Ink jet printer

Ink-jet computer printers are the type of printer most commonly sold to the individual computer user. Ink-jet technology was allegedly invented by Hewlett-Packard, whose printer division is still the most profitable division.

An ink-jet usually works by having a print cartridge with a series of tiny electrically-heated chambers that are constructed by photolithography. To print, the printer runs a pulse of current through the heating elements. A steam explosion in the chamber propels a droplet of ink. The ink's surface tension pumps another charge of ink into the chamber through a narrow channel attached to an ink reservoir.

Older ink-jet printers directed ink streams electrostatically; ultrasound was used to induce waves in the ink, which then broke into little droplets that would fall on the right place on the page.

Compared to earlier consumer-oriented printers, ink-jets have a number of advantages. Compared to ribbon printers like the old Apple Imagewriter family, for example, they're practically silent. Many are able to produce high resolutions, and color printing of quite reasonable quality is widely available.

Disadvantages include flimsy print heads that are prone to clogging, and ink cartridges that are expensive, sometimes costing $20-30 or more.

A common business model for ink-jet printers is to sell the actual printer nearly at cost, while significantly marking up the price of the ink cartriages. This sometimes generates ire and/or disappointment among ink-jet purchasers, who find their "inexpensive" printer turns out to be more expensive than they'd first imagined.