XJ128 and XJ128 Plus Printhead
XJ128 Guide to Operation
Xaar Document no: D031010302 Version A
Page 21
Do not operate the printhead without supplying ink to it
4.5 Mechanical system design
This section details important information that will aid in the design of the mechanical system used
with the printhead.
4.5.1 Printhead shock and vibration
It is recommended that the printhead is protected from shock and vibration as this will have a severe
impact on the printed image quality and printhead life.
4.5.2 Printhead enclosure
The surroundings in which the printhead will be used will have a strong influence on the
performance of the printhead and the maintenance it will require. It is recommended that
the printhead be used in as clean as environment as possible and the use of an
enclosure around the printheads can help to reduce environmental contamination.
4.5.3 Multiple printheads
When using multiple printheads grouped together, the printheads should be arranged as to minimise
the distance between printheads. This will help to minimise drop placement errors due to substrate
stretch and velocity variation between the first and last printheads.
4.5.4 Substrate / media or printhead motion
To ensure adequate print quality, the substrate/media motion should be smooth and as straight as
possible. Errors due to substrate motion can cause drop placement inaccuracies that may be visible
in the resulting print.
The description of a moving printhead applies to any printhead operating by either reciprocating over
media to generate a print wider than the printhead swathe width, or by indexing the printhead
between swathes where the principle movement is of the media.
The maximum acceleration/deceleration the printhead can tolerate before the ink meniscus breaks
(resulting in air ingestion, or flooding of the nozzle plate) is 4g. This threshold value will vary with the
negative pressure of the head of ink, the level of
’
damping
’
in the ink supply, the type of ink and the
ambient temperature.
The effects of system vibration can also be seen in the final print. Typical effects are light-and-dark
banding, caused by pressure fluctuations and stitching errors.