Bidirectional Inkjet Printing Dot Pattern Shift for Hue Uniformity
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Solution Overview
Problem
In serial inkjet printing, print misalignment between nozzle rows leads to hue and density unevenness, particularly in bidirectional multipass printing, where the stability of the dot pattern formed by multiple nozzle rows is compromised.
Innovation Solution
A printing method involving a first and second print element row, where the second row is shifted relative to the first by a distance corresponding to twice the resolution, with specific dot pattern arrangements in forward and backward scans to maintain uniformity and correct misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple nozzle rows are used to print at higher resolution, then printing resolution is improved, but hue unevenness and density unevenness occur due to print misalignment between nozzle rows
Solution Approach 1:
The patent applies asymmetry by intentionally designing the second nozzle row to be shifted relative to the first nozzle row by a distance corresponding to twice the resolution. This asymmetric arrangement ensures that even when print misalignment occurs, the dot patterns from both rows combine to maintain uniform hue and density, preventing the unevenness that would result from symmetric alignment.
Solution Approach 2:
The patent addresses misalignment issues by introducing a dimensional shift in the arrangement of the second nozzle row relative to the first. By shifting the nozzle row position by twice the resolution distance, the patent creates a multi-dimensional dot pattern arrangement that compensates for alignment errors and maintains printing quality.
2Productivity
If bidirectional multipass printing is performed, then printing speed is improved, but density unevenness occurs due to misalignment between forward and backward scans
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-arranging the dot patterns for both forward and backward scans. The dot groups are positioned at specific intervals with predetermined shift amounts, so that when misalignment occurs during bidirectional printing, the patterns are already configured to compensate and maintain uniform density.
Solution Approach 2:
The patent changes the parameters of dot pattern arrangement by setting specific intervals and shift amounts for dot groups in different scan directions. By adjusting these parameters (interval distances and shift amounts), the patent ensures that density uniformity is maintained despite misalignment in bidirectional multipass printing.
Data Source
AI summary
In a printing apparatus configured to print an image by bidirectional multipass printing while using multiple print element rows that apply color material of the same color, a high-quality image suppressed in hue unevenness and density unevenness is printed. To this end, the printing apparatus forms first and second dot patterns on a print medium in an overlapping manner. In the first dot pattern, dot arrays in which first dot groups are arranged at an interval B1 are arranged in a nozzle arrangement direction while being shifted from each other by C1 in a scanning direction of a print head. In the second dot pattern, dot arrays in which the first dot groups are arranged at the interval B1 are arranged in a nozzle arrangement direction while being shifted from each other by C2 in the scanning direction of the print head. Here, values of C1 and C2 are different.