Brother MFC 5490CN - Color Inkjet - All-in-One, Service Manual

Page: 53 / 439

3-16 Confidential
Damping
Without damping, ink pressure fluctuations directly affect the size of ink-jet head droplets,
risking lower print quality.
Each damper assembly has two chambers. The one on the right in the illustration below has a
loose film across its top and serves as a damper. The film immediately flexes in and out in
response to falls and rises in pressure, adjusting the chamber volume to counteract pressure
fluctuations in the ink supply tubes.
Air buffering
Liquid ink contains trace amounts of air. These molecules coalesce into air bubbles as the
piezoelectric ceramic actuators vary the pressure on the ink in the ink-jet head channel. (See the
illustration on
page 3-13 .) Removing as many of these bubbles as possible before the ink
reaches the ink-jet head is essential to maintaining proper print quality. The above illustration
shows how the damper assemblies provide air buffers, the chambers on the left, for
consolidating these air bubbles away from the ink-jet head and vent flow paths for purging them
at regular scheduled intervals.
Film
(DamperFunc)
Left chamber
This loose film flexes in and out in
response to changes in ink pressure.