inkjet printer is now virtually everywhere, in classrooms, small businesses, corporate of-
fices, and especially in homes. It provides a low-cost, high-quality printing solution with
a printer model to fit just about every need.
Inkjet printers appear to be slow, but when you consider that each of its dozens of
printhead nozzles is firing thousands of times every second to print a document or repro-
duceanimageastheprintheadmovesbackandforthacrossthepaper,itisactuallywork-
ing very fast.
However, inkjets do tend to be a bit slow when printing in color, not to mention that
their ink cartridges are a bit pricey, especially if a lot of color printing is being produced.
But, all in all, the inkjet printer is, for the majority of PC users, the low-cost alternative to
laser printers, particularly color laser printers. Today’s inkjet printers are a high-quality
color printing alternative at a price less than $300.Inkjet Technologies
Inkjet printing uses small drops of ink to print text and graphics on paper. An inkjet
printhead has a number of nozzles through which ink is jetted onto the paper. What dif-
fersfromonetechnologytothenextiswhatcausestheinktojettisonfromthenozzleonto
the page.
There are two general types of inkjet technology: continuous flow and drop-on-de-
mand. Drop-on-demand inkjet printing has two forms: Piezoelectric and thermal. Here is
a brief overview of the three major inkjet technologies in use: Piezoelectric One of two inkjet technologies included under drop-on-demand
inkjet approaches. In this approach to inkjet printing, a series of ink nozzles that
are connected to the printer’s ink supply are lined up vertically on the printhead.
As the printhead moves over the paper, Piezoelectric crystals in each nozzle are
charged with electricity, which makes the crystal expand. The expansion of the
crystal forces a droplet of ink out of the nozzle with enough force to strike the
paper. This process involves literally thousands of drops squeezed through a
nozzle smaller than a human hair hundreds of times a second.
Thermal The other drop-on-demand inkjet technology. It is very much like the
Piezoelectric but, as its name implies, heat is involved. The ink droplet is about
10 picoliters in volume (a picoliters is about one-trillionth of a liter). Between
the ink supply (called the reservoir) and the nozzle there are ink channels through
which the ink travels to the nozzle. As the ink moves down the channel, it is
heated and forms a bubble. When the bubble pops, a droplet of ink is forced
out of the nozzle onto the page. As one droplet is spraying onto the page, the
next droplet is being drawn into the channel and the process repeats as demanded.
Continuous flow As its name implies, the ink flows continuously through the
printhead. However, not all of the ink is put on the paper. Ink droplets are passed
through a variable charge chamber where they are selectively given an electricalChapter 17: Printers^415