Page 67 - DCAP101_BASIC_COMPUTER_SKILLS

Basic Computer Skills

Notes
Figure 4.16: A Dot-matrix Printer

Figure 4.17: Formation of Characters as Patterns of Dots

Since dot matrix printers produce printed output as patterns of dots, they can print any
shape of character that a gram can describe. They, therefore, can print many special
characters, different sizes of print, and also have the ability to print graphics such as charts
and graphs.
Dot-matrix printers are impact printers because they print by hammering the pins on the
inked ribbon to leave ink impressions on a paper. Hence, they can be used to produce
multiple copies by using carbon paper or its equivalent. Due to impact printing, dot-matrix
printers are noisy as compared to non-impact printers.
Dot-matrix printers are normally slow with printing speeds ranging from 30 to 600 characters
per second. However, they are cheap in terms of both initial cost and cost of operation.
Hence, they are preferred by individuals and organizations for generating printed outputs
if the speed and quality of printing are not important factors. They are also used for
applications requiring multi-copy output such as shipping forms and invoice that on impact
printing for generating multiple copies.

Inkjet Printers
Inkjet printers are character printers that form characters and all kinds of images by spraying
small drops of ink on paper. The print head of an inkjet printer contains up to 64 tiny nozzles
that can be heated up selectively in a few microseconds by an integrated circuit resistor. When
the resistor heats up, the ink near it vaporizes and is ejected Through the nozzle making a
dot on the paper placed in front of the print head. To print a character, the printer selectively
heats the appropriate set of nozzles as the print head moves horizontally. Figure 4.18 shows
an inkjet printer.

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