Eye Location Calibration in Head-Mounted Displays

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Solution Overview

Problem

Existing near-eye display systems face challenges in accurately determining the location of a user's eyes due to the variability of interpupillary distance (IPD) and the inconvenience of measuring it, which affects the precision of stereoscopic image rendering.

Innovation Solution

A head-mounted display (HMD) system that calibrates the eye location using a virtual marker aligned with a real-world target, allowing image sensors to determine the eye's position without the need for eye-tracking or gaze-tracking systems, utilizing a combination of image data and motion sensors for precise calibration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If IPD measurement is performed using traditional methods (millimeter ruler or corneal reflex pupillometer), then measurement precision is improved, but ease of operation deteriorates due to requiring professional assistance and additional expense

Engineering Contradiction:
ImproveIPD measurement precisionVSAvoidUser convenience in IPD measurement
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The system performs IPD measurement automatically using image sensors and processing algorithms without requiring professional operators. The HMD captures images of the user's eyes and computationally determines IPD, enabling self-service measurement that eliminates the need for optical professionals while maintaining measurement precision

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces traditional mechanical measurement tools (millimeter ruler, corneal reflex pupillometer) with an optical-digital system using image sensors and computational algorithms. This substitution enables automated IPD measurement through image processing rather than manual mechanical measurement

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If assumed IPD values are used to estimate eye location, then ease of operation is improved, but measurement precision deteriorates due to uncertainty from individual variability

Engineering Contradiction:
ImproveSimplicity of eye location estimationVSAvoidEye location accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The system performs preliminary IPD measurement and eye location calibration before actual use of the HMD. By measuring the user's specific IPD in advance and storing it for later use, the system eliminates the need to use assumed IPD values during operation, thereby improving eye location accuracy while maintaining ease of use through pre-computed calibration data

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If IPD value alone is used for eye location estimation, then device complexity is reduced, but measurement precision deteriorates due to limited information about eye position relative to display

Engineering Contradiction:
ImproveSimplicity of calibration systemVSAvoidEye position accuracy relative to display
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The HMD system performs multiple functions using the same image sensors: capturing images for IPD measurement, determining eye location, and calibrating the display system. This multi-functional approach allows the system to obtain comprehensive eye position information without adding separate specialized instrumentation, thereby improving measurement precision while keeping device complexity manageable

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

Data Source

PatentEP2994812B1Calibration of eye location
Publication Date: 2019.04.17 MICROSOFT TECHNOLOGY LICENSING LLC
  • EP2994812B1 patent drawingFigure 1~2
  • EP2994812B1 patent drawingFigure 3~5
  • EP2994812B1 patent drawingFigure 6

AI summary

Embodiments are disclosed that relate to calibrating a predetermined eye location in a head-mounted display. For example, in one disclosed embodiment a method includes displaying a virtual marker visually alignable with a real world target at an alignment condition. At the alignment condition, image data is acquired to determine a location of the real world target. From the image data, an estimated eye location relative to a location of the head-mounted display is determined. Based upon the estimated eye location, the predetermined eye location is then calibrated.