Pixel Driving Varistor Circuit for Trace Mura Mitigation

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Solution Overview

Problem

The Trace Mura phenomenon occurs in display panels, causing abnormal white lines to appear when a hard object scratches the screen without causing physical damage, leading to poor user experience, as the lines take a long time to disappear.

Innovation Solution

Incorporating a pixel driving structure with a first or second positive pressure coefficient varistor circuit connected between the switching transistor and the pixel electrode, which increases resistance and reduces the voltage on the pixel electrode when scratched, weakening the electric field and allowing liquid crystal molecules to quickly return to their original positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hard object scratches across the screen surface, then the liquid crystal molecules are displaced causing Trace Mura phenomenon, but the screen itself and surface film layer are not physically damaged

Engineering Contradiction:
Improvedisplay qualityVSAvoidTrace Mura phenomenon
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a cushioning layer between the screen surface and the liquid crystal layer that absorbs and dissipates the impact energy from hard objects before it reaches the liquid crystal molecules. This prior cushioning prevents the liquid crystal molecules from being displaced by external scratches, thereby preventing Trace Mura phenomenon while maintaining screen integrity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If the liquid crystal molecules are quickly restored to original positions, then the Trace Mura phenomenon is minimized, but additional circuit components are required

Engineering Contradiction:
Improvedisplay qualityVSAvoidpixel driving structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent modifies the electrical parameters of the pixel driving structure by introducing variable resistance elements that dynamically adjust the voltage applied to liquid crystal molecules. When impact is detected, the resistance changes to facilitate rapid restoration of liquid crystal molecules to their original positions, minimizing Trace Mura phenomenon without requiring complete structural redesign.

Inventive Principle:
Principle #35Parameter changes

3Object-affected harmful factors

If the resistance of varistor circuit increases when scratched, then voltage is divided and electric field is reduced, but the circuit structure becomes more complex

Engineering Contradiction:
ImproveTrace Mura phenomenonVSAvoidvaristor circuit
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces a varistor circuit as an intermediary element between the power supply and the liquid crystal layer. This mediator component automatically adjusts its resistance in response to mechanical stress from scratches, thereby controlling the voltage division and electric field strength without requiring complex control systems. The varistor acts as a passive protective intermediary that simplifies the overall control architecture.

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 solution effectively reduces the deflection angles of liquid crystal molecules, improving the display panel's performance by quickly restoring the original state after pressure is removed, thus mitigating the Trace Mura phenomenon.

Implementation Method 1

a first positive pressure coefficient varistor circuit, where a first end of the first positive pressure coefficient varistor circuit is electrically connected with a drain electrode of the switching transistor, and a second end of the first positive pressure coefficient varistor circuit is electrically connected with the pixel electrode

Methodology Applied
Scientific EffectPositive pressure coefficient effect: Piezoresistive Effect

Implementation Method 2

reducing the electric field and allowing liquid crystal molecules to quickly return to their original positions

Methodology Applied
Scientific EffectLiquid crystal response to electric field: Liquid Crystals

Data Source

PatentUS20230375888A1Pixel driving structure, preparation method and display panel
Publication Date: 2023.11.23 HKC CORP LTD
  • US20230375888A1 patent drawing
  • US20230375888A1 patent drawing
  • US20230375888A1 patent drawing

AI summary

A pixel driving structure includes a switching transistor, and further includes: a first positive pressure coefficient varistor circuit. A first end of the first positive pressure coefficient varistor circuit is electrically connected with a drain electrode of the switching transistor, and a second end of the first positive pressure coefficient varistor circuit is electrically connected with the pixel electrode. The pixel driving structure can improve a problem of occurrence of Trace Mura phenomenon of the display panel.