Asymmetric Diffuser for Display Optical Stack
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Solution Overview
Problem
Existing display systems, such as LCDs, suffer from undesirable defects like moire and optical defects, which prior attempts to mitigate result in reduced optical gain and contrast.
Innovation Solution
Incorporating an asymmetric diffuser in the optical stack, which is less diffusive along one direction and more diffusive orthogonal to it, to reduce these defects while maintaining optical gain and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional diffusers are used to reduce moire and optical defects, then optical defects are reduced, but optical gain and contrast are reduced
Solution Approach 1:
The patent applies asymmetry by using an asymmetric diffuser with different diffusion properties in orthogonal directions. The diffuser has a first diffusion coefficient in a first direction and a second diffusion coefficient in a second direction orthogonal to the first direction, where the coefficients are different. This asymmetric diffusion selectively scatters light to reduce moire patterns and optical defects while preserving optical gain and contrast in the display.
2Object-affected harmful factors
If symmetric diffusers are used to scatter light, then optical defects are reduced, but light transmission efficiency decreases
Solution Approach 1:
The patent applies local quality by creating direction-dependent diffusion characteristics in the asymmetric diffuser. The diffuser structure (such as elongated particles, oriented fibers, or anisotropic microstructures) provides different diffusion coefficients for different directions, allowing localized control over light scattering. This enables effective moire pattern reduction in critical viewing directions while maintaining higher light transmission efficiency overall.
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 asymmetric diffuser effectively reduces undesirable optical defects while maintaining brightness and contrast, with average effective transmission monotonically decreasing as the viewing angle increases from 35 to 55 degrees, thus enhancing display performance.
Implementation Method 1
an asymmetric light diffuser disposed on the reflective polarizer and being less diffusive along the first direction and more diffusive along a second direction orthogonal to the first direction
Implementation Method 2
The reflective polarizer substantially reflecting light having a first polarization state and substantially transmitting light having a second polarization state perpendicular to the first polarization state
Data Source
AI summary
The present disclosure describes an optical stack that includes an asymmetric diffuser. As described herein, use of an asymmetric diffuser in an optical stack reduces undesirable defects in a display while maintaining optical gain and/or contrast of the display. The asymmetric diffuser is less diffusive along a first direction that is parallel with linearly extending structures of an associated light directing film.