Magnetic Sensor Device Diagonal Phase Patterns Gap Stability
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Solution Overview
Problem
Magnetic sensor devices and encoder devices face challenges in maintaining high detection accuracy when the gap space dimension between the sensor device and the magnetic scale varies, particularly in detecting rotary magnetic fields, due to sensitivity differences in magnetic resistance patterns and waveform distortion.
Innovation Solution
The magnetic sensor device incorporates diagonally located 'A'-phase and 'B'-phase magnetic resistance patterns with phase differences of 90° and 180°, respectively, on a single board, allowing for equal sensitivity and improved interpolation precision, and a magnetic scale with a permanent magnet having a thickness of 1 mm or more to stabilize sine-wave component detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap space dimension between the magnetic sensor device and the magnetic scale is reduced to improve S/N ratio, then detection sensitivity is improved, but waveform distortion becomes larger
Solution Approach 1:
The patent changes the physical parameters of the magnetic scale by specifying a permanent magnet thickness of 1 mm or more, which modifies the magnetic field distribution and reduces waveform distortion even at reduced gap dimensions, thereby maintaining detection sensitivity while mitigating the harmful effect
Solution Approach 2:
The patent employs specific magnetic materials with predetermined properties for the permanent magnet, creating a composite structure that optimizes the magnetic field characteristics to reduce waveform distortion while maintaining high detection sensitivity at reduced gap distances
2Measurement precision
If two pieces of rigid boards are disposed to face each other with magnetic resistance patterns, then moving detection can be performed with phase difference, but offset varies when gap space dimension is varied due to sensitivity difference
Solution Approach 1:
The patent merges all magnetic resistance patterns (+a, -a, +b, -b phases) onto a single rigid board instead of using two separate boards, ensuring that all patterns experience identical gap space conditions and magnetic field environments, which eliminates sensitivity differences and prevents offset variations when gap dimension changes
Solution Approach 2:
By positioning all magnetic resistance patterns on the same board plane, the patent creates equipotential conditions where all patterns are subjected to equal magnetic field strength and gap distance, eliminating the potential differences that cause offset variations in the two-board configuration
3Measurement precision
If the permanent magnet thickness is increased to stabilize sine-wave component detection, then detection accuracy is improved, but the device volume increases
Solution Approach 1:
The patent optimizes the permanent magnet thickness parameter by setting it to 1 mm or more, which is the minimum threshold required to stabilize the sine-wave component detection. This parameter optimization achieves the desired detection accuracy while minimizing the volume increase, as any thickness below 1 mm would fail to provide sufficient magnetic field 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
This configuration ensures high detection accuracy and stability of the rotary magnetic field even when the gap space dimension is reduced, avoiding offset variations and enhancing sensitivity without manufacturing dispersion effects.
Implementation Method 1
a magnetic sensor device 1001 provided with a magneto-resistive element on its sensor face
Implementation Method 2
a magnetic scale 1009 which is provided with a permanent magnet and is relatively moved with respect to the magnetic sensor device 1001
Data Source
AI summary
A magnetic sensor device may include “A”-phase magnetic resistance pattern and “B”-phase magnetic resistance pattern which are provided with a phase difference of 90° from each other; wherein the “A” pattern is provided with “+a” phase magnetic resistance pattern and “−a” phase magnetic resistance pattern with a phase difference of 180° from each other for detecting movement of a magnetic scale, and the “B” pattern is provided with “+b” phase magnetic resistance pattern and “−b” phase magnetic resistance pattern with a phase difference of 180° from each other for detecting movement of the magnetic scale, and the “+a” pattern, the “−a” pattern, the “+b” pattern and the “−b” pattern are formed on a same face of one piece of board so that the “+a” pattern and the “−a” pattern are diagonally located and the “+b” pattern and the “−b” pattern are diagonally located.