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How to Determine Media Advance Correction
Introduction
As roll media passes over the capstan, the stress can cause the thickness to deviate from
its ideal, non-stressed state. This deviation can result in incorrect capstan encoder readings,
and lead to discrepancies in the amount the media advanced during each print swath.
This can cause banding to occur, in the form of either dark lines or white gaps. The figure
below illustrates this banding.
[84] Media Advance Banding
Note:
The actual thickness of the white gaps or dark lines in this figure may be thinner than
shown here.
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A) Understep can result in dark lines, where the media has not advanced enough and
the placement of a swath overlaps the prior swath.
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B) Overstep can result in white gaps, where the placement of a swath is displaced a
significant distance away from the prior swath.
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C) Perfect Step, where media advances correctly.
Purpose
The Media Advance Correction Factor (MACF) is a value that you can associate with
media that exhibits this banding to eliminate the effect. This section documents the
procedure to arrive at the ideal MACF for a particular media.
When to do
The MACF is only required when this particular banding occurs. If you don't see any
banding in your images, there is no need to change the value from its default setting of
50.
Chapter 6 - How to Operate the Roll Media Option 129
How to Determine Media Advance Correction