Bridge Emitter and Sensor Calibration for Waveguide Display Alignment
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Solution Overview
Problem
Electronic devices, particularly head-mounted devices like augmented reality glasses, face challenges in maintaining optimal optical alignment due to misalignments caused by drop events and other high-stress events, leading to unsatisfactory component performance.
Innovation Solution
Incorporation of an optical bridge sensor with vertical-cavity surface-emitting lasers (VCSELs) and photodiodes to monitor and adjust image data provided to projectors, using calibration light to detect misalignments and compensate for them through control circuitry, ensuring proper alignment between waveguides and projectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical components are mounted in head-mounted device, then display function is achieved, but misalignment occurs due to drop events and high-stress events
Solution Approach 1:
The patent implements preliminary calibration using VCSELs and photodiodes to establish accurate optical alignment before use. The system performs initial alignment calibration and continues to monitor for misalignment, allowing corrective actions to be taken before performance degradation occurs.
Solution Approach 2:
The patent employs feedback mechanisms through optical sensors that continuously monitor optical path alignment. The system detects misalignment conditions and provides feedback to control circuitry, which then adjusts image data or triggers realignment procedures to maintain optimal display performance.
2Measurement precision
If calibration light sources and sensors are added, then misalignment detection capability is improved, but device complexity increases
Solution Approach 1:
The patent designs the optical bridge sensor system to serve multiple functions: calibration of optical alignment, detection of misalignment conditions, and potential realignment control. The VCSELs and photodiodes are integrated into the nose bridge structure, allowing a single system to handle both calibration and detection requirements.
Solution Approach 2:
The patent merges the calibration light sources and detection sensors into an integrated optical bridge sensor system located in the nose bridge. This consolidation combines multiple functions into a single structural element, reducing the number of separate components needed while maintaining measurement precision.
3Reliability
If real-time calibration is performed, then display performance is maintained, but processing time and energy consumption increase
Solution Approach 1:
The patent implements periodic calibration rather than continuous real-time calibration. The system performs calibration at predetermined intervals or when misalignment conditions are detected, balancing the need to maintain display performance with the requirement to minimize processing time and energy consumption.
Solution Approach 2:
The system uses the optical bridge sensor to monitor its own alignment status and automatically triggers calibration procedures only when needed. This self-service approach allows the system to maintain performance stability while avoiding unnecessary processing time and energy consumption during normal operational conditions.
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
The system effectively maintains optimal display performance by actively compensating for misalignments in real-time, ensuring clear and comfortable image presentation in both eye boxes, even under varying mechanical and thermal stress.
Implementation Method 1
The optical bridge sensor may include light sources such as vertical-cavity surface-emitting lasers (VCSELs)
Implementation Method 2
optical sensors such as photodiodes
Implementation Method 3
The third waveguide may direct the calibration light towards the first and second waveguides
Implementation Method 4
Optical couplers on the third waveguide may couple the calibration light out of the third waveguide and towards the first and second waveguides
Implementation Method 5
Partial reflectors on the first and second waveguides may reflect the calibration light back towards the optical couplers as reflected light
Data Source
AI summary
An electronic device may include a first and second projectors, first, second, and third waveguides, light sources, and optical sensors. The sources may emit calibration light into the third waveguide, which splits the calibration light between the first and second waveguides. Couplers on the third waveguide may couple the calibration light out of the third waveguide and partial reflectors on the first and second waveguides may reflect the calibration light back towards the optical couplers as reflected light. The couplers may provide the reflected light to the sensors, which generate electrical signals using the reflected light. Control circuitry may compare the electrical signals between different sensor locations to identify relative angles between the first waveguide, the second waveguide, the first projector, and/or the second projector. The control circuitry may use the identified relative angles to adjust projector images to compensate for optical misalignments over time.