Inkjet Printhead Position Deviation Correction
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Solution Overview
Problem
Inkjet printing apparatuses with full-line printheads face challenges in maintaining printing quality due to errors in printhead attachment positions, leading to ink landing position deviations on the print medium, especially when the luminance difference between ink and background is small, which degrades pattern detection accuracy.
Innovation Solution
The apparatus includes a reading unit, shading data creation units, and correction units to accurately detect and correct signal values in images of test patterns, allowing for precise calculation of printhead position deviations, even with minimal luminance differences between ink and background.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If template matching is used for pattern detection, then the printing position adjustment can be performed, but the detection accuracy degrades when the luminance difference between ink and background is small
Solution Approach 1:
The patent applies preliminary action by performing shading correction on the read image before pattern detection. The system reads a white reference patch, calculates shading data representing luminance variations across the reading area, and uses this data to correct the test pattern image. This preliminary correction compensates for luminance differences caused by print medium characteristics, enabling accurate pattern detection even when ink luminance closely matches the background.
2Productivity
If full-line printhead is used to print entire surface, then printing efficiency is improved, but attachment position errors cause ink landing position deviation
Solution Approach 1:
The patent implements feedback by detecting the actual positions of test patterns printed by the printhead and using this information to calculate and correct attachment position deviations. The system reads the test pattern image, detects pattern positions, calculates deviation amounts from expected positions, and applies corrections to subsequent printing operations. This closed-loop feedback mechanism maintains manufacturing precision while preserving the high productivity of full-line printhead printing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enhances the accuracy of printing position adjustments, ensuring improved printing quality by effectively detecting patterns and correcting deviations, even on media with small luminance differences between ink and background.
Implementation Method 1
a reading unit configured to read an image
Data Source
AI summary
An inkjet printing apparatus obtains data of a second image by correcting, using shading data, signal values of pixels in an image of a read test pattern so that a signal value of a pixel lower than a value of the shading data becomes a value corresponding to a lowest luminance; specifies an area of a pattern of each of the plurality of inks in the image of the test pattern using the data of a first image and the data of the second image; and calculates a position deviation amount of a printhead based on a position of the pattern of the specified area.