Adhesive-Free Retardation and Polarizer Stack for Flexible Displays
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Solution Overview
Problem
Conventional polarizing plates for display devices, such as OLEDs and LCDs, face challenges in achieving flexibility and durability due to their thickness and the use of adhesive layers, which can cause issues like white turbidity and high production costs.
Innovation Solution
The solution involves eliminating the adhesive layer by directly stacking a retardation layer and a polarizer on the display panel without adhesives, using polymerizable liquid crystals to form these layers, which improves flexibility and reduces thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer is used to bond the polarizing plate to the display panel, then the bonding strength is improved, but the thickness increases and flexibility deteriorates
Solution Approach 1:
The adhesive layer is completely removed from the structure. The polarizing plate is designed to be directly bonded to the display panel without any adhesive layer, thereby eliminating the thickness contribution and flexibility issues caused by the adhesive while maintaining bonding through direct contact and curing of the liquid crystal material.
Solution Approach 2:
The polarizing plate and display panel are merged into a single integrated structure without an intermediate adhesive layer. The liquid crystal material serves both as the functional polarizing element and as the bonding medium, combining multiple functions into one component.
2Ease of operation
If a protective film is added to support thin polarizing plates, then the handleability is improved, but the thickness increases
Solution Approach 1:
The separate protective film is removed from the structure. Instead of adding a protective film layer, the invention uses the liquid crystal material itself and the alignment film as inherent protective and supportive elements, eliminating the need for an additional protective film while maintaining thin profile.
Solution Approach 2:
The alignment film and liquid crystal material serve multiple functions simultaneously: they provide structural support, protection during handling, and the polarizing function, eliminating the need for separate protective and support layers.
3Length of moving object
If the polarizing plate structure is simplified to reduce thickness, then the flexibility is improved, but the durability deteriorates due to adhesive layer issues
Solution Approach 1:
The invention uses a simple, thin structure without complex adhesive layers that are prone to degradation. The liquid crystal material and alignment film form a simple structure that, while thin, provides sufficient durability for the application without the reliability issues associated with adhesive layers.
4Stability of the object's composition
If adhesive layers are used in the polarizing plate, then the integration of members is improved, but white turbidity occurs during bending tests
Solution Approach 1:
The adhesive layer is completely removed from the structure. The polarizing plate is designed to be directly bonded to the display panel without any adhesive layer, thereby eliminating the white turbidity issue that occurs during bending tests while maintaining integration through direct contact and curing of the liquid crystal material.
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
This approach results in a display device with a thin profile, enhanced flexibility, and improved durability, overcoming the limitations of conventional polarizing plates.
Implementation Method 1
applying a solution containing first polymerizable liquid crystal to the first alignment film, and curing the first polymerizable liquid crystal to produce a retardation layer; and forming a second alignment film on the retardation layer, applying a solution containing second polymerizable liquid crystal and a dichroic material to the second alignment film, and curing the second polymerizable liquid crystal to produce a polarizer
Data Source
AI summary
The present invention provides: (I) a display device including a display panel, a retardation layer, and a polarizer which are stacked in the stated order from a back surface side to a viewing surface side and integrated without an adhesive layer; and (II) a method for producing a display device including: forming a first alignment film on a display panel, applying a solution containing first polymerizable liquid crystal to the first alignment film, and curing the first polymerizable liquid crystal to produce a retardation layer; and forming a second alignment film on the retardation layer, applying a solution containing second polymerizable liquid crystal and a dichroic material to the second alignment film, and curing the second polymerizable liquid crystal to produce a polarizer.