Multilayered Common Electrodes for LCD Flicker Reduction

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Solution Overview

Problem

LCD panels operating at low frequencies experience flicker issues due to brightness drops and increased parasitic capacitance, leading to noticeable flicker problems for human observers.

Innovation Solution

A pixel structure comprising a scan line, data line, switching element, planarization layer, first and second common electrodes, and insulating layers, where the pixel electrode is electrically connected through contact holes, and the second common electrode is separated from the pixel electrode, reducing parasitic capacitance and increasing storage capacitance to mitigate flicker.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the LCD panel operates at low frequency to save energy, then energy consumption is reduced, but brightness stability deteriorates causing flicker problems

Engineering Contradiction:

Improveenergy consumptionVSAvoidbrightness stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The common electrode is divided into a first common electrode and a second common electrode positioned on opposite sides of the liquid crystal layer. This segmentation allows independent optimization of each electrode's position and function, enabling better control of electric field distribution to maintain brightness stability at low frequencies while preserving energy savings.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a vertical dimension by placing common electrodes on both the upper and lower sides of the liquid crystal layer, rather than only on one side. This three-dimensional configuration enhances the electric field control capability, preventing brightness fluctuations and flicker at low operating frequencies while maintaining energy efficiency.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Device complexity

If the pixel structure uses conventional single-layer common electrode, then device complexity is low, but parasitic capacitance increases causing brightness drop

Engineering Contradiction:

Improveelectrode structure complexityVSAvoidparasitic capacitance

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The common electrode is segmented into two separate electrodes (first and second common electrodes) positioned on opposite sides of the liquid crystal layer. This segmentation reduces parasitic capacitance by minimizing the overlap between the common electrode and the pixel electrode, while the increased device complexity is offset by the significant improvement in brightness stability and reduction of flicker.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The liquid crystal layer acts as an intermediary between the first and second common electrodes, allowing the electric field to be controlled more effectively. This intermediary configuration reduces parasitic capacitance effects while maintaining the necessary electric field distribution for proper display operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If the common electrode is positioned close to the pixel electrode for efficient charging, then charging speed improves, but parasitic capacitance increases causing brightness fluctuation

Engineering Contradiction:

Improvecharging speedVSAvoidparasitic capacitance

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

By segmenting the common electrode into two separate electrodes positioned on opposite sides of the liquid crystal layer, the patent maintains efficient charging pathways while reducing parasitic capacitance. The first common electrode can be positioned to optimize charging for its side, while the second common electrode on the opposite side provides symmetric field distribution without creating excessive parasitic capacitance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent resolves the proximity-parasitic capacitance trade-off by moving to a three-dimensional configuration where common electrodes are positioned on both upper and lower sides of the liquid crystal layer. This allows optimal charging geometry from both directions while the separated electrode positions minimize parasitic capacitance effects, achieving both fast charging and brightness stability.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS10564500B2Pixel structure with multilayered common electrodes and touch panel thereof

Publication Date: 2020.02.18 AU OPTRONICS CORP

AI summary

A pixel structure includes a scan line, a data line, a switching element, a planarization layer, a first common electrode, a common line, a first insulating layer, a pixel electrode, a second insulating layer, and a second common electrode. The switching element includes a source and a drain. The common line is located on the planarization layer and directly connected with the first common electrode. The planarization layer is located on the scan line, the data line, and the switching element. The pixel electrode is electrically connected with the drain through a first contact hole, wherein the first contact hole penetrates through the planarization layer and the first insulating layer. The second common electrode is electrically connected with the first common electrode through a second contact hole, wherein the second contact hole penetrates through the first insulating layer and the second insulating layer. A touch panel is also provided.