Rotary Encoder Eccentricity Correction With Dual Inclined Code Rings
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Solution Overview
Problem
Conventional rotary encoders face issues with increased size, cost, and laborious installation due to the need for two detecting units to eliminate eccentric angle errors, which are not effectively addressed by existing methods.
Innovation Solution
A rotary encoder design using a single detecting unit with concentric first and second code patterns of different inclinations (+45 and -45 degrees) to calculate eccentricity and correct the angle of rotation, incorporating a light source, fixed slits, and light-receiving units to eliminate eccentric angle errors optically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two detecting units are arranged at positions that oppose each other across the center of rotation to eliminate eccentric angle error, then measurement precision is improved, but device complexity and apparatus size increase
Solution Approach 1:
The code pattern is segmented into two distinct concentric patterns: a first concentric code pattern and a second concentric code pattern. Each pattern is detected independently by the same detecting unit at different times during rotation, allowing eccentricity calculation without requiring multiple detecting units simultaneously positioned opposite each other.
Solution Approach 2:
The solution transitions from a spatial arrangement (two detecting units positioned opposite each other) to a temporal/dimensional arrangement (two concentric code patterns detected sequentially during rotation). This dimensional change allows the same detecting unit to gather information that would otherwise require two spatially separated units.
2Measurement precision
If two detecting units are used to generate angle data 180 degrees out of phase, then eccentric angle error is eliminated, but cost increases due to increased number of components
Solution Approach 1:
A single detecting unit performs multiple functions: it detects both the first concentric code pattern and the second concentric code pattern at different times during rotation. This multi-functionality eliminates the need for two separate detecting units, reducing component count while maintaining the capability to eliminate eccentric angle error.
3Measurement precision
If two detecting units are arranged to eliminate eccentric angle error, then measurement accuracy is improved, but ease of operation deteriorates due to laborious adjusting work
Solution Approach 1:
The system automatically calculates eccentricity from the detection results of the two concentric code patterns without requiring manual adjustment or alignment of multiple detecting units. The encoder processing unit performs the correction autonomously, eliminating laborious adjusting work during installation while maintaining measurement accuracy.
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 solution allows for effective and efficient elimination of eccentric angle errors without increasing apparatus size, reducing installation complexity and cost, while maintaining accuracy in angle calculation.
Implementation Method 1
a light source which irradiates the first code pattern and the second code pattern with light; and a light-receiving unit which detects light from the light source transmitted through the first code pattern and the fixed slit and which detects light from the light source transmitted through the second code pattern and the fixed slit
Data Source
AI summary
A rotary encoder which detects a rotation of a rotating disk 100 provided with an annular code pattern 110 by using a detecting unit 120 and which calculates an angle of rotation of the rotating disk 100 by using an encoder processing unit 130, wherein the code pattern 110 is constituted of a concentric first code pattern 111 and a concentric second code pattern 112, the first code pattern 111 is constituted of a plurality of first patterns having a first inclination with respect to a radial direction, the second code pattern 112 is constituted of a plurality of second patterns having a second inclination in a direction that differs from the first inclination with respect to the radial direction, and the encoder processing unit 130 calculates an eccentricity of the code pattern 110, based on a detection result of the first code pattern 111 by the detecting unit 120 and a detection result of the second code pattern 112 by the detecting unit 120 and corrects the angle of rotation according to the calculated eccentricity.