Epson Stylus 1500, Service Manual

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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.
When the ink charge or printhead cleaning operation is performed, ink in the cavity is vacuumed
out with a pump mechanism. During printing, 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.
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. The ink dot size in Micro Dot Printing Mode is
smaller than the normal dot and graded representation is larger than normal dot printing. This
mode is effective for 720 dpi printing on normal paper.
Normal
State
Ejecting
State
Vibration Plate
Vibration Plate
Cavity
No zzle
Pie zo
Pie zo
Cavity
Figure 2-3. Printing Operation States
Operating Principles
2-4 Rev. A