Figure 2-3. Principles Of The Printing Operation - Epson 4003353 Service Manual

Stylus Color Service Manual
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.
Nozzle
Normal
state
state

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
Operating Principles