How Images Are Processed; Bit Mapping; Job Recovery - Printronix L5000 Series Maintenance Manual

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.
This chapter presents more detailed operating principles for each printer section and
for the paper feed and transport systems.

How Images are Processed

Bit Mapping

The L5000 Series are page printers—they receive data from the host and store a
"page" of data in memory before printing. The printers do not print character-
by-character or line-by-line. Every print job is stored as a full-page bit-map in
random access memory.
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-map 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

Data are erased from memory only after the entire job has been printed. If a paper
jam occurs and only part of the page prints, the printer will reprint the same page
again, because the data still resides in memory. This feature is known as job recovery.
As shown on the next page, the printing mechanisms are divided into five sections
according to the printing processes:
1. Photoconduction Section
2. Developing Section
5–4
Principles of Operation