THERMAL INK JET PRINTHEAD WITH HEATER ELEMENT POSITIONED FOR MINIMIZED INK DROP MOMENTUM

摘要

An ink jet printhead comprises a plurality of nozzles each having a nozzle aperture; a bubble forming chamber corresponding to each of the nozzles respectively; an ejectable liquid inlet for establishing fluid communication between the nozzle aperture and an ejectable liquid supply, the ejectable liquid inlet and the nozzle aperture being aligned such that they have a common central axis; and a heater element disposed in each of the bubble forming chambers. Each heater element has two bubble nucleation regions suspended within the bubble forming chamber in a plane parallel to that of the nozzle aperture. The two bubble nucleation regions are laterally offset from the central axis, such that the lateral offset of one of the bubble nucleation regions is equal and opposite to the lateral offset of the other bubble nucleation region. The bubble nucleation regions are spaced from each other such that bubbles nucleated at each will grow until they unite to form the gas bubble that causes the ejection of a drop of ejectable liquid. The heater element is positioned such that a distance between a point of collapse of the gas bubble and the nozzle aperture is less than 50 microns.