Brother MFC260C Service Manual page 68

Pressure fluctuations do not affect the volume of a liquid (ink), but Boyle's Law says that the
volume of a gas (air) varies with the pressure on it. The main issue with air bubbles in the ink flow
path is their damping effect, absorbing the pressure from the piezoelectric ceramic actuators and
thus degrading ink-jet performance.
The above illustration shows an example of an extremely large air bubble reaching the head nozzle
from the channel ink flow path; the dotted line, the changes resulting from applying a voltage to the
laminated electrode, expanding the piezoelectric ceramic actuator. Note how contraction of the air
bubble absorbs the pressure from the piezoelectric ceramic actuator, preventing ink ejection.
[ Tip: What's so bad about air bubble growth? ]
Bubble (Without pressure)
Pressure chamber
(Channel)
Piezoelectric element
Bubble (High pressure)
3-17
(Head_bubble)
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