Scanning Laser Projection Pixel Masking for Eye Safety
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Solution Overview
Problem
Laser projection systems often fail to maintain eye-safe emission levels, particularly when high-power lasers are used, as they lack effective mechanisms to reduce accessible radiation levels in the presence of objects within the field of view, posing a risk to human eye safety.
Innovation Solution
The implementation of a scanning laser projection system with an automatic power reduction mechanism, utilizing an infrared laser to detect objects and reduce visible laser power through decimation of pixels or creation of power reduction zones, effectively creating a virtual protective housing to maintain eye-safe emission levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-power lasers are used in projection systems, then brightness and visibility of projected images are improved, but eye safety is compromised due to excessive accessible radiation levels
Solution Approach 1:
The laser projection system dynamically adjusts its output power based on real-time detection of objects in the projection path. The controller modifies the brightness of projected images by varying laser power levels, transitioning from static high-power operation to dynamic adaptive power control that maintains eye safety while preserving image quality when conditions permit
Solution Approach 2:
The system implements a feedback mechanism where sensors detect objects in the projection path and send signals to the controller, which then adjusts laser power accordingly. This closed-loop control enables the system to respond to changing conditions and automatically maintain safe radiation levels while optimizing brightness for visible projections
Solution Approach 3:
The system changes the power parameter of the laser based on detected conditions. When objects are detected in the projection path, the controller reduces laser power to safe levels; when no objects are present, full power is restored for optimal brightness, thereby dynamically adjusting the radiation parameter to resolve the safety-brightness contradiction
2Object-affected harmful factors
If physical protective housings are implemented to reduce accessible emission levels, then eye safety is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical protective housings with a virtual protective housing created through software-controlled pixel masking and power reduction. Instead of adding mechanical safety structures, the system uses digital processing to selectively reduce power in areas where objects are detected, thereby achieving eye safety through electronic control rather than physical barriers
Solution Approach 2:
The system creates a virtual copy of the protective housing function through software algorithms that simulate the safety behavior of physical housings. The virtual protective housing uses image processing and selective pixel masking to replicate the radiation-reducing effect of physical enclosures without the associated complexity and cost
3Object-affected harmful factors
If power reduction zones are created to mask pixels of image content, then eye safety is maintained, but image quality and brightness are reduced
Solution Approach 1:
The system applies power reduction selectively to specific regions of the projected image where objects are detected, rather than uniformly reducing power across the entire image. This local quality approach masks only the necessary pixels in power reduction zones while maintaining full brightness and image quality in areas where no objects are present, thereby resolving the contradiction between safety and image quality
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 solution ensures that the laser projection system maintains eye-safe emission levels by automatically reducing power in areas where objects are detected, thereby preventing exposure to harmful radiation, similar to physical protective housings, while allowing full power operation when safe.
Implementation Method 1
measuring a time-of-flight of the reflections
Implementation Method 2
measure one or more attributes of the reflections of the infrared laser light pulses from objects within the field of view
Data Source
AI summary
A scanning laser projection system includes a virtual protective housing circuit to automatically reduce accessible emissions of visible laser light by decimating areas of a projected image to reduce optical power exposure levels for safety, comfort, aesthetic, or system classification purposes. IR laser light pulses are scanned in a field of view, and a percentage of visible laser light pulses are blanked based on attributes of reflections of the IR laser light pulses.