Web Printing Width Compensation for Double-Sided Drying
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Solution Overview
Problem
The width of a web can expand or contract differently during each drying operation, causing the images on the front and back surfaces to deviate in their ratio to the web's width, making it difficult to suppress the difference between the images on both surfaces.
Innovation Solution
A web printing apparatus and method that includes first and second printing parts, drying parts, and image pickup parts to acquire test patterns on both surfaces, adjusting the image widths and positions based on obtained ratios to ensure alignment and consistency across both surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If double-sided printing with drying operations is performed on a web, then images are printed on both surfaces, but the web width expands or contracts differently in each drying operation causing image ratio deviation between front and back surfaces
Solution Approach 1:
The patent applies preliminary action by printing test patterns on the web before actual production printing, performing drying operations on these test patterns first, and measuring the resulting width changes. This preliminary measurement data is then used to calculate compensation values that are applied to the actual printing process, thereby preemptively correcting for the web expansion/contraction that occurs during production drying.
Solution Approach 2:
The patent implements feedback by using image pickup parts to measure the actual width of the web after drying operations on test patterns, comparing this measured width to the original web width, and using this feedback information to calculate and apply compensation values to the printing process. This closed-loop feedback system continuously adjusts the printing parameters based on actual web behavior.
2Productivity
If the web is dried after printing on front surface and then dried again after printing on back surface, then both surfaces are processed, but the ratio of image width to web width differs between the two drying operations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the printing parameters (such as image width, positioning, and scaling) based on the measured web width changes from the first drying operation. The control part calculates compensation values that modify the printing parameters for the second surface to account for the web dimensional changes, thereby maintaining consistent image-to-web width ratios despite the sequential drying operations.
3Manufacturing precision
If test patterns are printed and measured to calculate compensation values, then image alignment can be corrected, but additional printing and measurement steps are required
Solution Approach 1:
The patent applies partial action by printing test patterns that contain only the essential elements needed for measurement (such as reference marks and test images) rather than complete production images. This partial printing approach provides sufficient data for calculating web expansion/contraction while minimizing the additional material and time required compared to printing full production images.
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
The method effectively suppresses the difference in the ratio of image widths between the front and back surfaces by adjusting the image sizes and positions, ensuring precise alignment and overlap of images on both sides of the web.
Implementation Method 1
a drying part that dries the web by heating the web on which the printed image is printed
Implementation Method 2
the width of the web is expanded or contracted through two drying operations
Data Source
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AI summary
The ratios (Wp1/Wm1, Wp2/Wm2) of the pattern widths Wp1, Wp2 to the paper widths Wm 1, Wm2 are obtained, respectively, after the first drying and after the second drying (Step S109). Then, in accordance with these ratios, a range (in other words, the width) in which the back print image G2 is to be printed is adjusted in the width direction Aw (Step S204). As a result, when the double-sided printing is performed on the continuous form paper M by performing drying every time when the image is printed on each of the surfaces Ma, Mb of the continuous form paper M, it is possible to suppress the difference in the ratios of the widths of the images G1, G2 to the width of the continuous form paper M between the surfaces Ma and Mb of the continuous form paper M.