In-Cell Touch LCD Common Electrode Resistance Reduction

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Solution Overview

Problem

Current in-cell touch liquid crystal display panels face issues with poor touch signal detection at the center due to high resistance in common electrodes, leading to unreliable touch responses and reduced sensitivity.

Innovation Solution

A transparent conductive layer is deposited on the common electrodes, connected in parallel, to reduce the resistance of the common electrodes, improving signal detection and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transparent conductive layer is deposited on the common electrode, then the electrical conductivity is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improvetouch signal detection reliabilityVSAvoidlayer structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies composite materials by combining the common electrode material with a transparent conductive material (such as ITO - indium tin oxide) to form a composite electrode structure. This composite structure reduces the overall resistance of the common electrode while maintaining transparency, thereby improving touch signal detection reliability without fundamentally changing the device architecture

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes the electrical parameters of the common electrode by adding a transparent conductive layer with different electrical properties. This modifies the resistance and conductivity parameters of the common electrode, enabling better signal detection at the center of the display panel where signal strength is typically weakest

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the common electrode resistance is reduced by adding conductive layers, then the touch sensitivity is improved, but the manufacturing process complexity increases

Engineering Contradiction:
Improvetouch signal detection precisionVSAvoidmanufacturing process simplicity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The transparent conductive layer is deposited on the common electrode during the array substrate manufacturing process, before the final assembly is completed. This preliminary action ensures that the resistance reduction is built into the structure early, avoiding the need for additional post-assembly modifications and simplifying the overall manufacturing workflow

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The transparent conductive layer acts as an intermediary between the common electrode and the liquid crystal layer, providing a dual function: it serves as both a structural component of the electrode system and a conductive element that reduces resistance. This intermediary layer facilitates better electrical connection without interfering with the optical or liquid crystal functions

Inventive Principle:
Principle #24Intermediary (Mediator)

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 reduced resistance enables reliable touch signal detection across the panel, enhancing the sensitivity and accuracy of touch input, particularly at the center.

Implementation Method 1

A transparent conductive layer is deposited on the common electrodes

Methodology Applied
Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

connected in parallel, to reduce the resistance of the common electrodes

Methodology Applied
Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentEP2804043B1Touch liquid crystal display panel and manufacturing method thereof
Publication Date: 2021.03.03 SHANGHAI TIANMA MICRO ELECTRONICS CO LTD
  • EP2804043B1 patent drawingFigure 1~2
  • EP2804043B1 patent drawingFigure 3~4
  • EP2804043B1 patent drawingFigure 5~6

AI summary

An array substrate includes a plurality of pixel units, each of the pixel units includes a pixel electrode (202) and a common electrode (204) that are insulated from each other, and a conductive layer (206) that is electrically connected in parallel to the common electrode. A double-layer metal layer is deposited on the common electrode at an opaque region of the pixel electrode to form a ring structure around a transparent region of the pixel electrode, thus reducing the resistances of the common electrodes. The ring structure can be U-shaped, half-ring shaped, or full-ring shaped.