Inside Your Inkjet Printer: How Does it Work?
Have you ever wondered how your inkjet printer works? How does the ink get from the inkjet cartridge to the paper?
Why is the print quality is so clear? Why the printing is so
quiet? Generally, all that most people know is that there's some
movement and a faint high pitched sound when it's printing
something -- and then the finished document comes out. Unlike dot matrix and character printers that strike ribbons to
create an image, inkjet printers do not physically touch the
paper. All inkjet printers function using the same basic principles.
Tiny ink droplets are "jetted" (or pushed) out multiple holes
onto paper in a controlled and systematic fashion. This is
where the term "inkjet" comes from. The size of ink droplets, speed and reliability of this type of
printer has been continuously improving since its inception.
In 1993, Epson was the first manufacturer to produce an inkjet
printer using micro-piezo technology. The Epson Stylus 800
was the first printer to use the multi-layer actuator printhead
(the printhead is the part of the printer that holds numerous
tiny nozzles that actually squirts the ink onto paper). This specific printhead utilized an electro-mechanical
element that acted like a tiny control room. When pulses of
electricity passed through, it that gave specific signals to fire
individual or multiple nozzles loaded with ink. Micro-piezo technology utilized a tiny crystal in each
individual nozzle that when electrically energized, would
vibrate or bend causing a controlled amount of ink to be
forced out onto paper. When the electrical current is off, the
crystal bends back to its original shape, creating a vacuum,
thus pulling ink into the nozzle from the reservoir for the next
commanded fire. The Epson printhead was fixed to the carriage so it never
needed replacing (the printer carriage is what moves laterally
across the paper). This also kept the cost of ink cartridges low
since they were little more than reservoirs of ink. This breakthrough printer produced a whopping 360 dpi (dots
per inch) that was deemed, almost "letter quality" at the time.
With a printing speed of 150 - 180 characters per second, the
new Epson became the user favorite printer for home and
office. At the same time, HP was using a similar technology. A
thermal jetting system was utilized in their printhead. The
printhead still acted like the control room but each individual
nozzle was instead independently super heated by electricity,
which caused the ink to explode onto the paper. HP claims
the temperature of a fired inkjet nozzle approaches that of the
surface of the sun. HP elected to put the printhead on the inkjet cartridge itself
instead of mounting it permanently to the carriage. Since
each inkjet cartridge would have its own printhead,
replacement cartridges would be more expensive for these
printers. HP inkjet cartridges also could not print as fast as Epson
because each nozzle needed to cool after firing. This heating
technology also limited the types of inks that could be used. In the 1990's, Canon, Epson and HP engineered printheads
that applied even smaller droplets of ink, drastically
improving dpi and resolution. While Canon and HP could produce a 6 - 10 picoliter droplet
size from one nozzle, Epson was about half the size (between
3 - 6 picoliters). Currently, there are printers available which
will produce an amazing 1 picoliter droplet! To get an idea of
how small this is; a human hair is about 12 picoliters in
diameter. Most human eyes can't see one jetted droplet of
ink on paper. Inkjet printers have come a long way since their first
inception. Printers today are twice as fast as their predecessors were,
and are cheaper than ever. Many printers can easily produce
color photo quality images in at an incredible 6000 dpi. As time goes on and as demand for printing remains high,
the quality, speed and features of inkjet printers will only
continue to improve.
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