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Stylus Color Service Manual
Operating Principles
Principles of the Printing Operation
The
printhead
operates in one of two modes to inject ink from each nozzle:
■ Normal state
No electrical charge is applied to the
MLP
(Multi-Layer
Piezoelectric)
element attached to the
back of the cavity, and pressure inside the cavity is kept at a constant level.
■ Injecting state
The head data signal is applied to the specific nozzle control
line
to select the active nozzle for
printing, and the
MLP
element is gradually charged by the drive voltage. By charging the
MLP
element, the vibration plate is bent to compress the cavity. Then, ink is injected from the
nozzle.
Normal
state
Injectir
state
Nozzle
Nozzl
Ig
@
Figure 2-3. Principles of the Printing Operation
When the ink charge or
printhead
cleaning operation is performed, the ink
in
the cavity is
vacuumed out with the pump mechanism. During printing, on the other hand, the ink is
simultaneously supplied from the ink cartridge and injected from the nozzle, according to the
change of volume
in
the
cavity.
A thermistor is attached to the side of the color
printhead
drive board to monitor the temperature
because the viscosity of the ink varies, depending on the temperature. The detected temperature
level is fed back to the
printhead
drive voltage control circuit to change the time of the
Tc
pulse.
(The Tc pulse is shown in Section 2.3.2.5.)
Rev. A
2-3