In-Field Micro Illumination for Eye Tracking Accuracy
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Solution Overview
Problem
Existing eye tracking systems face challenges in accurately tracking users' points of attention, particularly for individuals with small eye areas and in systems with a wide field of view, due to limitations in illumination source placement outside the field of view.
Innovation Solution
An illumination assembly integrated with light in-field micro devices, such as micro-light emitting diodes and photodiodes, on a transparent substrate within the field of view, which emits light and detects reflections for tracking eye movement, including surrounding facial features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If glint sources are placed at the periphery of viewing optics outside the field of view, then the illumination structure is simplified, but the eye tracking accuracy deteriorates for users with small eye areas or wide field of view
Solution Approach 1:
The patent inverts the conventional placement of illumination sources from outside the field of view to inside the field of view. This inversion allows the light sources to be positioned closer to the optical axis, enabling better illumination of small eye areas and providing more angular diversity for wide field of view tracking, thereby resolving the accuracy limitation while maintaining structural simplicity through integration with the display substrate.
Solution Approach 2:
The patent transitions from a two-dimensional peripheral arrangement of light sources to a three-dimensional in-field distribution. By placing multiple micro light emitting devices at different positions within the viewing region, the system creates additional spatial dimensions for light emission, enabling denser illumination patterns and higher angular data capture that improve tracking accuracy without increasing overall device complexity.
2Adaptability or versatility
If multiple glint sources are used to generate light for tracking over a wide range of angles, then the field of view coverage is improved, but the difficulty of accurately estimating gaze direction increases
Solution Approach 1:
The patent segments the illumination function into multiple discrete micro light emitting devices distributed across the substrate. Each device emits light at a specific location and angle, creating distinct glint patterns. This segmentation allows the imaging sensor to receive differentiated reflected light from each source, enabling accurate estimation of gaze direction even when tracking across a wide field of view, as each segmented source provides unique angular information.
3Quantity of substance
If the cornea and iris area that can be imaged is limited by small eye area, then the device portability is improved, but the eye tracking accuracy deteriorates
Solution Approach 1:
The patent applies local quality by positioning multiple micro light emitting devices at specific locations across the substrate, each providing targeted illumination to different regions of the small eye area. This localized illumination strategy ensures that even limited corneal and iris areas receive sufficient light from optimally positioned sources, enhancing the imaging quality and tracking accuracy for compact devices without requiring larger eye surfaces.
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 the accuracy and performance of eye tracking systems by providing denser and more flexible illumination patterns, allowing for higher angular data capture and improved gaze angle tracking over a wider range of angles.
Implementation Method 1
The plurality of micro devices includes a plurality of sources. In embodiments, the plurality of micro devices may also include one or more sensors (e.g., photodiodes).
Implementation Method 2
The plurality of micro devices may also include one or more sensors (e.g., photodiodes). The reflected light is detected and used for tracking movement of one or both eyes
Data Source
AI summary
An illumination assembly includes a transparent substrate and a plurality of micro devices. The transparent substrate includes a first surface and a second surface opposite the first surface. The first surface includes a viewing region through which light passes prior to reaching an eyebox. The plurality of micro devices are coupled to respective conductive pathways that are affixed to the first surface. The plurality of micro devices including at least one micro device that is positioned within the viewing region. In some embodiments, the conductive pathways are arranged in a pseudo random manner. In some instances, the viewing region is composed of a circuity free region that is circumscribed by an outer region, and the plurality of micro devices are coupled to respective conductive pathways that are affixed to the first surface in the outer region.