Security Element Magnetic Coercivity Detection
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Solution Overview
Problem
Existing methods for testing security elements with multiple magnetic materials of different coercivity are complex and inefficient in detecting combined magnetic areas.
Innovation Solution
A method and device that expose security elements to a first strong magnetic field to pre-magnetize them, followed by a second weaker magnetic field to differentiate the magnetization of materials, allowing for the detection of magnetic signals that distinguish between areas with only the first, only the second, or both magnetic materials, thereby simplifying the detection of combined magnetic areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a third magnetization direction is used to detect combined magnetic areas, then detection reliability is improved, but test procedure complexity increases
Solution Approach 1:
The detection process is segmented into two distinct magnetization steps: first magnetizing the security element in a first direction to detect areas with only the first magnetic material, then magnetizing in a second direction perpendicular to the first to detect areas with only the second magnetic material and combined areas. This segmentation allows each step to target specific magnetic material configurations, improving detection reliability without requiring complex multi-directional simultaneous magnetization.
Solution Approach 2:
The first magnetization step serves as a preliminary action that prepares the security element by magnetizing areas with the first magnetic material in a specific direction. This preliminary magnetization state is then used in the second step to identify combined magnetic areas through differential signal analysis, eliminating the need for complex real-time multi-directional magnetization control.
2Measurement precision
If magnetic signals from combined magnetic areas are detected, then measurement precision is improved, but signal cancellation occurs
Solution Approach 1:
Instead of attempting to detect combined magnetic areas directly when their signals might cancel each other out, the method inverts the approach: it first detects areas with only the first magnetic material, then uses a second perpendicular magnetization to detect areas with only the second magnetic material. Combined areas are identified by the presence of signals in both detection steps, converting the signal cancellation problem into a differential detection advantage.
Solution Approach 2:
The method changes the magnetization direction parameter between detection steps. By magnetizing in a first direction for the first step and then in a second perpendicular direction for the second step, the magnetic signal characteristics change, allowing combined areas to be distinguished through parameter variation rather than direct signal measurement that would suffer from cancellation.
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 enables reliable and less complex detection of magnetic area types and positions by exploiting the significant difference in magnetic signals from materials with varying coercivity, even when combined, without signal cancellation.
Implementation Method 1
The security element is first exposed to a first magnetic field area with a first magnetic field strength, which is both greater than the first coercive field strength and greater than the second coercive field strength, in order to magnetize the two magnetic materials in a first direction of magnetization
Implementation Method 2
The security element is then exposed to a second magnetic field area with a second magnetic field strength, which is greater than the second coercive field strength but less than the first coercive field strength, in order to re-magnetize the second magnetic material in a second direction of magnetization
Implementation Method 3
a magnetic signal, which emanates from one or more magnetic areas, is detected precisely when the security element and thus the relevant magnetic area from which the magnetic signal emanates is exposed to the second magnetic field area
Data Source
Figure 1a
Figure 1b~2c
Figure 3a
AI summary
The invention relates to the inspection of security elements (11) for value documents (10), which security elements have a plurality of magnetic regions (h, k, l), which include at least one high-coercivity magnetic region (h) having a high-coercivity magnetic material, a low-coercivity magnetic region (l) having a low-coercivity magnetic material, and optionally a combined magnetic region (k), which contains both the high-coercivity magnetic material and the low-coercivity magnetic material. After the magnetisation of all magnetic materials or rather the magnetic regions (h, k, l) composed thereof in one direction by means of a first magnetic field region, only the low-coercivity magnetic material is remagnetised in another direction in a subsequent second magnetic field region. According to the invention, magnetic signals of the magnetic regions (h, k, l) are detected while the security element (21) is still exposed to the second magnetic field region. All three aforementioned magnetic region types (h, k, l) can be reliably distinguished on the basis of the signals.