Projection Screen Vibration for Speckle Reduction
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Solution Overview
Problem
Existing technologies for reducing speckle interference in display and projection systems are either costly, decrease brightness, or reduce reliability, as they often require additional parts or physical translation, which are not effective in mitigating speckle to acceptable levels.
Innovation Solution
Vibrating a projection screen within a predetermined frequency spectrum using a primary transducer, such as a voice coil, with a high elastic modulus substrate, to disperse power across a range of 30-500 Hertz, thereby mitigating speckle to less than 15% contrast at 15 feet, while minimizing audible noise to less than 40 dBm, and incorporating redundant transducers for failure detection and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a diffuser is used to reduce speckle, then speckle visibility is reduced, but device complexity increases
Solution Approach 1:
The patent applies mechanical vibration to the projection screen using transducers that generate vibrations within a predetermined frequency spectrum (primarily 30-500 Hz). This vibration causes the screen to oscillate, which modulates the reflected light and reduces speckle visibility through temporal averaging of the interference pattern, eliminating the need for additional diffuser components.
Solution Approach 2:
The patent changes the physical state and operational parameters of the projection screen by introducing controlled vibrations at specific frequency ranges. By adjusting the vibration frequency spectrum and power distribution, the system optimizes speckle reduction while maintaining screen integrity and minimizing audible noise, achieving a balance between performance and simplicity.
2Object-affected harmful factors
If screen vibration is increased to reduce speckle, then speckle reduction improves, but audible noise increases
Solution Approach 1:
The patent carefully controls the vibration frequency spectrum within the range of 30-500 Hz, with power dispersed across this spectrum. This parameter optimization ensures that the vibration frequency remains above the human hearing threshold (20 Hz) to minimize audible noise while maintaining sufficient amplitude to effectively reduce speckle visibility through optical modulation.
Solution Approach 2:
The transducers are designed to generate mechanical vibrations that primarily excite the screen in the 30-500 Hz range, which is above the lower limit of human hearing. This frequency selection reduces the perception of audible noise while maintaining effective speckle reduction, as the screen vibration modulates the reflected light pattern without producing excessive acoustic disturbance.
3Object-affected harmful factors
If transducers are added to vibrate the screen, then speckle reduction is achieved, but device complexity increases
Solution Approach 1:
The projection screen serves multiple functions: it displays the projected image and simultaneously acts as a vibration element for speckle reduction. By integrating the screen and transducer system, the patent eliminates the need for separate diffuser components, reducing overall device complexity while achieving effective speckle mitigation through the screen's dual role.
Solution Approach 2:
The transducers are mounted directly to the projection screen, utilizing the screen's existing structure as the vibration medium. This integration approach avoids adding separate mechanical components for speckle reduction, as the screen itself becomes the active element that modulates light through vibration, thereby minimizing increases in device complexity.
4Object-affected harmful factors
If vibration frequency is increased to reduce speckle, then speckle reduction improves, but power consumption increases
Solution Approach 1:
The patent optimizes the vibration frequency spectrum to be dispersed within 30-500 Hz, distributing the power requirements across multiple frequencies rather than concentrating energy at a single high frequency. This power dispersion strategy reduces peak power consumption while maintaining effective speckle reduction through cumulative modulation effects across the frequency range.
Solution Approach 2:
The transducers operate within the 30-500 Hz frequency range, which balances speckle reduction effectiveness with power consumption constraints. This frequency selection achieves sufficient screen modulation to reduce speckle visibility while avoiding excessively high frequencies that would require disproportionate power input, optimizing the energy efficiency of the speckle mitigation system.
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 speckle visibility to acceptable levels without causing excessive audible noise, using a high elastic modulus substrate to propagate vibrations efficiently across the screen, and redundant transducers ensure system reliability by only engaging when primary transducers fail.
Implementation Method 1
vibrating a projection screen within a predetermined frequency spectrum with at least one primary transducer mounted to the projection screen
Implementation Method 2
The predetermined frequency spectrum has power which is dispersed within the predetermined frequency spectrum
Implementation Method 3
The projection screen includes a high elastic modulus substrate, with an elastic modulus of greater than 0.4 GPa
Implementation Method 4
The at least one primary transducer which may be, for example, a voice coil
Implementation Method 5
a light diffusing unit that is vibratably provided to diffuse incident light by a vibration
Data Source
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AI summary
The present disclosure includes systems and methods for solving speckle problems by exciting the screen with a more complex vibration spectrum. A range of frequencies provides, in effect, a collection of overlapping patterns of high and low displacement, so that all regions of the screen have enough motion to reduce visible speckle. As previously discussed acceptable speckle may be approximately 15% contrast or less, preferably approximately 5% contrast or less at approximately 15 feet from the screen.