Graphics
The
print
head
To
urtderstand
dot graphics you need to know a little ‘about ‘how
your
printer's
print head works.
.
As the print head moves across the page, electrical impulses cause
the pins to fire.
Each
‘time a pm fires, it strikes the inked ribbon
and presses it against the paper to produce a small dot. As the head
moves across the page, the pins fire time after time in different
patterns to produce letters,
number&
or symbols.
Dot patterns
The
DFX’s
print head is able to print graphics as well as text
because graphic images are formed on the printer about the same
way that pictures in newspapers and magazines are printed. If you
look closely at a newspaper photograph, you can see that it is made
up of many small
dots,
Your
PIT&@;
also .forms its
images
with
patterns of dots, as many as
240
dot positions per inch horizontally
and
72
dots vertically. The images printed by the printer can,
therefore, be as finely detailed
as
the
one on page
4-10.
In
its’main
@aphics”mode,
ydur’prir&
‘tiiints
one
co&&‘-of
dots
for each code it receives, and it uses only the top eight of the nine
pins. Therefore,. your
,graphics
program
muat
send codes for dot
patterns, one
numb
for
~each.,colurnn
in a line.
.l$o.r
each o&hose
columns, the print
.head
printa-the.pattern of dots
-you
have
specified.
To print figures taller than eight dots, the print head makes more
than one pass, The printer prints one line, then advances the paper
and prints another,
just,
as it does with text.
To keep the print head from leaving
gaps‘between
the graphics lines
as it does between the text lines,
tho,line
spacing must be changed
to eliminate the
space&etween
<lined
,With
a
cw
in line spacing,
your printer can print finely detailed graphic images that give no
indication that they are made of separate lines,
‘each
no more than
8/72nds of an inch tall.
Software and
Graphics
4-11
