Head Mounted Display Posture Determination Using Cross Ratio
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) require additional configuration and synchronization cables to determine posture, which increases fabrication costs and prolongs the time required to determine the posture, especially as the number of light emitting devices increases.
Innovation Solution
A head-mounted display with light emitting devices that use a non-synchronized method to determine posture by employing a cross ratio based on the arrangement of light emitting devices on multiple surfaces, allowing for asynchronous recognition without the need for synchronization cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If synchronization cable and additional configuration are used to synchronize camera shutter with light emitting devices, then posture determination accuracy is improved, but fabrication cost increases
Solution Approach 1:
The patent removes the synchronization cable from the system by extracting the synchronization function and replacing it with a master-slave timing relationship where the slave camera uses the light emitting devices as natural synchronization signals, eliminating the need for additional physical synchronization components
Solution Approach 2:
The light emitting devices serve dual functions: they provide illumination for posture determination and simultaneously act as synchronization signals for the slave camera, eliminating the need for separate synchronization mechanisms
2Measurement precision
If number of light emitting devices is increased to improve posture determination accuracy, then measurement precision is improved, but time to determine posture increases
Solution Approach 1:
The patent uses periodic light emission patterns where light emitting devices emit light in regular intervals with specific on/off timing, allowing the slave camera to capture multiple frames that collectively provide complete posture information without requiring all devices to be active simultaneously
Solution Approach 2:
The master camera captures reference images of the light emitting devices in advance, establishing a baseline pattern that is stored and used for comparison, allowing rapid posture determination without重新 capturing all reference data
3Reliability
If synchronization cable is used to synchronize camera shutter with light emitting devices, then posture determination reliability is improved, but device complexity increases
Solution Approach 1:
The system uses its own light emitting devices to provide synchronization signals for the slave camera, making the system self-synchronizing without requiring external synchronization infrastructure or additional control cables
Solution Approach 2:
The light emitting devices act as intermediaries that translate the master camera's timing signals into visible synchronization cues for the slave camera, mediating the synchronization relationship without requiring direct electrical connection
Data Source
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AI summary
Disclosed is a head mounted display (HMD) having light emitting devices. The HMD includes a body (100) having a plurality of surfaces (103a, 103b, 103c, 103d, 103e, 103f); and a plurality of light emitting units (200a, 200b, 200c, 200d, 200e, 200f) formed on the plurality of surfaces (103a, 103b, 103c, 103d, 103e, 103f) and configured to emit light to outside of the body, wherein each of the plurality of light emitting units (200a, 200b, 200c, 200d, 200e, 200f) includes at least four light emitting devices that are disposed in a straight line in a spaced manner such that a specific cross ratio defines spacing for each of the plurality of light emitting units (200a, 200b, 200c, 200d, 200e,200f), a cross ratio of one of the plurality of light emitting units (200a, 200b, 200c, 200d, 200e,200f) being different from cross ratios of other light emitting units among the plurality of light emitting units (200a, 200b, 200c, 200d, 200e,200f). For determining the posture of the HMD.