Capacitive Yarn Inspection Circuit with Automatic Symmetry Adjustment

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Solution Overview

Problem

Existing capacitive measuring circuits for textile materials require manual and time-consuming symmetry adjustments, which are costly and prone to errors due to imperfections in real electrical components, necessitating a solution for automatic and quick adjustment.

Innovation Solution

Incorporating a capacitor arrangement that allows capacitance changes via electrical control signals, enabling automatic adjustment of the measuring circuit without mechanical interventions, and using a capacitance measuring bridge with variable capacitances for precise compensation and simulation of measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual adjustment with trimming capacitors is used, then measurement symmetry can be adjusted, but the process becomes time-consuming and expensive

Engineering Contradiction:
Improvemeasurement symmetryVSAvoidadjustment time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical manual adjustment system (screwdriver-based trimming capacitor adjustment) with an electrical control system. The control unit sends electrical control signals to the variable capacitance element, enabling electronic adjustment of the measuring circuit's symmetry without physical intervention. This substitution eliminates the time-consuming manual process while maintaining measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control unit automatically adjusts the variable capacitance element based on feedback from the measuring circuit, enabling self-adjustment of measurement symmetry. The system can perform automatic calibration and compensation without requiring operator intervention, thereby reducing adjustment time and eliminating manual labor while maintaining precise measurement capability.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If manual trimming is performed, then circuit symmetry can be adjusted, but device complexity increases due to opening and mechanical components

Engineering Contradiction:
Improvecircuit symmetryVSAvoidadjustment mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent eliminates mechanical trimming components (screwdrivers, adjustable capacitors requiring physical access) by implementing an electronically controlled variable capacitance element. The control unit manages the adjustment process through electrical signals, simplifying the device structure by removing mechanical adjustment mechanisms while maintaining the ability to achieve precise circuit symmetry.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the adjustment function from the mechanical domain and relocates it to the electrical/control domain. By separating the control function (implemented in the control unit) from the measuring function, the system eliminates the need for mechanical trimming components and their associated complexity, while preserving the essential symmetry adjustment capability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Measurement precision

If laser trimming is used, then adjustment precision improves, but cost and device complexity increase

Engineering Contradiction:
Improveadjustment precisionVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces expensive laser trimming equipment and processes with a cost-effective electrical control system. The variable capacitance element controlled by the control unit provides precise adjustment capability without requiring expensive laser equipment, specialized facilities, or complex manufacturing processes, thereby significantly reducing manufacturing costs while maintaining adjustment precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent achieves precise adjustment of circuit symmetry by dynamically changing the capacitance parameter of the variable capacitance element through electrical control signals. This approach allows for continuous, fine-grained adjustment of the circuit parameters without the need for expensive fixed-value laser trimming, enabling precise control at lower manufacturing costs.

Inventive Principle:
Principle #35Parameter changes

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 allows for simple, quick, and inexpensive automatic adjustment of the measuring circuit, improving measurement accuracy, reliability, and reproducibility, while also enabling simulation and testing of components without operator intervention.

Implementation Method 1

a measuring circuit with a measuring capacitor, which is designed as a plate capacitor, is made available. An electrical alternating voltage is applied to the measuring circuit, as a result of which an alternating electrical field is generated in the measuring capacitor.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

The dielectric properties of the test material are determined. Parameters of the test material such as mass per unit length and/or material composition are determined from the dielectric properties.

Methodology Applied
Scientific EffectDielectric properties: Dielectric

Data Source

PatentEP2347251B1Capacitive measuring circuit for yarn inspection
Publication Date: 2014.02.26 USTER TECHNOLOGIES AG
  • EP2347251B1 patent drawingFigure 1~2
  • EP2347251B1 patent drawingFigure 3~4
  • EP2347251B1 patent drawingFigure 5

AI summary

The measuring circuit (1) can be used for the capacitive analysis of a moving elongated textile test material, such as a card sliver, roving, yarn or woven fabric. It comprises a precision capacitor (2) for receiving the test material. It further includes a component (3) having a capacitance that can be varied by way of an electric control signal (71). In this way, the measuring circuit (1) can be aligned easily, quickly, cost-effectively and in particular automatically.