(^432) PC Hardware: A Beginner’s Guide
Multilevel This is a more advanced method of managing the four primary colors
of the laser printer to create multicolored images. Multilevel color printers have
the ability to adjust the intensity of each color to produce 256 shades of each color
(256 shades of cyan, 256 shades of magenta, etc.) and then mix the 256 shades of
each color to produce a total of over 16 millions colors that can be printed on
the page. This ability eliminates the need for dithering to produce a solid color.
Another name for this process is continuous-tone printing.
Continuous-tone printing mixes colors at the same spot and varies their intensity
(and therefore the resulting color) by controlling the amount of each color placed on the
dot. The range in laser printers is from bi-level four-color printers to full continuous-tone
printers. The common application is to use just enough multilevel processing to reduce
the amount of dithering required on an image. For example, a printer may use halftoning
with some multilevel processing by creating the halftone image in2x2cells and then us-
ingdifferentdotcolorcombinationsinthecelltocreatetheillusionofadditionalcolors.
Nearlyallprintersplaceonecolordotontopofanothercolordotandthenusethefus-
ing process to blend the dots into the final color. Some printers are able to control how
much toner is placed on a dot by controlling the size of the dot. For those printers that can
create larger or smaller dots, the amount of toner of a particular color that is used in a
“dot-stack” also controls the color that results from the dots. How long the laser is al-
lowed to strike the drum at a particular dot determines the size of the dot. A bigger dot
will collect more toner during developing. Shortening the time the laser beam contacts
the drum produces a smaller dot. A smaller dot collects less toner.
Toner
Toner is the dry granulated ink used in laser printers (and copy machines as well). It is made
from a variety of ingredients, but in general, toner is made from the following ingredients: Plastic The outer shell of each toner particle is made from styrene or a blend
of styrene and acrylic plastics. This part of the toner melts in the fusing phase
to adhere to the paper.
Iron As much as 40 percent of a toner particle is ferrous oxide, which is akin to
iron rust, that has very specific magnetic properties. Toner particles are held to the
drum and paper prior to fusing strictly with simple magnetism. The toner particles
are given a negative charge that attracts it to the drum and paper where it is
needed to form the image of a document.
Sand Silica (very fine sand) prevents the toner from clumping.
Charge dye This is added to control the electrostatic charge that can be
applied to the toner.
Wax The wax helps flow the toner when it melts during the fusing phase.
Carbon black This is added to black toner to deepen its color.