AR Waveguide Display With Tunable Focus for VAC Reduction
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Solution Overview
Problem
AR devices cause eyestrain due to vergence accommodation conflict (VAC) when users experience 3D images for extended periods, and there is a need to respond to a user's region of interest with multiple virtual images.
Innovation Solution
An AR device equipped with a focus tunable lens and eye tracker to adjust focal length and track user gaze, reducing VAC by aligning vergence and focal distances, and selectively blocking or transmitting light to focus on regions of interest.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is mounted on a mobile device to capture images for AR content, then AR functionality is enabled, but the captured image quality is degraded due to motion blur from device movement
Solution Approach 1:
The system performs preliminary actions by capturing a sequence of images before the actual AR content is needed, then processes these images offline to generate a depth map. This preliminary depth information is stored and reused during actual AR operations, eliminating the need for high-speed real-time depth sensing and reducing motion blur impact.
Solution Approach 2:
The patent introduces an intermediary processing step where captured images are processed through image processing algorithms to generate depth maps. This intermediary representation (depth map) serves as a mediator between the captured image and the final AR rendering, allowing the system to work with lower quality captured images while still achieving good AR results.
2Measurement precision
If multiple sensors are added to a mobile device to improve AR performance, then AR accuracy is enhanced, but the device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using expensive specialized depth sensing hardware, the system creates a computational copy of depth information by processing ordinary camera images through algorithms. The depth map is a computational representation that mimics what specialized sensors would provide, but is derived from standard camera data through image processing techniques.
Solution Approach 2:
The patent replaces mechanical/optical depth sensing systems with a computational approach. Instead of using time-of-flight sensors, structured light projectors, or other hardware-based depth sensing mechanisms, the system uses image processing algorithms to infer depth information from standard images, substituting computational methods for mechanical sensing systems.
3Measurement precision
If real-time depth sensing is implemented in mobile AR, then AR rendering accuracy improves, but power consumption increases
Solution Approach 1:
The system performs depth map generation in advance during idle or low-power periods, rather than continuously during AR operations. By pre-processing images to create depth maps and storing them for later use, the system eliminates the need for continuous power-intensive real-time depth sensing during actual AR rendering.
Solution Approach 2:
Instead of continuous real-time depth sensing, the system uses periodic batch processing where images are captured and processed in sequences. The depth maps generated from these periodic processing cycles are then reused for multiple AR rendering operations, reducing the overall power consumption compared to continuous sensing.
Data Source
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AI summary
An electronic device for displaying AR includes: an optical engine; a first polarizer; a polarization converter configured to maintain or convert a polarization direction of light of a real scene; a waveguide from which light of a virtual image is output and through which the light of the real scene is transmitted; a focus tunable lens; a second polarizer; and one or more processors. The one or more processors are configured to, during a first period, control the polarization converter to convert a polarization direction of a first light of the real scene such that at least part of the first light of the real scene is blocked by the second polarizer, and during a second period, control the polarization converter to maintain a polarization direction of a second light of the real scene such that the second light of the real scene is transmitted through the second polarizer.