Bridge-Circuited Magnetic Sensor with Fixed Resistor
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Solution Overview
Problem
Existing magnetic sensors for detecting the open and closed states of foldable devices face challenges in precision due to irregularities in central potential caused by temperature changes and have large size and high manufacturing costs, primarily because of the difficulty in matching the magnetization directions of magneto-resistive elements and the need for multiple element bases.
Innovation Solution
A magnetic sensor design that incorporates both magneto-resistive elements and fixed resistors with antiferromagnetic layers, multiple magnetic layers, a non-magnetic layer, and a protection layer, where the magneto-resistive element has a fixed magnetization direction and the fixed resistor has all magnetic layers with fixed magnetization directions, allowing for stable operation across temperature changes by maintaining consistent resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magneto-resistive elements are assembled using multiple element bases with matched magnetization directions, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple magneto-resistive elements onto a single element base, eliminating the need for multiple separate bases and their complex assembly. The elements are formed in different regions on the same substrate and electrically connected through bridge circuits, simplifying the overall structure while maintaining detection precision.
Solution Approach 2:
The element base is divided into multiple regions, each containing a magneto-resistive element with specific magnetization direction. This segmentation allows independent optimization of each element's magnetic properties while maintaining a unified substrate, resolving the contradiction between precision and complexity.
2Measurement precision
If magneto-resistive elements are assembled using multiple element bases with matched magnetization directions, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
By integrating multiple magneto-resistive elements on a single element base, the patent reduces the total number of components and assembly steps required. This merging approach lowers manufacturing costs while maintaining the detection precision achieved through proper magnetic configuration.
Solution Approach 2:
The element base serves multiple functions simultaneously: it provides mechanical support, electrical connections, and magnetic field management for multiple magneto-resistive elements. This multi-functionality reduces the need for separate components, thereby lowering manufacturing costs.
3Measurement precision
If fixed layers are magnetized in opposite directions to detect central potential changes, then measurement precision is improved, but temperature stability deteriorates
Solution Approach 1:
The patent applies different magnetization configurations to different regions of the element base. Some elements have opposite magnetization directions for precise central potential detection, while others are configured for temperature compensation, allowing both functions to coexist without interference.
Solution Approach 2:
The patent changes the magnetic parameters (magnetization directions) of the fixed layers in a controlled manner across different elements. By carefully selecting which elements have opposite magnetization and which have parallel magnetization, the system achieves both precise detection and temperature stability.
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 effectively suppresses temperature-induced irregularities in central potential, reduces sensor size, and lowers manufacturing costs by integrating magneto-resistive elements and fixed resistors on the same element base, ensuring precise detection of open and closed states without the need for precise magnetization direction matching.
Implementation Method 1
the magneto-resistive element (8) and the fixed resistor (9) have the same layer configuration... the magneto-resistive element constitutes a variable resistor in which a magnetoresistance effect is exhibited
Implementation Method 2
the antiferromagnetic layer being formed in contact with a surface opposite to the surface in which the non-magnetic of the fixed layer is formed... fixing the magnetization directions of all the magnetic layers
Data Source
Figure 1~2
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Figure 5
AI summary
The application provides a magnetic sensor which can suppress an irregularity of a central potential due to a change in a temperature, decrease size of the sensor, and lower the manufacturing cost of the sensor. A magneto-resistive element (8) and fixed resistor (9) are provided on an element base (7) and have the same configuration elements. A second magnetic layer (19) and non-magnetic layer (18) in the fixed resistor (9) are reversely laminated on each other in a manner different from the magneto-resistive element (8), and the second magnetic layer (19) is formed in contact with the first magnetic layer (17), thereby fixing the magnetization directions of the first magnetic layer (17) and the second magnetic layer (19) to the same direction. In this manner, the irregularity of the temperature coefficient between the magneto-resistive element (8) and the fixed resistor (9) is suppressed and the irregularity of the central potential due to the change in the temperature is suppressed.