Abstract: Methods for reducing cavitation in impulse or drop on demand ink jetting devices are provided. Impulse ink jet compositions comprising antioxidant are also provided which are suitable for printing clear, well-defined alphanumeric text or low spread, narrow bar width bar codes on porous substrates such as Kraft paper or corrugated cardboard. The ink compositions preferably comprise from about 20 to 50 percent by weight of a carbon black dispersion, from about 10 to 20 percent by weight of a dispersion medium, from about 40 to 60 percent by weight of a plasticizer and less than 2% of an antioxidant additive. The antioxidant additive lowers the dissolve oxygen level in the ink, thereby enhancing the jetting perfomance of the printhead.

Abstract: Impulse ink jet compositions are provided which are suitable for printing clear, well-defined alphanumeric text or low spread, narrow bar width bar codes on porous substrates such as Kraft paper or corrugated cardboard. In one embodiment, the ink compositions preferably comprise from about 20 to 50 percent by weight of a carbon black dispersion, from about 10 to 20 percent by weight of a dispersion medium, from about 40 to 60 percent by weight of a plasticizer and optionally an antioxidant additive. The antioxidant additive lowers the dissolved oxygen level in the ink, thereby enhancing the jetting performance of the printhead.

Abstract: Methods and apparatus are provided for preventing clogging in impulse inkjet printers. It has been found in accordance with the invention that ink clogging during quiescent periods can be prevented by providing an ink that has the property of forming a barrier of higher viscosity ink where the ink contacts the ambient air. As a result, the viscous barrier shields the remaining ink from the effects of air exposure during the quiescent period. Thereafter, the barrier is removed by a series of sub-pulses that re-homogenize the viscosity barrier and clear the nozzle.

Abstract: An impulse fluid jet apparatus having pulse generating circuitry for an impulse jet. The circuitry generates driving a longer pulse exciting the resonant frequency of the jet and a shorter pulse for exciting a higher harmonic frequency of the jet. The longer pulse changes the state of energization of the transducer in the jet to eject a droplet of fluid and the shorter pulse changes the state of energization so as to break off the tail of the droplet.