Frequency-Dependent Yarn Flaw Detection
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Solution Overview
Problem
Existing methods for detecting imperfections in yarns lack robustness against noise signals, which can lead to inaccurate quality control during yarn production.
Innovation Solution
A method and device that perform a frequency selection step to determine the noise magnitude at multiple frequencies, allowing the selection of a measurement frequency with low noise, thereby reducing interference and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional measurement methods are used to detect imperfections in yarn, then quality control can be performed, but the measurement is susceptible to noise signals which reduces reliability
Solution Approach 1:
The patent applies preliminary action by performing a frequency selection step before the actual measurement. The system预先 determines the noise spectrum at the detector across multiple frequencies and selects an optimal measurement frequency where noise is minimal. This preliminary characterization of noise allows the subsequent measurement to be performed under optimal conditions, improving both reliability and precision.
Solution Approach 2:
The patent changes the frequency parameter of the measurement system. Instead of using a fixed measurement frequency, the system varies the frequency and selects the optimal one based on noise characteristics. This parameter optimization resolves the contradiction by finding a frequency where noise interference is minimized, thereby improving both reliability and measurement precision simultaneously.
2Measurement precision
If a fixed measurement frequency is used, then the measurement process is simple, but noise interference cannot be minimized leading to reduced measurement accuracy
Solution Approach 1:
The frequency selection step is performed as a preliminary action before actual measurement. The system characterizes the noise spectrum once and stores the optimal frequency information, which is then used for subsequent measurements. This approach improves measurement precision without significantly increasing ongoing device complexity, as the frequency selection is a one-time setup procedure.
Solution Approach 2:
The system performs self-characterization of its noise environment by measuring the noise spectrum at the detector itself. This self-service approach allows the system to automatically determine optimal measurement parameters without requiring external calibration or complex manual adjustment, thereby improving precision while keeping the device complexity manageable.
3Reliability
If noise reduction techniques are implemented, then measurement reliability improves, but the measurement process time increases
Solution Approach 1:
The frequency selection step is performed as a preliminary action that needs to be done only once or occasionally to characterize the noise environment. Once the optimal frequency is determined, all subsequent measurements can be performed quickly at this pre-determined frequency without repeating the full frequency sweep. This approach improves reliability while minimizing time loss, as the time-consuming frequency characterization is performed only once.
Solution Approach 2:
The patent applies partial action by performing a frequency sweep over a limited frequency range rather than all possible frequencies. The system measures noise at multiple frequencies within a relevant range to identify the optimal measurement frequency, which is sufficient to achieve noise reduction without requiring an exhaustive search of all possible frequencies. This balances reliability improvement with time efficiency.
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 significantly improves the robustness of yarn quality control by minimizing noise interference, leading to more reliable detection of imperfections such as thick and thin spots, neps, and foreign fibers.
Implementation Method 1
Such methods measure, for example, the optical transmission or reflection of a yarn in order to be able to determine thin areas, thick areas, neps, foreign fibers, off-colors or other optically recognizable defects
Implementation Method 2
Such methods measure, for example, the optical transmission or reflection of a yarn
Implementation Method 3
the measuring light is modulated with a specific frequency, with the modulation frequency being generated by an oscillator whose feedback circuit contains the light source and the detector
Implementation Method 4
WO 99/30108 describes a method which switches the amplifier synchronously with the modulation frequency of the light source for the same reason
Data Source
Figure 1~3
Figure 4
AI summary
The method involves measuring a parameter of a yarn (10) and/or yarn sequence with a measuring frequency using a detector i.e. light sensor (12). A noise value in the detector is determined with multiple frequencies in a frequency selecting step, where the measuring frequency depends on the noise value determined in the frequency selecting step. The measuring frequency is set at a frequency, which possesses smallest noise in the frequency selection step. A temporal distribution of signals from the detector is determined, where the signal is divided into its frequency portions.