Capacitive Sensor Assembly Temperature Drift Control

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Solution Overview

Problem

Modern textile testing devices experience significant temperature drift due to heat loss from complex electronic circuits, leading to unstable measurement results, despite ventilation efforts which are also susceptible to temperature changes.

Innovation Solution

A capacitive sensor assembly with a temperature sensor and controllable electrothermal transducer, such as a Peltier element, is integrated to actively regulate the temperature of heat-sensitive components, ensuring stable measurements by maintaining constant thermal conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex electronic circuits are used for controlling measuring capacitors, then measurement functionality is improved, but temperature drift increases due to heat loss from electronic components

Engineering Contradiction:
Improvemeasurement functionalityVSAvoidtemperature drift
Core Design Contradiction:
Measurement precisionVSTemperature

Solution Approach 1:

The sensor assembly is divided into functionally independent parts: the capacitive measuring components and the electronic control circuits are separated spatially and thermally. This segmentation allows the electronic circuits to be isolated from the sensitive measuring capacitors, preventing heat generated by the circuits from causing temperature drift in the measuring components.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A thermally conductive but electrically insulating intermediate structure is introduced between the electronic circuits and the measuring capacitors. This intermediary component allows thermal management while maintaining electrical isolation, enabling the electronic circuits to be positioned closer to the measuring components without transferring harmful heat.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If ventilation is used to cool the sensor assembly, then heat dissipation is improved, but measurement stability deteriorates because outside air temperature changes cause thermal drift

Engineering Contradiction:
Improveheat dissipationVSAvoidmeasurement stability
Core Design Contradiction:
Loss of energyVSTemperature

Solution Approach 1:

The sensitive capacitive measuring components are extracted from the ventilated environment and placed in a thermally isolated chamber. By removing the measuring components from the path of temperature-fluctuating air flow, the system achieves effective heat dissipation for the electronic circuits while protecting the measuring components from thermal instability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Different thermal conditions are applied to different parts of the sensor assembly: the electronic circuits are exposed to active cooling through ventilation, while the capacitive measuring components are maintained in a thermally stable, isolated environment. This local differentiation of thermal management strategies optimizes both heat dissipation and measurement stability.

Inventive Principle:
Principle #3Local quality

3Reliability

If the entire sensor assembly is heated above ambient temperature for stability, then resistance to temperature and humidity changes is improved, but energy consumption increases and thermal equilibrium takes time to reach

Engineering Contradiction:
Improvestability to temperature changesVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The thermal management system transitions from a static heated state to a dynamic, adaptive system. Temperature sensors continuously monitor the actual temperature of the measuring components, and the heating elements are controlled in real-time to maintain optimal temperature only when and where needed, rather than maintaining a constant elevated temperature throughout the assembly.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the temperature parameter dynamically based on actual operating conditions rather than maintaining a fixed elevated temperature. By using feedback control to adjust the temperature of electronic components independently from the measuring components, the system achieves stability with lower overall energy consumption and faster thermal response.

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 effectively stabilizes the temperature of the capacitive sensor assembly, reducing temperature drift and providing consistent measurement results by actively managing heat loss and environmental temperature fluctuations.

Implementation Method 1

controllable electrothermal transducer, such as a Peltier element, is integrated to actively regulate the temperature

Methodology Applied
Scientific EffectPeltier effect: Peltier Effect

Data Source

PatentEP3164699B1Capacitive sensor assembly for a textile testing device
Publication Date: 2021.07.28 USTER TECHNOLOGIES AG
  • EP3164699B1 patent drawingFigure 1
  • EP3164699B1 patent drawingFigure 2
  • EP3164699B1 patent drawingFigure 3(a)~3(b)

AI summary

The capacitive sensor assembly (2) for a testing device (1) for testing an elongated textile sample comprises at least one measuring electrode as part of a measuring capacitor for the capacitive testing of the sample, and an electrical circuit that is electrically connected to the at least one measuring electrode. The capacitive sensor assembly (2) also comprises a temperature sensor for measuring a temperature of at least one part (4) of the capacitive sensor assembly (2), and a controllable electro-thermal converter (5) that is thermally connected to the at least one part (4) of the capacitive sensor assembly (2). In this way, the at least one part (4) of the capacitive sensor assembly (2) can be regulated to a desired temperature value, such that the capacitive sensor assembly (2) measures in a substantially stable manner and without temperature drift.