Eye Tracking Device Using Time-of-Flight Lens Reflection
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Solution Overview
Problem
Conventional eye tracking systems face challenges in tracking the eyes of individuals wearing standard eyeglasses due to occlusions and false specular reflections, which affect the accuracy of gaze detection.
Innovation Solution
An eye tracking device utilizing a time-of-flight camera and illumination source that transmits infrared energy, with a processor to distinguish reflections from the eye and ambient energy, allowing for accurate gaze direction determination without the need for special glasses, by using a fast shutter IR camera to capture only reflections from nearby objects and filtering out ambient IR illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct imaging systems are used to track eyes, then the sensor can directly image the eye region, but occlusion from eyelashes and disturbance to user vision occur
Solution Approach 1:
The patent introduces an indirect imaging path where infrared light reflects off a lens (intermediary object) before reaching the eye and returning to the sensor. This intermediary reflection path allows the sensor to track the eye without being directly in front of it, avoiding occlusion from eyelashes and disturbance to the user's field of view while maintaining tracking accuracy
2Object-affected harmful factors
If indirect imaging with hot mirror lenses is used, then occlusion is avoided, but special glasses are required which are not suitable for people with standard eyeglasses
Solution Approach 1:
The patent uses the existing lens of standard eyeglasses as an intermediary reflecting surface, copying the function of hot mirror lenses without requiring special glassware. The system leverages the optical properties of regular eyeglass lenses to achieve indirect imaging, making the eye tracking compatible with people who wear standard prescription glasses
Solution Approach 2:
The system is designed to work with any lens that can reflect infrared light, including standard eyeglass lenses, reading glasses, sunglasses, and contact lenses. This universal approach allows the same eye tracking system to function with multiple types of eyewear without requiring specialized components
3Adaptability or versatility
If standard eyeglasses are worn, then users can correct vision, but false specular reflections from the lens interfere with gaze detection accuracy
Solution Approach 1:
The patent extracts and isolates the infrared reflections from the eyeglass lens from other ambient infrared reflections in the environment. By using spectral filtering and temporal gating, the system separates the lens-reflected infrared signal from background interference, allowing accurate eye tracking even in the presence of standard eyeglasses with their associated specular reflections
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 reliable and unobstructed eye tracking for users wearing standard eyeglasses, improving accuracy and functionality in environments with uncontrolled lighting, while avoiding the need for hot mirror lenses.
Implementation Method 1
The illumination source transmits energy within a frequency band from a location proximate to an eye of a person
Implementation Method 2
The TOF camera detects reflections of at least the first portion of the transmitted energy, and distinguishes the detected reflections of the first portion of the transmitted energy from other energy detected by the TOF camera in said frequency band, based on times of flight of the reflections
Implementation Method 3
at least a first portion of the transmitted energy is reflected off a lens of eyewear worn by the person, to subsequently reflect off an eye of the person
Data Source
AI summary
An eye movement tracking device that can be mounted to standard eyeglasses as disclosed. The device comprises an illumination source, a time-of-flight (TOF) camera and a processor. The source transmits energy within a frequency band from a location proximate to an eye of a person, such that at least a first portion of the transmitted energy is reflected off a lens of eyewear worn by the person to subsequently reflect off the eye, and such that at least a second portion of the transmitted energy is transmitted through the lens to reflect off objects in the person's environment. The TOF camera detects reflections of at least the first portion of the transmitted energy, and distinguishes them from other energy detected by the TOF camera in said frequency band, based on TOF principles. The processor uses the detected reflections of the first portion of the transmitted energy to determine eye position.