Microwave Resonator Array for Absorbent Web Moisture Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in measuring absorbent hygiene articles, such as diapers, lies in the difficulty of accurately determining the moisture and density of absorbent bodies applied to a continuous web, especially when the web width exceeds the microwave resonator's measurement capabilities and the distance between diaper cores is smaller than the resonator's diameter, leading to incomplete empty calibration and unreliable measurement results.
Innovation Solution
The use of multiple microwave resonators offset in both the transverse and transport directions ensures a homogeneous field distribution, allowing for continuous measurement of the web's entire width, with each resonator averaging its values and correcting for offset to provide an overall average value independent of transport speed, and employing local minima detection to compensate for temperature and contamination influences without requiring empty calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single microwave resonator is used to measure the web, then the device complexity is low, but the measurement precision is insufficient because the web width exceeds the resonator's measurement capabilities
Solution Approach 1:
The web measurement is divided into multiple segments by using several microwave resonators arranged in the transverse direction. Each resonator measures a specific portion of the web width, and the individual measurements are combined to obtain the overall web properties. This segmentation allows the system to handle wider webs while maintaining measurement precision.
Solution Approach 2:
The measurement system is extended from a single resonator position to multiple positions in the transverse direction. By adding the transverse dimension to the measurement arrangement, the system can cover the entire web width while maintaining homogeneous field distribution through careful positioning.
2Measurement precision
If multiple microwave resonators are arranged to cover the entire web width, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
The web measurement is divided into multiple segments by using several microwave resonators arranged in the transverse direction. Each resonator measures a specific portion of the web width, and the individual measurements are combined to obtain the overall web properties. This segmentation allows the system to handle wider webs while maintaining measurement precision.
Solution Approach 2:
Multiple microwave resonators perform the same measurement function simultaneously across different transverse positions. This multi-functionality allows the system to measure the entire web width using identical resonator units, simplifying the design while improving coverage and precision.
3Stability of the object's composition
If the microwave resonators are offset in the transport direction, then the homogeneous field distribution is maintained, but the measurement precision requires correction for offset
Solution Approach 1:
The system performs preliminary correction calculations to account for the transport direction offsets of the resonators. By pre-calculating the required corrections based on known offset distances and transport speed, the system can accurately combine measurements from offset resonators without compromising measurement precision.
Solution Approach 2:
The system uses feedback from the measured values and known offset positions to correct the combined measurement results. The correction process accounts for the temporal displacement caused by transport speed, ensuring that measurements from offset resonators are properly aligned and combined for accurate web property determination.
4Productivity
If the distance between diaper cores is smaller than the resonator diameter, then the productivity is high, but the measurement precision deteriorates due to incomplete empty calibration
Solution Approach 1:
The system performs preliminary measurements during periods when no diaper core is present in the measurement zone, even if these periods are brief or partial. These preliminary empty resonator measurements are stored and used as reference values for subsequent correction calculations, enabling accurate measurement despite high production speeds and small core spacing.
Solution Approach 2:
The system continuously monitors for empty resonator conditions and uses feedback from these measurements to update the baseline reference values. When diaper cores are present, the system subtracts the stored empty resonator values from the measurements, correcting for the lack of complete empty calibration and maintaining measurement precision.
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 accurate measurement of mass and moisture content across the entire width of the web, independent of transport speed and distance between diaper cores, providing precise quality control in diaper production without the need for frequent empty calibration adjustments.
Implementation Method 1
Moisture and/or density of the absorbent bodies are recorded in two or more microwave resonators with the help of a resonant frequency shift (A) and a resonant frequency broadening (B)
Implementation Method 2
EP 1 933 132 A2 discloses a method for determining the moisture content of a running web of material, which is measured using a microwave resonator
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a device for measuring absorbent hygiene particles, in which absorbent bodies spaced apart from one another are applied to a continuous web, wherein moisture and/or density of the absorbent bodies is/are measured by using two or more microwave resonators with the aid of a resonant frequency shift (A) and a resonant frequency dispersion (B), wherein the web is transported through the microwave resonators and two microwave variables (A, B) are measured continuously, wherein, relative to a transport direction of the web, the two microwave resonators are arranged to be offset relative to each other in the transverse and transport direction in order to measure the entire width of the web.