Color Graphics; The Print Head - Epson LQ-860 User Manual

Color Graphics

With a color ribbon and the appropriate software, you can print
graphics in up to seven colors. Be sure your graphics program
supports color on the LQ-860.

The Print Head

To understand dot graphics you need to know a little about how
your printer's print head works.
The print head has 24 pins. As the print head moves across the page,
electrical impulses cause the pins to fire. Each time a pin fires, it
strikes the inked ribbon and presses it against the paper producing a
small dot. As the print head moves along, the pins fire time after
time in different patterns forming letters, numbers, and symbols.
Because the dots overlap each other both horizontally and vertically
in Letter Quality mode, it is difficult to see the individual dots.
Instead, the letters and symbols seem to be made up 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
handles the timing of pin firings so that the effect is that of 24 pins
arranged in a single vertical column.
Dot patterns
The print head is able to print graphics as well as text because
graphic images are formed on the printer in about the same way
that pictures in newspapers and magazines are printed. If you look
closely at a newspaper photograph, you will find that it is made up
of thousands of small dots. Your printer also forms its images with
patterns of dots, as many as 360 dots per inch horizontally and 360
dots per inch vertically. The images printed by this printer can,
therefore, be as finely detailed as the one at the beginning of this
section.
Software and Graphics 4-9