Integrated Capacitive and Resistive Sensor for Touch and Strain Detection

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Solution Overview

Problem

Capacitance touch sensors struggle to differentiate between user touch and other parameters such as strain, chemical presence, or contortion, as they primarily rely on capacitance changes, lacking integration with variable resistance sensors to provide comprehensive sensing capabilities.

Innovation Solution

Incorporating at least one variable resistor sensor within the capacitance touch sensor arrangement, which varies resistance based on sensed parameters, allowing for a single output signal that combines capacitance and resistance data to differentiate touch, hover, pressure, bending, twisting, and stretching inputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If only capacitance sensing is used, then the sensor structure remains simple, but the sensor cannot differentiate between user touch and other parameters such as strain, chemical presence, or contortion

Engineering Contradiction:
Improvetouch detection accuracyVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines capacitance sensing and resistance sensing into a single integrated sensor arrangement. The capacitance touch sensor arrangement includes at least one variable resistance sensor integrated within it, allowing simultaneous measurement of both capacitance and resistance changes from the same sensor structure rather than using separate sensors.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated sensor arrangement serves multiple functions: it detects user touch through capacitance changes, strain through resistance changes, and can differentiate between various input types (touch, hover, pressure, bending, twisting, stretching) by analyzing the combined signals from both sensing mechanisms.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If capacitance and resistance sensors are integrated, then comprehensive sensing capabilities are achieved, but the device complexity increases

Engineering Contradiction:
Improvesensing capabilitiesVSAvoidsensor integration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent integrates the variable resistance sensor within the capacitance touch sensor arrangement, sharing common structural elements and processing circuitry. This merging approach enables comprehensive sensing capabilities while minimizing the increase in device complexity through shared components and unified signal processing.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a single output signal combines both capacitance and resistance data, then signal processing is simplified, but the ability to differentiate between multiple parameters may be reduced

Engineering Contradiction:
Improvesignal processingVSAvoidparameter differentiation
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The signal processing circuitry analyzes the combined output signal by extracting information from both the capacitance component and resistance component. The system uses feedback mechanisms to differentiate between various parameters (touch, hover, pressure, bending, twisting, stretching) by pattern recognition and signal analysis, maintaining measurement precision while simplifying the output to a single processed signal.

Inventive Principle:
Principle #23Feedback

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 accurate detection and differentiation of user interactions and device contortion by processing orthogonal real and imaginary components of the output signal, enhancing the sensor's ability to provide detailed information on touch location, force, and deformation.

Implementation Method 1

A capacitance touch sensor arrangement may be used to detect a user touch. When a user touches the touch sensor arrangement charge is sourced from or sunk at the user changing the capacitance of the touch sensor arrangement.

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

at least one variable resistor sensor integrated within the capacitance touch sensor arrangement wherein the variable resistor sensor has a variable resistance that varies with a sensed parameter

Methodology Applied
Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentEP2820514B1Capacitive and resistive sensor
Publication Date: 2020.05.13 NOKIA TECHNOLOGIES OY
  • EP2820514B1 patent drawingFigure 1~4
  • EP2820514B1 patent drawingFigure 5
  • EP2820514B1 patent drawingFigure 6~7

AI summary

An apparatus including a capacitance touch sensor arrangement configured to have a variable capacitance that varies when a user finger touches the capacitance touch sensor arrangement; and at least one variable resistor sensor integrated within the capacitance touch sensor arrangement wherein the variable resistor sensor has a variable resistance that varies with a sensed parameter; the apparatus including an input configured to receive an input signal including a time varying component and an output configured to provide an output signal that depends upon both the capacitance of the capacitance touch sensor arrangement and the resistance of the variable resistance sensor.