MEMS Mirror Alignment Tracking Waveguide for HMD Misalignment
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Solution Overview
Problem
Mixed reality and virtual reality systems face misalignment issues between left and right images, leading to inferior user experiences due to manufacturing variations and component shifting, which can cause blurry images, headaches, and image quality issues, especially in head-mounted displays with stringent alignment requirements.
Innovation Solution
The use of microelectromechanical system (MEMS) mirrors and diffraction optical elements (DOEs) in an alignment tracking waveguide system to precisely direct and measure light signals from left and right display module assemblies, determining alignment indicators and adjusting the images to compensate for misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If head-mounted displays are used to create depth of perception with left and right display modules, then a simulated 3D view is achieved, but misalignment between left and right signals occurs due to manufacturing variations and component shifting, leading to inferior user experience
Solution Approach 1:
The system performs preliminary alignment tracking by directing light signals from light sources through MEMS mirrors and DOEs to reference markers on the waveguide before actual display operation. This pre-alignment measurement allows the system to detect misalignment between left and right display modules in advance and compensate for it, ensuring proper stereoscopic alignment during use despite manufacturing variations and thermal drift
Solution Approach 2:
The system continuously tracks alignment by detecting light signals reflected from reference markers using photosensors. The controller receives alignment information from the photosensors and uses this feedback to adjust the rendering of left and right images, compensating for misalignment in real-time. This closed-loop feedback mechanism maintains accurate stereoscopic alignment despite component shifting and thermal conditions
2Manufacturing precision
If stringent alignment requirements are imposed to maintain image quality, then user experience is improved, but device complexity increases due to the need for precise alignment tracking and compensation mechanisms
Solution Approach 1:
The system introduces an intermediary alignment tracking mechanism using light sources, MEMS mirrors, DOEs, and reference markers on the waveguide. This intermediary system measures alignment between left and right display modules without directly affecting the primary display function. The photosensors detect light signals from reference markers, providing alignment data to the controller for compensation, thus maintaining image quality without requiring the entire display system to be inherently precise
Solution Approach 2:
The system replaces complex mechanical alignment adjustment mechanisms with optical field-based alignment tracking. Instead of using movable mechanical components to physically adjust display module positions, the system uses light propagation through MEMS mirrors and DOEs to detect alignment status. The controller then compensates for misalignment through software-based image rendering adjustments, substituting mechanical complexity with optical and computational solutions
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 ensures accurate alignment of images within the stringent requirements of head-mounted displays, maintaining image quality and user experience across varying thermal conditions and long-term usage, even with inter-pupil-distance adjustments.
Implementation Method 1
using a first microelectromechanical system (MEMS) mirror, directing a first signal from the first light source to an alignment tracking waveguide
Implementation Method 2
using a first diffraction optical element (DOE) coupling the first signal to a first display waveguide
Implementation Method 3
receiving by a first photosensor a first portion of the first signal via the alignment tracking waveguide
Data Source
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AI summary
Devices, systems, and methods corresponding to addressing misalignment in display systems are provided. A method includes using a first microelectromechanical system (MEMS) mirror, directing a first signal from a first light source to an alignment tracking waveguide. The method further includes receiving by a first photosensor a first portion of the first signal via the alignment tracking waveguide and determining a first alignment indicator associated with the first portion of the first signal. The method further includes using a second MEMS mirror, directing a second signal from a second light source to the alignment tracking waveguide. The method further includes receiving by a second photosensor a second portion of the second signal via the alignment tracking waveguide and determining a second alignment indicator associated with the second portion of the second signal.