Ink jet printing systems

Abstract

We describe a method of generating data for driving an ink jet print head having a plurality of nozzles to print a portion of an image comprising a plurality of pixels, the method comprising: storing nozzle position data defining spatial positions of said nozzles with respect to said print head in terms of pixel offsets from a reference position on said print head; reading image data for said image, said image data comprising data for said plurality of pixels; inputting head position data defining a position for said print head; and processing said image data using said head position data and said nozzle position data to determine nozzle firing data for controlling said print head to deposit ink at said spatial positions of said nozzles with respect said head position in accordance with said image data.

1 . A method of printing using an ink jet print head having a plurality of nozzles to print at least a portion of an image comprising a plurality of pixels, the method comprising:
 reading nozzle position data from said print head prior to said printing, said nozzle position data defining spatial positions of said nozzles in terms of pixel offsets from a reference position on said print head; and afterwards printing said portion of said image by:   reading image data for said image, said image data comprising data for said plurality of pixels;   inputting head position data defining a position for said print head;   processing said pixel image data using said head position data and said nozzle position data to determine nozzle firing data for controlling said print head to deposit ink at said spatial positions of said nozzles with respect said head position in accordance with said image data, said processing including associating said nozzle position data in terms of pixel offsets with said pixels of said image; and   driving said print head using said determined nozzle firing data.   
     
     
         2 . A method as claimed in  claim 1 , further comprising storing said nozzle position data in said print head prior to said printing. 
     
     
         3 . A method of printing using a multiple head ink jet printer, the method comprising generating nozzle firing data for driving each head according to the method of  claim 1  using a common portion of said image data. 
     
     
         4 . A method as claimed  claim 1  further comprising, during printing with said ink jet print head, measuring one or both of a substrate rotation and substrate offset and correcting for one or both of said substrate rotation and substrate offset. 
     
     
         5 . A method of printing as claimed in  claim 1  further comprising generating said nozzle position data for said print head, said nozzle position data defining spatial positions of said nozzles in terms of pixel offsets from a reference position on said print head; and wherein said pixel offsets are defined with reference to a pixel spacing corresponding to a defined spatial resolution of an image to be printed by said print head. 
     
     
         6 . A carrier carrying processor control code to, when running, implement the method of  claim 1 . 
     
     
         7 . An image processing engine for generating data for driving an ink jet head having a plurality of nozzles to print a portion of an image comprising a plurality of pixels, said image processing engine being configured to:
 read nozzle position data from said print head prior to said printing, said nozzle position data defining spatial positions of said nozzles in terms of pixel offsets from a reference position on said print head;   read image data for said image, said image data comprising data for said plurality of pixels;   input head position data defining a position for said print head;   process said pixel image data using said head position data and said nozzle position data to determine nozzle firing data for controlling said print head to deposit ink at said spatial positions of said nozzles with respect said head position in accordance with said image data, said processing including associating said nozzle position data in terms of pixel offsets with said pixels of said image; and   drive said print head using said determined nozzle firing data.   
     
     
         8 . An ink jet printing system including the image processing engine of  claim 7 . 
     
     
         9 . A print head for use in the ink jet printing system of  claim 8 , comprising a data store configured to store nozzle position data for said print head, said nozzle position data defining spatial positions of said nozzles in terms of pixel offsets from a reference position on said print head. 
     
     
         10 . A print head as claimed in  claim 9 , wherein said pixel offsets are defined with reference to a pixel spacing corresponding to a defined spatial resolution of an image to be printed by said print head. 
     
     
         11 . A method of generating data for driving an ink jet print head having a plurality of nozzles to print a portion of an image comprising a plurality of pixels, the method comprising:
 reading nozzle position data from said print head defining spatial positions of said nozzles in terms of pixel offsets from a reference position on said print head;   reading image data for said image, said image data comprising data for said plurality of pixels;   inputting head position data defining a position for said print head;   reading said nozzle position data from said print head; and   processing said image data using said head position data and said nozzle position data to determine nozzle firing data for controlling said print head to deposit ink at said spatial positions of said nozzles with respect to said head position in accordance with said image data;   
     
     
         12 . A method as claimed in  claim 11 , further comprising storing said nozzle position data in said print head. 
     
     
         13 . A method as claimed in  claim 11 , further comprising storing said image data in pixel order in an image memory space using a memory location for each pixel, and wherein said processing comprises using said nozzle position data as a pointer to said image memory space storing said image data to read pixel data for each said nozzle from said memory space.