Multi-layer Piezoelectric Polymer Touch Sensor with Dielectric Core

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Solution Overview

Problem

Existing touch panel technologies face challenges in accurately detecting touch location and force magnitude due to high costs and limited durability of piezoelectric materials, as well as inefficiencies in signal detection and processing.

Innovation Solution

A touch sensor design incorporating a dielectric core layer between two poled piezoelectric polymer layers, with individually addressable electrodes on each layer, and circuitry to detect changes in electrical signals, allowing for precise detection of touch location and force magnitude by utilizing a multilayer structure that can be coextruded and stretched to align dipoles for enhanced piezoelectric properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If piezoelectric materials are used for touch detection, then touch location and force magnitude can be detected, but the cost and durability are limited

Engineering Contradiction:
Improvetouch detection precisionVSAvoiddurability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent uses a composite structure with a dielectric core layer and piezoelectric polymer layers. The dielectric core provides mechanical stability and durability, while the piezoelectric polymer layers enable touch detection. This composite approach resolves the contradiction by combining materials with complementary properties - the dielectric core enhances durability while the piezoelectric layers maintain measurement precision for touch detection.

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If piezoelectric layers are made thinner to reduce cost, then manufacturing cost decreases, but signal strength may be compromised

Engineering Contradiction:
Improvemanufacturing costVSAvoidsignal strength
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The dielectric core layer with high dielectric constant enhances the piezoelectric effect in the thinner polymer layers. The composite structure allows cost-effective thin piezoelectric layers while the dielectric core compensates for signal strength through its electrical properties, maintaining measurement precision despite reduced material quantity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the dielectric constant parameter by introducing a dielectric core layer with high dielectric constant material. This parameter change amplifies the piezoelectric signal generation in the thinner polymer layers, allowing cost reduction through thinner layers while maintaining sufficient signal strength for accurate touch detection.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a multilayer structure is implemented to enhance piezoelectric properties, then detection accuracy improves, but device complexity increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidstructure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The touch sensor is segmented into distinct functional layers: a dielectric core layer and piezoelectric polymer layers. This segmentation allows each layer to perform its specific function optimally - the dielectric core provides electrical enhancement and mechanical stability, while the piezoelectric layers handle touch signal generation. The segmented structure achieves high detection accuracy while managing complexity through clear functional division.

Inventive Principle:
Principle #1Segmentation

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 reduces the thickness and cost of piezoelectric layers while maintaining signal strength, enhancing stability and durability, enabling accurate touch location and force detection with improved electrical breakdown strength and reduced leakage current.

Implementation Method 1

The piezoelectric effect involves a change in electric field in response to a change in mechanical stress or force. A force applied to a piezoelectric material produces a change in the electric field across the material.

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

enabling accurate touch location and force detection with improved electrical breakdown strength and reduced leakage current

Methodology Applied
Scientific EffectDielectric effect: Dielectric

Data Source

PatentEP3072169B1Multi-layer piezoelectric polymer film device
Publication Date: 2020.01.01 3M INNOVATIVE PROPERTIES CO
  • EP3072169B1 patent drawingFigure 1~3
  • EP3072169B1 patent drawingFigure 4
  • EP3072169B1 patent drawingFigure 5~6

AI summary

A touch panel includes a touch sensor having a dielectric core layer disposed between first and second piezoelectric layers. Each piezoelectric layer comprises a poled piezoelectric polymer. The touch sensor further includes at least a first set of individually addressable electrodes disposed over the first piezoelectric layer and at least one second electrode disposed over the second piezoelectric layer. Circuitry is coupled to the first set of electrodes and the second electrode. The circuitry is configured to detect a change in an electrical signal of at least one electrode of the first set of electrodes referenced to the second electrode in response to a touch applied to the touch surface of the touch sensor.