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How does your printer work?
Most people have used printers at some stage for printing
documents but few are aware of how it works. Printed documents
are arguably the best way to save data. There are two types of
basic printers Impact and Non-impact.
Impact printers, as the very name implies means that the
printing mechanism touches the paper for creating an image.
Impact printers were used in early 70s and 80s. In Dot Matrix
printers a series of small pins is used to strike on a ribbon
coated with ink to transfer the image on the paper.
Other Impact Printers like Character printers are basically
computerized typewriters. They have a series of bars or a ball
with actual characters on them, which strike on the ink ribbon
to transfer the characters on the paper. At a time only one
character can be printed. Daisy Wheel printers use a plastic or
metal wheel. These types of printers have limited usage though
because they are limited to printing only characters or one type
of font and not the graphics.
There are Line printers where a chain of characters or pins,
print an entire line, which makes them pretty fast, but the
print quality is not so good. Thermal printers are nothing but
printers used in calculators and fax machines. They are
inexpensive to use. Thermal printers work by pushing heated pins
against special heat sensitive paper.
More efficient and advanced printers have come out now which use
new Non-impact Technology.
Non-impact printers are those where the printing mechanism does
not come into the contact of paper at all. This makes them
quieter in operation in comparison to the impact printers.
In mid 1980s Inkjet printers were introduced. These have been
the most widely used and popular printers so far. Colour
printing got revolutionized after inkjet printers were invented.
An Inkjet printer's head has tiny nozzles, which place extremely
tiny droplets of ink on the paper to create an image. These dots
are so small that even the diameter of human hair is bigger.
These dots are placed precisely and can be up to the resolution
of 1440 x 720 per inch. Different combinations of ink cartridges
can be used for these printers.
How an Inkjet printer works
The print head in this printer scans the page horizontally back
and forth and another motor assembly rolls the paper vertically
in strips and thus a strip is printed at a time. Only half a
second is taken to print a strip. Inkjet printers were very
popular because of their ability to colour print. Most inkjets
use Thermal Technology. Plain copier paper can be used in these
printers unlike thermal paper used for fax machines. Heat is
used to fire ink onto the paper through the print head. Some
print heads can have up to 300 nozzles. Heat resistant and water
based ink is used for these printers.
The latest and fastest printers are Laser Printers. They use the
principal of static electricity for printing it as in
photocopiers. The principle of static electricity is that it can
be built on an insulated object. Oppositely charged atoms of
objects (positive and negative) are attracted to each other and
cling together. For example, pieces of nylon material clinging
to your body, or the static you get after brushing hair. A laser
printer uses this same principle to glue ink on the paper.
How Laser Printer works:
Unlike the printers before, Laser printers use toner, static
electricity and heat to create an image on the paper. Toner is
dry ink. It contains colour and plastic particles. The toner
passes through the fuser in the computer and the resulting heat
binds it to any type of paper. Printing with laser printers is
fast and non-smudge and the quality is excellent because of the
high resolution that it can achieve with 300 dots per inch to
almost 1200 dpi at the higher end.
Basic components of a laser printer are fuser, photoreceptor
drum assembly, developer roller, laser scanning unit, toner
hopper, corona wire and a discharge lamp. The laser beam creates
an image on the drum and wherever it hits, it changes the
electrical charge like positive or negative. The drum then is
rolled on the toner. Toner is picked up by charged portion of
the drum and gets transferred to the paper after passing through
the fuser. Fuser heats up the paper to amalgamate ink and
plastic in toner to create an image. Laser printers are called
"page printers" because entire page is transferred to the drum
before printing. Any type of paper can be used in these
printers. Laser printers popularized DTP or Desk Top Publishing
for it can print any number of fonts and any graphics..
This is how the computer and printer operate to print
When we want to print something we simply press the command
"Print". This information is sent to either RAM of the printer
or the RAM of the computer depending upon the type of printer we
have. The process of printing then starts. While the printing is
going on, our computer can still perform a variety of
operations. Jobs are put in a buffer or a special area in RAM or
Random Access Memory and the printer pulls them off at its own
pace. We can also line up our printing jobs this way. This way
of simultaneously performing functions is called spooling. Our
computer and the printer are thus in constant communication.
About the author:
John Sollars is the managing director of Solar Electronics,
which are both ink and pc peripheral suppliers based in
Shropshire, UK. To access a comprehensive online shop of
original and re-manufactured printer ink cartridges please visit
http://www.stinkyinkshop.co.uk