Biased Guide Rail Mounts for Precise Interpupillary Adjustment

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Solution Overview

Problem

Existing head-mounted electronic devices face challenges in maintaining precise alignment of optical modules due to misalignment issues such as splay, image rotation, and vergence during interpupillary distance adjustments, which affect user comfort and image quality.

Innovation Solution

The use of guide rails with biased systems, including springs and kinematic mounts, to slidably mount optical modules, ensuring alignment by applying forces to maintain desired positions and minimize misalignment, combined with sensor monitoring for real-time adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If optical modules are slidably mounted on guide rails to allow interpupillary distance adjustment, then adaptability is improved, but alignment precision deteriorates due to misalignment issues such as splay, image rotation, and vergence

Engineering Contradiction:

Improveinterpupillary distance adjustmentVSAvoidoptical module alignment

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The biasing systems are pre-configured to apply forces that maintain optical module alignment within desired limits (less than +/- 0.5° misalignment) before adjustment occurs. The guide rails are pre-positioned and biased to hold the optical modules in correct alignment, and the sensor systems are pre-installed to monitor positions, ensuring alignment is maintained throughout the adjustment range without requiring real-time correction during operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Guide rail sensors monitor the positions of the guide rails and optical modules in real-time during interpupillary distance adjustments. This feedback information is used to detect any misalignment exceeding desired limits and triggers corrective actions through the biasing systems, which automatically adjust to maintain alignment precision within +/- 0.5° while allowing continuous adaptability.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If biasing systems are used to maintain alignment, then alignment precision is improved, but device complexity increases due to additional springs and biasing mechanisms

Engineering Contradiction:

Improveoptical module alignmentVSAvoidbiasing system structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The biasing systems are integrated directly into the guide rail structure, merging the alignment maintenance function with the existing support structure. The springs and biasing elements are incorporated as part of the guide rail assembly rather than separate add-on components, and the sensor systems are integrated into the optical module housings, reducing overall device complexity while maintaining alignment precision.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The biasing systems are designed to automatically maintain alignment without requiring external control or manual intervention. The springs self-adjust to compensate for misalignment as optical modules move along the guide rails during interpupillary distance adjustments, and the sensor systems automatically detect and trigger corrective biasing actions, making the alignment maintenance function self-regulating and reducing operational complexity.

Inventive Principle:

Principle #25Self-service

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

This configuration effectively maintains optical module alignment within desired limits, reducing misalignment to less than +/- 0.5°, enhancing user comfort and image stability during adjustments.

Implementation Method 1

A lower guide rail biasing system may have a spring that pushes a biasing member against an adjacent surface of the lower guide rail

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

The guide rails may be biased against the surfaces of the cylindrical openings and/or other portions of the optical modules using springs or other biasing systems

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP4204890B1Electronic devices with biased guide rails

Publication Date: 2025.10.29 APPLE INC

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AI summary

A head-mounted device may be provided with displays. The displays and lenses through which images on the displays are viewed may be mounted in optical modules. Positioners may be used to move the optical modules towards and away from each other to adjust the head-mounted device to accommodate different user interpupillary distances. To support and guide the optical modules, the optical modules may be slidably mounted to guide rails. The guide rails may be biased against the optical modules using biasing systems. By using the biasing systems, misalignment between the optical modules can be reduced. If desired, guide rail sensors may be used to monitor the positions of the guide rails. In some configurations, the optical modules may be mounted to the guide rails using kinematic mounting.