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(11) | EP 0 177 316 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Ink jet printer and method for fabricating a nozzle member |
| (57) In an ink jet printer, a print head (1) comprises a front nozzle member (2) having
a front channel (3), a housing (4) secured to the front nozzle member, and a rear
nozzle member (7) which defines with the housing a liquid chamber (5) and further
defines with the front nozzle member a laminar airflow chamber (10a). The rear nozzle
member has a forwardly projecting nozzle (8) and a rear channel (9) extending from
the liquid chamber through the projecting nozzle in axial alignment with the front
channel (3) to form a meniscus at the front end. The airflow chamber is connected
to an air supply for directing air to a point between the front and rear channels
(3. 9) so that it creates a sharp pressure gradient along a path therebetween. A dead
air region is created in a location adjacent the exit end of the rear channel to cause
the meniscus to take a dome-like shape which is stabilized against vibrations and
transients. An electric field gradient is established between the front channel and
the meniscus to cause the latter to extend toward the front channel and expelled through
the front channel. A portion (2a) of the front nozzle member is liquid-repellant to
prevent the field distribution from being seriously disturbed by an ink layer formed
on it by stray ink particles. |