Hard copies of electronic documents are often important to a business, and the means to achieve this is through a printer. By far the most common type of printer is an inkjet printer, this uses cartridges of ink and sprays finely controlled jets of this ink onto the paper in order to make up the text and/or images required.

There are two types of technology used for an ink cartridge, piezo crystal and heat process. With a piezo type inkjet cartridge, a small piezo crystal is used to act as a piston to force the microscopic ink droplets out of the ink cartridge nozzle, in this process the ink flows to the nozzle, and when ink is required an electric current is passed into the piezo crystal, which causes it to flex. It is this flexing that forces the ink from the ink cartridge and onto the paper.

The heat process approach works in a similar fashion in that the ink is force out from the cartridge, however the method of forcing out the ink is quite different. With the heat process a tiny heating element is present in the ink cartridge, when ink flow is required this element is turned on and this heats the ink above the nozzle, causing it to boil and so form a bubble – it is this expansion of the ink that forces the ink within the nozzle to flow. The heat process approach is more commonly referred to as bubble jet for the obvious reasons.

Ink cartridges are expensive consumables because part of the technology that makes the printer function is actually embedded in the ink cartridges themselves, thankfully the large volume of ink cartridge sales keeps these prices to relatively low levels.