Instruction manual

6–2
Principles of Operation
Line Matrix Printing
The LG
plus
Series printer creates characters and graphics by printing patterns
of ink dots on paper, an entire line at a time. This technique is called line
matrix printing.
Every text character is stored in printer memory as a pattern of dots on a
logical grid called the dot matrix. (See Figure 6–1.) The ink dots are made by
a row of small hammers mounted on a shuttle that sweeps rapidly back and
forth. Printer logic circuits divide every line of incoming data into horizontal
dot rows. The hammers put dots at the required positions for the entire line
by striking an inked ribbon and the paper.
112Column No.
0.10
0.00835
0.01389 ”
0.02 ”
”
”
First row and column
of next character.
Lowest descender
dot line.
First row and column of
next character line (at 6
LPI).
Figure 6–1. A Dot Matrix
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. After a line of characters is printed,
hammer action stops and the paper advances to the first dot row of the next
print line. The number of dot rows allowed for line separation depends on the
vertical line spacing the user selects.
The dot matrix patterns of text characters vary according to the font the user
selects. For example, in the data processing (DP) font at a line spacing of six
lines per inch (lpi), a dot matrix contains 12 dot rows from the top of one
character line to the top of the next. (See Figure 6–1 and Figure 6–2.) At
eight lpi there are nine dot rows per character line, at nine lpi eight dot rows
per character line, and so on.