Touch Sensor Electrode Layout for Simultaneous Position and Pressure Sensing

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Solution Overview

Problem

Existing touch sensors for mobile displays face challenges in detecting pressing pressure without hindering touch position sensing, particularly due to shielding effects from pressure detection electrodes in electrostatic capacitance schemes.

Innovation Solution

A touch sensor design featuring first and second electrodes for touch position sensing and third electrodes for pressure detection, with a flexible insulation layer between the first and third electrodes, ensuring the electric field is not completely shielded, allowing simultaneous touch position and pressure sensing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressing pressure detection electrodes are disposed to overlap touch position detection electrodes, then pressing pressure can be detected, but the sensing operation of touch position is hindered due to electric field shielding

Engineering Contradiction:

Improvepressing pressure detectionVSAvoidtouch position sensing

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies local quality by making the third electrode (pressing pressure detection electrode) have a smaller area than the first electrode (touch position detection electrode). This localized reduction in electrode area allows the third electrode to detect pressing pressure while minimizing its shielding effect on the electric field between the first and second electrodes, thus maintaining touch position sensing reliability.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If a pressure sensor is mounted on the display, then pressing pressure detection is enabled, but light emission is hindered due to the pressure sensor not being transparent

Engineering Contradiction:

Improvepressing pressure detectionVSAvoidlight emission

Core Design Contradiction:

Measurement precisionVSIllumination intensity

Solution Approach 1:

The patent replaces the mechanical pressure sensor with an electrostatic capacitance-based sensing system. Instead of using a physical pressure sensor that blocks light, the invention uses electrodes that detect pressing pressure through changes in electrostatic capacitance, allowing light to pass through transparently while still enabling pressure detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the area of the third electrode is reduced, then electric field shielding is minimized and touch position sensing is maintained, but pressing pressure detection sensitivity may be reduced

Engineering Contradiction:

Improvetouch position sensingVSAvoidpressing pressure detection

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent resolves the sensitivity issue by utilizing the vertical dimension (thickness direction) rather than relying solely on horizontal electrode area. The flexible insulation layer's deformation in the thickness direction under pressure creates a detectable change in electrostatic capacitance between the first and third electrodes, enabling effective pressure detection even with a smaller third electrode area.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 effective detection of touch positions using first and second electrodes while allowing for pressure sensing using first and third electrodes, maintaining optimal electric field integrity and optical characteristics.

Implementation Method 1

Electrostatic capacitance schemes are widely used for touch panels of mobile displays of smartphones or the like

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

detect a pressing pressure using the first electrode and the third electrode

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS11366542B2Touch sensor and display device with touch sensor

Publication Date: 2022.06.21 MAGNOLIA WHITE CORP

AI summary

First electrodes are formed on an insulation surface in such a manner that the adjacent first electrodes are connected in a first direction and are separated in a second direction intersecting the first direction. Second electrodes are formed on an insulation surface in such a manner that the adjacent second electrodes are connected in the second direction and are separated in the first direction. Third electrodes are formed in regions in which the third electrodes overlap with the first electrodes and do not overlap with the second electrodes in such a manner that the adjacent third electrodes are connected in the second direction and are separated in the first direction. A flexible insulation layer is formed between the first electrodes and the third electrodes. An area of each of the third electrodes is less than an area of each of the first electrodes.