Controlling a printing system using encoder ratios

摘要

A method for adjusting an encoder pulse count delay in a printing system for printing on a continuous web of print media using first and second printheads. First and second encoders are provided at different positions along the media transport path. An initial encoder pulse count delay is provided for use in printing with the second printhead. An initial ratio of the first encoder pulse rate to the second encoder pulse rate is determined. At a subsequent time a subsequent ratio of the first encoder pulse rate to the second encoder pulse rate is determined. An adjusted encoder pulse count delay is determined by adjusting the initial encoder pulse count delay responsive to the initial ratio and the subsequent ratio and used to control printing by the second printhead.

主权项

1. A method for adjusting an encoder pulse count delay in a printing system for printing on a continuous web of print media, comprising:
providing a first printhead at a first printhead position along a media transport path, the first printhead being adapted to print ink drops onto the print media as the print media travels along the media transport path past the first printhead position; providing a second printhead at a second printhead position along the media transport path, the second printhead being adapted to print ink drops onto the print media as the print media travels along the media transport path past the second printhead position; providing a first encoder at a first encoder position along the media transport path, the first encoder generating a first encoder pulse stream having a first encoder pulse rate, each pulse in the first pulse stream indicating the passage of a first defined length of print media past the first encoder position, wherein the first pulse stream controls a timing for printing of ink drops from the first printhead; providing a second encoder at a second encoder position along the media transport path, the second encoder generating a second encoder pulse stream having a second encoder pulse rate, each pulse in the second pulse stream indicating the passage of a second defined length of print media past the second encoder position, wherein the second pulse stream controls a timing for printing of ink drops from the second printhead; determining an initial ratio of the first encoder pulse rate to the second encoder pulse rate; providing an initial encoder pulse count delay for use in printing with the second printhead; controlling the first printhead responsive to the first encoder pulse stream to print ink drops on the print media in accordance with image data for a first image plane of a first printed image; controlling the second printhead responsive to the second encoder pulse stream and the initial encoder pulse count delay to print ink drops on the print media in accordance with image data for a second image plane of the first printed image; determining a subsequent ratio of the first encoder pulse rate to the second encoder pulse rate; using a processor to determine an adjusted encoder pulse count delay by adjusting the initial encoder pulse count delay responsive to the initial ratio and the subsequent ratio; controlling the first printhead responsive to the first encoder pulse stream to print ink drops on the print media in accordance with image data for a first image plane of a second printed image; controlling the second printhead responsive to the second encoder pulse stream and the adjusted encoder pulse count delay to print ink drops on the print media in accordance with image data for a second image plane of the second printed image.