Inkjet printers are the most commonly used form of computer printer and are widely utilised in both domestic and commercial settings. Inkjets have effectively replaced earlier incarnations of computer printer, such as the dot-matrix and daisy-wheel printer, and these days they provide a credible alternative to the laser printer, in terms of quality, but almost always at a lower cost. History The concept of spraying jets of ink onto paper to form an image goes back more than 100 years. However, the modern inkjet printer was first developed in 1976 and became widely available for the home computer enthusiast by the late 1980s with Hewlett Packard's Deskjet series of printers, followed by those developed by a number of other companies. Up until the last ten years or so inkjet printers were generally surpassed in quality by laser printers. However, changes in inkjet technology in the last few years have led to a rise in the quality of these printers so that they now satisfy even the most discerning of business and home users. The ongoing challenge for inkjet developers was to create a printer where the flow of ink could be controlled, but without the print head becoming clogged with dried ink. The big four companies producing most of these printers used in the home and in business today are Hewlett Packard, Lexmark, Canon and Epson. These, and a host of other companies, also produce the range of consumables used in inkjet printers, most notably inkjet cartridges. Technologies Used in Inkjets Two principal technologies are used in modern the printers; these are continuous inkjet (CIJ) and Drop on Demand (DoD). CIJ is the older of the two inkjet technologies and is widely used in industry for product and component labelling and marking. DoD is a more recent technology, first invented by Siemens in 1977, and uses a cartridge system for holding and releasing ink in response to an electronic pulse. Most domestic and many office printers use aqueous inks, whereas those utilised in larger-scale enterprises are more often based on solvent inks. Industrial printers are generally based on a fixed-head printing system. The inkjet printers found in most homes and offices, however, use the somewhat more flexible disposable head system, which employs inkjet cartridges. Clogging and drying out of print heads has traditionally been a problem with inkjets. Recent improvements to inkjet technology, however, have gone a long way towards resolving these issues. The Positives and Negatives Like all new technologies, inkjet printers were initially comparatively expensive. However, by the early 1990s good quality, relatively low-cost inkjet printers became available and their usage grew exponentially. Consumers particularly liked the fact that these new printers were much quieter than earlier types, such as daisy-wheel printers. Good quality inkjets were also capable of producing sharp, accurate images, but without the lengthy warm-up time of some laser printers. Nowadays, inkjet printers are invariably cheaper to purchase than laser printers of a similar quality. The consumables required to run an inkjet, particularly cartridges, nudge up the running costs of an inkjet when compared with those of a laser printer. Overall, however, the inkjet still seems to be a more economic purchase.