Possible diiculties with printhead alignment
The optimizer ink is invisible or hardly visible
The composite background to highlight the optimizer ink works for most substrates, but occasionally, with
some substrates, there is not enough contrast to highlight the optimizer ink. In these cases there are two
possible solutions:
●
Load a dierent substrate with more contrast to perform the alignment.
●
Insert an intermediate correction (A=15, B=20), assuming the optimizer is well aligned. In this case, take
a close look afterwards for associated defects, such as bleed, halo, or wicking (see Bleed, halo, wicking
on page 325).
Another possibility is that the optimizer printhead or the colored printheads may have too many clogged
nozzles, resulting in a poor background area ll, which makes it dicult to detect the optimizer bars. In this
case, see Check and clean the printheads on page 122.
The optimizer printhead is still misaligned in the substrate axis after alignment
The optimizer printhead is staggered and there is a gap between it and the other printheads, so in the
patterns A and B a substrate advance is needed to align it to the background and the reference black. If the
substrate advance is inaccurate, the optimizer correction for the substrate axis (pattern A) may not be valid.
You may detect some bleed in the boundaries between colors in the substrate axis direction, usually when
passing from high ink density areas to lower ink density areas. In this case, ensure that the substrate advance
is accurate (see Substrate-advance compensation on page 146) before performing alignment.
A pattern shows more than one good correction
Occasionally you may nd that a pattern has two or more possible good corrections, separated by two or
more steps. This could be due to wrinkles on the substrate that change the printhead-to-paper spacing along
the scan axis. To avoid this, ensure that the substrate is cold before starting the alignment, and advance it at
least 70 cm to ensure that it is not deformed by the curing of the previous job.
Printhead alignment diagnostics plot
The printer oers a printhead alignment diagnostics plot, to assess the quality of the current printhead
alignment. To print it, in the Internal Print Server select Printer > Printhead alignment > Verify alignment >
Print.
NOTE: You can use the diagnostics plot to check printhead alignment, then ne-tune the values by following
the instructions on the diagnostics plot. Also, if the substrate is similar to one that you already use, you can
print only the diagnostic plot (much faster than printhead alignment) and ne-tune the values in the Internal
Print Server.
The next picture shows an example of the diagnostics plot. Each part is described following the terminology
of the manual alignment. Row0 is the row of printheads closer to the substrate output, while Row1 is the row
of printheads closer to the substrate input. In the same plot there is an area in which the carriage layout is
described with the appropriate labels, just for reference.
140 Chapter 6 Printer calibration ENWW
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