Retardation Layer Stack Adhesive Modulus for Foldable Display Durability
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Solution Overview
Problem
Existing polarizing plates for light emitting and liquid crystal displays face challenges in durability, reliability, impact resistance, and bending properties, especially when exposed to high temperature and humidity or subjected to external impacts.
Innovation Solution
A polarizing plate design featuring a retardation layer stack with a second retardation layer, a first adhesive layer, and a first retardation layer sequentially stacked, where the first adhesive layer has a storage modulus of 1×105 Pa to 1×106 Pa at 25° C., and the second retardation layer and the first adhesive layer satisfy the relation 0.3≤T2/T1≤1, enhancing durability, impact resistance, and bending properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a polarizing plate uses a simple single-layer structure, then manufacturing is easier and device complexity is reduced, but durability and reliability deteriorate under high temperature and humidity conditions
Solution Approach 1:
The polarizing plate is divided into multiple functional layers including a polarizer layer, multiple retardation layers with different optical properties, and adhesive layers. This segmentation allows each layer to perform its specific function independently, improving overall durability and reliability under high temperature and humidity conditions while maintaining manageable complexity through modular design
Solution Approach 2:
The invention uses composite material structures combining different types of retardation layers (positive C-plate, negative A-plate, negative C-plate) with specific birefringence values and thicknesses. These composite layers work together to provide enhanced optical performance and improved durability, with the adhesive layers providing additional structural integrity under environmental stress
2Reliability
If the polarizing plate uses a multi-layer retardation structure, then optical properties are improved, but impact resistance deteriorates due to increased fracture and cracking risk
Solution Approach 1:
The invention optimizes specific parameters including the thickness of each retardation layer (first retardation layer: 50-150 μm, second retardation layer: 10-50 μm, third retardation layer: 10-50 μm) and the storage modulus of adhesive layers (1×10^5 to 1×10^6 Pa at 25°C). These parameter changes balance optical performance with impact resistance, preventing fracture and cracking while maintaining sustained optical properties
Solution Approach 2:
The adhesive layers with optimized storage modulus serve as cushioning elements between the rigid retardation layers. These layers absorb and distribute impact forces before they can propagate through the multi-layer structure, preventing fracture and cracking while maintaining the integrity of the optical layers
3Reliability
If the polarizing plate is made rigid to improve structural stability, then durability is improved, but bending properties deteriorate for foldable displays
Solution Approach 1:
The invention uses thin film structures for the retardation layers and adhesive layers that can bend without fracturing. The optimized thickness parameters and material selection provide flexibility for foldable displays while maintaining structural stability and durability through the layered composite structure that distributes stress during bending
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 polarizing plate achieves improved durability and reliability by preventing delamination and maintaining structural integrity under high temperature and humidity conditions, while also providing high impact resistance and excellent bending properties, along with enhanced front contrast and reduced light leakage and color variation.
Implementation Method 1
a first adhesive layer, and a first retardation layer sequentially stacked from the first surface of the polarizer
Data Source
AI summary
A polarizing plate and an optical display apparatus are disclosed. The polarizing plate includes a polarizer; and a retardation layer stack formed on one surface of the polarizer, wherein the retardation layer stack includes a second retardation layer, a first adhesive layer, and a first retardation layer sequentially stacked from the one surface of the polarizer, the first adhesive layer has a modulus of 1×105 Pa to 1×106 Pa at 25° C., and the second retardation layer and the first adhesive layer satisfy Relation 1.