The Print Head - Epson LQ-800 User Manual

I n c o m e B r e a k d o w n
The quickest and easiest way to print graphics on your LQ is to use
a commercial graphics program. With such programs you usually cre-
ate an image on your monitor and then give a command to send the
image to the printer.
If you use commercial software that produces graphics, all you
need to know about dot graphics is how to use the software. If, on the
other hand, you wish to do your own programming or merely wish to
understand how the LQ prints graphics, read on.

The print head

To understand dot graphics you need to know a little about how the
LQ's print head works.
The LQ's print head has 24 pins. As it moves across the page, elec-
trical impulses cause the pins to fire. Each time a pin fires, it strikes the
inked ribbon and presses it against the paper to produce a small dot.
As the head moves across the paper in draft or Letter Quality mode,
the pins fire time after time in different patterns to produce letters,
numbers, or symbols.
Because the dots overlap each other both horizontally and verti-
cally in the Letter Quality mode, it is difficult to see individual dots.
Instead, the letters and symbols seem to be made of unbroken lines.
In order for the dots to overlap vertically, the pins in the print head
are in more than one column, but the intelligence of the printer han-
dles the timing of pin firings so that the effect is that of 24 pins
arranged in a single vertical column.
6-2