Dithering unit for multi-segment printhead

Abstract

A dithering unit for a multi-segment printhead having a plurality of printhead segments that are positioned in a printhead to span a print area so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area, the dithering unit being configured to communicate with an interface to receive image data from the interface and a memory device to receive data relating to the characteristics of the multi-segment printhead, the dithering unit being configured to generate a set of dither matrices for each printhead segment so that each set has at least a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area, to generate lead-in/lead-out dither matrices for each common print area based on characteristics of the printhead segments of each common print area, to generate a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area and to interpolate the lead-in/lead-out dither matrices with the variable probability value to generate interpolated lead-in/lead-out dither matrices.

1 . A dithering unit for a multi-segment printhead having a plurality of printhead segments that are positioned in a printhead to span a print area so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area, the dithering unit being configured to communicate with an interface to receive image data from the interface and a memory device to receive data relating to the characteristics of the multi-segment printhead, the dithering unit being configured to generate a set of dither matrices for each printhead segment so that each set has at least a lead-in dither matrix associated with the lead-in area and a lead-out dither matrix associated with the lead-out area, to generate lead-in/lead-out dither matrices for each common print area based on characteristics of the printhead segments of each common print area, to generate a variable probability value that is dependent on a scalar value that corresponds to a position along a line spanning each common print area and to interpolate the lead-in/lead-out dither matrices with the variable probability value to generate interpolated lead-in/lead-out dither matrices.  
   
   
       2 . A dithering unit according to  claim 1  further configured to generate a dither matrix for each non-overlapping area of the printhead segments.  
   
   
       3 . An inkjet printer that comprises 
 a printhead that includes a number of printhead segments that span a print area, the printhead segments being positioned so that portions of consecutive printhead segments overlap in common print areas, with each printhead segment defining a lead-in area in one common print area and a lead-out area in a consecutive common print area;    an interface which is configured to receive image data;    a memory device that is capable of storing data relating to characteristics of the printhead;    a dithering unit according to claim;    a compositor that communicates with the dithering unit to receive data representing the interpolated lead-in/lead-out dither matrices and to composite the data into print data; and    a printhead interface that communicates with the compositor to receive the print data, the printhead interface being in communication with the printhead to provide the printhead with the print data.    
   
   
       4 . A printer as claimed in  claim 3  wherein each common print area defined by consecutive printhead segments has a width of at least 1 mm.