Printing Process; Printing Methods - Epson STYLUS 3000 Service Manual

2.2.2.2 Printing Process

Steps bellow describe how the ink is ejected from each nozzle with the on-demand ink jet system.
Step 1 Normal state
No print signal is applied to the PZT (Piezo electric element). In this state, the PZT does not displace and
no pressure is added to the ink inside the cavity. Therefore the pressure in the cavity is kept at a constant
level.
Step 2 Ejecting state
Print signal is applied to a specific nozzle via the head driver circuit to activate the PZT of the nozzle. The
voltage which activates the PZT is produced in the common driver circuit on the control board. When the
voltage is applied to the PZT, the PZT displaces and the pressure in the cavity changes. Then the ink
ejects as a result.
When no more print signal is applied to the PZT, the PZT recovers from the displaced status. With this
process, the cavity also returns to its normal size, which brings the pressure negative. The negative
pressure in the cavity then absorbs the ink from the cartridge to fill the cavity with the ink again for the next
printing motion. The ink which was not used for printing adheres on the nozzle surface and increases
viscosity in the nozzles, and it causes printing malfunction. Therefore the ink is periodically absorbed and
wasted into the waste ink drain pads by the pump mechanism. Ink viscosity varies depending on the
temperatures around the printhead. Since the change in the ink viscosity leads to decline in print quality,
the thermistor is attached to the color printhead to keep the drive voltage at a proper level based on the
detected printhead temperature.

2.2.2.3 Printing Methods

EPSON micro dot printing
Both black and color printings can be performed in the normal dot printing mode and EPSON micro
dot printing mode. In the normal dot printing mode, the printer uses less ink to create sharper dots.
Therefore the gradation range is expanded in more delicate tone. This mode is available when the
1440X720-dpi paper or glossy film is selected.


Micro weave printing
In this mode, the printer prints 1 line with multiple passes by using specific nozzles for each pass. The
paper is also fed in smaller increments for this operation. Since this mode eliminates white banding
problem, the graphic images quality is improved. However, decrease in paper feed speed is inevitable.
The Micro Weave printing can be selected through the printer driver.
Rev. A
Figure 2-3. Printing Operation States
EPSON Stylus COLOR 3000
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