Print Control Device for Overlapping Nozzle Density Correction
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Solution Overview
Problem
Ink jet printers with overlapping nozzle arrays face issues of density irregularity due to nozzle alignment errors, leading to image quality deterioration, as density correction values are shifted and not suitable for adjacent nozzles, making it difficult to suppress density irregularities effectively.
Innovation Solution
A print control device that prints test patterns and rules using overlapping nozzle arrays, computes density correction values based on image data, and associates nozzle positions with raster lines to apply appropriate corrections, ensuring no conspicuous shift of dot arrays and minimizing color shift or mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If density correction values are acquired for each dot array using conventional methods, then density irregularity can be suppressed in single nozzle array printing, but density irregularity cannot be sufficiently suppressed in overlapping nozzle array printing due to position shifts
Solution Approach 1:
The patent divides the correction process into two independent stages: (1) acquiring density correction values based on test patterns printed by overlapping nozzles, and (2) separately specifying nozzle positions using rules printed by individual nozzle arrays. This segmentation allows each stage to optimize for its specific function without interference from position shifts.
Solution Approach 2:
The patent introduces test patterns and rules as intermediary elements. Test patterns serve as mediators to acquire density correction values that are independent of nozzle position alignment, while rules act as mediators to specify actual nozzle positions. This intermediary approach decouples the density measurement process from the position alignment requirement.
2Productivity
If multiple nozzle arrays are disposed in overlapping arrangement to increase printing region, then printing productivity is improved, but alignment errors cause dot array shifts and image quality deterioration
Solution Approach 1:
The patent applies different processing methods to different parts of the printing system: test patterns are processed to acquire density correction values without position dependency, while rules are processed to specify nozzle positions with high accuracy. This local quality approach allows each part to be optimized for its specific function.
Solution Approach 2:
The patent performs preliminary actions by first printing test patterns and rules to acquire density correction values and specify nozzle positions before actual image printing. This preliminary characterization of the printing system allows subsequent printing to compensate for alignment errors and maintain high precision.
3Manufacturing precision
If density correction is performed using test patterns printed by overlapping nozzles, then density irregularity suppression is improved, but position shifts between nozzles cause incorrect correction value application
Solution Approach 1:
The patent segments the information acquisition process into two independent measurements: density information from test patterns and position information from rules. This segmentation prevents position shifts from corrupting the density measurement, as each measurement type is independently acquired and processed.
Solution Approach 2:
The patent uses rules as a copying mechanism to transfer position information from the physical nozzle arrangement to digital data. By printing rules with known geometries and analyzing their positions in the scanned image, the system creates an accurate digital copy of the actual nozzle positions, which can then be used to correctly apply density correction values.
Data Source
AI summary
A plurality of test patterns that are disposed in a predetermined direction are printed using dot arrays formed along an intersecting direction interesting with the predetermined direction using nozzles included in an overlapping portion of a first nozzle array and a second nozzle array, a plurality of rules lined in the predetermined direction are printed so as to be adjacent to the test patterns using nozzles included in the first nozzle array and the second nozzle array, density correction values are computed according to density of each of raster lines of the test patterns, and the positions of nozzles specified from the positions of rules are associated with the positions of the raster lines for which density correction values are computed.