HMD In-Field Light Control for Accurate Eye Tracking
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) face interference issues with eye-tracking systems due to the arrangement of illumination sources within the field of view, which impede accurate gaze tracking by causing occlusions and reducing the precision of eye-tracking measurements.
Innovation Solution
Incorporation of in-field light sources, such as micro-LEDs or VCSEL diodes, within the near-eye optical element, combined with active control mechanisms to selectively enable or disable these sources based on eye location and predicted movements, and a static keep-out zone to prevent direct-views from interfering with specular reflection detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If illumination sources are placed within the field of view of the HMD, then eye-tracking accuracy is improved by producing reference vectors close to the visual axis, but direct views of the light sources occlude specular reflections and impede accurate gaze tracking
Solution Approach 1:
The system dynamically controls the illumination sources by selectively enabling or disabling specific light sources based on the detected eye position and gaze direction. This dynamic adjustment allows the system to maintain high eye-tracking accuracy when needed while avoiding occlusion artifacts when the light sources would interfere with specular reflection detection
Solution Approach 2:
Different regions of the field of view are assigned different functional qualities: some areas contain illumination sources for eye-tracking while other areas are designated as keep-out zones to prevent occlusion. The system applies different control strategies to different light sources based on their specific locations and potential to cause interference
2Measurement precision
If multiple illumination sources are used to compensate for three-dimensional geometry and anatomical variations, then eye-tracking precision is maintained across full physiological range, but device complexity increases
Solution Approach 1:
Instead of continuously operating all illumination sources, the system activates only the specific subset of light sources needed for the current eye position and tracking requirements. This partial action approach maintains measurement precision while reducing the effective number of active components, thereby lowering device complexity and power consumption
3Productivity
If in-field light sources are actively controlled based on eye location and predicted movements, then occlusions are minimized and processing time is reduced, but control system complexity increases
Solution Approach 1:
The system performs preliminary actions by predicting future eye positions and preemptively adjusting which illumination sources are active before occlusion issues arise. This predictive control reduces processing time and prevents occlusion artifacts, improving productivity while the predictive algorithm manages the control complexity
Solution Approach 2:
The control system continuously receives feedback from eye-tracking measurements and camera data, using this feedback to dynamically adjust illumination source activation. This closed-loop feedback mechanism enables real-time optimization of tracking performance while managing control complexity through adaptive rather than purely predetermined control logic
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
Enhances eye-tracking accuracy and precision by minimizing occlusions and reducing processing time, allowing for faster and more reliable gaze tracking in HMDs.
Implementation Method 1
In-field light sources (e.g., micro-LEDs or VCSEL diodes) are disposed on a transparent substrate
Implementation Method 2
In-field light sources (e.g., micro-LEDs or VCSEL diodes) are disposed on a transparent substrate
Implementation Method 3
If at least one first reflection is detected, a position in the first image of the at least one first reflection is determined
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A method for the active control of in-field light sources of a head mounted display (HMD) includes receiving an image of an eye of a user of the HMD, where the image is captured by an eye-tracking camera in response to infrared light emitted by a plurality of in-field light sources. The method also includes selectively disabling at least one of the in-field light sources based on information from the image of the eye.