5525B/31/32 Line Matrix Printer Code V Programmer's Reference Manual

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Chapter 3 Bar Codes
Dark Print
Dark print bar codes double strike the wide bars, resulting in darker looking
bar codes. The extra darkness improves the Print Contrast Ratio (PCR) and
effectively extends the life of the ribbon. (The PCR describes the difference of
light reflection between bars and spaces as a measurement of light/dark
contrast in order to judge when a printed bar code is not dark enough to be
read accurately by a scanner.)
The extra dots to produce the darker bar code do not change the overall width
of the wide bars. Figure 7 illustrates how Dark Print adds two extra dot
columns to the wide bars without an increase in bar width.
Printing speed decreases somewhat when Dark Print is used. This is due to
the second stroke of the hammer bank required to plot the extra dot columns.
The slight decrease in printing speed should be weighed against the
significant increase in bar code PCR and extended ribbon life.
The KF command activates Dark Print. The format for the Dark Print
command is shown below. The Dark Print command includes your system
SFCC, KF to activate Dark Print, the data (the bar code command),
terminated with the SFCC, and followed by KF.
(cc) KF
data (cc) KF (cc)-
Figure 7. Dark Printing
NORMAL MODE
ADDED COLUMNS OF DOTS
DARK MODE