Printing Apparatus Ink Ejection Timing for Overlapping Sheets
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Solution Overview
Problem
In printing apparatuses that continuously print sheets, the overlap of sheets during printing leads to uneven ink landing times, causing image quality issues due to the varying distances between the printing unit and the sheets at overlapping and non-overlapping portions, resulting in positional deviations of the printed image.
Innovation Solution
The printing apparatus delays ink ejection timing for some ejection ports when printing at the overlapping portion compared to the non-overlapping portion, ensuring that ink lands accurately on both areas by adjusting the ink ejection timing based on the movement of the print head, thereby correcting the positional misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If sheets are conveyed to overlap during printing to improve throughput, then printing speed is improved, but image quality deteriorates due to uneven ink landing times
Solution Approach 1:
The patent applies different ink ejection timing to different spatial regions of the print medium. Specifically, the control unit determines whether each ejection port is ejecting ink onto an overlapping portion or a non-overlapping portion, and adjusts the timing accordingly. This local differentiation resolves the contradiction by allowing high-speed overlapping printing while maintaining image quality through region-specific timing correction.
Solution Approach 2:
The patent changes the temporal parameter (ink ejection timing) based on the spatial parameter (position on the sheet). The control unit adjusts the ink ejection timing for ports printing overlapping portions relative to those printing non-overlapping portions. This parameter adjustment compensates for the distance difference caused by sheet overlap, maintaining consistent ink landing timing and image quality across different sheet regions.
2Device complexity
If ink is ejected at the same timing for all ejection ports, then device complexity is reduced, but manufacturing precision deteriorates due to positional deviation
Solution Approach 1:
The control unit performs preliminary determination of whether each ejection port is targeting an overlapping or non-overlapping portion before actual ink ejection. Based on this preliminary assessment, the control unit pre-adjusts the ink ejection timing for relevant ports. This preliminary action enables precise image positioning without requiring complex real-time adjustments during the printing process.
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 solution enhances printing throughput while maintaining high image quality by ensuring precise ink placement across overlapping and non-overlapping sheet areas, preventing misalignment and improving overall print quality.
Implementation Method 1
a printing unit including an ejection port surface provided with a plurality of ejection ports for ejecting ink arrayed in a predetermined direction and configured to print a sheet by ejecting ink while moving over the sheet
Data Source
AI summary
A printing apparatus conveys preceding and following sheets to form an overlapping portion where a trailing edge of the preceding sheet and a leading edge of the following sheet overlap each other at a printing position facing an ejection port surface of a printing unit, and prints the preceding and following sheets by ejecting ink from ejection ports based on a relative movement between the printing unit and the preceding and following sheets. The printing unit delays ink ejection timing for printing the overlapping portion of a sheet located closer to the ejection port surface at a position facing the ejection ports from ink ejection timing for printing a non-overlapping portion where the preceding sheet and the following sheet do not overlap each other in one of the preceding sheet and the following sheet.