Appeal No. 1997-0316
Application No. 08/218,951
The invention is directed to a thermal inkjet printhead.
More particularly, an electrically activated heating element
is disposed in thermal communication with ink in the ink
firing chamber and a continuous thermally insulating layer
having at least one heterogeneous nucleation site in the form
of a discontinuity in the thermally insulating layer is placed
between the heating element and the ink firing chamber. The
discontinuity allows consistent location of the ink bubble at
a selected location on the thermally insulating layer since it
reduces the free energy of formation for the ink bubble.
Representative independent claim 1 is reproduced as 2
follows:
1. A thermal inkjet printhead arranged such that a
consistently located gas phase ink bubble is formed
comprising:
an ink firing chamber for containing ink;
an electrically activated essentially planar heating
element disposed in thermal communication with said ink firing
chamber;
a thermally insulating layer disposed continuously
between said heating element and said ink firing chamber, said
2The amendment after final filed July 19, 1996, Paper No.
11, has been treated as entered in accordance with the
examiner’s instructions even though, at the time of this
decision, it had not been physically entered.
2
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