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B
A Quick Look at Line Matrix Printing
The P4280–CT is an impact printer: it creates characters by printing ink dots
on paper. The dots are made by an array of steel hammers mounted on a
rapidly oscillating shuttle. The hammers strike the paper through a moving
ink ribbon. The dot patterns of characters and punctuation marks are mapped
in printer memory on invisible matrixes. (See Figure B–1.)
Serial matrix printers use a moving printhead in which pins are mounted to
form whole characters one at a time and one after another. But the P4280–CT
is a line matrix printer. It divides every printable line into horizontal dot
rows, then prints a dot row of the entire line at every lateral sweep of the
shuttle.
During each sweep of the shuttle, hammers are activated to print dots at the
required positions in the dot row. When the shuttle reaches the end of a
sweep, it reverses direction, the paper is advanced one dot row, and the
hammers print the next row of dots as the shuttle sweeps in the opposite
direction. (See Figure B–2.)
After a line of characters is printed, hammer action stops while the paper is
advanced to the first dot row of the next print line. The number of rows
allowed for line separation depends on the line spacing you select.
Line Matrix Printing
Figure B–1. Character Formation in a Dot Matrix Printer
Matrix visible only to the printer
Ink dots formed by hammer tips.
B–1
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