Method for aligning printhead cartridges

Abstract

A method for aligning print head cartridges arranged in a printing system along a print media propagation path, each print head cartridge having a plurality of print head tiles arranged spanning a width of the print media propagation path. The includes printing first Vernier patterns using a reference print head cartridge; printing second Vernier patterns over the first Vernier patterns using a second print head cartridge; and determining, from an interference pattern generated, a distance of separation along the print media propagation path of print head tiles in the second print head cartridge from corresponding print head tiles of the reference print head cartridge.

1 . A method for aligning a plurality of print head cartridges arranged in a printing system along a print media propagation path, each print head cartridge having a plurality of print head tiles spanning a width of the print media propagation path, the method comprising the steps of:
 selecting a first print head cartridge as a reference print head cartridge;   printing a first plurality of Vernier patterns using the reference print head cartridge, each of the first plurality of Vernier patterns corresponding to a print head tile of the reference print head cartridge;   printing a second plurality of Vernier patterns over the first plurality of Vernier patterns using a second print head cartridge; and   determining, from an interference pattern generated from the printing of the second plurality of Vernier patterns over the first plurality of Vernier patterns, a distance of separation along the print media propagation path of each of the plurality of print head tiles of the second print head cartridge from corresponding print head tiles of the reference print head cartridge.   
     
     
         2 . The method of  claim 1 , further comprising the step of:
 compensating for any misalignment indicated by the determined distance of separation.   
     
     
         3 . The method of  claim 2 , which comprises physically compensating by adjusting a position of at least one print head cartridge; and   
     
     
         4 . The method of  claim 2 , which comprises digitally compensating by vertically shifting dot data sent to at least one print head cartridge. 
     
     
         5 . The method of  claim 4 , wherein an amount of compensation required is stored in a memory of a print head controller. 
     
     
         6 . The method of  claim 1 , wherein the method is performed after replacing one or more of the print head cartridges.