Multi-planar Waveguide Display for Vergence-Accommodation Conflict
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Solution Overview
Problem
Binocular displays in artificial reality systems face the vergence-accommodation conflict (VAC), where users experience eye fatigue due to a mismatch between the accommodation depth and vergence depth, limiting the depth range of displayed images to between infinity and 1 meter without causing fatigue.
Innovation Solution
A near-eye-display (NED) system with a multi-planar display assembly and eye tracking system, utilizing a waveguide-lens stack with focal adjustment lenses and a multifocal module to dynamically adjust the focus of images based on eye tracking information, allowing for varied focal distances and mitigating VAC by ensuring images are in focus at the user's gaze angle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a waveguide display forms an image at a fixed accommodation depth, then the image is in focus for the user's eyes, but the depth range of displayed images is limited and causes eye fatigue when vergence depth differs from accommodation depth
Solution Approach 1:
The display system is segmented into multiple waveguide displays (first, second, third waveguide displays) arranged in optical series, each associated with a different focal distance. This segmentation allows the system to present images at multiple discrete depth planes, enabling the user to view content at various accommodation depths without eye fatigue while maintaining sharp focus at each plane.
Solution Approach 2:
The system dynamically switches between different waveguide displays based on eye tracking information and user gaze direction. The multifocal module receives eye tracking data and activates the appropriate waveguide display that corresponds to the user's current focal point, allowing real-time adaptation of the focal distance to match user needs and expand the effective depth range.
2Adaptability or versatility
If multiple waveguide displays are arranged in optical series with different focal distances, then the depth range is expanded, but the device complexity increases
Solution Approach 1:
Multiple waveguide displays are merged into a single integrated display assembly arranged in optical series. The waveguides are positioned sequentially along the optical path from the user's eye, with each waveguide coupled to its own display panel. This merging approach consolidates multiple focal planes into one compact unit while maintaining the optical independence of each waveguide channel.
Solution Approach 2:
Each waveguide display in the assembly serves multiple functions: it acts as both a display panel and an optical element for its specific focal plane, and collectively they provide a multi-focal display system that replaces what would traditionally require separate devices or complex adjustable mechanisms.
3Adaptability or versatility
If eye tracking system and multifocal module are added to dynamically adjust focus, then vergence-accommodation conflict is mitigated, but the device complexity and power consumption increase
Solution Approach 1:
The system implements a feedback loop where the eye tracking system continuously monitors user eye position and gaze direction, sends this information to the multifocal module, which then selects and activates the appropriate waveguide display. This closed-loop feedback mechanism enables automatic focus adjustment that responds to user needs in real-time, mitigating vergence-accommodation conflict without requiring manual intervention.
Solution Approach 2:
The display system performs self-adjustment of focal distance based on eye tracking information, eliminating the need for manual focus controls or additional user interaction. The multifocal module autonomously determines which waveguide display should be active based on the user's gaze, and the system automatically switches between focal planes to maintain optimal viewing comfort.
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 system effectively increases the depth range of displayed images without causing eye fatigue, allowing for more comfortable and immersive artificial reality experiences by ensuring images are in focus at the user's intended depth, thereby reducing VAC.
Implementation Method 1
a first waveguide display, a second waveguide display, and a third waveguide display arranged in an optical series and configured to emit light in accordance with multifocal instructions
Implementation Method 2
different combinations of focal adjustment lenses are associated with different focal distances
Data Source
AI summary
A near-eye display includes a display assembly, an eye tracking system, and a multifocal module. The display assembly emits image light at a particular focal distance in accordance with multifocal instructions. The display assembly includes focal adjustment lenses and waveguide displays arranged in optical series and configured to emit light in accordance with the multifocal instructions. Different combinations of focal adjustment lenses are associated with different focal distances. Each waveguide display is separated from one or more adjacent waveguide displays by one or more of the plurality of focal adjustment lenses, and is associated with a unique combination of one or more of the focal adjustment lenses and a corresponding focal distance. The eye tracking system determines eye tracking information for a user's eye. The multifocal module generates the multifocal instructions based on the eye tracking information and provides the multifocal instructions to the display assembly.