Flexible Display Substrate Stress Absorbing Layers

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Solution Overview

Problem

Flexible display devices face damage due to excessive stress when bent or folded, particularly affecting driving devices and pixels with solid inorganic layers.

Innovation Solution

Incorporating a flexible substrate with a thin film transistor, first and second stress absorbing layers, and protection layers to absorb and distribute excessive stress, preventing damage to the driving devices and pixels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible substrate is bent or folded to enable flexible display devices, then the flexibility and portability of the display device is improved, but excessive stress is applied to the driving devices and pixels causing damage

Engineering Contradiction:

ImproveflexibilityVSAvoiddamage to driving devices

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A buffer layer is formed between the flexible substrate and the driving devices/pixels before the bending stress is applied. This buffer layer absorbs and distributes the excessive stress that occurs during bending or folding, preventing direct transmission of stress to the fragile inorganic layers of the driving devices and pixels, thereby protecting them from damage while maintaining flexibility

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Adaptability or versatility

If a very thin substrate or flexible synthetic resin substrate is used to enable folding, then the flexibility of the display device is improved, but the structural strength to resist stress is reduced

Engineering Contradiction:

ImproveflexibilityVSAvoidresistance to stress

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The substrate structure is designed as a composite system combining the flexible substrate with a buffer layer having different mechanical properties. This composite structure allows the substrate to maintain its flexibility while the buffer layer provides additional stress resistance and distributes mechanical loads, solving the contradiction between flexibility and stress resistance

Inventive Principle:

Principle #40Composite materials

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 stress absorbing layers effectively reduce damage to the thin film transistors and pixels by distributing excessive stress, enhancing the durability of flexible display substrates during bending or folding.

Implementation Method 1

a first stress absorbing layer below the thin film transistor... a second stress absorbing layer on the thin film transistor

Methodology Applied

Scientific EffectStress absorption: Elasticity

Data Source

PatentUS7943932B2Display substrate, display device and method of manufacturing the same

Publication Date: 2011.05.17 LG DISPLAY CO LTD

AI summary

A flexible display substrate includes: a thin film transistor on the flexible substrate, the thin film transistor including a gate electrode, a gate insulating layer insulating the gate electrode, a channel layer on the gate insulating layer, a source electrode connected with the channel layer, and a drain electrode connected with the channel layer; a first stress absorbing layer below the thin film transistor; a first protection layer on the first stress absorbing layer; a second stress absorbing layer on the thin film transistor; a second protection layer on the second stress absorbing layer; and a pixel electrode on the second protection layer, the pixel electrode being connected with the drain electrode.