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Ribbon Drive
A continuous loop ribbon that can be replaced by
the operator is used in the printer. Two ribbon
feed rolls pull the ribbon through a slot from one
end of the ribbon box, around the print head, past
the print wires, and feed it into the other end of
the box. A half twist is placed in the ribbon during
manufacturing so that, as the ribbon passes the
print wires, the top half of the ribbon prints on
one pass and the bottom half prints on the next
pass.
The print head, ribbon box, and ribbon drive
mechanism are mounted on the print head carrier
and move left or right under control of the print
head stepper motor. The ribbon feed rolls are
driven by two monofilament lines through a series
of idler gears. The lines are looped around a double
clutch, located underneath the print carrier, that
drives the ribbon feed rolls. The clutches drive in
one direction and free wheel in the other. The lines
are looped so they both drive in the same direction,
providing a clockwise ribbon path whether the
print head carrier is moving left or right.
Double
Clutches
Feed
Roll
Ribbon twist is
controlled here
Monofilament
Manual Ribbon
Feed Knob
Ribbon Feed Rolls
~--_~
__ Ribbon roll before
drive action arranges
it in the ribbon box.
(I~ _~~=--~=~_~~--( ~
Double Clutches
9-8
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