Dual-Head Magnetic Sensor for Banknote Coercivity Detection
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Solution Overview
Problem
Existing sensors for reading security elements in banknotes and security papers struggle to accurately detect magnetic areas with different coercivity, especially when banknotes are not flat, and are prone to counterfeiting due to the transfer method used in metallized stripes.
Innovation Solution
A sensor system with two reading heads, one oriented with a high coercive magnet and the other with a low coercive magnet, capable of detecting magnetic areas with different coercivity values, allowing for reliable detection regardless of banknote orientation and flatness, and incorporating a design that reduces counterfeiting risks by using magnetic inks with varying coercivity and residual magnetism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single reading head with uniform magnetization is used, then the device complexity is reduced, but the measurement precision of magnetic areas with different coercivity deteriorates
Solution Approach 1:
The sensor is divided into two independent reading heads: a first reading head with magnetization in a first direction for detecting first magnetic areas, and a second reading head with magnetization in a second direction for detecting second magnetic areas. This segmentation allows each reading head to be optimized for detecting specific magnetic areas with different coercivity values, thereby resolving the contradiction between device complexity and measurement precision.
2Device complexity
If magnetic areas with different coercivity are detected using a single orientation magnet, then the device complexity is reduced, but the reliability of detection on creased banknotes deteriorates
Solution Approach 1:
Each reading head is equipped with magnetization in a specific direction tailored to its detection purpose. The first reading head has magnetization optimized for detecting first magnetic areas, while the second reading head has magnetization optimized for detecting second magnetic areas. This local quality differentiation ensures reliable detection on creased banknotes where uniform magnetization would fail to consistently detect all magnetic areas regardless of their orientation.
3Ease of operation
If magnetic areas are detected without considering orientation, then the ease of operation is improved, but the measurement precision of magnetic code detection deteriorates
Solution Approach 1:
The sensor dynamically adapts to different magnetic area orientations by using two reading heads with different magnetization directions. This dynamic capability allows the sensor to accurately detect magnetic codes regardless of the banknote's orientation or creases, maintaining measurement precision while simplifying the reading process as the user does not need to manually adjust the banknote orientation.
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
The sensor system enables reliable detection of security threads with high and low coercivity areas, even on creased banknotes, at high speeds, and reduces counterfeiting risks by generating distinct codes that are consistent across orientations, enhancing non-counterfeitability and decoding efficiency.
Implementation Method 1
a first reading head (21) for detecting the magnetic areas (3, 4) by means of a magnetic field oriented in a first direction
Implementation Method 2
detecting the magnetic areas (3, 4) by means of a magnetic field oriented in a first direction, which generates a first sequence of detection signals
Implementation Method 3
a second reading head (22) for detecting the magnetic areas (3, 4) by means of a magnetic field oriented in a second direction, which is different from the first direction
Implementation Method 4
detecting the magnetic areas (3, 4) by means of a magnetic field oriented in a second direction, which is different from the first direction, and which generates a second sequence of detection signals
Implementation Method 5
magnetic areas (3, 4) having mutually different values of coercivity and/or residual magnetism
Implementation Method 6
magnetic inks with varying coercivity and residual magnetism
Data Source
Figure 1~3c
Figure 4~6c
Figure 7
AI summary
A reading sensor (20) suitable to read a security element having magnetic areas with different coercivity, whose particularity resides in that it comprises at least one first reading head (21) and at least one second reading head (22), which are arranged parallel to each other and are capable of detecting two distinct signal sequences, and a permanent magnet (23) which is arranged between the reading heads (21, 22).