Optical Laminate Reddening-Resistant Layer Thermal Barrier
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Solution Overview
Problem
Optical laminates, particularly polarizing layers, face reddening issues when exposed to high temperatures, leading to changes in color coordinates and transmittance, which are exacerbated by their contact with thermally conductive substrates like soda lime glass in display devices.
Innovation Solution
Incorporating a reddening-resistant layer with voids or a porous structure adjacent to the optical functional layer, which reduces heat transfer and maintains low thermal diffusivity, surface area ratio, and infrared reflectance, thereby preventing or delaying reddening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the optical laminate is used in contact with thermally conductive substrates like soda lime glass, then heat transfer to the optical laminate is improved, but reddening occurs more easily under high temperature conditions
Solution Approach 1:
The patent introduces a reddening-resistant layer as an intermediary between the optical functional layer and the thermally conductive substrate. This layer has thermal diffusivity of 0.05 mm²/s or less, acting as a thermal barrier that mediates the heat transfer from the substrate to the optical functional layer, thereby preventing reddening while maintaining the beneficial thermal contact with the substrate.
Solution Approach 2:
The reddening-resistant layer is designed with a porous structure containing voids, which significantly reduces its thermal diffusivity to 0.05 mm²/s or less. The porous structure creates thermal resistance pathways that block heat flow to the optical functional layer, preventing reddening while allowing the layer to maintain adhesion and optical transparency.
2Reliability
If a reddening-resistant layer with low thermal diffusivity is introduced, then reddening is prevented, but the device structure becomes more complex
Solution Approach 1:
The reddening-resistant layer is designed to perform multiple functions simultaneously: it provides thermal insulation (thermal diffusivity of 0.05 mm²/s or less) to prevent reddening, maintains optical transparency for display functionality, and ensures adhesion to both the optical functional layer and substrate. This multi-functionality reduces the need for additional separate layers, thereby limiting the increase in structural complexity.
3Adaptability or versatility
If the optical functional layer is maintained at high temperature, then display device performance in harsh conditions is improved, but reddening occurs more easily
Solution Approach 1:
The patent converts the harmful high temperature condition into a beneficial scenario by designing the reddening-resistant layer with specific thermal properties (thermal diffusivity of 0.05 mm²/s or less) that allow it to withstand high temperatures while protecting the optical functional layer. The layer itself is stabilized to resist reddening, thereby enabling the display device to operate in harsh high-temperature conditions without degradation.
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 effectively prevents or minimizes color changes and transmittance loss in optical laminates even under harsh conditions, ensuring durability and performance in high-temperature applications.
Implementation Method 1
the reddening-resistant layer may have a thermal diffusivity in a predetermined range... the thermal diffusivity measured at 95°C with respect to the laminate is 90% or less relative to the thermal diffusivity of the polymer film alone
Implementation Method 2
the void-containing layer may have an infrared reflectance of 2% or more
Data Source
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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.