Direct Retinal Projector Gaze Tracking and Dynamic Focus
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Solution Overview
Problem
Conventional virtual reality (VR) and augmented reality (AR) systems suffer from accommodation-convergence mismatch issues, leading to eyestrain, headaches, and nausea due to the brain being confused by mismatched depth cues, causing discomfort and reducing user endurance.
Innovation Solution
A direct retinal projector system that includes a gaze tracking component and an adjustable focusing element, which automatically adjusts the projection of a scanned light field to match the user's pupil position and focus, eliminating the need for intermediate image planes and reducing accommodation-convergence mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional stereoscopic VR/AR systems display images at a fixed focal depth, then the system structure is simple, but the user experiences accommodation-convergence mismatch causing eyestrain and discomfort
Solution Approach 1:
The patent implements dynamic focus adjustment by scanning laser beams across the retina and controlling the focal depth of the projected image. The system dynamically changes the accommodation state of the user's eyes to match the convergence depth, resolving the accommodation-convergence mismatch through real-time optical adjustment rather than fixed focal planes
Solution Approach 2:
The system changes the focal depth parameter of the projected image dynamically. By adjusting the focal distance of the laser projection to match the perceived depth of virtual objects, the system aligns accommodation with convergence, eliminating discomfort without requiring complex mechanical reconfiguration
2Reliability
If the projected image focal depth is adjusted to match perceived depth, then accommodation-convergence mismatch is reduced, but the system requires complex focus control mechanisms
Solution Approach 1:
The system employs feedback control by monitoring the user's eye position and gaze direction, then adjusting the focal depth of the projected image accordingly. This closed-loop control ensures that the accommodation state always matches the convergence depth, maintaining depth cue consistency while automating the complex focus adjustment process
Solution Approach 2:
The patent replaces traditional mechanical focus adjustment mechanisms with optical scanning and electronic control. Instead of moving physical lenses or mirrors mechanically, the system uses scanned laser beams and electronic modulation to achieve dynamic focus control, reducing mechanical complexity while maintaining reliability
3Manufacturing precision
If a scanned light field is projected directly to the retina, then high-resolution images are achieved, but precise alignment with the user's pupil is required
Solution Approach 1:
The system implements self-aligning functionality by using the user's own eye movements as the alignment reference. The gaze tracking component detects pupil position and the system automatically adjusts the scan origin and beam direction to ensure the light field is always projected through the correct pupil location, making the system self-correcting rather than requiring external alignment procedures
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 reduces discomfort by ensuring that the projected images align with the user's natural focus, enhancing the VR/AR experience by minimizing eyestrain and nausea, and allowing for sharper, high-resolution images across a range of distances.
Implementation Method 1
a gaze tracking component that may be used in a direct retinal projector system to track position of a subject's pupil and automatically adjust projection of a scanned light field generated by a projector component of the system so that the scanned light field from the projector enters the subject's pupil
Implementation Method 2
an adjustable focusing element to provide adaptive optical functionality for the projector. In some embodiments, the adjustable focusing element may be located on the path of a combined light beam generated by light sources of the projector component of the direct retinal projector system and a scanning mirror of the projector component
Implementation Method 3
the direct retinal projector system adjusts focus of a combined light beam generated by the light sources via the adjustable focusing lens as the light beam is scanned to a curved ellipsoid mirror of the direct retinal projector system that reflects the scanned light beam to the subject's pupil
Data Source
AI summary
A direct retinal projector may include a gaze tracking system that tracks position of a subject's pupil and automatically adjusts projection of a scanned light field so that the light field enters the pupil. A control loop adjusts a scanning mirror to substantially center an IR beam on a position sensing detector (PSD). In so doing, the scanning mirror is correctly positioned so that the scanned light field from the projector enters the subject's pupil. In addition, a direct retinal projector may include an adjustable focusing element that adjusts focus of a combined light beam generated by a projector as the light beam is scanned to an ellipsoid mirror that reflects the light beam to the subject's pupil. The focusing of the scanned beam may be adjusted as the beam is scanned across the azimuth angle of the curved ellipsoid mirror.