AMT Datasouth 4500 Series manual Bar Code Quality, Bar Code Orientation

Media Settings

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 standard2 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).

Picket Fence (Horizontal) Bar Code

Ladder (Vertical) Bar Code

Figure 13 – Picket Fence and Ladder Bar Codes

2American National Standard for Information Systems – Bar Code Print Quality – Guideline, ANSI X3.182-1990, American National Standards Institute, Inc.

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