Magnetic Sensor Array for Absolute Position Detection on Code Tapes
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Solution Overview
Problem
Existing absolute measuring magnetic position sensors are not adaptable to different magnetic code objects, suffer from reduced measuring resolution due to magnetic disturbances, are sensitive to misalignments, and are affected by errors such as mechanical wear and changes in magnetization, and are not compatible with circularly curved code strips of varying diameters.
Innovation Solution
A sensor arrangement with a linear arrangement of magnetic field sensors that can detect magnetic bits with high spatial resolution in two directions, allowing for flexible spacing and adaptability to different magnetic patterns, and includes a learning mode to adjust for misalignments and errors, enabling accurate position detection on various magnetic code strips and tapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-track magnetic code strip is used, then the sensor arrangement can be used with magnetic code objects having different magnetic patterns, but the reading distance is limited
Solution Approach 1:
The sensor arrangement uses a linear array of magnetic field sensors with variable spacing that can be dynamically adjusted to match different magnetic code patterns. The distance between adjacent sensors can be adapted to the specific bit length and pole spacing of the code strip, enabling the same sensor arrangement to work with different magnetic patterns while maintaining optimal reading distance for each configuration.
2Measurement precision
If parallel tracks are used on the code strip, then absolute positioning is achieved, but magnetic disturbances reduce measuring resolution
Solution Approach 1:
The patent introduces a magnetic shielding layer as an intermediary between the parallel tracks on the code strip and the magnetic field sensors. This shielding layer redirects magnetic field lines and prevents cross-talk between adjacent tracks, thereby eliminating magnetic disturbances that would otherwise reduce measurement precision while still allowing absolute positioning to function.
3Ease of manufacture
If fixed sensor element spacing is used, then manufacturing is simplified, but the system is sensitive to misalignments
Solution Approach 1:
The sensor arrangement employs variable spacing between magnetic field sensors instead of fixed spacing. The distance between adjacent sensors can be changed to match the specific parameters of different magnetic code patterns, such as bit length and pole spacing. This parameter adaptability makes the system tolerant to misalignments and variations in code strip dimensions while maintaining ease of manufacture through standardized sensor modules.
4Ease of operation
If the code strip circumference is constrained to integral multiples of bit width, then circular code strips work, but adaptability to different diameters is limited
Solution Approach 1:
The sensor arrangement is designed with universal applicability to circular code strips of any diameter. By using a linear array of magnetic field sensors with adaptable spacing rather than a fixed circular sensor array, the system can accommodate circular code strips with circumferences that are not integral multiples of the bit width. The sensors can be positioned at optimal intervals regardless of the specific diameter, making the system multi-functional across different code strip configurations.
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 sensor arrangement provides robust and fault-tolerant position detection with high accuracy, enabling use with multiple magnetic code strips, cost savings, and autonomous operation, while maintaining reliability despite external influences and mechanical errors.
Implementation Method 1
two sensor elements detecting a magnetic field are arranged in a line in parallel to the magnetic code strips
Implementation Method 2
The SIN/COS position dependence of the components of the respective magnetic field vector is resolved or interpolated by means of an interpolator
Implementation Method 3
a magnetic code strip or a coded magnetic tape
Implementation Method 4
The distance between these sensor elements corresponds to a quarter of the magnetic pole spacing of the code strips
Data Source
AI summary
A sensor arrangement for an absolute measuring position detection system based on a magnetic code object has a substantially linear arrangement of magnetic field sensors, wherein a bit pattern encoded on a single-track magnetic code object having a uniform bit length is readable by the magnetic field sensors. In the case of a position detection system having the sensor arrangement, the values of magnetic bits are detected in the range of a detected bit sequence and the position of each 0→1 and 1→0 bit transition along a longitudinal axis of a code object is determined from the detected bit values.