Patent ID: 6447108
Filing Date: 2002-09-10
Classification: B41J

Abstract:
A method for controlling a multi-nozzle CIJ printhead having a pressure modulator for causing streams of ink emitted from the nozzles to be broken up into individual droplets, and charge electrodes and charge electrode controllers for controllably applying a charge to individual ones of the droplets in each stream, the method comprisinggenerating a modulation waveform to operate the pressure modulator to cause droplets to be generated in each stream; operating the charge controllers to supply a charge signal waveform to each charge electrode; comparing the charges applied to the streams of droplets to a reference or threshhold value; determining, a plurality of times in what number of the droplet streams the droplet charges exceed the reference or threshhold value and calculating a first average value for the number, repeating the step of determining, a plurality of times, in what number of the droplet streams in which the droplet charges exceed the reference or threshhold value and calculating a second average value for the number; and if the second average is less than the first average previously calculated then reducing the threshhold or reference value.