DROPLET FORMATION OF A THERMAL SIDESHOOTER INKJET PRINTHEAD

The present study aims to provide numerical predictions on the droplet formation process for a thermal sideshooter inkjet printhead, which d irectly affects the printing quality of the printhead. The calculation procedure starts from the heat up of the printhead by an input electr ical pulse, then obtains the pressure impulse response curve due to th e formation and collapse of a bubble in the ink, the ink flow motion i n the ink nozzle, and finally the evolution process of the ejected ink droplet outside the ink nozzle. The governing continuity and momentum equations for the flow motion in the ejected ink droplet are solved o n the Eulerian frame by an implicit finite-difference scheme. The ink droplet leading is then updated to the new location from the newly obt ained velocity. A comparison is made between the present numerical pre dictions with experimental results. A good agreement has been found. I n addition, the present study shows the effects of the operating volta ge of electrical pulse. the ink properties, and the gravity on the bre ak-off time of ejected droplet from the ink nozzle exit and the separa tion time of the long tail from main droplet. (C) 1998 Elsevier Scienc e Inc. All rights reserved.