PGL Programmer's Reference Manual

Chapter 2 Command Codes

Dark Printing

A DARK parameter, available in the Alpha, Reverse, and Bar Code

commands, is a double-strike feature which produces bolder, darker text,

denser black backgrounds for reverse print, and extra-dark, more readable

bar codes.

A DARK parameter used with alphanumeric text in the ALPHA command will

print using a bold font.

The extra darkness provided by the DARK parameter improves the Print

Contrast Ratio (PCR) and effectively extends the life of the ribbon. For bar

codes, the PCR describes the difference in light reflection between the bars

and spaces as a measurement of light/dark contrast in order to judge when a

printed bar code will not be dark enough to be read with accuracy by a

scanner. The extra dots used to produce the darker bar code do not change

the overall width of the wide bars. Figure 3 illustrates how the DARK

parameter adds two extra dot columns to wide bar code bars without

increasing bar width.

Due to the second hammer bank stroke required to plot the extra columns of

dots, print speed may be reduced up to half when the DARK parameter is

used with Bar Code commands. However, this decreased print speed should

be weighed against the significant increase in bar code PCR and extended

ribbon life.

Figure 3

. Dark Printing

NORMAL MODE

ADDED COLUMNS OF DOTS

DARK MODE