Print Position Adjustment Using Reference Patches in Wide-Format Inkjet
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Solution Overview
Problem
In wide-format inkjet printing with full-line printheads, existing print position adjustment methods using scanner devices with multiple image sensors suffer from reduced accuracy due to the need to estimate reference line positions from scan images under different conditions, leading to inaccuracies in print position correction.
Innovation Solution
A printing apparatus that scans a test chart using a plurality of optical sensors, calculates the rate of extension or contraction between scan images, and adjusts print positions based on this calculation to improve accuracy in print position adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a scanner device using a combination of a plurality of image sensors is used to scan large test charts, then the scan size coverage is improved, but the measurement precision of patch positions deteriorates due to estimation errors from different scan conditions
Solution Approach 1:
The patent introduces a reference patch as an intermediary element that is scanned under the same conditions as the target patches. This reference patch serves as a mediator to establish a common reference frame between multiple scan images, enabling accurate position calculation without requiring estimation from differently scanned images. The reference line is drawn based on positions of reference patches detected in the same scan conditions, thus resolving the measurement precision issue.
2Device complexity
If print position adjustment is performed based on estimated positions of printing element substrates from divided scan images, then the device complexity is reduced, but the manufacturing precision of print positions deteriorates
Solution Approach 1:
The patent segments the scan device into multiple image sensors that work together, with each sensor capturing a portion of the test chart. Instead of requiring a single complex high-resolution sensor, the system divides the scanning task among multiple sensors. The reference patch technique enables these segmented images to be accurately combined by providing a common reference frame, thus achieving high print position accuracy without requiring overly complex individual sensor components.
3Area of stationary object
If the printhead size is increased to match wide-format printing medium, then the printing width coverage is improved, but the measurement precision of reference line position deteriorates due to larger test chart size
Solution Approach 1:
The patent applies local quality by placing reference patches at specific strategic locations (near end portions of the printhead) rather than requiring precise measurement across the entire large printhead. This localized approach concentrates measurement resources at critical positions, enabling accurate reference line establishment even when the overall printhead and test chart size are large. The reference line is drawn based on these locally measured reference patch positions.
Data Source
AI summary
The technique of the present disclosure adjusts print positions properly even if a test chart printed on a printing medium is scanned in a divided manner. A print controller converts the representative positions of patches for printing element substrates on first and second scan images into position difference information in relation to an origin located in overlap regions of the scan images. Based on position difference information for the second scan image and an extension/contraction rate, the print controller converts the position difference information for the second scan image to bring the extension/contraction rate to 1, which means making a distance between particular patterns on the second scan image equal to a distance between the same particular patterns on the first scan image. On the first scan image, the print controller calculates a tilt of a reference line used to calculate amounts of positional shift between the printing element substrates.