Co-Aligned Light Source Camera for Differential Pupil Tracking
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Solution Overview
Problem
Existing eye tracking systems require substantial computational resources and are inefficient in capturing high-contrast images of pupils due to the need for multiple image captures and processing.
Innovation Solution
A tracking system utilizing a differential camera with a co-aligned light source camera assembly (LSCA) that asynchronously outputs data samples based on changes in brightness, allowing for the capture and isolation of pupil changes without the need for continuous image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional eye tracking systems use multiple image captures and processing, then measurement precision of pupil position is improved, but use of energy and computational resources increases substantially
Solution Approach 1:
The patent extracts only the essential information needed for eye tracking by using a differential camera to detect only changes in brightness. Instead of capturing and processing complete images, the system outputs only data samples where brightness changes occur, thereby extracting the minimum necessary data to achieve pupil position detection while dramatically reducing computational energy consumption.
Solution Approach 2:
The system uses periodic illumination from the light source to create alternating bright and dark pupil effects. By synchronizing the light source activation with the differential camera sampling, the system achieves precise pupil detection through periodic illumination cycles rather than continuous imaging, reducing overall energy consumption while maintaining measurement precision.
2Reliability
If traditional systems capture continuous images for eye tracking, then reliability of gaze detection is improved, but loss of time due to processing overhead increases
Solution Approach 1:
The differential camera extracts only the essential signal (brightness changes) needed for reliable gaze detection, discarding redundant information. This extraction approach maintains detection reliability by focusing on the actual pupil response to light while eliminating the time-consuming processing of unnecessary image data.
Solution Approach 2:
The system uses the eye's own physiological response (pupil constriction and dilation) to the periodic light source as the tracking signal. The eye itself provides the contrast mechanism through natural pupillary light reflex, eliminating the need for complex external imaging and processing while maintaining reliable gaze detection.
3Measurement precision
If multiple light sources and cameras are used to achieve high-contrast pupil images, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the light source and camera into a single co-aligned assembly where the light source is positioned at the same optical center as the camera. This merging eliminates the need for separate illumination and imaging optical paths, reducing device complexity while maintaining the ability to achieve high-contrast pupil images through the differential imaging approach.
Solution Approach 2:
The co-aligned light source and camera assembly serves multiple functions simultaneously: illumination, imaging, and differential signal generation. This multi-functional design replaces what would traditionally require separate components for each function, thereby reducing overall device complexity while maintaining measurement precision through the differential camera's ability to detect brightness changes.
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
The system achieves efficient eye tracking with reduced computational and power requirements, improved latency, and simplified downstream processing by focusing on high-contrast pupil changes.
Implementation Method 1
The light source is configured to emit light that is directed along an optical path towards an eye box including an eye of a user
Implementation Method 2
The differential camera sensor is configured to detect a change in brightness of the eye caused in part by the emitted light
Data Source
AI summary
A differential camera system for object tracking. The system includes a co-aligned light source camera assembly (LSCA) and a controller. The co-aligned LSCA includes a light source and a differential camera sensor. The light source is configured to emit light along an optical path that is directed towards an eye box including an eye of a user. The differential camera sensor is configured to detect a change in brightness of the eye caused in part by the emitted light, asynchronously output data samples corresponding to the detected change in brightness, wherein the optical path is substantially co-aligned with an optical path of the differential camera sensor. The controller is configured to identify a pupil of the eye based on data samples output from the differential camera sensor resulting from the emitted light, and determine a gaze location of the user based in part on the identified pupil.