Drop-on-demand Coating Contour Alignment
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Solution Overview
Problem
Current coating technologies face challenges in achieving high-resolution, step-free coatings on two- or three-dimensional surfaces with complex curvatures, leading to visible step formation and artifacts, especially when using multi-channel drop-on-demand heads with rigid nozzle arrangements.
Innovation Solution
The method involves dividing the coating area into multiple tracks with individually offset coating points, allowing for asynchronous drop release and precise alignment with contours, enabling the use of curved paths and varying point distances to minimize step formation and achieve seamless edge reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large number of nozzles are used in a coating head to achieve high coating rate, then productivity is improved, but manufacturing precision deteriorates due to rigid nozzle arrangements causing visible step formation at edges
Solution Approach 1:
The patent implements dynamic control of droplet ejection timing for each nozzle individually. Instead of synchronized droplet release from all nozzles, the system calculates and applies specific time offsets to each nozzle's droplet ejection based on its position and the surface geometry, enabling seamless coating of 3D surfaces while maintaining high productivity with multiple nozzles
Solution Approach 2:
The patent applies local quality by assigning individual droplet release time parameters to each nozzle based on its specific position and function. Nozzles at different locations and orientations receive customized timing parameters to compensate for varying distances and angles relative to the 3D surface, ensuring uniform coating quality across the entire coating area
2Device complexity
If orthogonal raster technology is used with rigid nozzle rows, then device complexity is reduced, but manufacturing precision deteriorates due to step formation at critical angles
Solution Approach 1:
The system transforms the static orthogonal raster pattern into a dynamic droplet placement system. Each droplet's position and release time are individually calculated based on the desired contour geometry, allowing the rigid physical nozzle arrangement to produce flexible, artifact-free contours on 3D surfaces through temporal and spatial modulation of droplet ejection
Solution Approach 2:
The system performs preliminary calculation of droplet release times and positions before actual coating. The control system pre-computes the exact timing and positioning parameters for each nozzle based on the surface geometry and desired coating pattern, enabling precise contour reproduction without modifying the physical nozzle arrangement
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 results in improved edge quality, reduced artifacts, and a more uniform coating with fewer defects, enabling high-resolution coatings on complex surfaces without visible step formation, even with low-resolution printing techniques.
Implementation Method 1
coating material is ejected through several or a multitude of nozzles as discrete droplets
Data Source
Figure 1~3b
Figure 4~6
Figure 7a~8
AI summary
The invention relates to a coating of a coating medium, produced by means of a multichannel printhead (5) in a coating region (3) on a two- or three-dimensional surface (2) of an object (1), which is built up from coating points (8) along tracks (7) of one or more coating paths (6), characterized in that the starting coating point (HP) of at least one track (7) is aligned with a starting contour (AK) and an end coating point (EP) of the track (7) is aligned with an end contour (EK).