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How Printers Work

© Chris Cruickshank

This week takes a look at how the various forms of printers work. This article will deal with the three main types - dot matrix, ink jet and laser. Chances are - if you have a printer - you have one of these!

Dot Matrix

The dot matrix is one of the oldest types of printer and has been around for many years. It is sometimes known as an "impact printer" as a printer ribbon (akin to a typewriter) is "pressed" (or impacted) upon the paper.

The printer head is made up of a row of pins - usually 9 or 25 pins forming a vertical bar. To form a letter, the pins are "fired" in quick succession to press the ribbon against the paper. If you look closely at a sample of output from a dot matrix printer you can see the "dots" that make up the characters.

Technology improves this technique by making the print head shift slightly so that the gaps between dots could be filled in (if you own a dot matrix printer and you print in "final" quality, you will notice that the printer head passes over a line of text twice - the second time is the "fill in" pass).

The more dots you have, the better the resolution, and 25-pin printers can produce reasonable output. One advantage that a dot matrix printer has over all other types is that it can use multi-part stationery. You cannot use multi-part stationery on the other types of printers mentioned here as neither an ink jet nor a laser impacts on the paper.

Dot matrix printers can handle graphics output by firing pins where pixels are set although shading can mean the paper crinkles and it is difficult to get a true "black."

Ink Jet

These printers actually "spray" ink on to the paper from a very fine nozzle. This gives true blacks and high quality output as no "dots" are evident as in a dot matrix printer (although the principle is still similar).

One problem with printers can be smudging - especially where a lot of black is required in a single area. If you can - try and avoid using solid black areas in graphics as even if the print does not smudge, the paper can crinkle due to being made very wet from the ink. You should also avoid touching the output until the ink has had a chance to dry.

Colour

This is where ink jets come into their own. By using two cartridges - one colour and one black, an ink jet can produce high quality colour output at an affordable price. There are a couple of points to bear in mind when using colour ink jets.

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