Reddening-Resistant Layer for Optical Laminates
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Solution Overview
Problem
Display devices, particularly those used in navigation and vehicle dashboards, face reddening issues due to high temperatures, which affect the durability of optical laminates like polarizing plates, especially iodine-based polarizing layers that degrade under harsh conditions.
Innovation Solution
An optical laminate with a reddening-resistant layer is introduced, which can be a void-containing layer or a porous layer applied adjacent to the optical functional layer, effectively blocking heat transfer and preventing, alleviating, or delaying reddening by maintaining a specific thermal diffusivity, surface area ratio, and infrared reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the optical laminate is used in contact with cover glass under high temperature conditions, then thermal conduction improves heat transfer, but reddening of the optical functional layer occurs and durability deteriorates
Solution Approach 1:
A reddening-resistant layer is introduced as an intermediary between the optical functional layer and the cover glass. This layer has lower thermal diffusivity than the cover glass, acting as a thermal buffer that reduces heat transfer to the optical functional layer while maintaining overall heat dissipation, thereby preventing reddening without compromising thermal management
Solution Approach 2:
The reddening-resistant layer is constructed as a composite structure containing voids or pores (5-50 μm in size) within a polymer matrix. This composite structure provides thermal insulation properties while maintaining mechanical integrity and optical compatibility, creating a material that balances heat resistance with structural requirements
2Reliability
If a reddening-resistant layer is added to protect the optical functional layer, then durability improves, but device complexity increases
Solution Approach 1:
The reddening-resistant layer is designed as a thin film structure (1-100 μm thickness) that can be flexibly integrated into the existing optical laminate architecture. This thin film approach provides protective functionality without significantly increasing overall device thickness or structural complexity, maintaining compatibility with conventional display device designs
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 reddening-resistant layer significantly reduces the change in a* value and transmittance of the optical laminate, ensuring durability and maintaining optical performance even under extreme heat conditions, thereby extending the lifespan of display devices.
Implementation Method 1
the reddening-resistant layer may have a thermal diffusivity which, at 95° C., is 90% or less of a thermal diffusivity of the polymer film alone
Implementation Method 2
the void-containing layer or the laminate comprising the void-containing layer may have an infrared reflectance of 2% or more
Data Source
AI summary
The present application relates to an optical laminate or a reddening-resistant layer. The present application can provide an optical laminate that does not cause a so-called reddening phenomenon even when driven or maintained under extremely harsh conditions (e.g., very high temperature conditions), or a reddening-resistant layer applied thereto.