Patent ID: 7654647
Filing Date: 2010-02-02
Classification: B41J

Abstract:
1. A method of ejecting drops of an ejectable liquid from 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 and having a bubble nucleation section of a smaller cross section than the rest of the heater element; 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; 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, the method comprising the steps of: heating the heater elements to a temperature above the boiling point of the bubble forming liquid to form a gas bubble that causes the ejection of a drop of an ejectable liquid from the nozzle and 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; and supplying the nozzle with a replacement volume of the ejectable liquid equivalent to the ejected drop, wherein said step of heating the at least one heater element is effected by applying an actuation energy of less than 500 nJ to each such heater element.