Transparent Lens IR LED Layout for Accurate Eye-Tracking Glints
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Solution Overview
Problem
Existing eye-tracking techniques in head-mounted systems lack accuracy and require multiple cameras to capture sufficient glints due to suboptimal light source placement, often on the device frame, which can lead to inaccurate gaze estimation and iris identification.
Innovation Solution
Incorporating infrared light sources, such as micro-IR LEDs, on a transparent substrate within the lens of a head-mounted device, allowing for a wider placement area and improved accuracy by positioning them closer to the optical axis, with a multi-stack architecture that is imperceptible to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light sources are placed on the device frame, then the structure is simple, but the gaze estimation accuracy is poor
Solution Approach 1:
The patent transitions from placing light sources on the two-dimensional frame surface to embedding them within the three-dimensional lens structure. This dimensional change allows light sources to be positioned closer to the optical axis, improving gaze estimation accuracy while maintaining structural integration.
Solution Approach 2:
The patent embeds light sources within the lens structure, nesting them inside the transparent substrate. This nesting approach allows the light sources to be integrated into the lens without adding external complexity, achieving both improved accuracy and structural simplicity.
2Reliability
If multiple cameras are used to capture sufficient glints, then the eye characteristic assessment is reliable, but the device complexity increases
Solution Approach 1:
The patent divides the lens into multiple zones with light sources positioned at different locations and depths. This segmentation creates multiple glint sources that can be captured by a single camera, eliminating the need for multiple cameras while maintaining assessment reliability.
Solution Approach 2:
The patent uses multiple light sources that create multiple glint reflections, effectively copying the function of multiple cameras by generating multiple measurement points from a single camera perspective. This allows sufficient glint data to be captured without additional camera hardware.
3Measurement precision
If light sources are placed on the lens surface, then the placement area is limited, but the gaze estimation accuracy is improved
Solution Approach 1:
The patent exploits the third dimension by embedding light sources within the lens substrate at different depths and positions. This transforms the two-dimensional surface constraint into a three-dimensional volume, providing extensive placement area while maintaining accuracy through optimal positioning near the optical axis.
Solution Approach 2:
The patent positions light sources at specific locations within the lens, particularly near the optical axis, where they provide the best gaze estimation accuracy. This local quality approach concentrates light sources in optimal regions rather than uniformly distributing them, maximizing accuracy while utilizing the available placement area efficiently.
4Length of stationary object
If the frame thickness is reduced, then the device is more compact, but the light source placement options are limited
Solution Approach 1:
The patent nests light sources within the lens structure itself, eliminating the need for separate frame mounting. This nesting allows the frame to be thinner while still providing adequate light source placement options, as the lens substrate serves as the mounting platform.
Solution Approach 2:
The patent moves light source placement from the two-dimensional frame surface to the three-dimensional lens volume. This dimensional transition provides ample placement options even with reduced frame thickness, as the lens substrate offers extensive internal space for light source integration.
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 characteristic assessment by improving gaze estimation and iris identification accuracy while reducing the device's thickness and minimizing perceptibility, using a spatial arrangement of IR LEDs connected via transparent conductors.
Implementation Method 1
The eye-tracking system may include one or more infrared (IR) LEDs (e.g., light source 230, 232, 234, 236, 238) that emit light toward the eyes of the user 25
Implementation Method 2
a plurality of reflections of light produced by the plurality of IR light sources and reflected from an eye
Data Source
AI summary
Various implementations disclosed herein include electronic devices, systems, and methods that detect reflections of light produced by a plurality of light sources reflected from an eye. An example electronic device may include a frame, an image sensor, a transparent substrate coupled to the frame, and a processor coupled to the plurality of IR light sources. The transparent substrate may include a plurality of infrared (IR) light sources that may be configured in a spatial arrangement within the transparent substrate or on a surface of the transparent substrate. The processor may be configured to receive sensor data from the image sensor. The sensor data may correspond to a plurality of reflections of light produced by the plurality of IR light sources and reflected from an eye.