Touch Sensor Shield Electrode Reducing Parasitic Capacitance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional touch sensors for electronic displays face issues with parasitic capacitance, sensitivity, and optical interference, which affect the thickness, conductivity, and manufacturing yield of the devices, leading to reduced transparency and increased mechanical stress.

Innovation Solution

A self-capacitive touch sensor design featuring a shield electrode and touch sensor electrodes made of conductive opaque materials, with a thin insulating layer, directly integrated onto the display panel, reducing parasitic capacitance and optimizing the layout to minimize light blocking and enhance sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional transparent touch sensors are used, then transparency is maintained, but parasitic capacitance increases and sensitivity decreases

Engineering Contradiction:

Improvetouch sensitivityVSAvoidparasitic capacitance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A shield electrode layer is introduced as an intermediary between the touch sensor electrode and the display panel electrodes. This shield layer acts as a mediator that blocks parasitic capacitance coupling while allowing the touch sensor to maintain high sensitivity. The shield electrode is connected to ground potential to actively cancel out parasitic electric fields.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The touch sensor structure is segmented into distinct functional layers: the display panel, the shield electrode layer, the insulating layer, and the touch sensor electrode. This segmentation allows each layer to perform its specific function independently, with the shield layer specifically targeting parasitic capacitance reduction without affecting the touch sensing function.

Inventive Principle:

Principle #1Segmentation

2Reliability

If opaque conductive materials are used for touch sensor electrodes, then conductivity is improved, but light blocking increases

Engineering Contradiction:

ImproveconductivityVSAvoidlight transmission

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The solution moves the opaque conductive material from the optical path dimension to a different dimensional arrangement. The shield electrode and touch sensor electrode are positioned in stacked layers separated by insulating material, allowing the opaque materials to provide high conductivity without blocking light in the primary viewing dimension. The electrodes are arranged to overlap display pixels minimally.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The opaque conductive materials are strategically positioned only where needed for electrical connectivity and shielding functions, rather than covering the entire touch sensor area. The electrodes are patterned to provide local conductivity enhancement while maintaining overall light transmission through the display panel.

Inventive Principle:

Principle #3Local quality

3Length of moving object

If touch sensor is integrated directly on display panel, then thickness is reduced, but manufacturing complexity increases

Engineering Contradiction:

Improvedevice thicknessVSAvoidmanufacturing process

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The touch sensor structure is merged with the display panel construction by integrating the shield electrode layer into the same manufacturing process sequence. The insulating layer is deposited over the display panel, and the touch sensor electrode is formed on top, creating a combined structure that reduces overall thickness while using compatible fabrication techniques.

Inventive Principle:

Principle #5Merging (Combining)

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 significantly reduces parasitic capacitance, improves touch sensitivity, and maintains optical quality by minimizing light blocking, allowing for thinner, more conductive, and uniformly sensitive touch sensors with reduced manufacturing defects.

Implementation Method 1

Conventional touch sensors for electronic displays face issues with parasitic capacitance

Methodology Applied

Scientific EffectParasitic capacitance: Parasitic Capacitance

Implementation Method 2

a thin insulating layer

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS10452201B1Touch sensor for display with shield

Publication Date: 2019.10.22 SHARP KK

AI summary

A display device includes a display panel including a plurality of sub-pixels; a shield electrode that is made of a first conductive and opaque material, is located directly on the display panel, overlaps a portion of the display panel in between a portion of the plurality of sub-pixels, and is connected to a touch sensor controller; an insulating layer that covers the shield electrode; a touch sensor electrode that is made of a second conductive and opaque material, is located on the insulating layer, overlaps a portion of the display panel in between some of the plurality of sub-pixels, and overlaps the shield electrode; and a feedline is connected to the touch sensor electrode, overlaps a portion of the display panel in between a portion of the plurality of sub-pixels that is not overlapped by the touch sensor electrode, and routes the touch sensor electrode to the touch sensor controller.