AR Display Alignment Correction via Camera Sampling

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Solution Overview

Problem

Conventional binocular augmented reality displays face challenges in maintaining accurate alignment of left-eye and right-eye displays due to lightweight and compact form factors, which are prone to misalignment from thermal and environmental variations, and inter-pupillary distance differences among users, leading to potential eye strain and increased complexity in optics.

Innovation Solution

A method for deriving alignment correction between the displays using cameras to sample and process images with alignment features, allowing for real-time adjustment and recalibration without specialized equipment, incorporating user inputs and 3D modeling to ensure precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If lightweight and compact form factor is implemented, then weight and size are reduced, but mechanical rigidity decreases leading to alignment variations

Engineering Contradiction:

Improveweight of augmented reality spectaclesVSAvoidalignment stability of displays

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts alignment parameters in real-time based on environmental conditions and user characteristics. The alignment correction values are not fixed but are continuously optimized through image sampling and processing, allowing the lightweight structure to maintain reliable alignment despite mechanical flexibility.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the alignment parameters electronically through image processing rather than relying on fixed mechanical alignment. By transforming the projected image using calibration matrices and adjusting alignment correction values, the system compensates for structural flexibility without requiring rigid mechanical components.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If rigid connection between projectors is used, then alignment is stable, but inter-pupillary distance cannot be adjusted for different users

Engineering Contradiction:

Improvealignment stabilityVSAvoidinter-pupillary distance adjustment

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system makes the alignment parameters dynamic and adjustable rather than fixed. The alignment correction values can be modified based on user-specific measurements and environmental conditions, allowing the same rigid structure to serve multiple users with different inter-pupillary distances through software-based adaptation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses parameter transformation through calibration matrices to adapt the fixed projector alignment to different user requirements. By changing the image coordinates and alignment correction parameters rather than the physical structure, the system achieves user-specific customization while maintaining structural stability.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If larger eye-box is designed to accommodate IPD variations, then all users can use the device, but optics become bulkier and more expensive

Engineering Contradiction:

Improveaccommodation of inter-pupillary distance variationsVSAvoidsize of optics

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

Instead of increasing the physical eye-box size, the system changes the alignment parameters through image processing. The calibration matrix transforms the projected image to compensate for different inter-pupillary distances, allowing a compact optical design to serve users with varying IPD through software-based parameter adjustment rather than hardware expansion.

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If electronic shift of image is used for fine alignment, then alignment precision is improved, but margins are consumed and complexity increases

Engineering Contradiction:

Improvealignment precisionVSAvoidcomplexity of alignment system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs self-alignment through automated image sampling and processing. The device uses its own camera to capture images, automatically derives alignment correction values, and adjusts the alignment without requiring external equipment or complex manual procedures. This self-service approach simplifies the overall system while achieving high precision.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11223820B2Augmented reality displays with active alignment and corresponding methods

Publication Date: 2022.01.11 LUMUS LTD

AI summary

Binocular augmented reality display devices and corresponding methods allow alignment calibration to be performed by an end user. According to one approach, a camera is positioned to have a field of view which includes simultaneously part of a projected image from the left-eye display and part of a projected image from the right-eye display. By projecting via each display at least part of a calibration image and identifying within the camera-sampled image right-field and left-field alignment features, an alignment correction can be derived. Alternative approaches employ correlation of images sampled by forward-looking cameras rigidly associated with the respective right-eye and left-eye display units, or require a user to input a manual adjustment for aligning transversely-swapped camera images with the real world view.