Eye Tracking Illuminator with Shadowing Reflector for Accuracy
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Solution Overview
Problem
Existing eye-tracking systems in artificial reality systems face accuracy issues due to the size of light sources used, which can result in imprecise determination of gaze direction and are affected by peripheral illumination and camera positioning, leading to obstructed views and reduced accuracy.
Innovation Solution
An eye-tracking system with a light source positioned within the user's field of view, using a substrate with reflectors to shadow the light source from the camera and direct reflected light towards the camera, enhancing accuracy and minimizing interference with the user's vision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light sources are positioned within the user's field of view for in-field illumination, then eye-tracking accuracy is improved, but the light sources may affect the quality of see-through real-world images and displayed images
Solution Approach 1:
The light source is segmented into multiple smaller emitters arranged in an array, where each emitter illuminates a specific region of the eye. This segmentation allows the system to maintain high eye-tracking accuracy while reducing the visibility impact of individual light sources in the user's field of view.
Solution Approach 2:
The illumination system uses local quality by directing light from specific positions within the field of view to specific regions of the eye, with each light emitter optimized for its local illumination task while minimizing overall visual interference.
2Device complexity
If cameras are positioned at the periphery of the user's field of view, then the system structure is simplified, but the accuracy of eye-tracking computations is reduced due to large observation angles
Solution Approach 1:
The system transitions from peripheral camera positioning to a forward-facing camera positioned along the optical axis, utilizing the z-dimension (depth) for optimal eye observation. This dimensional change enables accurate eye-tracking computations while maintaining a compact headset structure.
3Illumination intensity
If light sources with larger emission areas are used, then the illumination intensity is increased, but the glints in captured images become larger and their center locations cannot be precisely determined
Solution Approach 1:
The illumination system divides the light source into multiple small emitters arranged in an array, where each emitter produces a small, well-defined glint. This segmentation maintains sufficient total illumination intensity while ensuring that individual glint centers can be precisely determined for accurate eye-tracking.
Solution Approach 2:
The system changes the physical parameters of the light source by using multiple small emitters instead of a single large emitter, altering the emission area distribution to optimize both illumination intensity and glint precision for eye-tracking measurements.
4Measurement precision
If light sources are positioned within the user's field of view, then greater illumination accuracy is achieved, but the likelihood of camera view obstruction by facial features increases
Solution Approach 1:
The illumination system uses multiple small light emitters positioned within the field of view, each targeting specific eye regions. This segmentation provides accurate illumination while the distributed arrangement minimizes obstruction of the forward-facing camera's view compared to a single large peripheral light source.
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 configuration improves eye-tracking accuracy by reducing errors in gaze direction determination and maintaining a clear field of view, while ensuring the light source is invisible to the user.
Implementation Method 1
a first reflector configured to shadow the light source from a field of view of a camera
Implementation Method 2
a second reflector configured to receive light from the light source that is reflected by the eye of the user, and to direct the light toward the camera
Implementation Method 3
The light source may be configured to emit light that propagates between the first reflector and the second reflector
Data Source
AI summary
Disclosed herein are techniques for eye tracking in near-eye display devices. In some embodiments, an illuminator for eye tracking is provided. The illuminator includes a light source configured to be positioned within a field of view of an eye of a user; a first reflector configured to shadow the light source from a field of view of a camera; and a second reflector configured to receive light from the light source that is reflected by the eye of the user, and to direct the light toward the camera.