Optical Member With Diffraction Grating For Wide-Angle Display
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Solution Overview
Problem
Display devices with diffraction grating structures and differing refractive indexes suffer from increased reflectivity, leading to reduced contrast and visibility, especially in wide angle directions, due to light leakage and backscattering of external reflections.
Innovation Solution
An optical member comprising a substrate with a high refractive layer and a low refractive layer, where the refractive index difference between the layers is significant, and the interfaces are in a compatible state, with the high refractive layer having a diffraction grating structure and an anti-reflective layer to minimize reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffraction grating structure with large refractive index difference is used to emit light at wide angles, then light diffusion effect is improved, but reflectivity increases causing reduced contrast and visibility
Solution Approach 1:
An anti-reflective layer is introduced as an intermediary between the high refractive index layer (with diffraction grating) and the low refractive index layer. This intermediate layer has a refractive index between the two adjacent layers, serving as a transition that reduces the abrupt refractive index difference and thereby minimizes reflection at the interface while preserving the diffraction-based light diffusion effect.
Solution Approach 2:
The refractive index parameter is gradually changed across multiple layers rather than having an abrupt transition. By creating a gradient structure where the refractive index changes step-by-step from the high refractive index layer through the anti-reflective layer to the low refractive index layer, the reflection is reduced while maintaining the diffraction functionality.
2Illumination intensity
If particles with different refractive indexes are dispersed in transparent material to diffuse light, then wide angle light emission is improved, but back scattering of reflected external light occurs reducing contrast
Solution Approach 1:
The patent replaces the particle-based diffusion mechanism (mechanical dispersion of particles) with a wave-based diffraction mechanism using a diffraction grating structure. This substitution eliminates the random scattering and backscattering issues associated with particle dispersion while achieving controlled wide-angle light emission through diffraction.
3Object-generated harmful factors
If phase difference compensation film is used to correct light leakage, then front direction contrast is improved, but wide angle direction contrast remains insufficient
Solution Approach 1:
The patent transitions from correcting light leakage in the front direction only (single dimension optimization) to achieving wide-angle light emission control in multiple directions (multi-dimensional optimization) through the diffraction grating structure. The diffraction grating inherently directs light at various angles, providing contrast improvement across a wide viewing angle range rather than just in the normal direction.
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 enhances contrast and visibility by reducing reflectivity and maintaining high luminance and contrast in both front and wide angle directions, while preventing light reflection at interfaces with significant refractive index differences.
Implementation Method 1
a high refractive layer and a low refractive layer, wherein a refractive index of the high refractive layer is higher than a refractive index of the substrate, and the high refractive layer has a diffraction grating structure
Implementation Method 2
an anti-reflective layer to minimize reflection... preventing light reflection at interfaces with significant refractive index differences
Data Source
Figure 1A~1C
Figure 2A~3B
Figure 4
AI summary
An optical member, a polarization member, and a display device are provided. The optical member includes a substrate, and a functional layer provided on the substrate, the functional layer including a high refractive layer and a low refractive layer, wherein the high refractive layer has a higher refractive index than that of the substrate and a diffraction grating structure, and the low refractive layer has a lower refractive index than that of the high refractive layer, wherein an interface between the substrate and the high refractive layer and an interface between the high refractive layer and the low refractive layer are in states in which components of the respective layers with the respective interfaces therebetween are compatible with each other.