Brother MFC-3340CN Service Manual page 66

Air bubble growth
Liquid ink contains trace amounts of air. The amount varies with the pressure on the ink because
increasing the pressure raises the ink's ability to absorb air from its surroundings and lowering the
pressure forces the ink to give up some of this air.
The ink pressure fluctuations generated by the piezoelectric ceramic actuators repeatedly expand and
contract any air bubbles, causing them to gradually grow larger as the ink pressure changes
repeatedly expand and contract them.
The design therefore compensates by allowing the purging/flushing of air bubbles during printing to
keep the amount of air dissolved in the ink to a minimum.
Tube
Bubble
Tube
Bubble
Air
Air
Pressure
Pressure
Ink
Ink
Confidential
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