Magnetic Position Detection Using Segmented Pole Pairs
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Solution Overview
Problem
Existing magnetic position detection devices face limitations in improving position detection resolution beyond the magnetic pole limit length, requiring larger device sizes and increased costs, and struggle to enhance resolution without increasing the number of magnetosensitive elements or upsizing the magnetic gear.
Innovation Solution
A magnetic position detection device with a magnetized scale featuring alternating magnetic pole pairs of different widths and a magnetosensitive device with multiple elements arranged at specific pitches, allowing for improved resolution through parallel output analysis and binary value determination to calculate relative positions with increased precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the monopole length λ is reduced to improve position detection resolution, then the detection resolution is improved, but the magnetic field formed by the magnetized scale is weakened and the magnetosensitive element cannot detect the monopole length
Solution Approach 1:
The magnetized scale is divided into multiple magnetic pole pairs with different monopole lengths (first through fourth monopole lengths). By segmenting the scale into zones with different periodicities, the system can detect positions with higher resolution in regions where the magnetic field strength is sufficient, while still achieving fine resolution measurements where needed.
Solution Approach 2:
The patent changes the magnetic field parameters by introducing multiple monopole lengths (λ1, λ2, λ3, λ4) with different periods. This allows the system to operate in different detection modes depending on the required resolution and available magnetic field strength, effectively resolving the contradiction between resolution and field strength.
2Measurement precision
If eight magnetosensitive elements are arranged and processed by logic circuit to obtain pulse signal with three periods, then the position detection resolution is improved, but the device complexity increases
Solution Approach 1:
Instead of using multiple magnetosensitive elements arranged in a single pattern, the patent segments the detection task by using a single magnetosensitive element that reads multiple magnetic pole pairs with different monopole lengths. This achieves high-resolution detection through signal processing of multiple periodicities rather than through spatial multiplication of elements.
Solution Approach 2:
A single magnetosensitive element performs multiple detection functions by reading magnetic pole pairs with different monopole lengths. The element universally detects positions across different resolution requirements, eliminating the need for multiple specialized elements and their associated logic circuits.
3Measurement precision
If the diameter of cylindrical magnetized scale is increased to improve angle detection resolution, then the detection resolution is improved, but the device size increases and cost increases
Solution Approach 1:
The patent changes the periodicity parameter of the magnetized scale by introducing multiple monopole lengths. This allows high-angle detection resolution to be achieved through signal processing of multiple periodicities rather than through physical scaling up of the device diameter, thereby maintaining compact dimensions.
4Measurement precision
If magnetic gear is upsized to improve detection resolution, then the detection resolution is improved, but the device size increases
Solution Approach 1:
The magnetized scale is segmented into multiple magnetic pole pairs with different monopole lengths arranged in sequence. This segmentation allows the system to achieve high detection resolution through the combination of different periodicities without requiring an increase in the overall size of the magnetic gear.
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 enables improved detection resolution with a simple configuration, allowing for higher precision in position detection without the need for larger device sizes or increased numbers of magnetosensitive elements, effectively overcoming the limitations of existing technologies.
Implementation Method 1
a magnetosensitive element formed of a Hall element or a magnetoresistive element is arranged so as to be opposed to a magnetized scale
Implementation Method 2
a magnetosensitive element formed of a Hall element or a magnetoresistive element is arranged so as to be opposed to a magnetized scale
Implementation Method 3
a magnetized scale formed of N poles and S poles that are alternately arranged with fixed lengths λ
Data Source
AI summary
A magnetized scale (1a) in which magnetic pole pairs each formed of a first magnetic portion (11a) and a second magnetic portion (12a) having different magnetic properties are arranged with a period of a magnetic pole pair width 2λ, and a magnetosensitive device (2) in which n magnetosensitive elements (21a to 21e) are arranged with a magnetosensitive element pitch P so that λ=nP may be established are arranged so as to be opposed to each other with a predetermined air gap therebetween. Output values output from the n magnetosensitive elements (21a to 21e) in parallel are analyzed to calculate a relative position between the magnetosensitive device (2) and the magnetized scale (1a) as a position detection resolution of λ/n.