Patent ID: 8833904
Filing Date: 2014-09-16
Classification: B41J

Abstract:
1. A method for registering image planes in a digital printing system having a first printhead spaced apart from a second printhead, the first printhead for printing a first image plane and the second printhead for printing a second image plane along a transport path for transporting a print media in a direction, the second printhead being located downstream of the first printhead, the method comprising: providing a controller to control the operation of the digital printing system; providing a media transport for moving the print media relative to the first and second printheads, the media transport including an encoder for transmitting a displacement signal to the print controller; providing a mark detection system located downstream of the first and second printheads; causing the first printhead to print a first registration mark on the print media at a first initial encoder value; causing the second printhead to print a second registration mark on the print media at a second initial encoder value, the second registration mark being spaced apart from the first registration mark in an in-track direction which is in the direction of print media motion; detecting the first registration mark and the second registration mark using the mark detection system as each is transported past the mark detection system; measuring a displacement of the print media between the detection of the second registration mark and the detection of the first registration mark by the mark detection system using the displacement signal; and determining a cue delay value for the second printhead so that a subsequently printed first image plane and a second image plane are registered relative to each other using the displacement, the first initial encoder value, and the second initial encoder value, wherein the subsequently printed first image plane includes a first print-time crosstrack registration mark and subsequently printed second image plane includes a second print-time crosstrack registration mark to refine the registration of first image plane and the second image planes.