Waveguide Grating Scanning Assembly for Large Eyebox Near-Eye Displays
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Solution Overview
Problem
Conventional near-eye display systems face challenges in achieving a small form factor while maintaining a large eyebox, which is essential for compact and lightweight designs in virtual and augmented reality applications, due to the complexity of designing two-dimensional expansion using spatially separated output grating elements.
Innovation Solution
The near-eye display system incorporates a light source assembly, a scanning assembly with grating elements that diffract and scan light into multiple beams, and output waveguides that expand these beams along two dimensions, allowing for a larger eyebox with overlap in the eyebox area, thereby reducing the form factor and enhancing usability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional methods use two spatially separated output grating elements for two-dimensional expansion, then the eyebox can be expanded, but the form factor becomes large
Solution Approach 1:
The patent combines two spatially separated output grating elements into a single integrated waveguide structure. The first and second output gratings are positioned at different locations within the same waveguide, allowing two-dimensional expansion of the eyebox while maintaining a compact form factor. This merging eliminates the need for separate waveguides or spatially separated components.
Solution Approach 2:
The patent transitions from a one-dimensional scanning approach to two-dimensional expansion by incorporating both first and second output gratings that operate in orthogonal dimensions. The first output grating expands in one dimension while the second output grating expands in the orthogonal dimension, achieving large eyebox area without proportionally increasing form factor volume.
2Volume of moving object
If a compact waveguide display is designed, then the form factor is reduced, but achieving a large eyebox becomes challenging
Solution Approach 1:
The patent nests multiple functional elements within a single waveguide structure. The first and second output gratings are embedded within the same waveguide substrate, allowing the system to achieve large eyebox area through internal structural complexity rather than external size expansion. This nesting enables compact form factor while maintaining large functional area.
Solution Approach 2:
The patent utilizes orthogonal dimensions within the waveguide to achieve two-dimensional expansion. By positioning output gratings that operate in perpendicular directions, the system expands the eyebox in both horizontal and vertical dimensions without proportionally increasing the overall waveguide volume, thus maintaining compact form factor.
3Illumination intensity
If high power collimated laser beam is used for scanning, then brightness and efficiency are improved, but the system complexity increases
Solution Approach 1:
The patent replaces traditional mechanical scanning systems with a waveguide-based optical scanning approach using diffraction gratings. Instead of using high power collimated laser beams with mechanical scanners, the system uses waveguide modes and grating diffraction to achieve scanning functionality, reducing mechanical complexity while maintaining brightness and efficiency.
Solution Approach 2:
The patent changes the fundamental parameters of the lighting approach by using integrated waveguide modes rather than external high power laser beams. The waveguide confines and guides light through total internal reflection, and the output gratings diffract light at specific angles, achieving efficient light direction with reduced system complexity compared to traditional laser scanning methods.
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 solution enables a compact and lightweight near-eye display with a large eyebox, reducing ghost images from crosstalk between color channels and improving the field of view, while maintaining the brightness and resolution required for virtual and augmented reality applications.
Implementation Method 1
The scanning assembly includes grating elements that diffract the emitted light into a plurality of beams
Implementation Method 2
The output waveguide expands the beams at least along two dimensions to form expanded light for each respective beam
Data Source
AI summary
A near-eye-display is used for presenting media to a user. The near-eye-display includes a light source assembly, a scanning assembly, one or more output waveguides, and a controller. The light source assembly emits light that is at least partially coherent. The scanning assembly includes grating elements associated with a wave vector that diffract the emitted light into several beams, and scan the beams in accordance with display instructions. The output waveguide includes several input areas, and an output area. Each input area includes one or more coupling elements associated with respective wave vectors that receive a respective beam. The output waveguide expands the beam at least along two dimensions to form expanded light for each respective beam toward a different portion of an eyebox with an overlap in at least some portions of the eyebox. The controller controls the scanning of the scanning assembly to form a two-dimensional image.