Epson Stylus Color 640 Service Manual page 55

EPSON Stylus Color 440/640/740
2.1.1.6.1 Cap Mechanism
In the cap mechanism, in order to prevent ink from being thickened on
the head surface, it is controlled that the head surface stays adherent to
the rubber frame of the cap surface when the power is off. The absorber
is spread in the cap and can hold a certain amount of ink which is
absorbed from the head without draining it to the waste ink pad. Also, in
the bottom of absorber, there are two valves in order to control
adhesion of head and cap surface, and one exit to drain ink to the waste
ink pad. If the carriage is out of HP (in this case, in the printable area or
paper feed position), the valves on the cap mechanism stays in the
position A in the figure above and are always closed. In this condition,
the carriage collides with flag, actual ink absorption and slight ink
absorption are performed. Also, by moving the carriage to further right
side and colliding the flag for opening the valves with the frame,
negative pressure is released in the state that head surface and cap are
adhered. This makes it possible for ink on the nozzle plate surface to be
ready for leaving from the cap in the stable condition.
Chapter 2 Operating Principles
A
Flag for Carriage
Ink Eject Valve
Negative pressure
Valve
Close state
Figure 2-14. Cap Mechanism and Operation Principle
Revision A
B
Release state
Flag for frame
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