inkjet printer An output device that creates characters and graphics by firing a stream of ink drops at a surface from one or more banks of tiny nozzles. The rapid displacement required to eject the drops from the nozzles may be achieved by surface boiling of the ink using tiny electric heating elements behind each nozzle, or by mechanical pressure using piezoelectric crystals behind the nozzles. The technology has developed to the extent that such printers can (on suitable media) offer comparable resolution and quality to the laser printer but at a much lower cost. Inkjet technology is also suitable for color printing, nozzles being fed with three or four different color inks (see CMY, CMYK color models). Inkjet printers can also act as plotters.

There are three main types of inkjet device. In the continuous inkjet printer a continuous stream of electrically charged ink drops are fired toward the surface. The desired image is created by deflecting unwanted drops into a gutter. The drop-on-demand inkjet printer fires ink only at the points of the surface necessary to create the desired image. The phase-change inkjet printer uses solid ink that is heated so that it leaves the nozzle as a liquid but returns to the solid state as it reaches the image surface; a major advantage is that it does not need special paper for good results as other inkjet devices do.

Considerable advances have been made in recent years and some inkjet printers can produce prints of photographic quality, though there are still concerns about the long-term stability of the dyes used.