Pump Mechanism - Epson Stylus COLOR 440 Service Manual

EPSON Stylus COLOR 440, 640, and 740

Pump Mechanism

The pump mechanism, shown in Figure 2-12, actually performs three
different functions:


The pump itself removes ink from the ink cartridge, as part of the
head cleaning operation.


The cleaning blade removes dust and dirt from the printhead, as
part of the head cleaning operation.


The carriage lock retains the carriage in its home position, to ensure
that the printhead remains capped when the printer is not in use.
The cleaning blade and the carriage lock are mounted on the same
slider unit, and therefore extend or retract in tandem. The slider's
motion is controlled by the slider lever, which is held against the clutch
plate by a compression spring. Because the slider lever is operated by
friction instead of gears, the rest of the pump mechanism can continue
to turn even when the slider unit is fully extended or retracted.
However, this also means that even a minor obstruction can cause the
slider to stick.
The pump itself uses peristaltic compression. Rollers attached to the
pump drive wheel create a vacuum in the ink drain tube by squeezing
the tube along its length and forcing the ink to travel through it. This is
shown in Figure 2-12 at right, and schematically in
following page.
As mentioned above, the PF motor is the power source for both the
paper feed mechanism and the pump mechanism. The PF motor
powers the pump mechanism through the eject roller shaft, as shown in
Figure 2-10 and Figure 2-12 at right.
Figure 2-13 on the
Chapter 2 Operating Principles
Figure 2-12. Pump Mechanism
45