Appeal No. 1998-3131 Page 2
Application No. 08/192,224
heads, known as drop-on-demand type, employ thermal or
piezoelectric
mechanisms that are responsive to control signals for
expanding or compressing, respectively, small volumes of ink
near each print head nozzle to eject drops therefrom onto
print media.
The ink supplied from the pen reservoir flows in a single
path toward the print head and out a nozzle. When nozzles are
not ejecting drops, there is substantially no flow of supply
ink near the nozzle. When the printer is activated, but
between printing operations, the flow of supply ink is
generally still with respect to the entire print head.
The print heads of the inventive ink-jet pens are
supplied with ink circulated to and from the print head.
Passageways defined by the pen are oriented in fluid
communication with the firing chambers of the print head and
so that ink circulates near the chambers no matter whether the
print head is activated for ejecting ink drops.
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