Liquid Crystal Display Viewing Angle Expansion Film
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Solution Overview
Problem
Liquid crystal display devices face challenges in maintaining image quality and contrast ratio, especially when viewed at oblique angles and in varying ambient environments, with existing technologies failing to adequately address these issues.
Innovation Solution
Incorporating a viewing angle expansion film between the liquid crystal cell and polarizers, along with optical films that form circularly polarizing plates, to enhance visibility and contrast ratio by diffusing light and optimizing the refractive indices and retardation of the films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a viewing angle expansion film is added to improve visibility at oblique angles, then the device complexity increases
Solution Approach 1:
The patent introduces a viewing angle expansion film as an intermediary component between the liquid crystal cell and the front polarizer. This film acts as a mediator that expands the viewing angle without requiring fundamental changes to the existing liquid crystal cell or polarizer structures, thereby improving adaptability while controlling complexity through modular addition.
Solution Approach 2:
The viewing angle expansion film serves multiple functions: it expands the viewing angle, maintains contrast ratio, and works with various liquid crystal cell types (VA, IPS, TN modes). This multi-functionality allows a single component to address multiple display performance requirements, improving versatility without proportionally increasing complexity.
2Reliability
If optical films are added to form circularly polarizing plates to improve contrast ratio, then the device complexity increases
Solution Approach 1:
The patent combines the circularly polarizing function with the existing polarizer structure by adding optical films (such as λ/4 plates) to form integrated circularly polarizing plates. This merging approach consolidates multiple optical functions into unified components, improving contrast ratio while minimizing the increase in device complexity through functional integration.
Solution Approach 2:
The circularly polarizing plate is constructed using composite optical films including λ/4 plates and polarizers with specific retardation properties. These composite structures enable enhanced contrast ratio performance by combining materials with complementary optical characteristics, achieving superior reliability through material composition rather than simple structural addition.
3Manufacturing precision
If multiple optical films are added to optimize refractive indices and retardation, then the manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes optical performance by carefully selecting and controlling parameters such as the retardation values (e.g., λ/4 plate with 90-180 nm retardation), refractive indices, and thickness of each optical film. By adjusting these parameters within specific ranges, the invention achieves optimal contrast ratio and viewing angle expansion while maintaining manufacturability through standardized parameter specifications.
Solution Approach 2:
Different optical films are positioned at specific locations within the display structure with locally optimized properties: the λ/4 plate is placed between the liquid crystal cell and polarizer with specific retardation characteristics, while the viewing angle expansion film is positioned at the front with specific refractive index properties. This local optimization approach enables precise control of optical performance without requiring uniform high precision throughout the entire device.
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 solution significantly improves visibility at various oblique angles and enhances the contrast ratio, particularly in bright environments, by diffusing light and optimizing the refractive indices and retardation of the films, resulting in clearer and more consistent image quality.
Implementation Method 1
enhance visibility and contrast ratio by diffusing light
Implementation Method 2
optical films that form circularly polarizing plates
Implementation Method 3
the rear side polarizer and the rear side optical film constitute a rear side circularly polarizing plate, and the front side polarizer and the front side optical film constitute a front side circularly polarizing plate
Data Source
AI summary
A liquid crystal display device including, sequentially in the following order: a light source unit, a rear side polarizer, a liquid crystal cell, a front side polarizer, and a viewing angle expansion film. Alternatively, a liquid crystal display device including, sequentially in the following order: a light source unit, a rear side polarizer, a liquid crystal cell, a viewing angle expansion film, and a front side polarizer. The liquid crystal display device optionally includes a rear side optical film provided between the rear side polarizer and the liquid crystal cell; and a front side optical film provided between the front side polarizer and the liquid crystal cell.