Liquid Crystal Display Retardation Layers for Reflection and Leakage Control
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Solution Overview
Problem
Liquid crystal display devices with horizontal alignment face issues with poor image recognition in bright environments due to excessive reflection, and existing solutions for reducing reflection, such as using antireflection films and circularly polarizing plates, do not effectively address light leakage in the black display state when viewed from oblique directions.
Innovation Solution
A liquid crystal display device structure incorporating a viewing angle compensation film between the polarizer and the out-cell retardation layer or between the substrate and the polarizer, with specific retardation layers having controlled NZ coefficients and in-plane retardation values, and an antireflection film on the viewing surface, to minimize reflection and light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If antireflection films and circularly polarizing plates are used to reduce reflection, then reflection is reduced, but light leakage occurs in the black display state when viewed from oblique directions
Solution Approach 1:
The out-cell retardation layer is divided into multiple retardation layers with different optical properties (different NZ coefficients and in-plane retardation values). This segmentation allows each layer to contribute differently to the overall optical performance, enabling simultaneous reduction of reflection and suppression of light leakage in the black display state when viewed from oblique directions.
Solution Approach 2:
Different retardation layers are designed with specific local optical characteristics (different NZ coefficients and in-plane retardation values) to address different optical issues at different locations in the optical path. The first retardation layer targets reflection reduction while the second retardation layer addresses light leakage control, creating local quality optimization throughout the structure.
2Device complexity
If conventional retardation layers are used, then the device structure is simple, but image recognition is poor in bright environments due to excessive reflection
Solution Approach 1:
The patent employs a composite structure consisting of multiple retardation layers with different optical properties, an antireflection film, and a viewing angle compensation film. This composite material approach combines the strengths of each component to achieve superior reflection reduction and viewing angle performance compared to conventional single-layer retardation structures.
Solution Approach 2:
The patent introduces additional optical dimensions by incorporating layers with different NZ coefficients and in-plane retardation values, and by adding viewing angle compensation functionality. This multi-dimensional optical control enables effective reflection reduction and improved image recognition in bright environments while maintaining reasonable device complexity.
3Ease of manufacture
If the NZ coefficient and in-plane retardation values are not controlled, then manufacturing is easier, but light leakage occurs in the black display state when viewed from oblique directions
Solution Approach 1:
The patent specifies precise parameter ranges for the NZ coefficient (1.0 or greater and 1.1 or smaller for the first retardation layer, 0.7 or greater and 1.4 or smaller for the second retardation layer) and in-plane retardation values (120 nm or greater and smaller than 137.5 nm). These parameter changes enable manufacturers to produce devices with consistent optical performance that suppress light leakage in the black display state when viewed from oblique directions.
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 proposed structure significantly reduces external light reflection and light leakage in the black display state when viewed from oblique directions, enhancing image recognition and contrast ratio in bright environments.
Implementation Method 1
the out-cell retardation layer is a laminate including a first retardation layer having an NZ coefficient of 1.0 or greater and 1.1 or smaller and an in-plane retardation of 120 nm or greater and smaller than 137.5 nm; and a second retardation layer having an in-plane retardation of 0 nm or greater and 10 nm or smaller and a thickness retardation of 80 nm or greater and 150 nm or smaller
Implementation Method 2
an antireflection film on the viewing surface, to minimize reflection and light leakage
Implementation Method 3
voltage is applied to a liquid crystal composition sealed between a pair of substrates to change the alignment of liquid crystal molecules in the liquid crystal composition according to the applied voltage, whereby the amount of light transmitted is controlled
Data Source
AI summary
A liquid crystal display device includes sequentially from a viewing surface side: a first polarizer; an out-cell retardation layer; a first substrate; an in-cell retardation layer; a horizontally aligned liquid crystal layer; a second substrate; and a second polarizer. The liquid crystal display device includes a viewing angle compensation film between the first polarizer and the out-cell retardation layer or between the second substrate and the second polarizer. The out-cell retardation layer is a laminate including sequentially from a viewing surface side: a first retardation layer having an NZ coefficient of 1.0-1.1 and an Re of 120 nm or greater and smaller than 137.5 nm; and a second retardation layer having an Re of 0-10 nm and an Rth of 80-150 nm. The in-cell retardation layer is a third retardation layer having an NZ coefficient of 0.7-1.4 and an Re of 120 nm or greater and smaller than 137.5 nm.