Head-Mounted Display Optical Alignment Using 6-DOF Assembly
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Solution Overview
Problem
Existing head-mounted displays suffer from optical misalignments between projectors and waveguides due to manufacturing variabilities, leading to reduced optical quality and user experience.
Innovation Solution
A method for aligning optical components, such as waveguides and projectors, by using a support mechanism that allows for precise manipulation in six degrees of freedom, combined with optical alignment cameras to ensure alignment within predetermined thresholds, followed by secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional manufacturing methods are used for head-mounted displays, then manufacturing simplicity is maintained, but optical misalignments occur between projectors and waveguides due to manufacturing variabilities
Solution Approach 1:
The patent applies preliminary action by pre-aligning optical components (projectors and waveguides) using a six-degree-of-freedom manipulation system and optical alignment cameras before final assembly. This preliminary alignment process ensures that components are precisely positioned and oriented relative to each other and to fiducial markers on the frame, thereby achieving high optical alignment precision while compensating for manufacturing variabilities.
Solution Approach 2:
The patent uses fiducial markers as intermediaries to facilitate alignment. These markers are placed on the frame and serve as reference points for both the projector and waveguide alignment processes. The optical alignment cameras detect these fiducial markers to determine the precise position and orientation of components, enabling accurate alignment without direct mechanical coupling between all components.
2Manufacturing precision
If optical components are aligned using manual methods, then device complexity is reduced, but alignment precision falls below predetermined thresholds
Solution Approach 1:
The patent implements feedback through optical alignment cameras that continuously monitor the alignment status of projectors and waveguides relative to fiducial markers. The system provides real-time feedback on position and orientation deviations, allowing for precise adjustments to be made. This automated feedback loop ensures that alignment precision meets predetermined thresholds while reducing reliance on manual alignment operations.
Solution Approach 2:
The patent replaces manual mechanical alignment methods with an automated optical measurement and manipulation system. Instead of relying on mechanical fixtures and manual adjustment, the system uses optical alignment cameras to detect component positions and a six-degree-of-freedom manipulation system to automatically adjust component orientations, thereby achieving high precision alignment with increased automation.
3Manufacturing precision
If alignment thresholds are made more stringent, then optical quality improves, but measurement and detection difficulty increases
Solution Approach 1:
The patent applies segmentation by breaking down the alignment measurement task into discrete, manageable components. The system uses multiple optical alignment cameras positioned at different locations to measure different aspects of component alignment independently. Fiducial markers are placed at specific locations on the frame to provide localized reference points for each measurement, making the overall measurement process more manageable and accurate despite stringent thresholds.
Data Source
AI summary
The disclosed methods of assembling a head-mounted display may include supporting a head-mounted display frame, moving the head-mounted display frame to align a frame coordinate system with a fixed optical coordinate system, holding a projector assembly, and moving the projector assembly to align a projected image with the fixed optical coordinate system. The aligned projector assembly may be secured to the aligned head-mounted display frame. Various other methods and systems are also disclosed.