Foldable Display Panel Blocking Layer for Bending-Region Mura

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Solution Overview

Problem

The challenge is to address the mura issue that occurs on display panels near the bending region, which is exacerbated by the use of clear polyimide (CPI) substrates that experience high thermal stress, water absorption, and coefficient of thermal expansion.

Innovation Solution

A display panel design that includes a first transparent substrate, a blocking layer with a first blocking part in the bending region, a first inorganic layer covering the substrate and blocking layer, a semiconductor layer, and a second inorganic layer with a via in the bending region. The blocking layer prevents the via from exposing the transparent substrate, thereby mitigating mura formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If clear polyimide (CPI) substrate is used to improve transparency of under screen camera region, then transparency is improved, but thermal stress and water absorption increase causing mura near bending region

Engineering Contradiction:

ImprovetransparencyVSAvoiddisplay quality stability

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

A blocking layer is introduced as an intermediary between the transparent substrate and the via structure. This blocking layer prevents direct exposure of the transparent substrate to moisture and etching processes, thereby eliminating the mura issue while preserving the transparency benefits of the CPI substrate.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If via is formed in bending region to achieve full screen configuration, then full screen is achieved, but transparent substrate is exposed causing mura issue

Engineering Contradiction:

Improvefull screen configurationVSAvoiddisplay uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The blocking layer is formed in advance before the via etching process. This preliminary action ensures that when the via is later formed in the bending region, the transparent substrate is already protected and will not be exposed to etching processes, thus preventing mura formation while enabling full screen configuration.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If blocking layer is added to protect transparent substrate, then mura issue is alleviated, but device complexity increases

Engineering Contradiction:

Improvedisplay quality stabilityVSAvoidlayer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The blocking layer is selectively positioned only in the bending region where the via is formed, rather than covering the entire substrate. This local application provides targeted protection against mura while minimizing the increase in overall device complexity and maintaining manufacturing efficiency.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12205956B2Display panel and electronic device

Publication Date: 2025.01.21 WUHAN CHINA STAR OPTOELECTRONICS SEMICONDUCTOR DISPLAY TECHNOLOGY CO LTD

AI summary

An electronic device and a display panel are provided. The display panel has a display region and a bending region positioned at one side of the display region. The display panel includes a first transparent substrate, a first inorganic layer, a second inorganic layer, and a blocking layer positioned at one side of the first transparent substrate. The second inorganic layer has a first via in the bending region of the display panel. This alleviates the mura near the bending region due to the exposure of the first transparent substrate and thus alleviates the mura issue occurred on the conventional display panel close to the bending region.