Desktop printers ordinarily come in two kinds

The inkjet printer works by propelling droplets of ink onto a paper surface from a number of nozzles contained in a printhead. There are generally two methods through which this can be performed, piezoelectric vibrations or thermal heating.

With the piezoelectric method crystals are used to instigate electronic pulses which cause vibrations. These force droplets of ink to be propelled through the nozzles in the printhead. Because these vary in size it is possible for the inkjet to print its image in finer detail when required. Piezoelectric vibrations are able to use a superior quality of ink in comparison with other methods whilst at the same time minimising printer ink usage. However the technology involved in this has been patented by Epson and thus can't be offered by any other provider.

The thermal heating method on the other hand involves placing a metal plate inside the inkjet's cartridge which receives an electric current that heats the element and thereby causes the ink to bubble and to expand. The pressure created by the bubbles causes the ink to pass through the nozzles. When the bubbles cool down a vacuum is created permitting fresh ink to enter the nozzle. The technology is efficient because the droplets that are not used return to the tank automatically.

It is because bubble technology is used that printers utilising it are often referred to as bubble jet printers. This is the most popular of all the inkjet printers.

One problem which inkjet print technology has historically faced in respect of the printer ink that it uses has been that of the conflicting requirements for a colouring agent that will stay on the surface and for the quick dispersal of the carrier fluid.

There have also been difficulties caused by ink drying on the printhead's nozzles. To prevent this from occurring most inkjet printers are equipped with a mechanism that allows them to reapply moisture onto the printhead. Because there is not any solvent available to perform this task, ink itself is fired to the printhead as a means of remoistening it.

Desktop inkjet printers, making no differentiation between household and industrial models, generally use aqueous inks comprising a mixture of water, glycol and pigments or dyes. Aqueous inks are generally used in printers with thermal inkjet heads, because they require water in order to perform.