Printronix L5535, Maintenance Manual

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Chapter 8
How Images Are Processed
electrically discharged. This forms a latent image of the bit-mapped data
on the drum. The image is made up of charged and uncharged areas.
4. Developing: The latent uncharged image areas of the drum attract
charged toner from the developing unit to form the developed image on
the drum. Since the charged areas of the drum have the same charge as
the toner, they repel the toner.
5. Transferring: Another thin wire electrode, the transfer corona, puts a
high electrostatic charge on the paper. This charge attracts the toner,
transferring the toner from the OPC drum to the paper.
6. Fusing: High-intensity light fuses the transferred toner image onto the
paper.
7. Cleaning: As the drum continues to turn, erase LEDs remove all residual
electrostatic charge from the drum. The cleaning unit then removes
unused toner from the drum.
The remainder of this chapter presents more detailed operating principles for
each printer section and for the paper feed and paper transport systems.
How Images Are Processed
The L5535 printer is a page printer—it receives data from the host and stores
a “page” of data in memory
before printing. The printer does not print
character-by-character or line-by-line. Every print job is stored as a full-page
bit map in printer random access memory.
Bit Mapping
With bit mapping, a full page is logically divided into “dots,” the smallest parts
of the page that can be individually printed. Joined together, the dots form a
discrete, bit-mapped grid that is
all-points addressable . Thus, each dot is
individually subject to program control and has a corresponding memory bit
location that can be activated, either ON (1) or OFF (0). When the bit is ON,
the corresponding dot prints black; when the bit is OFF, the dot is “white” and
does not print.
Job Recovery
If a paper jam occurs, any pages that have not completely exited the printer at
the time of the jam will be reprinted, and no data will be lost. This feature is
known as
job recovery .