Method for setting focus of a multichannel printhead

摘要

A method for setting focus of a multichannel printhead for an imaging apparatus (10) comprises moving the printhead (500) to a premove position. A first set of patches (82) is printed wherein a focus position of the printhead is varied in a first random pattern from one patch to another. A second set of patches (83) is printed wherein the focus position of the printhead is varied in a second random pattern from one patch to another. A density for each of the patches is measured in the first series of patches. A density for each of the patches is measured in the second series of patches. An optimum focus position is calculated for the multichannel printhead based on a polynomial curve (72) of density and focus position for each of the patches.