Figure 2-3. Printing Operation States - Epson Stylus 1500 Service Manual

Operating Principles
The printhead operates in one of two states to eject ink from each nozzle:
Normal state
No electrical charge is applied to the piezoelectric element attached to the back of the cavity, and
pressure inside the cavity is kept at a constant level.
Ejecting state
The head data signal is applied to a specific nozzle control line to select the active nozzle for
printing, and the piezoelectric element is gradually charged by the drive voltage. Charging the
piezoelectric element bends the vibration plate to compress the cavity. Ink is then ejected from the
nozzle.
Normal
State
Ejecting
State
When the ink charge or printhead cleaning operation is performed, ink in the cavity is vacuumed out
with a pump mechanism. During printing, the ink is simultaneously supplied from the ink cartridge
and ejected from the nozzle, depending on changes in the volume of the cavity.
A thermistor is attached to the side of the black ink printhead driver 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 driver voltage control circuit to change the time of the Tc
pulse.
3. EPSON Micro Dot Printing Mode
The Stylus 1500 has a special black ink printing mode called EPSON Micro Dot Printing Mode. This
mode can be selected when using a special paper type (such as glossy or transparency). Selecting this
printing mode via the printer driver can improve output quality because it eliminates banding that can
sometimes occur in normal mode. In normal dot printing mode, the print dot consists of two ink dots
combined into a single dot. In EPSON Micro Dot Printing Mode, the print dot consists of a single ink
dot only. Using this mode, the ink dot size is smaller than the normal dot and the graded
representation is larger than normal dot printing. This mode is effective for
720 dpi printing on normal paper.
2-2
Cavity
Nozzle
Cavity

Figure 2-3. Printing Operation States

Stylus 1500 Service Manual
Piezo
Vibration Plate
Pie zo
Vibration Plate
Rev. A