Inkjet Printing on Curved Container Surfaces
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Solution Overview
Problem
Inkjet printing on curved surfaces, such as PET bottles and glass bottles, faces challenges due to imprecise printing caused by curved container surfaces and the use of line-type print heads, leading to deviations in the printed image, especially with uneven contours and tilted nozzle rows.
Innovation Solution
The method involves moving the curved surface relative to the print head with aligned or obliquely positioned nozzles, adjusting ink droplet ejection times based on printing pitch, and compensating for errors by shifting pixels on the image template, allowing for precise printing on three-dimensional surfaces without individual nozzle control adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If line-type print heads are used for fast throughput on curved container surfaces, then productivity is improved, but manufacturing precision deteriorates due to imprecise printing and deviations from the template
Solution Approach 1:
The patent applies dynamics by making the print head movable relative to the container surface, allowing adaptive positioning and orientation of multiple nozzle rows to match the curved surface geometry. The print head can adjust its position and angle dynamically during printing, enabling precise ink droplet placement on uneven contours while maintaining high throughput speeds.
Solution Approach 2:
The patent segments the printing system into multiple independent nozzle rows arranged at different positions and orientations. Each nozzle row can be independently controlled with specific ejection timings, allowing the system to address different sections of the curved surface with optimized printing parameters, thereby achieving both speed and precision.
2Productivity
If multiple rows of nozzles are used to cover the surface, then productivity is improved, but manufacturing precision deteriorates due to different pressure distances and offset rows causing errors
Solution Approach 1:
The patent implements local quality by assigning different ejection timings to different nozzle rows based on their specific positions, orientations, and distances from the container surface. Each nozzle row is optimized locally for its position on the curved surface, compensating for variations in pressure distance and offset, thereby maintaining uniform print accuracy across the entire multi-row system.
3Manufacturing precision
If ejection timings are individually adjusted for each nozzle, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the control of multiple nozzle rows into a unified control system that calculates and manages ejection timings for all rows simultaneously. By integrating the control logic and using a coordinated timing mechanism, the system achieves precise individual nozzle control without requiring separate complex control circuits for each nozzle, thereby reducing overall device complexity while maintaining manufacturing precision.
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 approach reduces errors and maintains homogeneous print quality across the surface by compensating for relative movement, surface irregularities, and nozzle geometry, ensuring accurate image reproduction on containers with dimensional tolerances.
Implementation Method 1
different flight time of the ink droplets, by irregular surfaces and/or a design-related offset and oblique impact of ink jets with respect to a given printing position
Data Source
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Figure 5~6
AI summary
The method involves moving a print surface relative to rows of nozzle (4) which are aligned transversely or diagonally to movement direction (5). Ink drops (9) are discharged to ejection points for the individual ink droplets as a function of the respective printing gap (6) of the ejecting nozzle (4a) to be set. The nozzles are provided lying one behind the other in the movement direction, and also the ejection timing can be set between the rows of nozzles as a function of a distance (X). An independent claim is included for a device for ink jet printing on curved surfaces of containers such as polyethylene terephthalate (PET) bottles or glass bottles.