Bright Pupil Eye Tracker Using Analog Position Sensor
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Solution Overview
Problem
Current eye tracking technologies are cumbersome, expensive, and unsuitable for use in children, as they require digital streaming and high frame rate image acquisition, which limits their speed and usability in applications like ophthalmology and neurology, and often require invasive methods like scleral search coils that cause discomfort.
Innovation Solution
A fast and accurate eye tracking device that uses retro-reflected light from the ocular fundus to capture the image of the pupil, employing an analog duo-lateral position sensor or profile sensor to extract minimal information for X-Y tracking, allowing for low-throughput transmission and storage, and utilizing image intensifiers for low light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If digital image-based sensors are used for eye tracking, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts only the essential information needed for eye tracking from the complete digital image - specifically the pupil center position and radius. Instead of processing entire high-resolution images, the system identifies and extracts minimal geometric parameters (x, y coordinates and radius) that define eye position, thereby simplifying the system while maintaining tracking precision
Solution Approach 2:
The patent creates a simplified geometric model (circle representation) of the pupil that copies only the essential spatial information needed for tracking. This geometric copy replaces the need for complex image processing of the actual pupil image, enabling precise tracking with minimal computational requirements
2Speed
If high frame rate digital image acquisition is used, then speed of eye tracking is improved, but loss of time for data transmission and storage increases
Solution Approach 1:
The patent extracts only the minimal necessary data (pupil center coordinates and radius) from each frame, reducing the data volume from complete high-resolution images to a few numerical parameters. This extraction enables fast data transmission and processing while maintaining high tracking speed
Solution Approach 2:
The patent performs only the partial action necessary for eye tracking - acquiring just enough image data to determine pupil position and size. By doing less than acquiring complete high-resolution images, the system achieves high speed tracking without the time penalty of transmitting and storing large amounts of data
3Speed
If scleral search coils are used for fast eye tracking, then speed is improved, but object-affected harmful factors increase due to discomfort and invasiveness
Solution Approach 1:
The patent replaces the mechanical scleral search coil system with an optical imaging system. Instead of mechanically attaching coils to the eye and measuring magnetic signals, the system uses non-invasive optical imaging to detect pupil position, eliminating the discomfort and invasiveness while maintaining measurement capability
Solution Approach 2:
The patent introduces an optical intermediary (the pupil image) that allows indirect measurement of eye position. By imaging the pupil rather than directly measuring eye movement with coils, the system achieves fast tracking without the harmful effects of mechanical attachment
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 fast, non-invasive, and cost-effective eye tracking without the need for high frame rate digital image acquisition, suitable for use in children and other applications, with the ability to measure rapid eye movements at high speeds without requiring individual calibration or fixation on a target.
Implementation Method 1
the light entering the pupil of the eye is retro-reflected by the fundus of the eye back toward the light source
Implementation Method 2
optical means for capturing the light retro-reflected by the fundus of the eye to form a bright image of the pupil of the eye
Data Source
AI summary
The present invention provides for very fast detection of gaze direction using retro-reflected light from the ocular fundus that is cost-efficient, small, and portable. These eye trackers are useful in many areas of science and technology, including but not limited to remote control, space, defense, medical and psycho-physiological applications, to identify for example subtle neurologic deficits that occur with cerebellar or vestibular disorders, Parkinson's disease, strokes, traumatic brain injury, possible concussions during sports matches, some forms of reading disability, or simply fatigue or inebriation. In ophthalmology, with two such devices operating simultaneously, the variability of relative eye alignment over time can be measured, without requiring individual calibration, and without requiring fixation on a specified target, ideal for use with small children. Such instruments have widespread application as noninvasive screening devices in infants and young children or patients of any age for defects of binocular function such as strabismus and amblyopia.