In order to avoid ribbon rollover in a high speed impact
printer, a crown roller, having a crown offset from the
roller’s center, is used to guide the ribbon. The crown
tends to center the ribbon about itself and the roller is
dimensioned so that the distance from the crown to the
end ?ange of the roller is suf?ciently far that under all
operating conditions the ribbon will remain separated
from the ?ange and hence will avoid rollover. In partic
ular the roller is positioned so that the print head will
initially impact the advancing ribbon off center toward one edge ‘of the ribbon. As printing continues, this re peated impacting will cause that edge of the ribbon to
wear, the result being that the tension across the ribbon
will decrease and the crown roller will constantly repo
sition the ribbon as if it were of an ever decreasing
width. This constant repositioning (or precision) will
present unwom sections of the ribbon to the print mech
anism and will simultaneously advance the worn edge
toward the ?ange which is located a distance far
enough from the crown to prevent rollover.