Epson Stylus Photo 820 - Printing Process; Printing Method

EPSON Stylus PHOTO 810/820 Revision A
Operating Principles Overview 30
2.1.2.1 Printing Process
This section explains the process which the Printheads of On-Demand inkjet printers
eject ink from each nozzle.
1.
Normal state :
When the printing signal is not output from C418 Main board, or the PZT drive
voltage is not applied, the PZT does not change the shape. Therefore, the PZT does
not push the ink cavity. The ink pressure inside the ink cavity is kept normal. (refer
to Figure 2-4 : Normal state)
2.
Ejecting state :
When the print signal is output from the C418 Main board, the nozzle selector IC
located on the Printhead latches the data once by 1-byte unit. Based on the drive
waveform (common voltage) generated on the Main board, the PZT selected by
the nozzle selector IC pushes the top of the ink cavity. By this operation, the ink
stored in the ink cavity is ejected from nozzles. (refer to Figure 2-4 : Ejecting state)
Figure 2-4. Printhead printing process
2.1.2.2 Printing Method
For printing dot system, the Stylus PHOTO 810/820 has the following two kinds of
printing mode.

Multiple shot printing

Variable dot printing
The above two printing modes are automatically selected depending on the media and
the resolution setting of the printer driver. The following explains each printing mode.

Multiple shot printing
This printing mode is developed to improve the print quality on plain paper or
transparencies in low resolution. The multiple shot printing mode uses normal dot,
and the number of dot shot varies from 1 shot to maximum 3 shots depending on
the print data to enable to output sharp image even in a low resolution.

Variable dot printing
This printing mode is developed to improve the print quality on exclusive paper.
This mode is basically the same as variable dot printing mode used on other
products; micro dot, middle dot and large dot compose this mode. The printing dot
size varies according to the print data and this mode enables to output even sharper
image on exclusive paper.
Ink path
PZT
Ink cavity
Nozzle
Nozzle plate
PZT drive voltage
Normal state
Ejecting state