Light-Guide Eye Tracking Optics Using Redirected Eye Light
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Solution Overview
Problem
Existing optical systems for near-eye displays and head-up displays face challenges in accurately tracking the gaze direction of the observer's eye due to the proximity of the eye to the optical components, which obstructs natural viewing and complicates imaging, and existing solutions for eye tracking are either obstructive or difficult to implement.
Innovation Solution
An optical system that utilizes a light-transmitting substrate with a light redirecting a light redirecting arrangement associated with a substrate with a light-transmitting substrate with a light redirecting arrangement associated with a light-transmitting substrate with a light, an optical arrangement that redirects light from the eye to an optical sensor, which deflects the light from the eye to an optical sensor via a light redirecting arrangement, allowing for unguided propagation to an optical sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera is deployed directly in front of the eye to enable high-quality EMB imaging, then measurement precision is improved, but the viewer's natural view is obstructed
Solution Approach 1:
The patent introduces a light redirecting arrangement as an intermediary component that captures eye reflection light and redirects it to the camera sensor. This mediator allows the camera to be positioned away from the eye while still achieving accurate eye tracking, thus eliminating view obstruction while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical approach of positioning a camera directly in front of the eye with an optical solution using light redirecting arrangements. This substitution eliminates the need for physical proximity between the camera and eye, thereby removing the obstruction to natural viewing while preserving eye tracking capability.
2Measurement precision
If the eye is imaged within the EMB via the LOE by coupling light reflected from the eye into the LOE, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The light redirecting arrangement is designed to perform multiple functions: it redirects eye reflection light to the camera for tracking, and can also work with illumination light from the display system. This multi-functionality reduces the need for separate dedicated optical paths, thereby reducing overall device complexity while maintaining tracking precision.
Solution Approach 2:
The patent merges the eye tracking optical path with the display optical path by using the same light redirecting arrangement for both capturing eye reflection light and directing display light to the eye. This consolidation eliminates redundant optical components and simplifies the overall system architecture.
3Device complexity
If a light guide optical element is used to multiply aperture for compact device, then device complexity is reduced, but eye tracking becomes difficult due to proximity constraints
Solution Approach 1:
The light redirecting arrangement serves as an intermediary that enables eye tracking despite the proximity constraints imposed by the compact LOE design. It captures light from the eye and redirects it to the camera, overcoming the difficulty of imaging the eye when it is close to the optical components.
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 gaze direction tracking without obstructing the viewer's natural view, suitable for near-eye displays and head-up displays, by using a light redirecting arrangement to deflect eye-tracking light to an optical sensor, effectively determining the gaze direction.
Implementation Method 1
a light redirecting arrangement associated with a light-transmitting substrate configured to deflect light from the eye toward the optical sensor
Implementation Method 2
The coupled-in image 18 propagates along the substrate 10 by repeated internal reflection from the faces 12, 14
Data Source
AI summary
A light-transmitting substrate has at least two major surfaces and is deployed with a first of the major surfaces in facing relation to an eye of a viewer. A light redirecting arrangement is associated with the light-transmitting substrate and deflects light from the eye toward an optical sensor that senses light, such that the light deflection occurs at the light-transmitting substrate and the deflected light that reaches the optical sensor is unguided by the light-transmitting substrate. A processor derives current gaze direction of the eye by processing signals from the optical sensor.