Tip: What's So Bad About Air Bubble Growth? - Brother MFC5490CN Service Manual

-------------------------- [ Tip: What's so bad about air bubble growth? ] --------------------------

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.
Pressure chamber
(Channel)
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.
------------------------------------------------------------------------------------------------------------------
Piezoelectric element
Bubble (Without pressure)
Bubble (High pressure)
3-18
(Head_bubble)
Confidential