Patent ID: 6422677
Filing Date: 2002-07-23
Classification: B41J

Abstract:
A method for extending the temperature range over which the volume of ejected ink droplets from nozzles of a thermal ink jet printhead may be controlled, the printhead having a selectively addressable heating element for each nozzle to produce momentary ink vapor bubbles that eject an ink droplet when the heating elements are addressed with an ink-nucleating electrical pulse in response to data signals received by the printhead, the method comprising the steps of:sensing the temperature of the printhead; applying a plurality of non-nucleating electrical pre-pulses to the selected heating elements in response to data signals received; applying a nucleating pulse to each of the selected heating elements subsequent to the plurality of non-nucleating pre-pulses to eject ink droplets from the printhead nozzles; providing clocking signals having predetermined units per time period; and controlling the number of non-nucleating pre-pulses, the pre-pulse width, and time width between pre-pulses based upon a look-up table established to take into account the printhead temperature, the pre-pulse width and time width being independently variable multiple whole units of clock signals to maintain the desired droplet volume.