Varifocal VR Headset Optics for Vergence-Accommodation Conflict
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Solution Overview
Problem
Virtual reality headsets fail to correctly render depth and cause visual fatigue and nausea due to an inability to compensate for vergence and accommodation conflicts, leading to discomfort for users.
Innovation Solution
A virtual reality headset automatically adjusts its focus based on the user's gaze point within a virtual scene by using a varifocal element to change the focal length of the optics block, tracking eye positions, and refining vergence depth with geometric data, while dynamically adding depth of field blur to provide depth cues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed focal length optics block is used in the virtual reality headset, then the device structure is simple and manufacturing is easier, but vergence-accommodation conflicts occur causing visual fatigue and nausea
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed focal length optics block to a variable focal length optics block that can dynamically adjust its focus. The optics block now includes a varifocal element that changes the focal length based on the vergence depth of the gaze point, allowing the system to adapt to different viewing conditions and eliminate vergence-accommodation conflicts that cause visual fatigue and nausea.
Solution Approach 2:
The patent applies the parameter changes principle by modifying the focal length parameter of the optics block. Instead of maintaining a constant focal length, the system varies the focal length parameter in response to changes in vergence depth, enabling the optics to properly accommodate different depths in the virtual scene and prevent visual discomfort.
2Object-affected harmful factors
If the focal length of the optics block is dynamically adjusted using a varifocal element, then vergence-accommodation conflicts are mitigated and user comfort is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies the intermediary principle by introducing a varifocal element as a mediator between the display system and the user's eyes. This varifocal element acts as an intermediate component that adjusts the optical path and focal length, enabling the system to resolve vergence-accommodation conflicts without requiring fundamental changes to the entire headset architecture.
3Extent of automation
If eye tracking and gaze point determination are implemented, then focus adjustment can be automatically controlled, but the device complexity and processing requirements increase
Solution Approach 1:
The patent applies the feedback principle by implementing an eye tracking system that continuously monitors the user's gaze and provides feedback to the focus adjustment mechanism. The system determines the gaze point based on eye position data and uses this information to automatically adjust the focal length of the optics block, creating a closed-loop control system that adapts to user viewing behavior in real-time.
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 effectively mitigates vergence-accommodation conflicts, keeping users' eyes in a comfortable zone and enhancing the virtual reality experience by accurately focusing images and providing realistic depth cues, reducing visual fatigue and nausea.
Implementation Method 1
a varifocal element (e.g., an element that mechanically changes a distance between a lens system in the optics block and the electronic display element, an element that changes shape of one or more lenses in the lens system in the optics block, etc.)
Data Source
AI summary
A virtual reality headset displays a three-dimensional (3D) virtual scene and includes a varifocal element to dynamically adjust a focal length of an optics block included in the virtual reality headset based on a location in the virtual scene where the user is looking. The headset tracks a user's eyes to approximate gaze lines and determines a plane of focus for a frame of the virtual scene as the intersection of the gaze lines. The varifocal element adjusts the focal length of the optics block so the optics block is focused at the plane of focus, which keeps the user's eyes in a zone of comfort as vergence and accommodation change. Based on the plane of focus, the virtual reality headset may provide depth cues, such as depth of field blur, to planes in the virtual scene deeper in the user's field of view than the plane of focus.