paper. The paper is then pushed into the output tray, and you have your printed page.

This process, although it sounds complicated, happens very quickly, printing many copies per minute. But it’s kind of cool to understand it, don’t you think?

Inkjet printers – let us spray

Inkjet printers literally spray liquid ink through a miniature nozzle similar to your garden hose nozzle. These printers are very quiet and are moderately priced. And the print quality rivals that of a laser printer. Here’s how they do that.

The printhead contains 4 cartridges of different colored ink: cyan (blue), magenta, yellow and black (CMYK). It moves along a bar from one side of the paper to the other, writing as it goes. The formatting information and data sent to it activates the chambers of the ink cartridges.

When the designated nozzle is selected, an electrical pulse flows through thin resistors in the ink chambers that form the character to be printed. The resistor is heated and used to heat a thin layer of ink in each selected chamber, causing the ink to boil or expand to form a bubble of vapor.

This expansion causes pressure on the ink, which pushes it through the nozzle onto the paper. Your page is printed.

Don’t sweat the complicated stuff – just print your page

So now you know how printers work. Once you understand the principle of electrophotography, you’ll have a basic knowledge of the inner workings of not only printers, but photocopiers and fax machines as well. Isn’t it amazing how such a complex system can be made to sound so simple? That’s the purpose of these articles. So as we said, don’t sweat it – just put your paper in the printer and print your image. And if everything’s working ok – WYSIWYG!

About The Author

Gareth Marples is a successful and experienced freelance writer providing valuable tips and advice for consumers purchasing inkjet refill kits, printer cartridges and ink refill kits. His numerous articles offer moneysaving tips and valuable insight on typically confusing topics.