Angular Position Sensor Cylindrical Reading Surface
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Solution Overview
Problem
Existing angular position determination systems for rotating members are unreliable due to sensitivity to reading distance dispersions during sensor mounting, leading to mediocre magnetic signal quality and precision issues in determining absolute angular positions.
Innovation Solution
The system arranges magnetic sensitive elements along a constant reading surface perpendicular to the multipolar magnetic tracks, allowing for reliable detection of rotating magnetic fields with reduced sensitivity to reading distance variations, using a processing device that applies the vernier principle to determine absolute angular position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If patterns of sensitive elements are arranged along the same reading area at a substantially constant reading distance from the multipolar magnetic tracks, then each pattern can detect a comparable magnetic signal level, but the system becomes too sensitive to variations in reading distance during sensor mounting
Solution Approach 1:
The patent transitions from a planar reading area arrangement to a three-dimensional cylindrical reading surface. The sensitive element patterns are arranged on the lateral surface of a cylinder rather than on a flat plane, allowing the reading distance to remain substantially constant while accommodating variations in mounting position. This dimensional change enables the system to maintain consistent magnetic signal detection without being overly sensitive to reading distance variations during sensor mounting.
2Device complexity
If a single sensor is used to read both tracks with patterns arranged along a surface extending to the reading distance, then the reading distance is constrained, but the magnetic signal quality deteriorates due to track proximity
Solution Approach 1:
The patent employs a cylindrical reading surface that extends in the axial direction perpendicular to the radial arrangement of the magnetic tracks. This allows the single sensor to read both tracks while maintaining adequate spacing between them, preventing signal interference. The cylindrical geometry provides sufficient axial length for the reading surface to extend beyond the reading distance of both tracks, ensuring high-quality magnetic signal detection while using only one sensor.
3Ease of manufacture
If patterns are jointly positioned along the same reading area, then manufacturing is simplified, but the reading distance must be precisely controlled which increases manufacturing difficulty
Solution Approach 1:
The cylindrical reading surface provides a geometric structure where the reading distance is naturally maintained constant along the circumferential direction. This allows patterns to be positioned along the cylindrical surface with greater manufacturing tolerance, as the constant radius of the cylinder automatically ensures consistent reading distance without requiring precision control of the reading distance parameter itself.
Solution Approach 2:
The patent changes the geometric parameters of the reading surface from planar to cylindrical, which fundamentally alters how reading distance is controlled. Instead of controlling the reading distance as a critical dimension in a flat arrangement, the cylindrical geometry makes the reading distance a function of the cylinder radius, which can be manufactured with standard tolerances while maintaining constant reading distance across the entire pattern array.
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 enhances the precision and reliability of absolute angular position determination by ensuring consistent magnetic signal detection and processing, improving the accuracy of angular position measurements without requiring initial rotation of the rotating member.
Implementation Method 1
a sensor having two patterns of magnetic sensitive elements capable of detecting the signals delivered by the tracks of the encoder
Data Source
Figure 1a~1c
Figure 2a~2b
AI summary
The invention relates to an assembly of a system for determining angular position on a rotating member, said system comprising: an encoder (1) comprising a main magnetic track (2) and a secondary magnetic track (3); and a sensor (4) having two patterns (5) of sensitive elements which are capable of detecting the signals delivered by the tracks (2, 3) of the encoder (1), each pattern (5) being arranged along a reading surface (S) which extends to a reading distance (L) of a track (2, 3) to form a signal representative of the angular position of said track, said sensor further comprising a device (6) for processing the signals from the patterns (5) to determine the absolute angular position of the rotating member;each sensitive element of the patterns (5) having at least one sensitive layer (7) based on a magnetoresistive material whose resistance varies according to the magnetic signal of the track (2, 3) to be detected, each pattern (5) being arranged so that said sensitive layer extends in a general plane (P) which is perpendicular to the reading surface (S) of said track.;