Printers
Printers
and monitors are two most common used output devices used with the computer. A
monitor gives Soft Copy Output means
the output displayed on the monitor is temporary and the output goes off when
power supply to monitor is switched off or the moment output is changed.
The
printers give Hard Copy Output on a
paper or on some other medium like overhead projector that can be viewed, field
and used at a later stage. Printers now can provide high quality single and
multicolour print output at very high speed. Printers are also capable of
producing images other than plain text on the paper. Printers are classified
based on mechanism used by the printer to print the image and an also be classified
based on image formation method used by them.
Printers can be classified in the following two categories –
(1) Line Printers – These printers print the
character by physically striking the typing devices against an inked ribbon and
paper.
(2) Non Impact Printers – These
printers form the character by using heat, ink and laser beam. There is no
physical contact between paper and ribbon.
Impact Printers -
(1) Line Printers – The speed of such printers is about 300 line per minute. These printers
are useful where the data volume is large. The drawback of these printers is
that they do not support graphics. These printers are of two types –
(a) Chain Printers –
As the name indicates the character set of a
chain printer revolves at a very high speed representing each character in turn
all along the length of print line. Print hammers hit at appropriate points as
the latter flies past.
(b) Drum Printers – It is also called as a barrel printer. It has a drum around which there
is a complete set character and inked ribbon lies between the character and
printing. Each character in turn is represented by rotation of a drum and
similar characters I a line all printed simultaneously. One complete line is
printed in one complete rotation of the drum.
(2) Character
Printers -
(a) Dot Matrix
Printers – These printers do not have character embossed
or otherwise in view. The arrangement of tiny hammers or pins strike the ribbon
to produce the desired characters. These tiny pairs are in a matrix of 7 dots
across 9 dots down. These printers are noisy but can print text and graphics.
(b) Daisy Wheel
Printers – These Printers use a daisy wheel which is a
flat disk having a set of spokes. Each spoke has a single character embossed at
the top. The hub of the wheel rotates to bring the desired character into position
and in turn is struck by a hammer mechanism to form the image on the paper.
Non Impact Printers -
(1) Laser Printers – Laser printers produce
very high quality printing with sharp images. Laser technology is used in such
printers and a microprocessor controls the laser beam. The output quality of
these printers is very good and these printers are fast in speed. The cost of
these printers is also high.
(2) Inkjet Printers – These Printers are very
popular these days. The technology used in these printers is similar to dot
matrix printers but instead of using ribbons ink is forced out of tiny holes
directly on the paper to form characters. The inkjet printers are higher priced
than dot matrix printers. The printer quality of those printers is closer to
that of laser printers. We can also have a colour print out form these
printers.
(3) Plotters and Tracers – A
plotter is a print which is used to create representation visuals charts and
diagrams prepared from statistical data. In a plotter a pen moves up and down
on the paper and draw figures or writes text. A plotter can be connected to a
PC through parallel port. A plotter is software dependent and need much more
instruction than a printer to produce an output.
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