Axial Reading Encoder Magnetic Track Geometry
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Solution Overview
Problem
Existing systems for determining rotation parameters of rotating members with low pole pairs face challenges in maintaining sinusoidality and amplitude of the magnetic field, leading to poor measurement precision and increased encoder thickness, which complicates integration in reduced dimensions and magnetization.
Innovation Solution
A radial reading encoder system with a magnetic track featuring an alternation of North and South poles separated by transitions along a helix, allowing independent selection of pole pairs and polar width, combined with sensors arranged to deliver quadrature signals, effectively reconciling periodicity and amplitude without size constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If radial reading encoder with low pole pairs is used, then space constraints are satisfied, but magnetic field sinusoidality deteriorates and measurement precision decreases
Solution Approach 1:
The patent transitions from traditional radial reading to axial reading geometry. By positioning sensors on the axial side of the encoder disk rather than radially, the system achieves better magnetic field sinusoidality while maintaining compact radial dimensions. This dimensional change allows the magnetic track to be read effectively without requiring large radial pole widths.
Solution Approach 2:
The patent changes the reading geometry parameter from radial to axial direction. This parameter change fundamentally alters how the magnetic field is detected, enabling low pole pair encoders to maintain good sinusoidality by reading the magnetic transitions along the axial direction rather than radially, thus resolving the contradiction between compact size and measurement precision.
2Volume of moving object
If radial reading encoder with low pole pairs is used, then space constraints are satisfied, but encoder thickness increases
Solution Approach 1:
The patent changes the reading direction from radial to axial, which redistributes the dimensional requirements. Instead of increasing radial pole width or encoder thickness, the axial reading geometry allows thin encoder construction while maintaining measurement quality, as the sensors detect magnetic transitions along the axial direction.
3Volume of moving object
If radial reading encoder with low pole pairs is used, then space constraints are satisfied, but magnetization complexity increases
Solution Approach 1:
The axial reading geometry simplifies the magnetization requirements compared to radial reading. The magnetic transitions can be aligned more straightforwardly with the axial reading direction, reducing the complexity of achieving proper magnetic saturation and transition sharpness in the encoder material.
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 approach enables precise determination of rotation parameters with improved sinusoidality and amplitude, enhancing performance, reducing energy consumption, and allowing for better integration in constrained spaces.
Implementation Method 1
an encoder emitting a periodic magnetic field as well as a sensor capable of detecting said magnetic field
Implementation Method 2
each sensitive element may comprise at least one pattern based on a tunnel magnetoresistive material (TMR) whose resistance varies according to the detected magnetic field
Data Source
Figure 1a~3
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Figure 7~8
AI summary
The invention relates to a system comprising an encoder having an alternation of North (2n) and South (2s) magnetic poles separated by transitions (3) extending along a helix of pitch p and angle α, the magnetic track (2) having Npp pairs of North (2n) and South (2s) poles and a polar width Lp measured along a normal to the transitions (3) which are such that: Npp = πa/l and Lp = p.cosα; and at least one sensor capable of detecting the rotating magnetic field in a plane perpendicular to said magnetic track and to said transitions by means of an assembly (4, 4') of at least two magnetic sensing elements (5), said assembly being arranged at a radial reading distance from the magnetic track (2) and being arranged to deliver quadrature signals.