Epson LX-80, Operating Manual

Page: 36 / 193

Chapter 3
Elements of Dot Mat rix Printin g
T his chapter is fo r tho se who want to go into how the print er works .
It is a simp l e, non - technical explan a tion of the basics of d ot matrix
printing whic h will give you a better understanding of som e of the
l ate r chapte r s.
The LX-SOuses a print h e ad with nine pins or wires mount ed verti-
ca l ly. These pin s make th e dots by being pushed out of th eir resting
position. Since this is analogous to s hooting with a gun , it i s k nown
as making the pin " fire " . Each time a pin is fired , it strikes th e inked
r ibbon a n d p r es ses it against the paper to produce a dot . Thi s dot is
about lI 7 2nd o f a n inch in diameter . The size varies slightl y depend-
ing upon the a g e of the ribbon and the type of paper u se d. As the
head moves h ori z ontally across the page , these pins are fir ed time
after t i me i n different patterns to produce letters, number s, sym-
bols, or g r a phics.
For exam p le, to print a pica capit a l T , the head fires th e t op pin,
moves lI60t h of an inch , fires the top pin again , moves l I 60 t h of an
inch, fires the top s even pins , moves l I 60th of an inch , fir es t h e top
p i n, moves a nother 1 I 60th of an inch , and fires the top pin once
more to fini s h the letter . All this happens in only 1 I 100th of a
second .