Waveguiding Layer Refractive Index for High PPI Displays
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Solution Overview
Problem
Current virtual and augmented reality displays, as well as transparent displays, face challenges in achieving high Pixels Per Inch (PPI) and efficient light management due to limitations in traditional LCD and OLED technologies.
Innovation Solution
A display device design featuring an upper and lower substrate with a liquid crystal layer, a wave guiding layer, and electrode structures, where the refractive index of the wave guiding layer is higher than adjacent film layers, and grating coupling structures are used to control light direction and color, allowing for high PPI and potentially eliminating the need for color filters by using a collimated light source and transparent materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional LCD and OLED panels are used for virtual/augmented reality displays, then the display can be implemented, but the Pixels Per Inch (PPI) is limited and light management efficiency is poor
Solution Approach 1:
The patent replaces traditional mechanical light management structures (color filters, complex layer arrangements) with an optical waveguiding system using total internal reflection and grating coupling. This substitution enables high PPI by controlling light propagation through refractive index differences and optical interference rather than physical pixel structures, achieving virtual/augmented reality displays with superior resolution and light efficiency
Solution Approach 2:
The patent changes the refractive index parameter of the waveguiding layer to be higher than adjacent film layers, enabling total internal reflection and efficient light guidance. This parameter change allows the system to achieve high PPI by controlling light propagation angles and coupling efficiency through refractive index matching, eliminating the need for traditional color filters and complex pixel structures
2Illumination intensity
If color filters are used in traditional displays, then color accuracy is achieved, but light transmission efficiency decreases and transparency is reduced
Solution Approach 1:
The patent extracts and eliminates the color filter layer from the display structure, achieving color accuracy through spectral control of the light source and selective grating coupling instead. This extraction dramatically improves light transmission efficiency and enables transparency while maintaining color fidelity through the waveguiding and diffraction mechanisms
Solution Approach 2:
The patent achieves color control without traditional color filters by using a collimated light source with specific spectral characteristics and controlling which wavelengths are coupled out at different pixel locations through the grating structure. This approach maintains color accuracy while maximizing light transmission and enabling transparent display functionality
3Reliability
If the refractive index of the wave guiding layer is made higher than adjacent film layers, then light guidance efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating a waveguiding layer with higher refractive index only in the specific region where light guidance is needed, while maintaining standard refractive indices in adjacent layers. This localized modification achieves efficient light guidance through total internal reflection at the waveguide boundaries without requiring complete restructuring of the entire display stack, simplifying manufacturing
Solution Approach 2:
The patent uses composite material structures where the waveguiding layer is formed with materials having higher refractive index properties, combined with adjacent layers of standard refractive index. This composite approach enables efficient optical confinement and guidance while using commercially available materials and standard fabrication processes, balancing performance with manufacturability
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
This design enhances display contrast, facilitates near-eye mode monocular focusing, and achieves high PPI without color filters, enabling transparent and high-transparency virtual/augmented reality displays.
Implementation Method 1
a wave guiding layer arranged on a side of the lower substrate facing the upper substrate, wherein a refractive index of the wave guiding layer is at least greater than a refractive index of a film layer in contact with the wave guiding layer
Implementation Method 2
a plurality of grating coupling structures arranged on the surface of the wave guiding layer facing the upper substrate, and in correspondence to the plurality of electrode structures in a one-to-one manner
Implementation Method 3
a liquid crystal layer arranged between the upper substrate and the lower substrate; a plurality of electrode structures arranged on a side of the upper substrate facing the lower substrate, wherein the plurality of electrode structures are arrayed in correspondence to a plurality of sub-pixels in a one-to-one manner
Data Source
AI summary
The disclosure provides a display device including an upper substrate (001) and a lower substrate (002) arranged opposite to each other, a liquid crystal layer (003), a wave guiding layer (004), electrode structures (005), and a collimated light source (006). The liquid crystal layer (003) is arranged between the upper substrate (001) and the lower substrate (002); the wave guiding layer (004) is arranged on a side of the lower substrate (002) facing the upper substrate (001), and a refractive index of the wave guiding layer (004) is at least greater than a refractive index of a film layer in contact with the wave guiding layer (004); the plurality of electrode structures (005) are arranged on a side of the upper substrate (001) facing the lower substrate (002), and the plurality of electrode structures (005) are arrayed in correspondence to sub-pixels in a one-to-one manner; and the collimated light source (006) is at least arranged on one side of the wave guiding layer (004). The display device can control a display grayscale.