AMT Datasouth Codewriter 4500 Series - Manual (Page 46)

Media Settings
36
Bar Code Quality
Printing bar codes represents one of the primary applications of the CodeWriter 4500
Series printers. The American National Standards Institute (ANSI) provides a
standard
2 by which bar code image quality is measured. This section provides
assistance toward obtaining ANSI ‘A’ Grade bar codes by identifying favorable bar
code printing settings.
Bar Code Orientation
Bar codes printed on a label may be oriented vertically along the label feed
direction (ladder) or horizontally (picket fence) across the label’s width (see
Figure 13). On thermal printers the print orientation has a significant impact
upon the ANSI Grade obtained.
When printing bar codes in a picket fence fashion, the individual bars align
with the printhead heating elements such that an element is either on or off
while printing the bar code. This results in very controlled geometric qualities
of the bars and spaces and the best quality bar codes.
Bar codes printed in a ladder orientation require the modulation of the heating
elements to control the widths of the bars and spaces. Controlling the heating
and cooling of printhead heating elements to establish geometric relationships
is inherently less precise than relying on the fixed positions of the heating
elements across the printhead width. This results in slightly lower bar code
read quality (possibly reduced by one ANSI Grade Level).
Figure 13 – Picket Fence and Ladder Bar Codes
2 American National Standard for Information Systems – Bar Code Print Quality – Guideline, ANSI
X3.182-1990, American National Standards Institute, Inc.
Ladder (Vertical) Bar Code
Picket Fence
(Horizontal)
Bar Code