Stretchable Display Interconnect Layout for Curved-Area Stress Relief
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Solution Overview
Problem
Existing display devices face challenges in minimizing stress and improving stretching rates, particularly in curved areas, which can lead to cracks and reduced reliability.
Innovation Solution
A display device with a flexible substrate and connection substrates featuring different modulus of elasticity patterns, including a first connection pattern in straight areas and a second connection pattern with lower elasticity in curved areas, along with opening grooves and filling members to disperse stress, enhances stretching reliability and fatigue life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a uniform connection substrate structure is used in both straight and curved areas, then the device structure is simple, but the stretching reliability is reduced due to stress concentration in curved areas
Solution Approach 1:
The connection substrate is designed with different modulus of elasticity patterns in different areas: a first connection pattern with higher modulus of elasticity in straight areas and a second connection pattern with lower modulus of elasticity in curved areas. This local differentiation allows the curved areas to better accommodate stretching deformations while maintaining structural integrity, thereby improving stretching reliability without requiring complete structural redesign throughout the entire device.
2Adaptability or versatility
If connection lines are disposed in curved areas, then the device can be stretched, but tensile stress concentrates and causes cracks
Solution Approach 1:
The modulus of elasticity parameter of the connection substrate is specifically adjusted in curved areas by introducing a second connection pattern with lower modulus of elasticity. This parameter change allows the material in curved regions to be more compliant and better withstand tensile stress during stretching, preventing crack formation while maintaining the stretching capability of the device.
Solution Approach 2:
The opening grooves are pre-formed in the connection substrate at curved areas before the connection lines are disposed. These grooves act as stress relief features that beforehand cushion the tensile stress that will occur during stretching, preventing stress concentration at critical points and reducing the likelihood of crack initiation in the connection lines.
3Productivity
If the connection substrate is made more flexible to improve stretching rate, then the stretching rate improves, but the structural stability decreases
Solution Approach 1:
Rather than making the entire connection substrate uniformly flexible, the invention applies flexibility locally only in curved areas where stretching deformations occur. The first connection pattern in straight areas maintains higher structural stability, while the second connection pattern in curved areas provides the necessary flexibility for stretching. This localized approach improves stretching rate without compromising overall structural stability.
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 tensile stress and improves the stretching rate of connection lines, leading to increased fatigue life and reliability of the display device.
Implementation Method 1
a second connection pattern and a first connection pattern different from the second connection pattern, the second connection pattern having a different modulus of elasticity from that of the first connection pattern
Implementation Method 2
an opening and a filling member may disperse a stretching stress applied to a curved area
Implementation Method 3
the connection line is disposed on a neutral plane of a curved area to reduce or minimize a crack of the connection line
Data Source
AI summary
According to an aspect of the present disclosure, a display device includes a plurality of pixel substrates disposed on a flexible substrate to be spaced apart from each other and whereon at least one pixel is disposed. The device includes a plurality of connection substrates configured to connect a plurality of adjacent pixel substrates. Each connection substrate includes a curved area and a straight area. The device includes a plurality of connection lines configured to electrically connect pads disposed on the plurality of adjacent pixel substrates on the plurality of connection substrates. The plurality of connection substrates includes a first connection pattern and a second connection pattern which has a different modulus of elasticity from that of the first connection pattern and is disposed only in the curved area, thereby improving a stretching reliability.