XJ128 and XJ128 Plus Printhead
XJ128 Guide to Operation
Xaar Document no: D031010302 Version A
Page 39
7.3.2 Vacuum fed negative pressure ink supply
The second, more complex technique is a
vacuum ink supply system, where a vacuum
controls the pressure of the ink at the inlet to
the printhead. The ink reservoir is isolated
from atmospheric pressure.
This
technique
requires
additional
components to accurately control the
pressure above the ink, such as a digital
vacuum sensor and regulator. The volume
of the vacuum supply must be sufficient to
avoid small pressure fluctuations in the ink
supply.
Figure 7.2
–
Vacuum fed ink supply system
7.4 Ink supply system design
An ink supply system should consist of several components. A small ink reservoir (a), stores a small
volume of filtered ink supplying it to the printhead, as it is required at the recommended pressure. As
the ink in the small reservoir is consumed this must be replaced. Most commonly a small liquid pump
(b) supplies this ink, through a system filter (c) to the small reservoir, from a main ink tank (d). The
pump is controlled by a feedback system (f) and sensor (e) in the small reservoir. Finally, compatible
ink tubing provides the ink flow path between the components.
Figure 7.3 - Ink supply system components (system shown
–
vacuum fed ink supply)
+ve head of ink
Vacuum
-ve
a
b
c
d
f
e
Vacuum
NOT TO SCALE
