Near-Eye Display Eye Tracking Using Fresnel Light Deflectors
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Solution Overview
Problem
Current eye-tracking systems in near-eye display systems face challenges in accurately tracking the user's gaze direction with high precision, especially when the user's eyes change viewing angles or when facial features, such as eyelids, obscure parts of the eye, and they require multiple cameras which increase cost, weight, and power consumption.
Innovation Solution
An eye-tracking system that includes one or more light sources and a substrate with light deflectors, such as a Fresnel lens or reflective grating, to illuminate and capture images of the user's eye from different angles, forming multiple images in a single frame for more accurate tracking, using a combination of reflective and smooth surfaces to direct light towards a camera.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple cameras are used to track eye from different angles, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The substrate is divided into multiple regions, each containing a light deflector oriented at different angles. These segmented regions collectively capture eye reflections from multiple angles simultaneously, achieving multi-view eye tracking without requiring multiple separate cameras.
Solution Approach 2:
The patent transitions from temporal/multiplicative camera arrangement to spatial/angular dimension by using light deflectors at different orientations on a single substrate. This allows multiple viewing angles to be captured in a single image frame through angular multiplexing rather than requiring multiple temporal camera captures.
2Measurement precision
If multiple cameras are used to capture eye images, then measurement precision is improved, but weight increases
Solution Approach 1:
Multiple light deflectors are merged onto a single substrate, which is then integrated into the near-eye display system. This consolidation reduces the number of separate optical components and cameras needed, thereby reducing overall system weight while maintaining multi-angle eye tracking capability.
Solution Approach 2:
The substrate serves multiple functions: it acts as both the display optical element and the eye tracking optical element. The light deflectors on the substrate simultaneously guide display light and redirect eye reflections to the camera, eliminating the need for separate eye tracking cameras and reducing weight.
3Measurement precision
If multiple cameras are used for eye tracking, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The eye tracking function is merged with the display optical path by integrating light deflectors on the same substrate. This allows a single camera to capture multiple eye views simultaneously, reducing the total number of active sensors and lowering power consumption compared to multiple separate cameras.
Solution Approach 2:
The light deflectors are pre-configured at specific angles during manufacturing to automatically direct eye reflections to the camera from multiple viewing angles. This preliminary optical arrangement eliminates the need for active multiple cameras, reducing continuous power consumption while maintaining precision.
4Adaptability or versatility
If light deflectors are added to the substrate, then adaptability is improved, but device complexity increases
Solution Approach 1:
The substrate surface is segmented into multiple regions, each with light deflectors oriented at different angles. This segmentation allows the system to adapt to various viewing angles by using the appropriate segment, expanding viewing angle coverage while keeping each individual segment simple in structure.
Solution Approach 2:
Different regions of the substrate are given different local qualities through varying light deflector orientations and properties. This allows each region to optimize for specific viewing angles while the overall substrate maintains a unified simple structure, improving adaptability without proportionally increasing complexity.
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 approach allows for accurate and robust eye tracking with high precision, reducing the need for multiple cameras and minimizing power consumption, while maintaining accuracy across varying viewing angles and facial obstructions.
Implementation Method 1
The reflective device may reflect the light reflected by the user's eye at certain directions towards the camera
Implementation Method 2
a Fresnel lens having Fresnel facets with a partially reflective coating
Implementation Method 3
the smooth surface may specularly reflect the light reflected by the user's eye towards the camera according to the law of reflection
Implementation Method 4
one or more light sources configured to illuminate a user's eye
Data Source
AI summary
Techniques for eye-tracking in a near-eye display system are disclosed. One example of a near-eye display system includes a waveguide-based display substrate that is transparent to visible light and configured to be placed in front of a user's eye. The waveguide-based display substrate includes a first surface area configured to specularly reflect a first portion of invisible light reflected by the user's eye to a camera to form a first image of the user's eye in a first area of an image frame, and a light deflector embedded in the waveguide-based display substrate or formed on a second surface area of the waveguide-based display substrate. The light deflector is configured to direct a second portion of the invisible light reflected by the user's eye to the camera to form a second image of the user's eye in a second area of the image frame.