Magnetic Encoder Track Layout for Variable-Diameter Angle Sensing
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Solution Overview
Problem
Existing magnetic encoder devices face limitations in design flexibility, size, weight, and production cost due to fixed specifications and separate component attachment, while tape-like scales lack resolution improvement and phase signal output at ends.
Innovation Solution
A sheet-shaped encoder magnetic material with alternating N and S poles is wound around a rotary body, allowing adjustable diameter production without molds, integrated design, and high-resolution angle detection with correction for diameter variations, including a correction calculator to ensure accurate angle calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a camera module is disposed at each corner of the sensor array, then the angle detection range is expanded, but the device complexity and number of components increase
Solution Approach 1:
The sensor array is divided into multiple regions with different camera module configurations. Corner regions have camera modules for expanded angle detection, while edge and center regions have different configurations optimized for their specific detection needs. This segmentation allows expanded angle detection without uniformly increasing complexity across the entire device.
Solution Approach 2:
Different regions of the sensor array are assigned different camera module configurations based on local detection requirements. Corner regions receive camera modules with wider field of view for expanded angle detection, while other regions have configurations optimized for their specific functional requirements, creating local optimization rather than uniform design.
2Measurement precision
If multiple camera modules are arranged in a specific pattern, then the angle detection accuracy is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The camera modules are arranged in an asymmetric pattern rather than a symmetric grid. This asymmetric arrangement optimizes the field of view and detection accuracy for each region while providing tolerance in positioning requirements. The asymmetric design allows for more flexible manufacturing and assembly processes while maintaining detection precision.
3Adaptability or versatility
If the sensor array covers a wide field of view, then the detection coverage is expanded, but the resolution and detail detection capability decrease
Solution Approach 1:
The sensor array is segmented into multiple regions, each with camera modules optimized for their specific field of view. Corner regions provide wide-angle coverage for expanded detection area, while edge and center regions provide higher resolution for detailed detection. This segmentation allows the system to achieve both wide coverage and high resolution simultaneously.
Solution Approach 2:
Different regions of the sensor array have different optical characteristics optimized for their specific functions. Corner regions are optimized for wide field of view and detection coverage, while edge and center regions are optimized for resolution and detail detection. This local optimization allows the overall system to achieve both expanded coverage and maintained resolution.
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
Enables high-resolution angle detection with reduced size and weight, simplified structure, and lower production costs, while supporting various rotary body diameters and avoiding seam influence.
Implementation Method 1
a first light receiving element and a second light receiving element, respectively, in a first row and a second row of the sensor array
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
An angle detecting device (4) includes: an encoder unit (6) having a magnetic track on which N poles and S poles are alternately arrayed; and a magnetic sensor (7) facing the magnetic track with a gap interposed therebetween. The magnetic track has, when being expressed with a reference magnetic pole width (P) and a reference magnetic pole pair number (n), a main track (2) having a magnetic pole width of (P) and a sub track (3) having a magnetic pole width of (Pn/(n-1)), the main track (2) and the sub track (3) being provided adjacent and parallel to each other along a longitudinal direction of a sheet-shaped encoder magnetic material (1). The encoder unit (6) is formed of the sheet-shaped encoder magnetic material (1) which has a length not larger than a reference length (L=2Pn) and which is wound around and fixed to an outer circumference portion or an inner circumference portion of a rotary body (5). The angle detecting device (4) further includes a correction calculator (10) configured to multiply an absolute angle calculated by a calculator (9) of the magnetic sensor (7) by a correction coefficient based on a diameter of the encoder unit (6), to correct the absolute angle of the rotary body.