Symmetric Diffusion Film for LCD Viewing Angle Compensation
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Solution Overview
Problem
Conventional liquid crystal display (LCD) technologies face challenges in achieving wide viewing angles, high image quality, and low production costs due to the need for expensive compensator films and complex structures, leading to issues like gray scale inversion, color shift, and image washout at various viewing angles.
Innovation Solution
A symmetric diffusion film (SDF) composed of two materials with different refractive indices is integrated into the LCD structure without a viewing angle compensation film, improving image quality by scattering collimated light within a specific range and eliminating the need for costly compensators, thus enabling wide viewing angles and stable color representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional VA mode LCD uses expensive optimal compensator, then viewing angle performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the expensive optimal compensator from the LCD structure and replaces it with a symmetric diffusion film that has specific refractive index properties. The diffusion film extracts and utilizes natural light scattering properties to achieve viewing angle compensation without requiring the complex and costly compensator layer.
Solution Approach 2:
The patent changes the optical parameters of the system by using a diffusion film with specific refractive indices (n1 and n2 where n1 < n2) and controlling the half-width at half-maximum (HWHM) of scattered light to be between 5-20 degrees. This parameter optimization allows the system to achieve wide viewing angles without the compensator.
2Reliability
If FFS mode LCD is used, then wide viewing angle is achieved, but manufacturing cost and complexity increase
Solution Approach 1:
The patent extracts the viewing angle compensation function from the complex FFS mode structure and implements it through a simple symmetric diffusion film layer. This eliminates the need for the complex electrode patterns and multiple layers required by FFS mode while maintaining wide viewing angle performance.
Solution Approach 2:
The patent uses a composite diffusion film made from multiple materials with different refractive indices to achieve the desired optical properties. This composite structure provides the necessary light scattering characteristics in a single integrated layer, simplifying the overall device structure.
3Manufacturing precision
If collimated light is used in LCD, then image quality is improved, but viewing angle performance deteriorates
Solution Approach 1:
The symmetric diffusion film acts as an intermediary between the collimated light source and the liquid crystal display. It introduces controlled light scattering that widens the viewing angle while maintaining sufficient image quality. The film mediates between the conflicting requirements by transforming the light distribution in a controlled manner.
Solution Approach 2:
The patent optimizes the scattering parameters of the diffusion film, specifically controlling the HWHM to be between 5-20 degrees and selecting appropriate refractive indices. This parameter control allows the system to achieve an optimal balance between image quality and viewing angle performance.
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 SDF enhances image quality by maintaining contrast ratios and color accuracy across various viewing angles, reducing gray scale inversion and hue shift, and simplifying the manufacturing process, making it suitable for mass production across different LCD modes.
Implementation Method 1
a symmetric diffusion film (SDF) disposed at one side of the upper polarizer... a half-width at half-maximum (HWHM) of the collimated light scattered by the SDF is in a range of 5 degree to 20 degree
Implementation Method 2
The SDF comprises at least two different materials including a first material having a first refractive index mixed with a second material having a second refractive index, and the first refractive index is different from the second refractive index
Data Source
AI summary
A symmetric diffusion film (SDF) and a flat panel display applied with the same are provided. The SDF comprises at least two different materials of a first material having a first refractive index mixed with a second material having a second refractive index, and the first refractive index is different from the second refractive index. The flat panel display comprises a symmetric diffusion film (SDF) disposed at one side of the upper polarizer, and the upper polarizer adapting no compensation film.