Magnetic Sensor Asymmetric Resistor Layout for Skew Error Reduction
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Solution Overview
Problem
Magnetic sensors used in encoders often experience reduced detection accuracy due to skewing, particularly when magnetoresistive elements are arranged along the longitudinal direction of a magnetic scale, leading to distorted waveforms and harmonic distortion.
Innovation Solution
A magnetic sensor configuration with first to fourth resistors, each comprising magnetoresistive elements, is arranged such that the center of gravity of each resistor group is symmetrical about an imaginary straight line, with the resistors connected in series and positioned orthogonally, reducing error components and improving detection accuracy by minimizing the impact of skewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive elements are arranged along the longitudinal direction of a magnetic scale to detect position, then detection capability is improved, but skewing causes waveform distortion and reduces measurement precision
Solution Approach 1:
The patent applies asymmetry by intentionally introducing a predetermined asymmetry in the arrangement of magnetoresistive elements. Specifically, the distance between adjacent elements is set to satisfy a particular relationship (L1 ≠ L2) that creates an asymmetric pattern. This asymmetric arrangement causes the sensor to be insensitive to skewing errors, as the distortion effects cancel each other out when the elements are positioned according to the specified distance relationships. This resolves the contradiction by maintaining high measurement precision while achieving reliability under skewing conditions.
Solution Approach 2:
The patent changes the spatial parameters (distances) between magnetoresistive elements to specific values that satisfy predetermined relationships. By setting the distances L1 and L2 to meet specific mathematical relationships (such as L1/L2 = specific ratio), the sensor achieves immunity to skewing. This parameter optimization allows the system to maintain accurate position detection even when the sensor is skewed relative to the magnetic scale, thereby resolving the contradiction between measurement precision and reliability under misalignment.
2Measurement precision
If multiple magnetoresistive elements are arranged at specific distances to cancel harmonics, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by arranging magnetoresistive elements with different local characteristics (different distances from reference points) to achieve specific functions. Each element is positioned at a carefully calculated distance to contribute to harmonic cancellation. This localized positioning strategy allows the sensor to achieve high waveform accuracy through precise spatial distribution of elements, while the overall structure remains relatively simple compared to other harmonic cancellation methods.
3Area of stationary object
If magnetoresistive elements are arranged in a compact configuration, then device size is reduced, but skewing sensitivity increases
Solution Approach 1:
The patent transitions from a one-dimensional linear arrangement to a two-dimensional spatial configuration by positioning magnetoresistive elements at specific distances in multiple directions from a reference point. This dimensional approach allows compact packaging of elements while maintaining their functional relationships. The specific distance relationships are designed so that the compact 2D arrangement provides skewing immunity, thus achieving both small sensor area and high reliability under skewing conditions.
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 configuration effectively suppresses the occurrence of skew-related errors, ensuring accurate detection of the magnetic field generator's position by reducing harmonic distortions and maintaining detection accuracy even when the sensor is skewed.
Implementation Method 1
first to fourth resistors each configured to change in resistance with strength of the magnetic field component
Data Source
AI summary
A magnetic sensor includes first to fourth resistors, a power supply port, a ground port, a first output port, and a second output port. The first resistor and the second resistor are located in a first region and connected in series via a first connection point connected to the first output port. The third resistor and the fourth resistor are located in a second region and connected in series via a second connection point connected to the second output port, at least a part of the second region being located at a position different from the first region in a direction parallel to an X direction. The first and second resistors are located between the third and fourth resistors in a direction parallel to a Y direction.