Dynamic Diffraction Grating for AR Waveguide Color Uniformity
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Solution Overview
Problem
Augmented Reality (AR) image display systems face issues with inferior color uniformity due to uneven light diffracted in waveguides, leading to non-uniform recognition of virtual images by the user's eyes.
Innovation Solution
An image display apparatus comprising a first and second waveguide with diffraction gratings, where a processor identifies the quantity of light diffracted and adjusts the shape of the second diffraction grating to compensate for variations, ensuring uniform light distribution across the waveguides, using active diffracting devices like liquid crystal plates or lenses, and controlling the optical path to achieve consistent color recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light is diffracted in a waveguide using a diffraction grating, then virtual images are displayed to the user, but the light distribution becomes uneven causing inferior color uniformity
Solution Approach 1:
The patent applies local quality by varying the properties of the diffraction grating across different regions of the waveguide. Specifically, the diffraction grating has different periods or orientations in different areas to compensate for the non-uniform light distribution, ensuring that each region diffracts the appropriate amount of light to achieve uniform color perception across the entire field of view.
Solution Approach 2:
The patent employs a liquid crystal diffraction grating that can dynamically adjust its diffraction characteristics. By controlling the liquid crystal molecules' orientation through applied voltages, the system can modify the diffraction efficiency and light distribution in real-time, enabling uniform color output despite variations in light propagation through the waveguide.
2Productivity
If a diffraction grating is used to couple light into the waveguide, then virtual images are generated, but the quantity of diffracted light varies across different regions
Solution Approach 1:
The diffraction grating is designed with spatially varying parameters such as period, orientation, or depth across different regions of the waveguide. This local variation compensates for the non-uniform coupling efficiency, ensuring that each region of the waveguide receives the appropriate amount of light to maintain uniform virtual image brightness across the field of view.
3Adaptability or versatility
If multiple waveguides are stacked to increase field of view, then the AR display capability is enhanced, but the complexity of the system increases
Solution Approach 1:
The patent divides the AR display system into multiple stacked waveguide layers, with each waveguide responsible for a specific angular range or portion of the field of view. This segmentation allows the system to achieve a broader overall field of view while maintaining manageable complexity within each individual waveguide layer.
Solution Approach 2:
The patent employs a universal liquid crystal diffraction grating design that can be applied across all waveguide layers. This multi-functional component serves both as a coupling grating and an output grating, and can be dynamically controlled to adjust light distribution, thereby reducing overall system complexity despite the multi-layer architecture.
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 ensures that virtual images are recognized with uniform color by the user's left and right eyes, addressing the issue of non-uniformity and enhancing the AR experience by maintaining consistent light distribution and color representation.
Implementation Method 1
at least a portion of light incident on the first waveguide is diffracted from the first diffraction grating
Implementation Method 2
The second diffraction grating may include at least one from among a liquid crystal (LC) plate, an LC lens, and an active diffracting device
Data Source
Figure 1
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AI summary
An image display apparatus includes a first waveguide, a second waveguide positioned at one side of the first waveguide, a first diffraction grating positioned at an other side of the first waveguide, a second diffraction grating positioned between the first waveguide and the second waveguide and a display engine configured to control a shape of the second diffraction grating according to a quantity of light diffracted from the first diffraction grating, wherein at least a portion of light incident on the first waveguide is diffracted from the first diffraction grating, and at least a portion of light incident on the second waveguide, is diffracted from the second diffraction grating.