HP 0706124 REV B - Manual (Page 141)

Banding B-9
Banding
This is an explanation of the varieties of banding that may occur
in output from the DisplayMaker Mach 12.The names applied to
the banding here are also an attempt to generate a common lan-
guage for describing and discussing types of banding.
Stitch Banding “Stitch banding” results from inaccurate media advance and/or
inaccurate head-to-head Y-axis registration. It can be described
as regularly appearing bands, equally spaced according to the
width of the print swath. Bands will be darker than the sur-
rounding area if there is too little advance, or lighter than the
surrounding area if there is too much advance.
To eliminate or reduce stitch banding:
1. Run an automatic or manual head-to-head calibration to cor-
rect any Y-offsets, especially if printing in 2x6 or 2x4 print
modes.
2. Run a Media Advance Calibration to correct the media
advance rate.
3. Re-run an automatic or manual head-to-head calibration to
compensate for any Y-offset changes created by adjusting the
media advance. Do this for both 1x and 2x print modes.
4. Run a test print to verify that banding has been eliminated.
Repeat steps 2 and 3 if banding persists.
Edge Banding Edge banding (or “spears”) results from either the service station
configured for “Spit Only 30 seconds,” broken mechanical parts
in the service station or carriage, or a missing service station.
Without regular wiping, ink builds up on the printhead orifice
plates during printing. As the liquid component of the ink evap-
orates, solids are left behind. New ink is jetted through the dried
particles, which are picked up and deposited on the media, cre-
ating a dark band. If the build-up on the printhead is sufficiently
heavy it will inhibit jetting and lead to light bands.
Prints will generally look good at the beginning, but will deteri-
orate as their printed length increases. Bands will be equally
spaced down the length of the print. Banding will be most
apparent at the outside left and right edges of the print and will
taper off and possibly disappear altogether toward the center.
To reduce or eliminate edge banding:
1. Clean the printheads.
2. Confirm that the service station is installed.