Laser Safety Circuit for Wearable Heads-Up Display
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Solution Overview
Problem
Conventional laser projectors and wearable heads-up displays face challenges in ensuring user safety due to potential eye damage from excessive laser power, and they often lack aesthetic appeal and are bulkier than conventional eyeglasses.
Innovation Solution
A laser projector system with a laser safety circuit that includes a photodetector, a latch, and a switch to interrupt power to the laser diodes when excessive power is detected, combined with a processor to modulate the laser and store a flag for safe reboot, integrated into a wearable heads-up display design that combines red, green, blue, and infrared laser diodes for safe and stylish operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser power is increased to provide high-quality images, then image quality is improved, but eye safety is compromised
Solution Approach 1:
The patent implements a feedback mechanism where a photodetector continuously monitors the actual laser light power and compares it against a predetermined safety threshold. When the monitored power exceeds the threshold, the system automatically interrupts power to the laser diode, creating a closed-loop control system that dynamically adjusts laser output to maintain safety while enabling high-quality imaging when conditions permit.
Solution Approach 2:
The system performs preliminary safety verification by monitoring laser power before allowing normal operation to proceed. The photodetector continuously checks power levels in advance, and the control circuit is prepared to interrupt power immediately if thresholds are exceeded, preventing harmful exposure before it can occur rather than reacting after damage happens.
2Reliability
If laser safety monitoring is added, then eye safety is improved, but device complexity increases
Solution Approach 1:
The laser safety system is self-monitoring and self-regulating. The photodetector automatically detects power levels, the control circuit autonomously compares readings against thresholds, and the system self-corrects by interrupting power when needed. This self-service approach eliminates the need for external safety monitoring equipment or complex control systems, achieving high reliability with minimal added complexity.
Solution Approach 2:
The safety monitoring function is integrated into the existing laser driver circuitry. The photodetector, control circuit, and power interruption mechanism are combined with the laser diode driving system, allowing safety monitoring to be implemented without requiring completely separate, additional complex subsystems. The control circuit serves dual purposes of both driving the laser and monitoring its safety.
3Volume of moving object
If wearable heads-up display is made compact, then aesthetic appeal is improved, but safety monitoring capability is reduced
Solution Approach 1:
The safety monitoring components are nested within the compact wearable device structure. The photodetector is positioned to receive a portion of the laser light within the device housing, and the control circuit is integrated into the existing electronics. This nesting approach allows comprehensive safety monitoring to be implemented without increasing the external dimensions of the wearable device, maintaining aesthetic appeal while ensuring safety.
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 system effectively prevents eye damage by automatically reducing laser power when exceeding safe thresholds and maintains safety during reboots, while providing high-quality images in a compact, aesthetically appealing wearable format.
Implementation Method 1
a photodetector responsive to laser light output by the at least one laser diode
Implementation Method 2
at least one laser diode
Implementation Method 3
at least one laser diode
Data Source
AI summary
Laser safety systems, devices, and methods for use in laser projectors are described. A laser projector includes any number of laser diodes that each emit laser light, a shared laser diode power source, a photodetector to detect a power/intensity of a portion of the laser light, a beam splitter to direct a first portion of the light towards the photodetector and a second portion of the light towards an output on the projector, and a laser safety circuit responsive to signals from the photodetector. The laser safety circuit selectively electrically couples/uncouples the laser diodes from the power source depending on the power/intensity of the laser light detected by the photodetector. Particular applications of the laser safety systems, devices, and methods in a wearable heads-up display are described.