Scleral Coil Eye Tracking System for VR Headsets
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Solution Overview
Problem
Conventional scleral coil eye tracking systems are not suitable for head-mounted displays due to their large size and restrictive head movement limitations, making them inefficient for virtual and augmented reality applications where a small form factor and freedom of movement are required.
Innovation Solution
A wearable eye tracking system utilizing a pair of looping coils in a Helmholtz configuration and an additional looping coil, generating uniform and non-uniform magnetic fields to induce electric signals in a scleral lens, allowing for accurate eye orientation estimation and enhanced accuracy with a portable form factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional generator coils are used to create a uniform magnetic field, then accurate eye orientation estimation is achieved, but the system size becomes large and head movement is restricted
Solution Approach 1:
The patent divides the magnetic field generation into multiple smaller coils arranged in specific configurations (Helmholtz pair and additional coil) rather than using one large generator coil. This segmentation allows the system to create the necessary uniform and non-uniform magnetic fields with smaller components, enabling portable form factor while maintaining measurement accuracy.
Solution Approach 2:
The patent employs different coil configurations to create different magnetic field characteristics in different regions. The Helmholtz pair creates uniform magnetic fields in the central region, while the additional offset coil creates non-uniform magnetic fields. This local differentiation of field quality enables accurate eye tracking in a compact configuration.
2Measurement precision
If conventional generator coils surround the subject entirely, then accurate eye tracking is achieved, but freedom of movement is restricted
Solution Approach 1:
By segmenting the magnetic field generation into multiple localized coils rather than a single large surrounding coil, the patent enables head movement freedom. The distributed coil configuration allows the head to move within the field without requiring the entire subject to be surrounded by a large coil structure.
Solution Approach 2:
The patent introduces a third dimension by adding an additional coil offset from the Helmholtz pair configuration. This additional coil in a different spatial position creates non-uniform magnetic fields that complement the uniform fields from the Helmholtz pair, enabling accurate tracking without restricting head movement in any particular direction.
3Measurement precision
If larger generator coils are used, then eye orientation estimation accuracy improves, but device portability deteriorates
Solution Approach 1:
The patent achieves accurate orientation estimation without requiring large individual coils by segmenting the magnetic field generation into multiple smaller coils. The Helmholtz pair and additional coil work together to create the necessary magnetic field patterns, allowing compact coil sizes while maintaining measurement precision.
Solution Approach 2:
The patent merges the functions of multiple coil configurations (Helmholtz pair for uniform fields and additional coil for non-uniform fields) into a single integrated system. This combination allows the system to achieve the accuracy previously requiring large coils by utilizing the synergistic effect of multiple smaller coils working together.
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
Enables accurate eye tracking in a portable form factor, allowing users to move freely while using head-mounted displays for virtual or augmented reality, improving the estimation of eye orientation and providing a benchmark for other eye tracking systems.
Implementation Method 1
Magnetic fields generated by the pair of looping coils and the additional looping coil induce electric signals at the scleral lens, according to an orientation of an eye of the user
Data Source
AI summary
A wearable eye tracking system includes a pair of looping coils in a Helmholtz configuration and an additional looping coil. In one configuration, areas enclosed by the pair of looping coils in the Helmholtz configuration are in parallel with each other, while an area enclosed by the additional looping coil is offset from (i.e., not parallel with) the areas enclosed by the pair of looping coils. In this configuration, the pair of looping coils generates uniform magnetic fields between the two areas of the pair of looping coils in a first direction orthogonal to the areas of the pair of looping coils, and the additional looping coil generates additional non-uniform (or divergent) magnetic fields in a second direction transversal to the first direction.