Nearly
every computer user has an inkjet printer, yet most people have no clue
how it works. This article gives a brief history of inkjet printer
technology advancements, and explains what's going on inside your
printer when you click that "Print" button.
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 1976. 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.
