Patent ID: 7618127
Filing Date: 2009-11-17
Classification: B41J

Abstract:
1. A printer system which incorporates a printhead, the printhead comprising: a plurality of nozzles, each nozzle having a respective bubble forming chamber; at least one heater element disposed in each of the bubble forming chambers respectively, the heater element being configured for thermal contact with a bubble forming liquid; drive circuitry corresponding to each of the nozzles for controlling the operation of the heater element via electrodes connected between the drive circuitry and the heater element; such that, heating the heater element to a temperature above the boiling point of the bubble forming liquid forms a gas bubble that causes the ejection of a drop of an ejectable liquid through the nozzle corresponding to that heater element; wherein, part of the drive circuitry is disposed on one side of the bubble forming chamber, and part of the drive circuitry is formed on the opposing side of the bubble forming chamber, and the heater element has a bubble nucleation section of a smaller cross section than the rest of the heater element so that the temperature of the bubble nucleation section is heated to above said boiling point before the rest of the heater element, the heater element being configured so that the bubble nucleation section and the rest of the heater element are co-planar and remain co-planar when the heater element is heated, wherein each heater element is configured such that an actuation energy of less than 500 nanojoules (nJ) is required to be applied to that heater element to heat that heater element sufficiently to form said bubble in the bubble forming liquid thereby to cause the ejection of said drop.