Contour-Exact Digital Printing of Flat Workpieces
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Solution Overview
Problem
Existing devices for printing decorative images on flat workpieces, particularly those mimicking grained wood surfaces, face challenges in maintaining contour accuracy and preventing inkjet overprinting beyond the workpiece edges, leading to overspray and inefficient ink consumption due to tolerance fluctuations in workpiece dimensions.
Innovation Solution
Incorporating a measuring station with contour sensors, such as light band sensors, ultrasonic sensors, or digital cameras, to determine workpiece contours and communicate this data to the print controller, which then prevents printing beyond the workpiece edges by blocking inking elements that would apply pixels outside the contour, ensuring precise edge application without recalculating image data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the decorative image is printed slightly larger than the workpiece contour to ensure complete coverage, then the image quality and visual impression are improved, but inkjet overprinting occurs beyond the workpiece edges causing overspray and increased ink consumption
Solution Approach 1:
The system performs preliminary measurement of the workpiece contour using contour sensors before the printing process. The measured contour data is stored and used to pre-calculate which image pixels should be printed, allowing the system to prepare the exact print mask in advance and avoid overprinting beyond the workpiece edges.
Solution Approach 2:
The system uses contour sensors to continuously monitor the workpiece position and contour during the printing process. The measured contour data is fed back to the print controller, which adjusts the printing process in real-time to ensure that ink is applied only within the actual workpiece boundaries, preventing overspray and reducing ink consumption.
2Manufacturing precision
If masking is applied to protect the workpiece edge from overprinting, then the visual impression and edge quality are improved, but the device complexity and processing time increase
Solution Approach 1:
The system replaces the mechanical masking approach with a digital control solution. Instead of using physical masks to prevent overprinting, the system uses contour sensors to detect the workpiece edges and digitally controls the inkjet nozzles to stop printing exactly at the measured contour, eliminating the need for masking components and reducing device complexity.
Solution Approach 2:
The system changes the control parameter from fixed print boundaries to dynamic contour-based boundaries. By measuring the actual workpiece contour and using this data to control the printing process, the system adapts the print parameters to match the actual workpiece geometry, achieving precise edge quality without masking.
3Device complexity
If the printing system uses fixed print boundaries to simplify control, then the device complexity is reduced, but manufacturing precision deteriorates due to tolerance fluctuations in workpiece dimensions
Solution Approach 1:
The system transitions from static fixed print boundaries to dynamic contour-adaptive boundaries. The contour sensors continuously measure the actual workpiece dimensions and position, and the print controller dynamically adjusts the print boundaries based on these measurements, allowing the system to handle tolerance fluctuations while maintaining simple control logic.
Solution Approach 2:
The system creates a universal printing solution that can handle various workpiece shapes, sizes, and tolerance variations using the same contour measurement and adaptive control approach. The measured contour data serves as a universal reference for all printing operations, eliminating the need for different control strategies for different workpiece variations.
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
Enables borderless printing with precise edges on workpieces of varying shapes and sizes, reducing overspray and ink consumption while maintaining high image quality, even at small edge resolutions perceivable by the human eye.
Implementation Method 1
a point measurement, for example using a light barrier, is sufficient to determine the contour coordinates of the workpiece
Implementation Method 2
Instead of such a simple light barrier, however, contour sensors such as light band sensors, ultrasonic sensors or digital cameras are preferably used
Implementation Method 3
Instead of such a simple light barrier, however, contour sensors such as light band sensors, ultrasonic sensors or digital cameras are preferably used
Implementation Method 4
Instead of such a simple light barrier, however, contour sensors such as light band sensors, ultrasonic sensors or digital cameras are preferably used
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The device has a printing station (3) with digitally controlled color application elements. The printing station and a measurement station (4) are connected upstream, which with the contour sensors takes the outline data of the workpiece (1) and works together with the printing control (12) so that the pixels lying outside of the contour of the workpiece of the decoration picture are not printed, while the remaining pixels remain uninfluenced. The transport equipment (2) for transporting the workpieces and a printing control for printing digital decoration graphic data is provided.