Eye Tracking Illumination Calibration

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Solution Overview

Problem

Existing eye tracking systems suffer from inaccuracies due to uneven illumination by light sources, leading to errors in gaze estimation, particularly in wearable devices.

Innovation Solution

An eye tracking system with a controller that adjusts the intensity of multiple light sources based on their illumination contribution, ensuring even illumination by processing multiple images acquired with different light source configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If multiple light sources are used to illuminate the user's eye, then the illumination coverage is improved, but the evenness of illumination deteriorates

Engineering Contradiction:
Improveillumination coverageVSAvoidevenness of illumination
Core Design Contradiction:
Area of stationary objectVSIllumination intensity

Solution Approach 1:

The patent applies local quality by adjusting the intensity of each light source individually based on its specific illumination contribution to different regions of the eye. The controller modifies the output of each light source separately to compensate for positional variations, ensuring that each region receives appropriate illumination intensity for accurate feature detection.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the intensity parameter of each light source dynamically. By measuring the illumination contribution of each light source and adjusting its intensity accordingly, the system transforms the illumination parameters to achieve uniform overall illumination across the eye surface while maintaining comprehensive coverage.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If the intensity of light sources is increased to improve image quality, then the illumination level is improved, but the risk of eye damage increases

Engineering Contradiction:
Improvegaze estimation accuracyVSAvoideye damage risk
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent optimizes the intensity parameter of light sources to achieve the minimum necessary illumination level for accurate gaze estimation. By precisely controlling and adjusting the intensity of each light source based on its contribution, the system maintains measurement precision while minimizing the total light exposure to safe levels.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system implements feedback by measuring the actual illumination contribution of each light source and using this information to adjust subsequent illumination levels. This closed-loop control ensures that sufficient light is provided for accurate measurement while preventing excessive illumination that could cause eye damage.

Inventive Principle:
Principle #23Feedback

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

Improves gaze estimation accuracy by evenly illuminating the user's eye, enhancing the quality of gaze tracking performance.

Implementation Method 1

a plurality of light sources that are arranged to illuminate a user's eye

Methodology Applied
Scientific EffectLight emission: Light

Implementation Method 2

the reflection of the light is captured by an image sensor

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4722872A2An eye tracking system
Publication Date: 2026.04.08 TOBII TECH AB
  • EP4722872A2 patent drawingFigure 1~2
  • EP4722872A2 patent drawingFigure 3~4A
  • EP4722872A2 patent drawingFigure 4B~4C

AI summary

A method for calibrating an illuminance level of a plurality of light sources (441) in an eye tracking system (300), the method comprising the steps of: setting a first current level to a one or more of the plurality of light sources (310-319), illuminating at least a first surface (438) by the one or more of the plurality of light sources (310-319), determining illumination contribution of the one or more of the plurality of light sources (310-319) on the illuminance level of the eye tracking system (300), configuring the illuminance level of the eye tracking system (300) by setting an adjusted current level on the one or more of the plurality of light sources (310-319).