Printhead Slant Adjustment for Inkjet Print Shift
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Solution Overview
Problem
Conventional inkjet printing apparatuses fail to adequately adjust for print position shifts due to both slant and upstream-downstream differences in nozzle distance, leading to noticeable ruled line shifts and degraded image quality, particularly in high-speed printing.
Innovation Solution
A printing apparatus and method that includes a printhead with a nozzle array, a conveyance unit, a carriage, and adjustment mechanisms to print patterns at different speeds, allowing for the calculation and adjustment of slant and distance-related print shifts, thereby reducing position errors and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional adjustment methods are used that only consider slant, then the adjustment process is simple, but the print position accuracy is insufficient due to unaccounted upstream-downstream distance differences
Solution Approach 1:
The adjustment process is segmented into two independent components: slant adjustment and upstream-downstream distance adjustment. By separating these adjustment dimensions, the system can address each source of print position shift independently, improving overall accuracy without creating an unmanageably complex unified adjustment mechanism.
Solution Approach 2:
The invention adds a new adjustment dimension (upstream-downstream distance) to the existing slant adjustment dimension. This transforms the adjustment process from a single-dimensional approach to a two-dimensional approach, enabling comprehensive correction of print position shifts in multiple directions simultaneously.
2Productivity
If high-speed printing is performed to increase productivity, then printing speed improves, but print position shift errors become more noticeable due to amplified slant and distance effects
Solution Approach 1:
The system performs preliminary adjustment of both slant and upstream-downstream distances before high-speed printing begins. By pre-calculating and pre-adjusting the print head positioning parameters based on measured deviations, the system eliminates position shift errors that would otherwise be amplified at higher printing speeds, enabling both high productivity and high precision.
Solution Approach 2:
The system uses feedback from printed test patterns to measure actual print position shifts caused by slant and upstream-downstream distance variations. This measured feedback is then used to calculate correction values that are applied to adjust the print head positioning, creating a closed-loop control system that maintains accuracy even during high-speed operation.
Data Source
AI summary
In an embodiment of the present invention, even though there is a print shift due to a gap between a nozzle in an upstream side and a nozzle in a downstream side of a printhead, a printing apparatus capable of precisely adjusting a slant of a printhead with respect to a conveyance direction in a nozzle surface of the printhead is provided. According to the embodiment, two adjustment patterns are printed at two different carriage speeds, respectively, and a print shift due to a slant of the nozzle surface of the printhead with respect to a conveyance direction of a print medium is adjusted based on these two print results.