MEMS Projection Device Laser Safety Compliance
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Solution Overview
Problem
Existing projection devices often exceed the maximum accessible emission limits for laser safety classifications due to high concentrations of photons and pulsed laser emissions, posing risks to users' eyes and necessitating classification as class 2 or higher, which compromises safety.
Innovation Solution
A method that calculates and adjusts the number of black pixels in the pixel stream to maintain the projection device within a selected laser class's safety standards by determining the relationship between maximum accessible emission limits and distance, modifying the pixel stream to ensure compliance with desired luminosity limits, and dynamically adjusting the number of black pixels based on measured distances or accelerations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the laser light is focused or collimated to project high-quality images, then the image quality is improved, but the maximum accessible emission limit is exceeded, causing the device to be classified as class 2 or higher
Solution Approach 1:
The image is segmented into active image pixels and black pixels. The black pixels are inserted at specific locations (such as at the edges or corners of the image) to divide the concentrated laser emission into separate regions, thereby reducing the maximum accessible emission limit while preserving the overall image quality through the active pixels.
2Speed
If the MEMS mirror oscillates at high speed to scan light across the display screen, then the projection speed is improved, but the distance between successive pixels becomes shorter, causing higher photon concentration that exceeds safety limits
Solution Approach 1:
Black pixels are preliminarily inserted into the pixel stream at predetermined positions before the image is projected. This preliminary action ensures that when the MEMS mirror scans at high speed, the black pixels are already in place to reduce photon concentration at critical locations where successive pixels would otherwise be too close together.
3Use of energy by moving object
If pulsed laser emissions are used to define pixels, then the energy efficiency is improved, but the high concentration of photons in short time intervals exceeds the maximum accessible emission limit
Solution Approach 1:
Different regions of the projected image have different qualities: active image pixels contain the necessary light information for image formation, while black pixels (located at specific positions such as edges or corners) have the quality of zero or reduced light emission. This local differentiation allows energy-efficient pulsed laser operation while ensuring safety compliance at critical locations.
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 approach ensures that projection devices operate within safe laser class limits, preventing eye damage and maintaining safety standards by dynamically adjusting pixel stream parameters to match desired emission levels, thereby preventing classification as higher-risk classes.
Implementation Method 1
a MEMS mirror which oscillates about one or more oscillation axes to scan light from one or more lasers, across a display screen, to project pixels which define an image onto a display screen
Data Source
AI summary
Disclosed is a projection device including a MEMS mirror which oscillates about one or more oscillation axes to scan light from one or more lasers, across a display screen, to project pixels which define an image onto a display screen. Also disclosed is a display method including selecting a laser class for the projection device; calculating a relationship between maximum accessible emission limit and distance, for the selected laser class; and selecting a desired maximum accessible emission limit for an image which is to be projected by the projection device onto said display screen.