Optically Anisotropic Film Stack Solid Crystal Alignment
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Solution Overview
Problem
Conventional multilayer reflective polarizers for display systems are thick due to birefringence limitations, leading to blurry images from reflected light and reduced coupling efficiency for unpolarized light sources like micro LEDs, necessitating a thinner, optically efficient solution.
Innovation Solution
An optically anisotropic film stack comprising alternately stacked first and second films, where at least one second film includes a solid crystal with aligned crystal molecules and a distinct refractive index, and the first film has an alignment structure to partially align these molecules, achieving higher in-plane optical anisotropy and reduced thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional liquid crystals are used to fabricate polarization selective optical elements, then the devices can be made with current material properties, but the thickness is increased leading to blurry images and reduced coupling efficiency
Solution Approach 1:
The patent changes the material parameter from liquid crystal to solid crystal, exploiting the inherently higher birefringence of solid crystals to reduce the optical path length required for achieving the same polarization selectivity, thereby reducing thickness while maintaining optical efficiency
Solution Approach 2:
The patent creates a composite structure combining solid crystal material with alignment layers, where the solid crystal provides high birefringence and the alignment layers ensure proper molecular orientation, achieving both thinness and high optical performance
2Length of moving object
If the thickness of the polarizer is reduced, then image clarity and coupling efficiency improve, but the birefringence requirements become more stringent
Solution Approach 1:
The patent changes the material state from liquid to solid crystal, which provides naturally higher and more stable birefringence values, reducing the precision required in controlling film thickness while maintaining performance
Solution Approach 2:
The alignment structure acts as an intermediary that mediates between the solid crystal material and the substrate, ensuring proper molecular orientation and enabling precise control of optical anisotropy without requiring extreme manufacturing precision
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 film stack reduces the overall thickness while maintaining high extinction ratio and optical efficiency, enhancing image clarity and coupling efficiency for polarized light in display systems.
Implementation Method 1
at least one first film of the plurality of first films includes an alignment structure configured to at least partially align the crystal molecules of the solid crystal in the predetermined alignment direction
Implementation Method 2
Optical characteristics of the polarization selective optical elements may depend on the refractive index and/or birefringence of LCs
Data Source
AI summary
A film stack includes a plurality of first films and a plurality of second films alternately stacked. At least one second film of the plurality of second films includes a solid crystal including crystal molecules aligned in a predetermined alignment direction. At least one first film of the plurality of first films includes an alignment structure configured to at least partially align the crystal molecules of the solid crystal in the predetermined alignment direction.