Concave Magnetic Field for Security Coating
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Solution Overview
Problem
Existing methods for producing security features with a positive rolling bar effect face challenges, particularly in avoiding physical contact between the magnet and the wet coating layer, which can disrupt the optical effect layer during industrial processes.
Innovation Solution
The use of magnetic-field-generating devices that produce positively curved magnetic field lines on the side opposite to the coating layer, allowing for the orientation of non-spherical magnetic or magnetizable pigment particles to create a positive rolling bar effect without direct contact, using configurations such as bar dipole magnets and pole pieces to generate the necessary magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a magnet is disposed on the same side as the coating layer to produce a positive rolling bar effect, then the pigment particles can be oriented correctly, but the magnet physically contacts and disrupts the wet coating layer
Solution Approach 1:
The patent inverts the conventional approach by placing the magnet on the opposite side of the substrate from the coating layer. This allows the magnetic field to penetrate through the substrate and orient the pigment particles from the reverse side, achieving the desired concave curvature orientation without physical contact with the wet coating layer.
Solution Approach 2:
The patent transitions from a single-sided magnet configuration to a multi-dimensional field arrangement. By positioning magnets on the reverse side of the substrate, the magnetic field lines traverse through the substrate thickness, creating a three-dimensional field pattern that achieves concave curvature without direct contact with the coating layer.
2Object-affected harmful factors
If a magnet is disposed on the opposite side of the substrate to avoid contact with the coating layer, then the coating remains undisturbed, but generating the correct concave magnetic field lines becomes more complex
Solution Approach 1:
The patent divides the magnetic field generation function into multiple discrete dipole magnets arranged in specific patterns (such as alternating polarity arrays). This segmentation allows each magnet to contribute to the overall concave field line pattern, making the complex field generation achievable through simpler, modular components.
Solution Approach 2:
The substrate itself acts as an intermediary medium that transmits the magnetic field from the reverse side to the coating layer. By using the substrate as a field transmission path, the system achieves indirect magnet-coating interaction, simplifying the overall device architecture while maintaining field effectiveness.
3Device complexity
If the magnetic field lines are straight or convex, then the device is simpler, but the desired positive rolling bar optical effect cannot be achieved
Solution Approach 1:
The patent employs asymmetric magnet arrangements with alternating polarities positioned at specific locations on the reverse side of the substrate. This asymmetric configuration creates the necessary concave curvature in the magnetic field lines, which is essential for achieving the positive rolling bar effect, while maintaining reasonable device complexity through systematic positioning.
Solution Approach 2:
The patent specifically designs the magnetic field configuration to produce concave curved field lines rather than straight or convex patterns. This curvature is achieved through strategic magnet placement and polarity arrangement, directly enabling the concave orientation of pigment particles that produces the desired optical effect.
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 effectively produces optical effect layers with a positive rolling bar effect, enhancing security features by ensuring the magnetic field lines are correctly aligned without disturbing the coating, thus maintaining the intended optical effect.
Implementation Method 1
exposing the coating composition in a first state to the magnetic field of a magnetic-field-generating device receiving the supporting surface, thereby orienting at least a part of the non-spherical magnetic or magnetizable pigment particles
Implementation Method 2
a magnetic-field-generating device for producing an optical effect layer (OEL) made of a hardened coating, said magnetic-field-generating device being configured for receiving a supporting surface carrying a coating composition comprising a plurality of non-spherical magnetic or magnetizable pigment particles
Data Source
Figure 1~2b
Figure 3a~4
Figure 5~5d
AI summary
The invention relates to the field of the protection of security documents such as for example banknotes and identity documents against counterfeit and illegal reproduction. In particular, the invention relates to magnetic-field-generating devices which produce positively curved magnetic field lines in a concave fashion. The invention also relates to the use of these magnetic-field-generating devices for producing optical effect layers OEL which exhibit the optical impression of a positive rolling bar effect and to processes using these magnetic- field-generating devices, e.g. in the field of document security.