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Unit 5: Computer Hardware

Figure 5.20: A line Printer
Notes

Drum Printers. These printers print the line by a rotating drum having a ring of characters for each
print position. The hammer strike each character of the drum simultaneously so that entire line is
printed for one full rotation of the drum. These printers are also called Barrel Printers. The printouts
obtained from these printers have even character spacing but uneven line height.
Chain Printers. These printers print the line by a rotating chain having ring of characters for each
print position. Their printing mechanism is similar to drum printers. The printouts obtained from
these printers have uneven character spacing but even line height.
(ii) Non-impact Printers. The printers that print the characters without striking against the ribbon
and onto the paper, are called Non-impact Printers. These printers print a complete page at a time,
therefore, also called as Page Printers. Page printers are of three types—(a) Laser Printers, (b) Inkjet
Printers, and (c) Thermal Printers.
(a) Laser Printers. These printers look and work like photocopiers as shown in Figure 5.21. They are
based on laser technology, which is the latest development in high speed and best quality printing.
In these printers, a laser beam is used to write the image on a paper. First, the image is formed by
electrically charging thousands of dots on a paper by laser beam. Then, the paper is sprayed with a
toner having the opposite charge and is passed over a heated roller to make the image permanent.

Figure 4.21: A laser Printer

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