Variable Focus Element and PDLC Diffusers for AR Vergence-Accommodation Mismatch
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Solution Overview
Problem
Conventional augmented reality display systems fail to provide a comfortable and realistic three-dimensional experience due to mismatched vergence and accommodation, leading to user discomfort such as eye fatigue and headaches, as they do not effectively mimic the human visual system's natural focus and depth perception mechanisms.
Innovation Solution
The system projects virtual content at varying depths using multiple or variable plane focus systems, incorporating spatial light modulators, variable focus elements, and eye-tracking subsystems to dynamically adjust the focus and depth planes, ensuring that virtual content is perceived at realistic distances, aligning with the user's natural focus and motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereoscopic wearable glasses are used to present three-dimensional images, then depth perception is improved, but user comfort deteriorates due to vergence-accommodation mismatch
Solution Approach 1:
The patent implements dynamic focus adjustment by varying the focal plane of the display system in real-time based on the depth of virtual objects. The focal plane is adjusted to match the vergence distance of stereoscopic pairs, enabling the display to dynamically adapt between different depth states (near, intermediate, far) while maintaining both depth perception and user comfort through coordinated focus changes
Solution Approach 2:
The system incorporates eye-tracking subsystems that provide feedback on user gaze and accommodation state. This feedback is used to dynamically adjust the focal plane and vergence parameters, creating a closed-loop system that continuously optimizes the match between vergence and accommodation to prevent discomfort while maintaining accurate depth perception
2Measurement precision
If cameras and displays are positioned to capture and present stereoscopic images, then three-dimensional visualization is improved, but the natural field of view is blocked
Solution Approach 1:
The patent transitions from blocking the user's view to presenting AR content that integrates with the real-world view. By using augmented reality displays that overlay virtual objects onto the natural field of view rather than completely blocking it, the system provides three-dimensional visualization while preserving the user's ability to see the real world around them
Solution Approach 2:
The system uses transparent or semi-transparent display media as an intermediary between the user's eyes and the real world. This allows light from the real environment to pass through while simultaneously presenting stereoscopic virtual content, enabling both functions without complete occlusion of the natural field of view
3Area of stationary object
If monocular displays are used to present augmented digital imagery, then the real world view remains unobstructed, but binocular three-dimensional experience is lost
Solution Approach 1:
The patent implements a multi-functional display system that can operate in both monocular and binocular modes. The same AR display infrastructure is used to provide unobstructed real-world viewing while also presenting stereoscopic virtual content to both eyes, enabling the system to deliver both functions simultaneously rather than requiring separate systems
4Measurement precision
If multiple depth planes are projected to simulate natural focus, then depth perception realism is improved, but system complexity increases
Solution Approach 1:
The patent segments the continuous depth space into discrete focal planes (near, intermediate, far) that correspond to natural human accommodation states. Rather than attempting to provide continuous focus adjustment across all depths, the system divides the visual field into manageable depth layers, reducing computational and optical complexity while maintaining perceptual realism through the segmentation of depth information
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 approach allows for a more comfortable and realistic augmented reality experience by accurately simulating the human visual system's depth perception, reducing user discomfort and enhancing the perception of virtual objects in three dimensions.
Implementation Method 1
a variable focus element (VFE) that varies a focus of light from the spatial light modulator
Implementation Method 2
a stacked PDLC diffuser arrangement that diffuses the focused light and increases a numerical aperture of the light beam
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
An augmented reality display system (1500), comprising a spatial light modulator (1504) operatively coupled to an image source for projecting light associated with one or more frames of image data; an eye tracking system to determine a focus of a user's eyes; a variable focus element, VFE, (1510) coupled to a set of optics for focusing at least a frame of the one or more frames of image data on a depth plane based at least in part on the focus of the user's eyes; and a plurality of switchable polymer-dispersed liquid crystal, PDLC, diffusers (1620) to increase a numerical aperture of the light associated with one or more frames of image data; wherein the number of PDLC diffusers (1620) in the plurality corresponds to a number of depth planes in which the system is configured to generate images.