Magnetic Position Detection Apparatus Bridge Circuit
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic position detection apparatuses with bridge circuits formed of multiple magneto-electric converting elements face issues with manufacturing variances in sensitivity and temperature characteristics, leading to increased costs and complexity due to differences in magnetic characteristics and combining positions of these elements with the magnet.
Innovation Solution
The apparatus is designed with first and second magneto-electric converting elements disposed such that their electric resistance values are balanced when not opposed to a magnetic mobile object, with the second element positioned on or near the magnetic pole's center line and perpendicular to the magnetization direction, ensuring equal sensitivity and reducing manufacturing variances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magneto-electric converting elements are used in a bridge circuit to enhance detection sensitivity, then measurement precision is improved, but manufacturing precision deteriorates due to variances in sensitivity and magnetic characteristics
Solution Approach 1:
The patent positions the first and second magneto-electric converting elements at locations where they experience substantially the same magnetic field strength when the magnetic mobile object is not opposed to the magnet. This equipotential arrangement ensures that both elements have equal sensitivity and electric resistance values under no-load conditions, eliminating differential outputs caused by manufacturing variances and enabling mass production without individual adjustment.
Solution Approach 2:
The patent changes the spatial arrangement parameter of the magneto-electric converting elements, specifically positioning them at symmetric locations relative to the magnet's magnetic pole. By altering their positions to satisfy the equipotential condition, the system achieves balanced sensitivity without requiring post-manufacturing adjustment, thus resolving the contradiction between enhanced detection and manufacturing precision.
2Measurement precision
If multiple magneto-electric converting elements are disposed with spacing to enhance spatial resolution, then measurement precision is improved, but device complexity increases due to balancing requirements
Solution Approach 1:
The patent employs asymmetric positioning of the magneto-electric converting elements relative to the magnet's geometry. Specifically, the elements are placed at locations that are asymmetric with respect to the magnet center but symmetric with respect to the magnetic field distribution. This asymmetric-yet-balanced configuration enables differential output for position detection while maintaining equal sensitivity, thereby enhancing spatial resolution without increasing device complexity.
3Measurement precision
If magneto-electric converting elements are positioned to achieve differential output, then measurement precision is improved, but temperature characteristics worsen due to sensitivity variances
Solution Approach 1:
By positioning the magneto-electric converting elements at equipotential locations in the magnetic field, the patent ensures that both elements experience identical magnetic field conditions and thus have matched temperature characteristics. This eliminates differential outputs caused by temperature-induced sensitivity variances, improving temperature stability while maintaining the benefits of differential measurement.
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 stabilizes the output signal and improves sensitivity characteristics, particularly temperature characteristics, by balancing electric resistance values and reducing manufacturing variances, thus facilitating cost-effective production and enhanced performance.
Implementation Method 1
The magneto-electric converting element referred to herein means an element whose electric resistance value varies with a magnetic field applied thereto, such as an MR (Magneto-Resistance) element
Data Source
AI summary
A magnetic position detection apparatus includes a substrate, a magnet, a bridge circuit including first through fourth magneto-electric converting elements formed on the substrate, and a detection circuit. A substrate surface is substantially perpendicular to a magnet magnetization direction. The second and third magneto-electric converting elements are, when viewed along the magnet magnetization direction, disposed to be on or in the vicinity of a straight line passing through a center point of a magnetic pole of the magnet and parallel to a straight line perpendicular to both the magnet magnetization direction and the magnetic mobile object. The first and fourth magneto-electric converting elements are disposed so that, when not opposed to the magnetic mobile object, a component of a substrate of a magnetic field to be applied thereto is substantially same as that of a magnetic field to be applied to the second and third magneto-electric converting elements.