Low-Density Transparent Traces for Line-of-Sight Eye Illumination
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Solution Overview
Problem
Existing eye-tracking systems use oblique illumination, which requires higher optical power and may reduce the amount of light returned to the sensor, limiting the accuracy of gaze direction estimation.
Innovation Solution
A "line-of-sight" or "look-through" light source is developed, comprising a transparent or reflective substrate with a low-density set of light-emitting elements that are small and spaced far apart, allowing direct illumination of the eyes or face without interfering with the observer's line of sight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If oblique illumination is used in eye-tracking systems, then the light source can be positioned away from the line of sight, but the optical power required increases and the amount of light returned to the sensor decreases
Solution Approach 1:
The patent extracts the light source from the oblique positioning and places it directly in the line of sight through the transparent substrate. This removes the need for oblique illumination geometry while maintaining effective illumination of the eye, thereby reducing the optical power required and increasing the light returned to the sensor.
Solution Approach 2:
The patent uses a transparent substrate that is invisible or negligibly visible to the naked eye, allowing the light source to be positioned in the line of sight without obstructing the observer's view. This optical property enables direct illumination while maintaining line-of-sight transparency.
2Measurement precision
If a transparent substrate with low-density light-emitting elements is used, then direct illumination of the eyes is achieved without obstructing the line of sight, but the structural complexity of the substrate and trace arrangement increases
Solution Approach 1:
The patent employs a low-density arrangement of light-emitting elements and electrically conductive traces on the transparent substrate, creating a sparse, porous-like structure. This allows light to pass through the substrate and scene while maintaining electrical connectivity and light-emitting functionality, achieving direct illumination without significant visual obstruction.
Solution Approach 2:
The patent integrates multiple functional layers including transparent substrate, light-emitting elements, and electrically conductive traces into a composite structure. This composite approach combines optical transparency with electrical functionality and light emission in a single integrated component.
3Loss of information
If light-emitting elements occupy less than 25% of the areal extent, then visual observation through the substrate is enabled, but the illumination coverage area is reduced
Solution Approach 1:
The patent transitions from a two-dimensional planar illumination approach to a three-dimensional spatial arrangement where light-emitting elements are positioned at specific locations on the transparent substrate. This allows light to propagate through the substrate and illuminate the eye from multiple angles, effectively increasing illumination coverage without increasing the areal footprint of the light-emitting elements.
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 solution enables more accurate eye-tracking by providing direct illumination that is not obstructive, improving the detection of light reflected from the eyes and reducing the need for high-output light sources or sensitive sensors.
Implementation Method 1
The substrate is transparent or reflective for visible light... enable visual observation of a scene through or reflected by the substrate along a sight line that passes through the set of electrically conductive traces
Data Source
AI summary
An inventive apparatus includes a substrate and a set of multiple electrically conductive traces. The substrate is transparent or reflective for visible light. The electrically conductive traces are sufficiently transparent, or are less than 200 μm wide and occupy less than 25% of an areal extent of the set, so as to enable visual observation of a scene through or reflected by the substrate along a sight line that passes through the set of electrically conductive traces.