HMD Lightguide Integrity Monitoring via Embedded Conductor Feedback
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Solution Overview
Problem
Conventional near-eye displays face issues with light being inadvertently redirected into the user's eye due to damage to optical combiners, causing discomfort and disrupting the displayed image.
Innovation Solution
Implementing an elongated conductor proximal to the optical combiner in a head-mounted display to monitor for fractures or damage by detecting changes in electrical characteristics, such as impedance or connectivity, and generating a signal to alert the user or disable the light source to prevent discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an optical combiner is used to transport light from the light source to the user's eye, then the display function is improved, but the risk of light being inadvertently redirected into the user's eye due to damage increases
Solution Approach 1:
The patent applies preliminary action by embedding an elongated conductor within the lightguide structure before operation, enabling proactive monitoring of the lightguide's integrity. The conductor continuously tracks structural health through electrical characteristic changes, allowing the system to detect damage early and generate warnings before harmful light redirection occurs, thus preventing rather than reacting to the harmful effect.
Solution Approach 2:
The patent implements feedback by creating a closed-loop monitoring system where the elongated conductor continuously measures electrical characteristics (resistance, impedance, capacitance) and feeds this information to a controller. When damage occurs, the change in electrical properties triggers an immediate feedback signal to alert the user or disable the light source, establishing a real-time monitoring mechanism that dynamically responds to structural changes in the lightguide.
2Ease of operation
If the optical combiner is exposed to potential damage in eyeglass frame configuration, then the ease of operation is improved, but the manufacturing precision and structural integrity may deteriorate
Solution Approach 1:
The patent applies merging by integrating the elongated conductor directly into the lightguide structure during manufacturing, creating a unified composite component. This combination ensures the conductor moves with the lightguide and maintains consistent electrical contact, while the lightguide provides mechanical support and protection for the conductor. The merged structure simplifies assembly and ensures the monitoring system remains intact throughout the device's operational life.
Solution Approach 2:
The patent implements universality by designing the elongated conductor to serve multiple functions: it acts as both a structural reinforcement element within the lightguide and a sensing element for damage detection. The conductor's dual role as both mechanical support and electrical sensor reduces the need for separate components, simplifies the overall structure, and enhances the reliability of the monitoring system while maintaining the wearability of the device.
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
Effectively detects and prevents high levels of refracted light from entering the user's eye by monitoring for damage to the optical combiner, ensuring a safe and functional display experience.
Implementation Method 1
monitoring for fractures or other damage to the lightguide by monitoring for a change in an electrical characteristic of the elongated conductor
Implementation Method 2
the lightguide configured to transport display light input by the incoupler to the outcoupler for output
Data Source
AI summary
Lightguide integrity monitoring in a head mounted display is facilitated by monitoring an elongated conductor disposed proximal a lightguide in an optical combiner. When a sufficient change in one or more electrical characteristics of the elongated conductor is detected, a signal indicating that the lightguide has been damaged may be generated, which may alert the user to the damage or disable one or more light sources in the HMD to prevent eye discomfort. The monitored electrical characteristics of the elongated conductor may include connectivity, impedance, and gain, among others. A sufficient change in the one or more electrical characteristics may be detected based on a percentage change in an electrical characteristic, a change in more than one electrical characteristic, or a change in a ratio of two electrical characteristics, among others.