Printronix L5535, Maintenance Manual

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8
Principles of Operation
Printing System Descriptions
General
The operation of an LED printer is similar to that of a laser printer, but quite
different from that of an impact printer.
Quiet and fast, with excellent output resolution, LED printers are “page
printers.” They produce an entire page at once, compared to line printers,
which produce only successive character lines.
The LED printer has two basic functional sections: the print “engine” and the
controller module. The engine is responsible for the mechanical aspects of
producing the page. The controller controls the printer and is responsible for
electronic data manipulations, as well as interfacing with the control panel and
with a host computer.
The print engine contains the engine controller board, also known as the MC
board, or MC-PCBA (mechanism control printed circuit board assembly). The
controller module contains the printer controller, also known as the controller
board, or LVX040 controller.
The printing process is simple. A host computer sends data to the printer,
which feeds that data to an LED printing system. The LEDs create a latent
image of the desired page on a
selenium photoconductive drum . The drum
transfers toner to the areas of the latent (hidden) image. The drum rotates
past the paper, and the toner image is transferred to the paper. The paper is
then pulled through the fuser, which uses high-intensity light to fix the image
onto the paper. The paper then exits the printer, and the drum is cleaned.
The Printing Process
The electrophotographic printing process consists of the following steps:
1. Charging: The charge corona is a thin wire electrode that extends across
the width of the paper. This electrode places a high-voltage, electrostatic
charge on the selenium photoconductive drum.
2. Imaging: Based on data received from the host computer, a bit-mapped
image of the page is generated in random access memory (RAM) located
on the printer controller board.
3. Exposing: The LED array exposes areas of the drum that are to be
imaged (i.e., black). Areas that are exposed to the light become