Dual-Layer Diffusion Sheet for LCD Luminance Uniformity
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Solution Overview
Problem
LCD devices face challenges in meeting TCO'03 luminance requirements due to high manufacturing costs associated with reflective polarizer sheets and difficulty in maintaining luminance uniformity across viewing angles, especially with wider display screens.
Innovation Solution
A diffusion sheet with a base film and two diffusion material layers, one on the upper surface and one on the lower surface, each with a haze range of 10-40%, is used to scatter light and minimize brightness differences across angles, replacing the need for a reflective polarizer sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reflective polarizer sheet is used to meet TCO'03 luminance requirements, then luminance uniformity across viewing angles is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces the expensive reflective polarizer sheet with a cost-effective diffusion sheet that has a specific haze value (30-70%). This diffusion sheet achieves the required luminance uniformity without needing the high-cost reflective polarizer, directly reducing manufacturing cost while maintaining performance.
Solution Approach 2:
The patent changes the key parameter of the optical sheet from using a reflective polarizer with high reflectivity to a diffusion sheet with controlled haze value (30-70%). This parameter change allows the system to meet TCO'03 luminance requirements through diffusion rather than reflection, eliminating the need for expensive polarizer materials.
2Area of stationary object
If the display screen aspect ratio is increased to 16:9, then display area is expanded, but difficulty in meeting TCO'03 luminance requirements increases
Solution Approach 1:
The patent applies local quality by using a diffusion sheet with specifically controlled haze value (30-70%) that is optimized for wide-angle viewing. This localized optimization of the diffusion sheet's optical properties enables the wide 16:9 display to maintain uniform luminance across all viewing angles, solving the problem posed by the expanded display area.
3Manufacturing precision
If a diffusion sheet with high haze value is used to scatter light, then brightness difference across oblique directions is reduced, but light transmission is reduced
Solution Approach 1:
The patent optimizes the haze value parameter of the diffusion sheet to fall within the specific range of 30-70%. This parameter optimization balances two competing requirements: sufficient light scattering to achieve brightness uniformity across viewing angles, while maintaining enough light transmission to preserve display brightness. The specific haze range represents the optimal compromise between these two parameters.
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 diffusion sheet improves luminance characteristics across viewing angles while reducing manufacturing costs by maintaining a haze within the optimal range, allowing the LCD device to meet TCO'03 requirements and enhance visibility without the high-cost reflective polarizer.
Implementation Method 1
a diffusion sheet configured to scatter the light
Data Source
AI summary
A diffusion sheet adapted to minimize brightness difference between lights progressing in its oblique directions is discussed. The diffusion sheet according to an embodiment includes: a base film; a first diffusion material layer formed on an upper surface of the base film and configured to have a haze range of about 10˜40%; and a second diffusion material layer formed on a lower surface of the base film.