Bent Display Encapsulation Structure for Crack-Resistant Touch Areas
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Solution Overview
Problem
Existing display devices face challenges in maintaining structural integrity and minimizing cracking when a portion of the display area is bent, particularly due to stress from bending, which can affect layers such as the thin-film encapsulation and touch sensing layers.
Innovation Solution
Incorporating a thin-film encapsulation layer with alternating layers of inorganic and silicon carbon compound materials, and a touch sensing layer with specific conductive and insulating layers, which are designed to withstand bending stress by using materials like silicon oxycarbide and silicon oxide, and flexible connection portions for trace lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a display area is bent to achieve flexible form factors, then adaptability and versatility are improved, but structural integrity and reliability deteriorate due to bending stress causing cracking
Solution Approach 1:
The encapsulation layer is divided into multiple thin alternating inorganic and organic layers instead of a single thick layer. This segmentation allows each thin layer to flex independently during bending, preventing crack formation while maintaining the overall encapsulation function and moisture barrier properties
Solution Approach 2:
The encapsulation layer uses a composite structure combining inorganic insulating material layers and organic silicon carbon compound material layers. This composite structure leverages the complementary properties of both material types: inorganic layers provide barrier properties while organic layers provide flexibility, enabling the encapsulation to withstand bending stress without cracking
2Length of moving object
If the encapsulation layer is made thinner to reduce device thickness, then device thickness is reduced, but resistance to bending stress and cracking prevention worsen
Solution Approach 1:
Instead of using a single thin encapsulation layer that would be vulnerable to cracking, the encapsulation is segmented into multiple alternating inorganic and organic layers. Each thin sub-layer is flexible enough to bend without cracking, while the stacked structure collectively provides sufficient mechanical strength and stress distribution
Solution Approach 2:
Different regions of the encapsulation structure have different material properties optimized for their specific functions: inorganic layers provide local barrier properties against moisture, while organic layers provide local flexibility and stress absorption, creating a heterogeneous structure that simultaneously achieves thinness and bending resistance
3Reliability
If alternating inorganic and organic layers are stacked to prevent cracking, then reliability under bending is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning different material properties to different layers: inorganic layers provide barrier properties where needed, while organic layers provide flexibility where needed. This localized functional differentiation resolves the contradiction by making each layer specialized rather than using a uniform complex structure throughout
Solution Approach 2:
The alternating composite structure of inorganic and organic layers creates a synergistic effect where the simple repeating pattern provides both mechanical flexibility and barrier properties. This regular composite structure achieves high reliability under bending without requiring complex irregular patterns, maintaining manufacturing simplicity
Data Source
AI summary
A display device includes a display area and a peripheral area. A display layer includes a plurality of display elements arranged thereon. A thin-film encapsulation layer is arranged on the display layer and includes first, second, and third encapsulation layers. The second encapsulation layer is on the first encapsulation layer. The third encapsulation layer is on the second encapsulation layer. A touch sensing layer is arranged on the thin-film encapsulation layer and includes touch electrodes and trace lines. The display area is partially bent about an axis, and the third encapsulation layer is bent along the axis and has a structure in which a first layer and a second layer are alternately stacked. The first layer includes an inorganic insulating material, and the second layer includes a silicon carbon compound material.