Method of generating halftone print data that accommodates overlapping printhead chips
View Patent ↗A method of generating halftone print data for overlapping end portions of a pair of consecutive printhead chips in an array of two or more printhead chips where an end portion of a first printhead chip overlaps an end portion of a second printhead chip, each printhead chip including a plurality of ink ejection nozzles, includes generating continuous tone print data for the array of printhead chips, The continuous tone print data for said overlapping end portions is interpolated according to an algorithm such that ink ejection nozzle utilization decreases in each said overlapping end portion towards respective ends of the printhead chips.
1. A method of generating halftone print data for overlapping end portions of a pair of consecutive printhead segments in an array of two or more printhead segments where an end portion of a first printhead segment overlaps an end portion of a second printhead segment, each printhead segment including a plurality of ink ejection nozzles, the method comprising the steps of:
generating continuous tone print data for the array of printhead segments;
generating an initial dither matrix to be applied to said continuous tone print data;
generating an overlap signal representing an extent of overlap of the end portions; and,
interpolating the continuous tone print data for said overlapping end portions according to an algorithm such that ink ejection nozzle utilization decreases in each said overlapping end portion towards respective ends of the printhead segments.
2. A method as claimed in claim 1 , which includes the step of generating an initial dither matrix to be applied to said continuous tone print data and the step of generating an overlap signal representing an extent of overlap of the end portions.
3. A method as claimed in claim 2 , in which the step of applying the overlap data to the initial dither matrix includes the step of receiving, as an input to an adder, a current dither value representing the dither matrix and the overlap signal.
4. A method as claimed in claim 2 , in which the step of applying the output value to the continuous tone print data includes the step of receiving, as an input to a comparator, a signal representing the output value and a signal representing the continuous tone print data.
5. A method as claimed in claim 2 , in which the step of applying the output value to the continuous tone print data includes the step of receiving, as an input to a subtractor, a signal representing the output value and a signal representing the continuous tone print data.
6. A method as claimed in claim 1 , in which the step of generating the overlap signal includes the step of measuring a temperature of the printhead segments to determine an extent of thermal expansion or contraction of the printhead segment.
7. A method as claimed in claim 1 , in which the step of generating the overlap signal includes the step of determining relative displacement of the printhead segments using fiducial strips positioned on the printhead segments and an interferometric technique.