Structured Light Gaze Tracking for HMDs
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Solution Overview
Problem
Conventional gaze-tracking techniques in head-mounted display apparatuses face inaccuracies due to occlusion of reflections, ambient light interference, and pupil geometry changes, leading to inaccurate gaze detection and increased device complexity.
Innovation Solution
A gaze-tracking system utilizing phosphorescent or fluorescent particles to produce structured light for illumination, captured by a camera and processed to determine gaze direction, which minimizes occlusion errors and accommodates pupil geometry changes while reducing device complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple illuminators are used to produce multiple reflections for pupil position determination, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple illuminator functions into a single structured light source that projects a patterned light (e.g., grid or array of points) onto the user's eye. This single source replaces what would traditionally require multiple separate illuminators, reducing device complexity while maintaining the ability to capture multiple reflection points for accurate pupil position determination.
Solution Approach 2:
The patent transitions from using multiple discrete light sources in three-dimensional space to using a single light source that creates a structured two-dimensional light pattern on the cornea. This dimensional transformation allows the system to achieve the same measurement precision with fewer physical components.
2Device complexity
If conventional illumination is used, then device simplicity is maintained, but reflection occlusion by eyelids leads to measurement inaccuracies
Solution Approach 1:
The patent applies structured light with specific spatial characteristics (patterns, orientations, and distributions) that are optimized for different regions of the eye. The structured light pattern ensures that reflections are generated in areas less susceptible to eyelid occlusion, while maintaining overall system simplicity.
3Ease of operation
If ambient light sources are present, then natural viewing conditions are maintained, but reflection detection accuracy decreases due to false reflections
Solution Approach 1:
The patent employs structured light at specific wavelengths (e.g., infrared) that differ from ambient visible light. The imaging sensor is configured to detect reflections at these specific wavelengths, allowing the system to distinguish structured light reflections from ambient light reflections and other sources, thereby maintaining natural viewing conditions while improving detection accuracy.
4Device complexity
If pupil geometry changes are not compensated, then system simplicity is maintained, but geometric aberrations and reflection artifacts increase
Solution Approach 1:
The patent uses the structured light reflection pattern as a reference frame that remains stable despite pupil geometry changes. By tracking the position and orientation of this reference pattern along with the pupil, the system compensates for geometric aberrations and artifacts, improving gaze detection accuracy without requiring complex additional hardware.
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 achieves accurate and efficient gaze tracking by distinguishing structured light reflections from ambient light and accommodating pupil geometry changes, enhancing detection accuracy and simplifying device design.
Implementation Method 1
at least one first optical element comprising particles of a phosphorescent or fluorescent material dispersed therein, the particles of the phosphorescent or fluorescent material being dispersed in a manner that when excited by electromagnetic radiation incident thereupon, the particles produce structured light of a given wavelength
Implementation Method 2
at least one first optical element comprising particles of a phosphorescent or fluorescent material dispersed therein, the particles of the phosphorescent or fluorescent material being dispersed in a manner that when excited by electromagnetic radiation incident thereupon, the particles produce structured light of a given wavelength
Implementation Method 3
capturing an image of reflections of the structured light from the user's eye
Data Source
AI summary
A gaze-tracking system for use in a head-mounted display apparatus. The gaze-tracking system includes: at least one first optical element comprising particles of a phosphorescent or fluorescent material dispersed therein, the particles of the phosphorescent or fluorescent material being dispersed in a manner that when excited by electromagnetic radiation incident thereupon, the particles produce structured light of a given wavelength, wherein the produced structured light illuminates a user's eye; at least one camera for capturing an image of reflections of the structured light from the user's eye, wherein the image is representative of a form of the reflections and a position of the reflections on an image plane of the at least one camera; and a processor coupled in communication with the at least one camera, wherein the processor is configured to process the captured image to detect a gaze direction of the user.