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.
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.
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.
efficient and advanced printers have come out now which use
new Non-impact Technology.
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.
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.
an Inkjet printer works
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.
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.
Laser Printer works:
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.
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
is how the computer and printer operate to print
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.