Duplex Web Printing Apparatus Elongation Correction
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Solution Overview
Problem
Conventional printing apparatuses fail to address elongation or contraction in the transport direction of printing paper, leading to white streaks and reduced print quality, especially when printing long web paper, as they do not accurately correct back surface image data based on elasticity information.
Innovation Solution
A printing apparatus that includes a front surface print head, a back surface image data corrector, a detector, and a back surface print head, which corrects back surface image data based on elasticity information to account for elongation or contraction in the transport direction, ensuring accurate alignment and preventing white streaks by adjusting image size and page intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If back surface printing is done with the same page length as front surface printing, then printing process is simple, but white streaks occur due to paper elongation in transport direction
Solution Approach 1:
The system performs preliminary action by detecting the cue mark printed on the front surface before back surface printing, measuring the actual page length including elongation, and using this measurement to correct the back surface image data. This preliminary detection and correction prevents white streaks by accounting for paper elongation before the back surface printing occurs.
Solution Approach 2:
The system implements feedback by detecting the cue mark position on the front surface, measuring the actual page length, and using this measured information to adjust and correct the back surface image data. The detected elongation information is fed back into the image processing system to ensure accurate back surface printing that matches the actual physical dimensions of the printed paper.
2Productivity
If web paper is transported under tension, then transportation is efficient, but paper elongates in transport direction causing misalignment
Solution Approach 1:
The system replaces mechanical measurement methods with an optical detection system. Instead of using mechanical sensors to measure paper elongation, the system uses an optical detector to read the cue mark position on the front surface, thereby determining the actual page length and elongation amount. This optical substitution enables precise measurement without adding mechanical complexity to the transportation system.
Solution Approach 2:
The system changes the parameter of image data by correcting the back surface image dimensions based on the detected page length. When elongation is detected, the back surface image data is scaled and adjusted to match the actual physical dimensions. This parameter correction ensures that the printed images align properly despite the paper elongation that occurred during tensioned transportation.
3Ease of operation
If conventional sensors are used to detect page length, then detection is simple, but elongated images are cut halfway causing white streaks
Solution Approach 1:
The system uses the cue mark printed on the front surface as a reference copy to determine the actual page length. By detecting the position of this known reference mark, the system accurately determines how much the paper has elongated and uses this information to adjust the back surface image data accordingly, preventing incomplete printing.
Data Source
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AI summary
A printing apparatus for printing on a front surface of a printing medium, and thereafter printing on a back surface of the printing medium. The apparatus includes the following elements: a front surface print head for printing a cue mark, and printing a front surface image based on front surface image data with reference to the cue mark; a back surface image data corrector for creating corrected back surface image data based on elasticity information in a transport direction after printing of the front surface image; a detector for detecting the cue mark; and a back surface print head for printing the corrected back surface image data on the back surface of the printing medium with reference to the cue mark detected by the detector.