Overlapping Sheet Conveyance for High-Speed Inkjet Printing
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Solution Overview
Problem
Printing apparatuses face challenges in increasing printing speed while preventing cockling, paper jams, and image quality degradation due to overlapping sheets during high-density inkjet printing, especially in double-sided printing.
Innovation Solution
A printing technique that controls the conveyance of sheets to overlap their leading and trailing edges, using a system with a pinch roller, conveyance roller, and MPU to manage sheet alignment and rotation speeds, ensuring precise positioning and skew correction to prevent ink spreading and sheet floating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sheets are conveyed with overlapping margins to increase printing speed, then productivity is improved, but cockling occurs due to ink moisture causing sheets to float and potentially graze the printhead
Solution Approach 1:
The system performs preliminary actions by pre-positioning the leading edge of the succeeding sheet to overlap the trailing edge of the preceding sheet before printing completes. This allows continuous printing without sheet change intervals, improving productivity while the control system monitors and manages sheet positions to prevent cockling and grazing issues
2Manufacturing precision
If high-density printing is applied to overlapping sheet areas, then image quality is improved, but sheet floating increases causing stains and paper jams
Solution Approach 1:
The control system implements feedback by detecting the position of sheet leading edges and adjusting conveyance timing accordingly. This feedback mechanism allows the system to maintain precise sheet positioning during overlapping conveyance, enabling high-density printing on overlapping areas while preventing sheet floating, stains, and paper jams through real-time position monitoring and adjustment
3Productivity
If the interval between printing sheets is shortened to increase productivity, then productivity is improved, but ink landing position shifts due to unstable distance between printhead and sheet
Solution Approach 1:
The system performs preliminary positioning of the succeeding sheet's leading edge to overlap the preceding sheet's trailing edge before the printing operation completes. This pre-positioning allows the printhead to maintain a stable distance relationship with the sheet surface throughout the printing process, enabling shortened sheet intervals and improved productivity without compromising ink landing precision
Data Source
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AI summary
A printing apparatus includes feeding means (2) for feeding a printing sheet stacked on stacking means (11), conveying means (5) for conveying the printing sheet fed by the feeding means, printing means (7) for printing the printing sheet conveyed by the conveying means, and control means for controlling the feeding means and the conveying means. When continuously printing on the first surfaces of a plurality of printing sheets, the feeding means forms an overlap state in which a trailing edge of a preceding sheet and a leading edge of a succeeding sheet overlap each other, and the conveying means conveys the printing sheets while keeping the overlap state. When performing double-sided printing on the first surface and the second surface of the printing sheet, the feeding means does not form the overlap state.