Thin Polarizing Plate Heat Shock Crack Prevention
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Solution Overview
Problem
In optical display apparatuses, polarizing plates with small diameter holes are prone to bubble formation and crack generation due to heat shock, leading to usability issues and light leakage, especially when laminated with adhesive films.
Innovation Solution
A polarizing plate with a polarizer thickness of 10 μm or less, a coefficient of thermal expansion of 100 μm/(m·°C) or less, and an adhesive layer with a storage modulus of 40 kPa or more at 100°C, which minimizes bubble formation and crack generation even under heat shock conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a physical method (punching) is used to form a hole in the polarizing plate, then the manufacturing cost is reduced and the hole can be formed easily, but bubbles enter the hole during adhesive layer attachment and become observable, deteriorating usability
Solution Approach 1:
The patent applies preliminary action by forming the hole in the polarizing plate before attaching the adhesive layer. This sequence allows the hole to be prepared in advance, and the adhesive layer is then applied to fill and seal the hole, preventing bubble formation during subsequent operations. The preliminary hole formation enables controlled filling with adhesive material that prevents bubble entrapment.
Solution Approach 2:
The adhesive layer serves as an intermediary substance that fills the hole formed by punching. This intermediary material not only seals the hole to prevent bubble observation but also provides structural bridging between the polarizing plate and the substrate, eliminating the harmful effect of the physical punching method while maintaining its manufacturing advantages.
2Shape
If the hole diameter is reduced to make it unobservable, then the aesthetic quality improves, but the polarizing plate becomes more susceptible to crack generation under heat shock
Solution Approach 1:
The adhesive layer acts as a stress-distributing intermediary that fills the small hole and provides structural reinforcement. This intermediary material prevents stress concentration at the hole edges during heat shock, thereby preventing crack generation while maintaining the small, unobservable hole size for aesthetic purposes.
Solution Approach 2:
The patent creates a composite structure by combining the polarizing plate material with the adhesive layer filling the hole. This composite construction provides enhanced mechanical strength and thermal shock resistance at the hole location, allowing the hole to be made small and unobservable without compromising the overall structural integrity or crack resistance of the polarizing plate.
3Length of moving object
If the polarizer thickness is reduced to provide thickness reduction, then the overall device size is reduced, but the structural integrity under heat shock is compromised
Solution Approach 1:
The patent employs composite materials by combining a thin polarizer with an adhesive layer that fills the hole and provides structural reinforcement. This composite construction allows the polarizer to be made thin for device miniaturization while the adhesive layer compensates for the reduced thickness, maintaining structural integrity and heat shock resistance through the combined material properties.
Solution Approach 2:
The patent applies parameter changes by modifying the adhesive layer properties (storage modulus of 40 kPa or more at 100°C) to compensate for the thin polarizer thickness. This parameter adjustment in the adhesive layer's mechanical properties provides the necessary structural support and thermal stability, allowing the polarizer to be thin without compromising overall heat shock resistance.
4Reliability
If the coefficient of thermal expansion is reduced to prevent crack generation under heat shock, then the reliability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by controlling the coefficient of thermal expansion (CTE) of the polarizing plate to 100 μm/(m·°C) or less. This parameter adjustment prevents excessive thermal stress and crack generation under heat shock conditions. The CTE control is achieved through material selection and formulation, balancing reliability improvement with manufacturability by establishing a clear, measurable target value.
Solution Approach 2:
The adhesive layer serves as an intermediary that compensates for thermal expansion differences between the polarizer and the substrate. This intermediary material absorbs and distributes thermal stress, reducing the impact of CTE variations on the overall structure. It provides a buffer that maintains reliability under heat shock while allowing for practical manufacturing precision levels.
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 prevents bubble formation and crack generation in polarizing plates with small diameter holes, ensuring improved usability and light transmission by maintaining structural integrity under heat shock conditions.
Implementation Method 1
the polarizing plate has a coefficient of thermal expansion (CTE) of 100 μm/(m·°C) or less, as measured in a machine direction of the polarizer after the polarizing plate is left under the following heat shock conditions
Data Source
AI summary
A polarizing plate and an optical display apparatus including the same are disclosed. A polarizing plate includes a polarizer and a protective film formed on a surface of the polarizer, wherein the polarizer has a thickness of 10 μm or less and the polarizing plate has a coefficient of thermal expansion (CTE) of 100 μm/(m·° C.) or less, as measured in a machine direction of the polarizer after application of heat shock conditions.