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Forming Drops without Ligaments

IP.com Disclosure Number: IPCOM000114167D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Lee, HC: AUTHOR [+2]

Abstract

Ink jet drops are typically formed by pressurizing an ink chamber with volumetric changes by a piezoelectrically actuated diaphragm. The attached shows the electric pulse typically used to actuate the piezoelectric device and generate drops on demand. As the pulse rises exponentially the diaphragm deflects outward, increasing the chamber volume. In this phase, the ink flows into the chamber through an inlet while the meniscus at the nozzle retracts. This refill phase is followed by a wait in which the nozzle miniscus stabilizes. Then, in the eject phase, the pulse falls, pressurizing the chamber and ejecting ink through the nozzle. In this phase, some ink flows out through the inlet.

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Forming Drops without Ligaments

      Ink jet drops are typically formed by pressurizing an ink
chamber with volumetric changes by a piezoelectrically actuated
diaphragm.  The attached shows the electric pulse typically used to
actuate the piezoelectric device and generate drops on demand.  As
the pulse rises exponentially the diaphragm deflects outward,
increasing the chamber volume.  In this phase, the ink flows into the
chamber through an inlet while the meniscus at the nozzle retracts.
This refill phase is followed by a wait in which the nozzle miniscus
stabilizes.  Then, in the eject phase, the pulse falls, pressurizing
the chamber and ejecting ink through the nozzle.  In this phase, some
ink flows out through the inlet.

      The result of using this pulse scheme, where the rise and fall
times are nearly equal, is a problem in the formation of satellite
drops between main drops and/or ligaments attached to the main drops.
Satellites and ligaments form extraneous spots degrading the print
quality.  It is shown that the drop formation characteristic is
directly related to the way the chamber pressure is modulated.  In
general, an elongated wait period, and longer time period between
pulses would improve the efficiency, but it generally degrades the
drop rate.  It is noted that too short wait periods, can lead to
suction of air through the orifice.

      A scheme is proposed to optimize the drop formation with the
object of eliminating satellites an...