Brother GTX-4, Service Manual

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Before Using Your Printer for the First Time
<TIPS: Problems caused by the development of air bubbles>

What happens when air bubbles are created within the ink?
The volume of ink does not change under pressure variation while the volume of air changes when subjected to pressure
(Boyle's law).
This means that once air bubbles are created, they serve as dampers absorbing the pressure change, inhibiting the performance
of the ink-jet.
The following diagram depicts the situation where a large air bubble is formed in the ink channel leading to the nozzle.
The dotted line indicates the condition where the piezoelectric element is extended under the voltage applied to the laminated
electrode. The pressure generated by the piezoelectric element is absorbed by the contracting air bubble, preventing the ink from
being discharged.
Piezoelectric element
Pressure chamber
(Channel) Bubble (Without pressure)
Bubble (High pressure)