Capacitive Sensor for Textile Fiber Thickness and Height Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring transverse geometric parameters of textile fibrous structures, such as thickness and height, are limited by ambient conditions and cannot accurately measure small thicknesses or fibers where height significantly exceeds thickness, especially using capacitive sensors.
Innovation Solution
A capacitive sensor system comprising a pair of plate capacitors with different electrode distances, where the textile fiber passes through both, allowing for the determination of height and thickness by measuring capacitance changes and relative permittivity, with calibration to account for measurement errors and variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single plate capacitor is used for measurement, then the device structure is simple, but it cannot determine both height and thickness of flat textile fibers where height significantly exceeds thickness
Solution Approach 1:
The measurement system is segmented into two distinct plate capacitors with different electrode distances. The first capacitor measures one geometric parameter while the second capacitor measures another parameter, allowing determination of both height and thickness of flat textile fibers. This segmentation resolves the limitation of single-capacitor systems that cannot distinguish between height and thickness when height significantly exceeds thickness.
Solution Approach 2:
The invention introduces a dimensional variation by using two plate capacitors with different electrode distances (spacings). By measuring capacitance changes at two different dimensional scales (different electrode gaps), the system can distinguish between height and thickness parameters that would be indistinguishable in a single-capacitor configuration. This dimensional approach enables accurate measurement of flat textile fibers with varying height-to-thickness ratios.
2Measurement precision
If optical sensor is used for measurement, then light absorption provides measurement signal, but ambient lighting conditions, component wear, and impurities negatively impact measurement accuracy
Solution Approach 1:
The invention replaces the optical measurement system with a capacitive measurement system. Instead of using light sources, light receivers, and diffusers that are susceptible to ambient lighting conditions and component wear, the system uses electrical fields and capacitance measurements. This substitution eliminates the harmful factors affecting optical sensors, such as ambient lighting conditions, light source wear, and impurity interference, while providing more stable and reliable measurements.
3Measurement precision
If capacitive sensor with standard electrode distance is used, then capacitance changes reflect fiber properties, but measurement accuracy deteriorates for fibers with varying height-to-thickness ratios
Solution Approach 1:
The invention applies local quality by using two plate capacitors with specifically different electrode distances tailored for different measurement needs. The first capacitor with one electrode distance is optimized for measuring certain geometric parameters, while the second capacitor with a different electrode distance is optimized for measuring other parameters. This local optimization at different measurement points (different capacitors) enables accurate measurement of various fiber types with different height-to-thickness ratios, improving both precision and adaptability.
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
Enables precise measurement of small thicknesses and fibers with varying height-to-thickness ratios, improving accuracy and reliability over existing technologies by using a pair of plate capacitors with distinct electrode spacings and calibration processes.
Implementation Method 1
The basic component of a capacitive sensor is, for example, a twoelectrode air plate capacitor. In the space between two parallel metal electrodes an electric field is created by the action of alternating voltage. If a yarn of variable thickness moves in this field, the capacitance of the plate capacitor also changes.
Implementation Method 2
In the space between two parallel metal electrodes an electric field is created by the action of alternating voltage
Implementation Method 3
The change in capacitance depends on the amount of fibers in the yarn, on the dielectric constant of the material
Data Source
Figure 1~2
AI summary
The invention relates to a method of measuring transverse geometric parameters of flat ribbon-shaped textile fibrous structures by a capacitive sensor, in which the textile fibrous structure passes through a measuring slot in a plate capacitor, whereby the textile fibrous structure passes through a measuring slot of a first plate capacitor and subsequently through a measuring slot of a second plate capacitor, whereby in each plate capacitor the capacitance is measured, which is converted by an RC circuit into a pulse of width τM and compared with an adjustable pulse of width τK generated by a compensation generator, which corresponds to the pulse width generated by the plate capacitor without the textile fibrous structure, and the time difference of pulses of width Δτ between the pulse of the RC circuit and the pulse of the compensation generator is converted by a counter counting the pulses from an auxiliary oscillator into a number of pulses p and information about the number of pulses p1, p2 of each of the two counters is sent to an evaluation circuit for calculating the geometric parameters of the textile fibrous structure.