Optically-Anisotropic Layer with Regional Diffraction for AR Clarity
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Solution Overview
Problem
Existing AR glasses using liquid crystal diffraction elements for exit pupil expansion suffer from insufficient image clarity due to light being diffracted at multiple positions outside the light guide plate.
Innovation Solution
An optically-anisotropic layer composed of regions with varying liquid crystal alignment patterns and diffraction efficiencies, including cholesteric liquid crystal layers, is integrated into the light guide plate to enhance image clarity by uniform brightness and controlled diffraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light is diffracted at multiple positions outside the light guide plate to expand viewing zone, then exit pupil expansion is achieved, but image clarity becomes insufficient
Solution Approach 1:
The light guide plate is divided into multiple diffraction regions (first diffraction region and second diffraction region) with different diffraction efficiencies. The first diffraction region has higher diffraction efficiency for coupling light into the waveguide, while the second diffraction region has lower diffraction efficiency for emitting light to the user's eye. This segmentation allows simultaneous achievement of effective light coupling and clear image output without mutual interference.
Solution Approach 2:
Different regions of the light guide plate are assigned different optical properties (diffraction efficiencies) according to their specific functions. The first diffraction region is optimized for high diffraction efficiency to maximize light coupling from the display, while the second diffraction region is optimized for controlled light emission to ensure image clarity at the exit pupil. This local optimization resolves the contradiction between viewing zone expansion and image clarity.
2Productivity
If diffraction efficiency is increased to improve light coupling, then light propagation efficiency improves, but brightness uniformity across the viewing zone deteriorates
Solution Approach 1:
The patent applies different diffraction efficiencies to different spatial regions of the light guide plate. The first diffraction region (near the display coupling point) has higher diffraction efficiency to maximize light input, while the second diffraction region (near the user's eye) has lower diffraction efficiency to prevent hotspots and maintain uniform brightness distribution across the exit pupil. This spatial variation in diffraction efficiency simultaneously optimizes both light coupling and brightness uniformity.
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 optically-anisotropic layer improves image clarity and brightness uniformity by optimizing diffraction efficiency across the viewing zone, addressing the clarity issues in AR glasses.
Implementation Method 1
an optically-anisotropic layer which diffracts incident light
Implementation Method 2
a region A having a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating
Implementation Method 3
including cholesteric liquid crystal layers
Implementation Method 4
an optically-anisotropic layer formed of a composition containing a liquid crystal compound
Implementation Method 5
an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating
Data Source
AI summary
An optically-anisotropic layer that is an optically-anisotropic layer formed of a composition containing a liquid crystal compound, the optically-anisotropic layer including a region A having a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, a region B having a liquid crystal alignment pattern in which an orientation of an optical axis derived from the liquid crystal compound changes while continuously rotating in at least one in-plane direction, and a region not having the liquid crystal alignment pattern, in which the region A, the region B, and the region not having the liquid crystal alignment pattern are provided in the same in-plane direction of the optically-anisotropic layer.