Head-Mounted Virtual Content Depth Matching for Clear Focus
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Solution Overview
Problem
Head-mounted devices often present virtual content at a depth that does not match the user's eye focus depth, leading to blurriness.
Innovation Solution
The device includes sensors to determine the eye focus depth and adjusts the virtual content depth and lens focus distance to match the user's gaze and head movements, using vergence angle and head rotation as criteria to lock or unlock the content depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the virtual content is displayed at a fixed depth, then the device complexity is reduced, but the image clarity deteriorates when the user's eye focus depth does not match the content depth
Solution Approach 1:
The patent implements dynamic depth adjustment by continuously monitoring the user's eye focus depth through sensors (such as vergence angle sensors) and adjusting the virtual content depth in real-time to match the user's focus. This transforms the fixed depth system into a dynamic one that adapts to user needs, resolving the contradiction between simplicity and clarity.
Solution Approach 2:
The system employs feedback mechanisms where sensors detect the user's eye focus depth and provide this information to the control system, which then adjusts the virtual content depth accordingly. This closed-loop feedback ensures that the content remains clear by continuously matching the display depth to the user's actual focus point.
2Reliability
If the virtual content depth is continuously adjusted to match eye focus depth, then the image clarity is improved, but the device complexity increases due to additional sensors and control mechanisms
Solution Approach 1:
The patent leverages existing head-mounted display components (such as lenses and displays already present in the system) to perform multiple functions. The lenses not only focus light but also serve as part of the depth adjustment mechanism, while the display system handles both rendering and depth modulation, reducing the need for entirely separate complex subsystems.
Solution Approach 2:
The system adjusts depth by changing optical parameters (such as lens focus distance and display content depth) rather than adding complex mechanical structures. By modifying existing parameters of current components, the system achieves depth matching with minimal additional hardware complexity.
3Speed
If the focus distance of lenses is adjusted rapidly to match depth changes, then the responsiveness is improved, but the stability of the focus adjustment deteriorates
Solution Approach 1:
The patent implements periodic sampling of eye focus depth through sensors at controlled intervals, rather than continuous adjustment. This periodic measurement and adjustment approach allows the system to respond quickly to significant depth changes while avoiding over-adjustment and instability from excessive feedback frequency.
Solution Approach 2:
The system applies partial adjustment by only modifying the focus distance when the change exceeds a threshold, rather than continuously adjusting at full speed. This prevents unnecessary rapid adjustments that would cause instability, while still maintaining responsiveness to meaningful depth changes.
Data Source
AI summary
In a head-mounted device, a gaze-tracking sensor may measure a vergence angle associated with the user's eyes. The vergence angle may be used to determine the user's eye focus depth. Virtual content may be presented at a depth that is equal to the eye focus depth. When the depth of the virtual content is not equal to the eye focus depth, the virtual content may be shifted towards the eye focus depth. Once the depth of the virtual content is approximately equal to the eye focus depth, the depth of the virtual content may be locked. The depth of the virtual content may remain locked until one or more unlock criteria are met. The unlock criteria may be based on the vergence angle of the user's eyes, a head rotation, and/or a head position.