Waveguide Combiner Calibration for Stereoscopic HMD Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing head-mounted display (HMD) devices face challenges in maintaining precise alignment of stereoscopic image projectors due to factors like temperature changes, physical stress, and bending, leading to misalignment and vergence-accommodation conflict, which affects user experience, and existing solutions like rigid frames or inertial measurement units are either bulky or lack precision.
Innovation Solution
An optical calibration system using a waveguide combiner and boresight sensors to maintain alignment between left-eye and right-eye projectors, allowing for a compact form factor by combining optical paths and using boresight sensors to adjust images based on detected alignment, thereby reducing misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid frames or inertial measurement units are used to maintain projector alignment, then alignment stability is improved, but device bulkiness and weight increase
Solution Approach 1:
The patent replaces mechanical alignment maintenance systems (rigid frames, inertial measurement units) with an optical-based calibration system. The waveguide combiner combines multiple optical paths into a shared path, and boresight sensors optically detect alignment between projectors without requiring heavy mechanical structures. This substitution of mechanical systems with optical systems resolves the contradiction by maintaining alignment stability while reducing device weight and bulkiness.
2Reliability
If rigid frames are used to maintain projector alignment, then alignment stability is improved, but device complexity and bulkiness increase
Solution Approach 1:
The patent replaces complex mechanical alignment maintenance structures with a simplified optical calibration system. The waveguide combiner and boresight sensors create an optical path combination and detection mechanism that is structurally simpler than rigid frames or inertial measurement units, while achieving the same alignment stability function.
3Weight of moving object
If compact form factor is achieved by removing rigid structures, then device portability is improved, but projector alignment stability deteriorates
Solution Approach 1:
The patent introduces an optical intermediary system consisting of the waveguide combiner and boresight sensors. This intermediary enables alignment detection and calibration without requiring heavy mechanical structures. The waveguide combiner acts as an intermediary that combines optical paths, and the boresight sensors serve as intermediaries that detect alignment, allowing compact design while maintaining stability.
4Device complexity
If optical paths are combined using waveguide combiner, then device compactness is improved, but optical path alignment precision requirements increase
Solution Approach 1:
The patent implements a feedback mechanism using boresight sensors to detect alignment of the combined optical paths. The sensors provide feedback information about alignment status, enabling real-time monitoring and calibration of the optical paths. This feedback system ensures that even with the increased precision requirements from path combining, the alignment accuracy is maintained through active detection and adjustment.
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
The solution effectively maintains stereoscopic display calibration in a compact HMD form factor by accurately aligning image projectors, improving user experience and reducing bulkiness and weight.
Implementation Method 1
a waveguide combiner in which the first optical path and the second optical path combine into a shared optical path
Implementation Method 2
one or more boresight sensors. Each boresight sensor is configured to detect calibration image light traveling along one or more of the first optical or the second optical path
Data Source
AI summary
Examples are disclosed that relate to calibration of a stereoscopic display system of an HMD via an optical calibration system comprising a waveguide combiner. One example provides an HMD device comprising a first image projector and a second image projector configured to project a stereoscopic image pair, and an optical calibration system. The optical calibration system comprises a first optical path indicative of an alignment of the first image projector, a second optical path indicative of an alignment of the second image projector, a waveguide combiner in which the first and second optical paths combine into a shared optical path, and one or more boresight sensors configured to detect calibration image light traveling along one or more of the first optical or the second optical path.