Self-Calibrating Near-Eye Display for Binocular Disparity
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Solution Overview
Problem
Near-eye displays, particularly in AR and VR headsets, face challenges with binocular disparity and visual defects due to misalignment between waveguides and projectors, leading to uncomfortable form factors and image quality issues.
Innovation Solution
A self-calibrating display system that uses test light and test images projected by both projectors, detected by a photodetector array, to assess and adjust for binocular disparity and other visual defects in real-time, allowing for precise alignment and uniform image delivery to both eyes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If projectors are placed on the eye side to reduce headset form factor, then device size and weight are reduced, but binocular disparity and misalignment between waveguides and projectors occur
Solution Approach 1:
The patent applies preliminary action by projecting test patterns before actual use and detecting them with photodetectors to pre-calibrate the optical alignment. This allows the system to compensate for manufacturing tolerances and assembly variations in waveguide-projector alignment, enabling projector placement on the eye side without suffering from binocular disparity issues.
Solution Approach 2:
The system performs self-calibration by using its own projectors to project test patterns and its own photodetectors to detect them, automatically determining and correcting alignment parameters without external equipment. This self-service approach enables real-time compensation for misalignment while maintaining the compact form factor.
2Volume of moving object
If compact displays are used to reduce headset size, then device volume is reduced, but image quality and visual uniformity deteriorate
Solution Approach 1:
The patent implements feedback by using photodetectors to detect test patterns projected through the waveguides, comparing the detected patterns with expected patterns, and using this information to calculate and apply corrections to the projection system. This closed-loop feedback ensures uniform image quality and true-color reproduction in compact displays.
Solution Approach 2:
The system changes parameters by adjusting projection characteristics based on detected test pattern variations. The controller modifies projection parameters such as brightness, color balance, and geometric alignment to compensate for manufacturing tolerances and assembly variations, maintaining image uniformity in compact form factors.
3Measurement precision
If self-calibration with test patterns is implemented, then alignment precision is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent applies universality by making the projectors serve dual functions: displaying actual content to the user and projecting test patterns for self-calibration. Similarly, the photodetectors serve both to detect test patterns for alignment and to monitor displayed content. This multi-functionality reduces the need for separate dedicated calibration components.
Solution Approach 2:
The system performs self-calibration using its own existing components (projectors and photodetectors) without requiring external calibration equipment or additional specialized parts. The test patterns are generated by the display system itself, and the alignment measurements are taken by the system's own sensors, eliminating the need for separate calibration devices.
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 enables the reduction of the headset's form factor by allowing projector placement on the eye side, ensuring consistent and true-color images for both eyes, thereby enhancing user experience and comfort.
Implementation Method 1
a waveguide to propagate the light from the projector to an eyebox
Implementation Method 2
detected by a photodetector array
Data Source
AI summary
A self-calibrating display can detect and compensate for binocular disparity or other visual imperfection of the display. The display includes a pair of projection units for projecting test light carrying test images through waveguides, which are normally used to carry images to left and right eyes of a user. A detection unit detects the test light propagated through the waveguides, and extracts the test images. Position of reference features in the detected test images may be used to determine binocular disparity, and luminance and color distribution across the test images may be used to determine the illumination and color uniformity of the images displayed to the user. After the visual defects have been detected, they may be reduced or compensated for by pre-emphasizing or shifting images to be displayed to the left and right eyes of the user.