Backplane Substrate Dummy Pixel Slits for Flexible Display
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Solution Overview
Problem
Flexible displays face issues with damage and water permeation due to repeated folding, leading to turn-on failure and image quality deterioration, as high physical stress causes cracks and water permeation at the folding edges, which propagate to the center.
Innovation Solution
A backplane substrate with a dummy pixel configuration that includes slits in the edge portion to separate dummy pixels, preventing stress propagation and water permeation, featuring a flexible base with active and dummy pixel areas, buffer stacks, interlayer insulation, and slits defined by removing insulation layers to expose buffer stacks or wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If repeated folding operations are performed on flexible display, then the display can be folded and unfolded multiple times, but cracks and water permeation occur at the folding edges and propagate to the center
Solution Approach 1:
The dummy pixel region is divided into multiple separate dummy pixels by forming slits between them. This segmentation prevents stress and cracks from propagating continuously across the entire edge region, as the slits act as discontinuities that break the stress path.
Solution Approach 2:
The slits are formed by removing the interlayer insulation layer and underlying buffer layers in the dummy pixel regions. This extraction of material creates physical gaps that prevent crack propagation and water permeation paths along the folding edges.
2Ease of manufacture
If dummy pixels are configured continuously along the edge, then the structure is simple and manufacturing is easy, but stress and cracks propagate along the edge during folding
Solution Approach 1:
Instead of configuring dummy pixels as a continuous region, the patent segments them by forming slits between adjacent dummy pixels. This segmentation maintains manufacturing simplicity while effectively preventing crack propagation along the edge during folding operations.
3Reliability
If the interlayer insulation layer is removed to form slits, then crack propagation is prevented, but the structure becomes more complex
Solution Approach 1:
The formation of slits is merged with the existing etching process for contact holes. The same etching steps used to create contact holes are extended to also form slits in the dummy pixel regions, thereby preventing crack propagation without adding separate processing steps.
4Reliability
If slits are formed in dummy pixels, then water permeation and crack propagation are prevented, but manufacturing precision requirements increase
Solution Approach 1:
The slit formation is combined with the contact hole etching process, using the same masks and etching conditions. This merging ensures that slit positioning and dimensions are controlled by the well-established contact hole fabrication process, thereby maintaining manufacturing precision without requiring new precision standards.
Data Source
AI summary
Disclosed are a backplane substrate, which has a modified dummy pixel configuration, thereby preventing water permeation and cracks from the side surface due to repeated folding, and a flexible display using the same. A plurality of slits is provided in a dummy pixel portion and separates an interlayer insulation stack for respective dummy pixels.