Light Field HUD Calibration with Eye-Tracking Feedback

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Solution Overview

Problem

Existing HUD systems face challenges in maintaining high visual quality due to compounding calibration errors, particularly from thermal drift and other factors, leading to degraded performance and user experience.

Innovation Solution

A system and method for on-the-fly correction of calibration errors based on user experiences, utilizing tracking means to determine the relative location of a user's eyes and head, and adjusting the optical combiner to correct relative positions in real-time, ensuring accurate display of virtual content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional calibration methods are used for HUD subsystems, then initial visual quality can be maintained, but calibration errors accumulate over time due to thermal drift and other factors, leading to degraded visual performance

Engineering Contradiction:
Improvevisual quality consistencyVSAvoidcalibration accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The system implements a feedback mechanism where the HUD controller continuously receives data from eye-tracking and head-tracking subsystems, monitors user gaze behavior, and automatically adjusts calibration parameters in real-time to compensate for drift, thereby maintaining measurement precision without requiring manual recalibration

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The HUD system performs self-calibration by utilizing the user's own eye movement patterns and head position data as reference signals. The system automatically detects calibration errors through user interaction patterns and corrects them without external intervention, making the system self-maintaining over time

Inventive Principle:
Principle #25Self-service

2Reliability

If manual recalibration procedures are implemented to correct calibration errors, then visual quality can be restored, but system complexity and user burden increase significantly

Engineering Contradiction:
Improvevisual quality consistencyVSAvoidcalibration system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system automatically performs calibration corrections using onboard sensors and algorithms, eliminating the need for manual user intervention. The HUD controller continuously monitors tracking data and applies corrections autonomously, reducing both system complexity from the user perspective and operational burden

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The tracking subsystems serve multiple functions: they track user position for rendering purposes, detect calibration drift through gaze pattern analysis, and provide correction data simultaneously. This multi-functionality reduces overall system complexity by consolidating calibration capabilities within existing hardware

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If frequent recalibration is performed to maintain calibration accuracy, then visual quality can be maintained, but loss of time and user disruption increase

Engineering Contradiction:
Improvecalibration accuracyVSAvoidrecalibration time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

Instead of periodic discontinuous recalibration, the system continuously adjusts calibration parameters in real-time based on ongoing tracking data. The HUD controller processes eye and head movement data continuously, applying incremental corrections without interrupting the user experience or requiring dedicated recalibration time sessions

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system uses continuous feedback from tracking subsystems to detect and correct calibration drift as it occurs. By monitoring user gaze behavior and head position in real-time, the system identifies and compensates for calibration errors immediately, eliminating the need for time-consuming periodic recalibration cycles

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

Enhances user experience by providing clear and realistic virtual content presentation, correcting small imperfections dynamically and improving overall visual quality through real-time adjustments.

Implementation Method 1

an optical combiner arranged on an optical path of the light field display unit and on an optical path of a real-world light field of a real-world environment... wherein the optical combiner is employed to reflect a first part and a second part of the synthetic light field towards the first eye and the second eye

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4632540A1On-the-fly correction of calibration errors based on user experience
Publication Date: 2025.10.15 DISTANCE TECHNOLOGIES OY
  • EP4632540A1 patent drawingFigure 1~2
  • EP4632540A1 patent drawingFigure 3A~3B
  • EP4632540A1 patent drawingFigure 4~5A

AI summary

A light field image is generated, based on a relative location of a first eye (308a, 610a) and of a second eye (308b, 610b) of a user (612) with respect to an optical combiner (106, 306, 614). The light field image is displayed to produce a synthetic light field (304a, 620) presenting virtual content (302, 622), wherein the optical combiner reflects a first part (L) and a second part (L) of the synthetic light field towards first eye and second eye, respectively, whilst optically combining the first and second parts with a real-world light field (616). These steps are repeated for a given time period, during which it is detected when the user has made a head movement, whilst fixating on a portion of the virtual content. Upon detection, a current relative location is corrected, a current light field image is generated and displayed to produce a current synthetic light field (304b).