Patent ID: 8123326

Claim:
A method for calibrating a multi-printhead printing system, the method comprising the steps of: (a) employing an encoder to track movement of a media through the printing system; (b) providing a first printhead that prints a first image plane that includes a first test mark at a first defined location on the media as the media moves relative to the first printhead; (c) providing a second printhead that prints a second image plane that includes a second test mark at a second defined location on the media as the media moves relative to the second printhead; (d) employing a first image capture device that captures an image that includes both the first and second test marks; (e) determining an error factor based on the placement of the second mark relative to the first mark in the captured image; (f) using a clock to measure a frequency in a pulse train of the encoder; and (g) using the clock to create a frequency-shifted pulse train of the encoder in which the frequency shift is based on the error factor; wherein the first printhead prints the first image plane in response to output of the encoder and the second printhead prints the second image plane in response to the frequency-shifted pulse train of the encoder.