Projection Screen Magnetic Vibration for Speckle Mitigation
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Solution Overview
Problem
Existing projection systems using laser illumination suffer from subjective speckle artifacts due to interference between the screen surface and the human eye, which are difficult to mitigate with optical design changes, especially on large screens, causing visual noise and uneven reflectivity.
Innovation Solution
A projection screen coated with magnetic material, such as iron powder in a binder, is shaken using non-contact electromagnetic actuators positioned at a distance, generating magnetic fields to alter the screen's surface features and reduce speckle visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser illumination is used for projection, then brightness and coherence are improved, but speckle artifacts are generated causing visual noise
Solution Approach 1:
The projection screen is made to vibrate mechanically through magnetic actuation, causing the screen surface to oscillate and thereby temporalizing the speckle pattern. This vibration prevents the speckle from appearing as a static noise pattern, reducing its visual impact while maintaining laser illumination benefits.
Solution Approach 2:
The screen transitions from a static surface to a dynamically moving surface through electromagnetic actuation. By making the screen surface features move over time, the speckle pattern becomes temporal rather than static, reducing its perceptibility to observers.
2Object-affected harmful factors
If the screen surface is made rough to reduce speckle, then speckle visibility is reduced, but reflectivity becomes uneven
Solution Approach 1:
Instead of permanently roughening the screen surface, the invention uses dynamic vibration to temporarily alter surface features. This maintains the original smooth surface properties for uniform reflectivity while creating temporal variations that reduce speckle visibility during operation.
Solution Approach 2:
The screen surface parameters are dynamically changed through vibration rather than permanently modified. The surface maintains its original optical properties for uniform reflectivity while experiencing temporal variations that reduce speckle, achieving both goals through parameter modulation over time.
3Object-affected harmful factors
If optical design changes are made to mitigate speckle, then speckle is reduced, but device complexity increases
Solution Approach 1:
Instead of modifying the complex optical system to reduce speckle, the invention substitutes by adding a mechanical vibration component to the screen. This replaces the need for complex optical modifications while achieving speckle mitigation through a simpler mechanical approach.
Solution Approach 2:
The screen itself acts as an intermediary element that can be independently actuated with magnetic drivers. This allows speckle mitigation to be achieved through screen modification rather than projector optical system modification, simplifying the overall system architecture.
4Ease of operation
If magnetic material is applied to the screen, then electromagnetic actuation is enabled, but manufacturing complexity increases
Solution Approach 1:
The screen is modified by adding magnetic material with specific electromagnetic parameters that enable actuation. This parameter addition allows for simple electromagnetic driving while maintaining relatively straightforward manufacturing processes through coating or lamination techniques.
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 method effectively reduces the perceptibility of speckle artifacts by temporally changing the screen's surface features, minimizing visual noise and reflectivity inconsistencies.
Implementation Method 1
the electromagnetic actuator generates magnetic fields in response to the transmitted one or more signals. In some variants, the generated magnetic fields interact with the magnetic material to move the projection screen
Implementation Method 2
the generated magnetic fields interact with the magnetic material to move the projection screen for at least partly mitigating a visual perceptibility of the speckle
Data Source
AI summary
Methods and apparatus for mitigating speckle on an image projection screen are disclosed. A non-contact shaking or vibrating of the projection screen may be achieved using lightweight material. For example, magnetic material such as iron powder (suspended in a binder material) may be coated onto the screen, and one or more electromagnetic actuators may be positioned at a distance and generate magnetic fields that cause the shaking from the distance. A controller may generate and transmit signals toward the electromagnetic actuator, the signals configured to cause generation of the magnetic fields that cause the screen to shake at one or more prescribed frequencies. Such motion may at least partly mitigate a visual perceptibility of the speckle.