Yarn sensor for optically sensing a yarn moved in the longitudinal direction of the yarn
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Solution Overview
Problem
Existing optical yarn sensors are prone to soiling due to dust, dirt particles, and finishing agents being deposited on their surfaces, leading to distortions in measured values during yarn monitoring.
Innovation Solution
A yarn sensor utilizing the principle of frustrated total internal reflection (FTIR) with a light guiding element that brings the yarn into contact with its outer surface, causing scattered light to be detected, which is proportional to the yarn's presence and quality, and features a self-cleaning effect due to the yarn's hairiness and boundary layer flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the yarn is guided within a measurement gap without contact, then the yarn can be monitored optically, but dust, dirt particles and finishing agents are conducted to the sensor surfaces and cause soiling that distorts measured values
Solution Approach 1:
The harmful air draft that carries contaminants is extracted and redirected away from the sensor surfaces. The housing design channels the air flow to move contaminants away from the measurement gap, preventing deposition on sensor surfaces while maintaining contactless yarn monitoring
Solution Approach 2:
A housing structure serves as an intermediary element that mediates between the yarn monitoring function and the contaminant protection function. The housing with its specific air flow channels acts as a protective barrier that prevents contaminants from reaching sensor surfaces
2Object-affected harmful factors
If cleaning mechanisms are added to the yarn sensor, then sensor surface soiling can be reduced, but the device complexity increases
Solution Approach 1:
The housing structure provides self-cleaning functionality through its air flow channel design. The air draft automatically removes contaminants from sensor surfaces without requiring external cleaning mechanisms, maintaining simplicity while addressing the soiling problem
Solution Approach 2:
Air flow is utilized as a pneumatic cleaning mechanism. The housing channels air to create a flow that removes contaminants from sensor surfaces, providing cleaning functionality without mechanical moving parts or complex systems
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 significantly reduces environmental influence-induced soiling, provides reliable yarn monitoring with minimal component structure, and allows for accurate detection of yarn presence, diameter, and contaminants, enhancing monitoring quality in textile processes.
Implementation Method 1
essentially only light from a light source that is reflected by the yarn reaches two receivers for reflected light
Implementation Method 2
at least part of the light is coupled out of the light guiding element by contact with the yarn
Data Source
AI summary
In order to optically sense a yarn moved in the longitudinal direction of the yarn, a yarn sensor has a light source, a detector and a light guiding element. The yarn sensor is based on the effect of frustrated total internal reflection (FTIR). Because of the FTIR effect, scattered light exiting the light guiding element in the contact region between the yarn and an outer surface of the light guiding element is detected by means of the detector, in which case sensing of the yarn lying against the outer surface is enabled. Alternatively, the reduced intensity in the totally internally reflected beam is then sensed by the detector. The intensity in the totally internally reflected beam is reduced mainly by the scattered light coupled out of the light guiding element.