Drainage Sieve Microwindows for Security Paper Motifs
Solution Overview
Problem
Existing drainage screens for producing security paper with window security threads have limited design options, as all known variants have windows that are open over the entire width of the thread, restricting the ability to create motif elements that match the shape of window areas where the security thread is visible.
Innovation Solution
The development of a drainage screen with microwindows produced during papermaking, where the width of these microwindows is less than 50% of the thread width, and their length is between 0.2 mm and 4 mm, allowing for varied and complex patterns, characters, or codes, which can form motifs, and can be integrated with other security features like watermarks or diffraction structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional drainage screens with full-width windows are used, then the security thread is visible across the entire width, but the design freedom is limited and complex motifs cannot be created
Solution Approach 1:
The window area is segmented into multiple individual microwindows (each less than 50% of thread width) instead of using a single full-width window. These micrawindows are arranged in specific patterns to form complex motifs, allowing both design freedom and precise control over thread visibility areas.
2Adaptability or versatility
If micrawindows with width less than 50% of thread width are created, then complex patterns and motifs can be formed, but the manufacturing precision requirements increase
Solution Approach 1:
The drainage screen incorporates a multi-ribbed mold with locally varied rib structures that correspond to different motif elements. Each rib section is designed with specific dimensions and spacing to create the desired micrawindow patterns, allowing complex motifs to be formed through localized structural variations rather than requiring high precision across the entire window area.
3Reliability
If the window width is reduced to less than 50% of thread width, then security against unauthorized reproduction is improved, but the visibility of the security thread is reduced
Solution Approach 1:
Instead of relying on a single large window for visibility, the invention uses multiple smaller micrawindows arranged in two-dimensional patterns. This dimensional approach allows the security thread to remain visible through the combined effect of multiple small windows while maintaining the security benefit of limited individual window width, and the patterned arrangement provides additional verification complexity.
Data Source
Figure 1~3
Figure 4~5
Figure 6(a)~7
AI summary
The invention relates to dewatering screens for the production of security paper with a window security thread which, after its embedding on at least one surface of the security paper, is visible in predetermined window areas of the security paper. A dewatering screen according to the invention comprises a carrier screen which, in a partial area, is provided with an injection-molded insert having a relief with motif elements extending upwards from a base body and projecting beyond the surface of the carrier screen. These motif elements are formed in the shape of the predetermined window areas of the security paper in which the window security thread is to be visible. The motif elements for generating micro-windows comprise micro-motif elements which, transverse to the direction of travel of the thread to be embedded, have a width that is less than 50% of the thread width and lies between 0.2 mm and 4 mm.