TMR Sensor Stacked on PCB for Continuous Magnetic Image Detection
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Solution Overview
Problem
Existing magnetic image identification sensors face challenges such as low magnetic field sensitivity, large size, low resolution, high power consumption, and undetected areas due to the arrangement of sensors.
Innovation Solution
A magnetoresistive magnetic imaging sensor using TMR sensors is designed with a lateral detection mode, where magnetoresistive sensor chips are arranged in a staggered or stacked manner on a PCB, and a permanent magnet assembly is used to enhance magnetic field detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If audio magnetic head technology with coil is used to increase magnetic field sensitivity, then magnetic field sensitivity is improved, but device size increases and power consumption increases
Solution Approach 1:
The patent replaces the audio magnetic head technology (electromagnetic induction with coils) with magnetoresistive sensor technology (TMR effect). This substitution eliminates the need for large coils and complex mechanical structures, achieving high magnetic field sensitivity with a compact device size. The TMR sensor uses quantum tunneling effect in magnetic tunnel junctions to detect magnetic fields, providing superior sensitivity without the size penalty of traditional coil-based systems.
Solution Approach 2:
The patent changes the detection principle from electromagnetic induction to magnetoresistive effect (TMR), fundamentally altering the physical parameter used for magnetic field detection. This parameter change enables the system to achieve higher sensitivity with smaller dimensions, as the TMR effect provides a stronger signal response to magnetic field changes compared to electromagnetic induction.
2Measurement precision
If audio magnetic head technology with coil is used to increase magnetic field sensitivity, then magnetic field sensitivity is improved, but power consumption increases
Solution Approach 1:
The patent replaces the power-intensive coil-based electromagnetic induction system with the low-power magnetoresistive TMR sensor. The TMR sensor requires minimal current to operate, as it detects magnetic fields through resistance changes in magnetic tunnel junctions rather than inducing currents in large coils. This substitution dramatically reduces power consumption while maintaining or improving magnetic field sensitivity.
3Area of stationary object
If magnetic sensors are arranged in rows and columns to detect large-scale magnetic images, then detection coverage is improved, but undetected areas appear between adjacent sensors
Solution Approach 1:
The patent transitions from a two-dimensional row-column arrangement to a three-dimensional stacked arrangement of magnetoresistive sensor chips. By stacking multiple sensor layers vertically, the system achieves complete spatial coverage of the magnetic image plane, eliminating gaps between sensors that exist in planar arrangements. This vertical dimension addition ensures that every region of the magnetic image is detected by at least one sensor.
Solution Approach 2:
The patent employs multiple magnetoresistive sensor chips stacked in layers, with each layer potentially detecting different magnetic field components or providing redundant coverage. The nested multi-layer structure ensures comprehensive detection coverage, where inner and outer sensors work together to eliminate blind spots and undetected areas between adjacent sensors.
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 solution achieves high magnetic field sensitivity, small size, low power consumption, and ensures continuous detection areas without undetected regions, improving the overall efficiency and accuracy of magnetic image identification.
Implementation Method 1
uses a magnetoresistive sensor, for example, a TMR magnetic sensor, to implement detection on magnetic nano-particle images of banknotes
Implementation Method 2
a permanent magnet assembly is used to enhance magnetic field detection
Data Source
Figure 1~3
Figure 4~6
Figure 7(a)~8(b)
AI summary
A magnetoresistive magnetic imaging sensor for identifying a magnetic image comprises a PCB (1) and several magnetoresistive sensor chips (2), wherein the several magnetoresistive sensor chips (2) are located on the PCB (1), and the PCB (1) is perpendicular or parallel to the magnetic image detection surface (3). It has a lateral detection mode and front detection mode, In the lateral detection mode, each side face (2(1)) of the several magnetoresistive sensor chips (2) is parallel or coplanar with the side (1(1)) of the PCB(1), and parallel to the magnetic image detection surface. The several magnetoresistive sensor chips (2) have the same magnetic sensing direction. In the lateral detection mode, the adjacent magnetoresistive sensor chips (2) are stacked, while in the front detection mode, the adjacent magnetoresistive sensor chips (2) are arranged in a staggered manner, in order to achieve continuity of the detection area in the magnetic image detection surface. The magnetoresistive magnetic imaging sensor may also comprise a permanent magnet assembly and a housing. The sensor has several advantages, including continuity across the detection area, good signal reproduction, high sensitivity, and low power consumption.