Rotary Encoder Segmented Patterns Maintain Synthesis Tolerance
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Solution Overview
Problem
Miniaturization of rotary encoders leads to reduced synthesis tolerance, making it difficult to maintain accurate absolute angle calculation due to increased inter-track errors caused by misalignment between the rotor and stator.
Innovation Solution
The rotary encoder design includes a rotor with a first pattern and a second pattern having a maximum common divisor of two or more unit patterns, ensuring a sufficient synthesis tolerance by maintaining the period of detection signals and using an electromagnetic induction type stator for accurate angle calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the rotary encoder is miniaturized, then the size is reduced, but the synthesis tolerance becomes smaller and inter-track error worsens
Solution Approach 1:
The rotor is divided into multiple independent rotor patterns (first rotor pattern with first plurality of unit patterns, second rotor pattern with second plurality of unit patterns). Each pattern has a different number of unit patterns with a maximum common divisor of two or more, creating segmented tracking systems that independently contribute to angle detection. This segmentation allows the system to maintain adequate synthesis tolerance even when miniaturized, as each segmented pattern provides redundant detection capability.
Solution Approach 2:
The invention uses a composite detection system combining multiple rotor patterns with different unit pattern counts. By compositeing the detection signals from multiple patterns (first rotor pattern and second rotor pattern) with maximum common divisor of two or more, the system achieves enhanced synthesis tolerance that maintains accuracy despite miniaturization. The composite approach combines the strengths of different pattern configurations.
2Measurement precision
If the number of unit patterns is increased to improve detection accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The invention optimizes the parameters of rotor patterns by specifying that the number of unit patterns in different rotor patterns must have a maximum common divisor of two or more. This parameter constraint ensures that the least common multiple of the periods is minimized, maintaining adequate synthesis tolerance. By carefully selecting and constraining the parameters (number of unit patterns) rather than simply increasing them, the system achieves good measurement precision without excessive complexity.
3Measurement precision
If the period of rotor patterns is reduced to improve resolution, then measurement precision improves, but synthesis tolerance becomes smaller
Solution Approach 1:
The detection system is segmented into multiple rotor patterns with different unit pattern counts. By segmenting the detection function across multiple patterns with maximum common divisor of two or more, the system achieves fine detection resolution through the combined effect of multiple patterns while each individual pattern can maintain a larger period, thus preserving synthesis tolerance.
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 allows for miniaturization while maintaining a synthesis tolerance similar to pre-miniaturized encoders, preventing accuracy deterioration in rotation angle calculations and ensuring reliable operation.
Implementation Method 1
an electromagnetic induction type, a magnetic type, or the like
Data Source
AI summary
A rotary encoder that is capable of securing a sufficient synthesis tolerance while achieving miniaturization is provided. The rotary encoder 1 includes a rotor 3, a stator 4, and a calculating unit 5 for calculating the rotation angle. The rotor 3 has a first rotor pattern 31 with a plurality of unit patterns 310 arranged along the measurement direction around the rotating shaft 2, and a second rotor pattern 32 with fewer unit patterns 320 than the plurality of unit patterns 310 in the first rotor pattern 310 arranged along the measurement direction. The number of the plurality of unit patterns 310 of the first rotor pattern 31 and the number of the plurality of unit patterns 320 of the second rotor pattern 32 are provided such that the maximum common divisor therebetween is two or more. The calculating unit calculates the rotation angle of the rotor 3 based on the detection signals from the first rotor pattern 31 and the second rotor pattern 32.