Light Diffusing Film Haze Control for LCD Luminance
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Solution Overview
Problem
Conventional liquid crystal display devices face issues with luminance unevenness, particularly oblique luminance unevenness and reduced front luminance, due to the use of high haze diffuser sheets which increase scattering and reduce light transmission, and existing solutions either compromise on image quality or productivity.
Innovation Solution
A light diffusing film comprising a thermoplastic resin with light-transmitting particles of specific size and refractive index, providing a haze value between 5 to 40% and an average film thickness of 20 to 200 μm, which minimizes refractive index difference and surface concavoconvex shape to enhance luminance uniformity and image quality while maintaining high front luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a light diffusing sheet with high haze value (60-80%) is used to eliminate moire and luminance unevenness, then luminance uniformity is improved, but front luminance is reduced due to backward scattering and wide-angle scattering
Solution Approach 1:
The invention changes the particle size parameter to 1-10 μm (specifically 3-6 μm in preferred embodiments) and controls the haze value to 10-40% (specifically 20-35%), which optimizes the balance between light diffusion for uniformity and forward transmission for luminance. This parameter optimization eliminates oblique luminance unevenness while maintaining high front luminance.
Solution Approach 2:
The invention uses a composite structure consisting of transparent resin particles dispersed in a transparent resin matrix. The specific combination of particle size (1-10 μm), refractive index matching (difference of 0.01 or less), and controlled haze (10-40%) creates a material that achieves both luminance uniformity and high front luminance without the scattering problems of high haze materials.
2Stability of the object's composition
If multiple light diffusing sheets are stacked to eliminate moire and prevent luminance unevenness, then image quality is improved, but light loss increases due to reflection on front and back surfaces
Solution Approach 1:
The invention extracts the essential light diffusing function into a single optimized sheet with specific particle size (1-10 μm) and haze value (10-40%), eliminating the need for multiple stacked sheets. This single sheet achieves moire elimination and luminance uniformity while minimizing reflection losses at interfaces.
Solution Approach 2:
The invention combines multiple functions (moire elimination, luminance uniformity, and anti-reflection) into a single light diffusing sheet with optimized transparent resin particles. The refractive index matching (difference of 0.01 or less) and controlled haze (10-40%) allow one sheet to perform what previously required multiple sheets, reducing light loss.
3Stability of the object's composition
If the refractive index difference between thermoplastic resin and light-transmitting particles is increased to enhance light scattering, then luminance uniformity is improved, but front luminance is reduced
Solution Approach 1:
The invention optimizes the refractive index difference parameter to 0.01 or less between the thermoplastic resin and light-transmitting particles. This specific parameter range enables sufficient light scattering for luminance uniformity while maintaining high forward transmission for front luminance, avoiding the trade-off present in conventional designs.
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 effectively eliminates oblique luminance unevenness and maintains high front luminance, improving image quality and productivity by optimizing light scattering and transmission in liquid crystal display devices.
Implementation Method 1
A light diffusing film comprising a thermoplastic resin with light-transmitting particles of specific size and refractive index, providing a haze value between 5 to 40%
Data Source
AI summary
A light diffusing film contains a thermoplastic resin as the main component and containing, in the thermoplastic resin, (A) a light-transmitting particle having an average primary particle diameter of 1 to 10 μm, wherein there is substantially no refractive index difference between the thermoplastic resin and the light-transmitting particle, wherein one surface has concavoconvex shape, the total haze value is from 5 to 40%, and the average film thickness is from 20 to 200 μm.