Unformatted text preview: lent. However due to
impact printing, chain/band printers are noisy in operation and often use a cover to reduce
the noise level. A chain/band printer is shown in Figure .9.32.
Since chain/band printers use inked ribbon to produce printed output, they are usually
monochrome. Typical speeds of chain/band printers are in the range of 400 to 3000 lines
Laser printers are page printers that print one page at a time. The main components of a
laser printer are a laser beam source, a multi-sided mirror, a photoconductive drum and
toner (tiny particles of oppositely charged ink). To print a page of output the laser beam
is focused on the electro statically charged drum by the spinning multi-sided mirror. The
mirror focuses the laser beam on the surface of the drum in such a manner that it creates
the patterns of characters/images to be printed on the page. As the drum is
photoconductive, a difference in electric charge is created on those parts of the drum
surface that are exposed to the laser beam. As a result, the toner, which is composed of
oppositely charged ink particles, sticks to the drum in the places the laser beam has
charged the drum's surface. The toner is then permanently fused on the paper with heat
and pressure to generate the printed output. The drum is then rotated and cleaned with a
rubber blade to remove the toner sticking to its surface to prepare the drum for the next
page printing. A laser printer is shown in Figure 9.33.
Laser printers produce very high quality output because they form characters by very tiny
ink particles. The most common laser printers have resolutions of 600 dpi, whereas some
high-end laser printers have resolutions of 120 dpi. Because of their high resolution, these
printers give excellent graphics art quality.
Since laser printers produce printed output as patterns generated by the laser beam, they
can print any shape < characters that a programmer can describe. This allows the printer
to print many special charact...
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This document was uploaded on 04/07/2014.
- Spring '14