Magnetic Sensor with Perpendicular Sensitivity for Coercive Area Detection
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Solution Overview
Problem
Existing magnetic sensors struggle to reliably differentiate between documents of value with magnetic areas of different coercivity, particularly those with magnetic coding made of materials having varying coercive field strengths, due to the difficulty in distinguishing high and low-coercive magnetic areas when they enter the detection area simultaneously.
Innovation Solution
A magnetic sensor system with two sensor lines, each containing a plurality of magneto-sensitive elements with different main sensitivity directions, oriented perpendicular to the transport direction, allowing for selective detection of high and low-coercive magnetic areas by aligning the sensitivity directions with the magnetization directions of the magnetic fields applied by two distinct magnetization sections, ensuring that only magnetic fields parallel to the sensitivity direction are detected while those perpendicular deliver minimal or no signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single inductive magnetic head sensitive parallel to the transport direction is used to detect magnetic areas, then the detection of high-coercive magnetic areas is achieved, but low-coercive magnetic areas cannot be distinguished when both types enter the detection area simultaneously
Solution Approach 1:
The single magnetic sensor is divided into two separate sensor lines, each with magneto-sensitive elements having different main sensitivity directions (first and second directions). This segmentation allows independent detection of magnetic areas magnetized in different directions, enabling distinction between high-coercive and low-coercive magnetic areas without increasing overall system complexity
Solution Approach 2:
The solution introduces a new dimension of detection by adding a second sensitivity direction perpendicular to the first. Instead of trying to detect both types of magnetic areas with a single sensor oriented in one direction, the system uses two sensor lines oriented in perpendicular directions, thereby detecting magnetic fields from different spatial dimensions
2Adaptability or versatility
If different coercive magnetic materials are used for magnetic coding, then two types of magnetic areas (high-coercive and low-coercive) can be formed, but reliable differentiation between them becomes difficult when they enter the detection area at the same time
Solution Approach 1:
Before the document reaches the detection area, two magnetization sections are used to magnetize the document in two different directions. The first magnetization section magnetizes in a first direction, and the second magnetization section magnetizes in a second direction perpendicular to the first. This preliminary action ensures that high-coercive and low-coercive magnetic areas are magnetized in different directions, allowing the two sensor lines to reliably differentiate between them during detection
Solution Approach 2:
Different regions of the document are magnetized with different properties: high-coercive magnetic areas retain magnetization in the first direction, while low-coercive magnetic areas are magnetized in the second direction. The sensor system uses local quality differentiation by having sensor lines with different sensitivity directions detect these locally distinct magnetic properties, enabling reliable identification of different magnetic area types
3Measurement precision
If magnetic areas are magnetized in the transport direction and detected with an inductive magnetic head, then detection is possible, but magnetic areas magnetized perpendicular to the transport direction cannot be detected
Solution Approach 1:
The magnetic sensor system is designed with multi-functionality to detect magnetic fields in multiple directions. By equipping the sensor with two sensor lines having magneto-sensitive elements with different main sensitivity directions (first and second perpendicular directions), the system can detect magnetic areas magnetized in either direction, making the detection system universal for different magnetization orientations
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 solution enables the reliable and independent detection of high and low-coercive magnetic areas, allowing for accurate recognition and differentiation of magnetic codings on documents of value, even when combined magnetic areas are present, thereby enhancing the authentication and identification of document types.
Implementation Method 1
The magneto-sensitive elements are designed as magnetoresistive elements, inductive elements or Hall elements
Implementation Method 2
first and a second magnetization section for magnetizing the document of value are arranged along the transport path
Data Source
Figure 1
Figure 2a~2c
Figure 2d~2e
AI summary
The invention relates to a magnetic sensor for checking value documents and to a device and to a method in which a magnetization device for magnetizing a value document and the magnetic sensor for detecting magnetic signals of the value document are used. The magnetic sensor comprises two sensor rows that have a plurality of magnetosensitive elements with different main sensitivity directions, said directions in particular being oriented perpendicular to one another. The first sensor row selectively detects first magnetic areas of the value document with a first coercive field strength and the second sensor row selectively detects second magnetic areas of the value document with a second coercive field strength. Since the various coercive magnetic areas of the value document are detected independently of one another, two magnetic codes from different coercive magnetic areas located on the same value document can be reliably and independently determined.