Yarn Impurity Detection Using Dual-Wavelength Normalization
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Solution Overview
Problem
Existing methods for detecting impurities, such as foreign fibers, in longitudinally moving yarn using optical signals are hindered by diameter-dependent light reflection and transmission variations, which are influenced by yarn structure and homogeneity, leading to inaccurate contamination detection.
Innovation Solution
Assigning reference values to transmission or reflectance values based on mean values calculated over a yarn length, allowing for continuous adjustment and compensation of influencing factors, thereby eliminating diameter dependency and improving contamination detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If optical methods are used to detect impurities in yarn, then contamination detection capability is improved, but measurement precision deteriorates due to diameter-dependent light reflection and transmission variations
Solution Approach 1:
The patent applies parameter changes by using multiple wavelengths of light to measure different physical properties of the yarn. Specifically, a first wavelength measures light transmission (affected by yarn diameter), while a second wavelength measures light reflection (affected by both diameter and surface properties). By changing the wavelength parameter, the system can differentiate between diameter variations and actual impurities, thereby improving measurement precision while maintaining contamination detection capability
Solution Approach 2:
The patent introduces an intermediary approach by using the relationship between transmission and reflection measurements at different wavelengths as a mediator. The system calculates a contamination indicator based on the ratio or difference between reflection and transmission signals, which serves as an intermediary parameter that cancels out the diameter dependency while preserving the impurity detection signal
2Illumination intensity
If yarn diameter variations are present, then light reflection intensity changes, but this leads to false contamination signals
Solution Approach 1:
The system changes the wavelength parameter to separate the effects of diameter from the effects of impurities. By measuring at two different wavelengths and comparing the results, the system can identify when intensity changes are due to diameter variations versus actual contamination, thereby maintaining reliability despite diameter variations
Solution Approach 2:
The system uses feedback by continuously monitoring both transmission and reflection signals and using the transmission signal (which indicates diameter) to correct or compensate for the reflection signal. This feedback mechanism allows the system to distinguish between diameter-induced intensity changes and impurity-induced intensity changes, maintaining detection reliability
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 approach enables reliable and efficient detection of impurities at higher yarn throughput speeds by normalizing measurement signals, reducing the impact of yarn parameters and other variables, ensuring accurate contamination identification.
Implementation Method 1
light being emitted in the direction of the yarn and with a remission value, which represents the intensity of the light remitted by the yarn
Implementation Method 2
an associated transmission value, which represents the intensity of the light transmitted by the yarn
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a method and a device having an analysis and control device (6) for detecting impurities, particularly outside fibers, in longitudinally moving yarn (1), wherein light is emitted in the direction of the yarn and wherein a remission value (R) representing the intensity of the light remitted by the yarn and an associated transmission value (T) representing the intensity of the light transmitted by the yarn are detected, and wherein the respective transmission value (T) is associated with a reference value (Rm) and the current remission value (R) is compared to the reference value (Rm) or wherein the respective remission value (R) is associated with a transmission dependent reference value (Tm) and the current transmission value (T) is compared to the reference value (Tm).