Rotary Screen Printing Raster Layout to Prevent Moire Defects
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Solution Overview
Problem
Rotary screen printing of textile materials is prone to Moire defects due to interference between the pattern of screen openings and the imaged lacquer layer, which affects the quality of the printed image, and the existing technologies have not effectively addressed the need for Moire effects, which are not effectively addressed the need for high print definition and edge sharpness.
Innovation Solution
The use of a printing screen with a parallelogram pattern of screen openings, preferably orthogonal, and an imaged lacquer layer with open areas arranged in an orthogonal raster, reducing the likelihood of Moire defects by optimizing the alignment and symmetry between the screen and lacquer layer patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a regular pattern of screen openings (e.g., hexagonal) is used in rotary screen printing, then the printing process can be efficiently carried out, but Moire defects occur due to interference between the screen pattern and the imaged lacquer layer
Solution Approach 1:
The patent applies asymmetry by using a screen opening pattern with 4-fold rotational symmetry (parallelogram/rhombus grid) instead of the conventional 6-fold symmetry (hexagonal pattern). This asymmetric change in symmetry order breaks the periodic interference that causes Moire defects when the screen pattern overlaps with the imaged lacquer layer raster, while still maintaining efficient ink transfer for productive printing
Solution Approach 2:
The patent changes the geometric parameters of the screen opening pattern from hexagonal to parallelogram/rhombus configuration. This parameter change alters the angular relationships and spacing between screen openings, preventing the formation of Moire patterns when the screen is rotated at standard angles (e.g., 15°, 45°, 75°) relative to the substrate grain or lacquer layer raster
2Object-affected harmful factors
If the imaged lacquer layer is oriented at an angle to the hexagonal pattern of screen openings, then some Moire effects may be reduced, but the degree of freedom for selecting angles is limited and interference still occurs
Solution Approach 1:
By changing the screen pattern from 6-fold to 4-fold symmetry, the patent creates asymmetric angular relationships that prevent Moire interference across a broader range of orientation angles. This allows greater adaptability in selecting screen angles relative to substrate grain or raster patterns without encountering interference problems
Solution Approach 2:
Instead of adjusting the lacquer layer orientation to avoid Moire effects with a fixed hexagonal screen, the patent inverts the approach by fixing the lacquer layer in standard orientations and changing the screen pattern itself. This reversal provides more freedom in angle selection while effectively eliminating Moire defects
3Quantity of substance
If the screen openings are arranged in a hexagonal pattern, then good ink distribution is achieved, but interference with pixel-based image elements reduces print definition
Solution Approach 1:
The patent replaces the hexagonal pattern with a parallelogram/rhombus pattern that has different angular characteristics. This asymmetric change maintains adequate ink distribution across the screen while preventing periodic interference with pixel-based image elements, thereby improving print definition and edge sharpness
Data Source
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AI summary
A method of screen printing an image on a substrate (14), such as rotary screen printing, using a printing screen (22) having a surface structure at its printing side (40) and attached imaged lacquer layer (48) having open areas defining the image to be printed is disclosed, wherein the image comprises pixel based design elements, the printing screen (22) has a parallelogram pattern, preferably an orthogonal pattern, of screen openings (46) and the open areas of the imaged lacquer layer (48) representing the pixel based design elements are arranged in an orthogonal raster.