Laminated Body with Anisotropic Layer for Oblique Light Leakage Control
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Solution Overview
Problem
Conventional optical films used in flat panel display devices suffer from inadequate light leakage control when viewed from an oblique direction during black display, particularly when one of these films is used.
Innovation Solution
A laminated body comprising a substrate and an optically anisotropic layer with specific birefringence characteristics, where the optically anisotropic layer is composed of a polymerizable liquid crystal compound and a photopolymerization initiator, and an oriented film layer is included to regulate the orientation of the liquid crystal compound, ensuring minimal light leakage by optimizing the refractive indices and birefringence values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional optical film is used, then the display device can be manufactured with standard optical properties, but light leakage occurs when viewed from an oblique direction during black display
Solution Approach 1:
The patent applies parameter changes by precisely controlling the birefringence ratios at different wavelengths (Δn50(450)/Δn50(550) ≤ 1.00 and 1.00 ≤ Δn50(650)/Δn50(550)) and the refractive index relationship (nz > nx ≅ ny) of the optically anisotropic layer. These parameter specifications ensure that the optical film maintains consistent performance across different viewing angles and wavelengths, effectively suppressing light leakage during black display while preserving reliability.
Solution Approach 2:
The patent employs composite materials by combining a substrate with specific optical properties (nx, ny, nz refractive indices) and an optically anisotropic layer with controlled birefringence characteristics. This composite structure creates synergistic optical effects that suppress light leakage from oblique directions while maintaining overall device reliability, as the interaction between the substrate and anisotropic layer provides enhanced optical control compared to single-material films.
2Object-affected harmful factors
If the birefringence and refractive index are optimized to reduce light leakage, then optical performance is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges and relationships (Δn50(450)/Δn50(550) ≤ 1.00, 1.00 ≤ Δn50(650)/Δn50(550), nz > nx ≅ ny) that provide clear manufacturing targets. These parameter specifications enable manufacturers to control birefringence and refractive indices within acceptable tolerances, reducing light leakage while maintaining feasible manufacturing precision requirements through well-defined quality criteria.
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 laminated body effectively restricts light leakage when the display device shows black display, even when viewed from an oblique direction, by utilizing the oriented film layer to control the polymerizable liquid crystal compound's orientation and aligning the refractive indices and birefringence values for improved optical performance.
Implementation Method 1
a composition containing a polymerizable liquid crystal compound, a photopolymerization initiator, and a solvent
Implementation Method 2
Δn50(450), Δn50(550) and Δn50(650) represent the respective birefringences of the optically anisotropic layer
Data Source
AI summary
Laminated body including a substrate and an optically anisotropic layer. This layer satisfies the following expressions (1), (2), and (3): Δn50(450)/Δn50(550)≤1.00 (1), and 1.00≤Δn50(650)/Δn50(550) (2) wherein Δn50(450), Δn50(550) and Δn50(650) represent the respective birefringences of the layer that are derived from retardation values of the laminated body that are obtained by measuring the laminated body at wavelengths of 450 nm, 550 nm and 650 nm in the state of inclining the fast axis of the layer at an angle of 50 degrees to act as an inclined central axis; and nz>nx≅ny (3) wherein nx and ny represent the respective refractive indexes of the substrate in directions parallel with the plane of the substrate, these directions being orthogonal to each other, and nz represents the refractive index of the substrate in a direction orthogonal to each of the directions about nx and ny.