Datasheet

Installation and Configuration of Printers 73
Parts of a Laser Printer
An electrophotographic laser printer consists of the following major components:
Printer Controller A large circuit board that acts as the motherboard for the printer.
It contains the processor and RAM to convert data coming in from the computer into
a picture of a page to be printed.
Toner Cartridge and Drum A powdery mixture of plastic resin and iron oxide. The plas-
tic allows it to be melted and fused to the paper, and the iron oxide allows it to be moved
around via positive or negative charge. Toner comes in a cartridge, like the one shown in
Figure 1.25.
The drum is light sensitive; it can be written to with the laser scanning assembly. The toner
cartridge in Figure 1.25 contains the print drum, so every time you change the toner car-
tridge, you get a new drum. In some laser printers, the drum is a separate part that lasts
longer, so you don’t have to change it every time you change the toner.
FIGURE 1.25 An EP toner cartridge
SIDE VIEW
Charge corona assembly
Cleaner blade
Paper
Print drumDeveloper roller
Toner
Primary Corona (Charge Corona) Applies a uniform negative charge (around –600V) to
the drum at the beginning of the printing cycle.
Laser Scanning Assembly Uses a laser beam to neutralize the strong negative charge
on the drum in certain areas, so toner will stick to the drum in those areas. The laser
scanning assembly uses a set of rotating and fixed mirrors to direct the beam, as shown
in Figure 1.26.
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