Patent ID: 9010893
Filing Date: 2015-04-21
Classification: B41J

Abstract:
1. A method for operating an inkjet printer comprising: moving with a transport an image receiving surface in a process direction past a plurality of inkjets in at least one printhead, the plurality of inkjets being arranged in a cross-process direction; ejecting a plurality of ink drops from the plurality of inkjets to form a printed test pattern on the image receiving surface; generating with an optical sensor image data of the printed test pattern; identifying with a controller a plurality of locations of a plurality of printed marks in the test pattern from the image data, each printed mark being formed by one inkjet in the plurality of inkjets; identifying with the controller a process direction offset for each inkjet in the plurality of inkjets with reference to the location of each printed mark in the test pattern formed by each inkjet and a predetermined location on the image receiving surface; modifying with the controller an image data correction parameter associated with image data that correspond to each inkjet in the plurality of inkjets to reduce a first portion of the identified process direction offset for each inkjet; modifying with the controller a firing signal waveform parameter associated with each inkjet in the plurality of inkjets to reduce a second portion of the identified process direction offset for each inkjet; and storing with the controller the modified image data correction parameters and the modified firing signal waveform parameters in a memory for use in operating the plurality of inkjets to eject ink drops with reduced process direction offset between the ink drops ejected by the plurality of inkjets.