Projection Screen With Angled Passages To Reduce Moiré Effects
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Solution Overview
Problem
Perforated and woven screens used for video applications often suffer from visible Moiré effects when combined with fixed pixel projectors due to the alignment of holes or threads being parallel to the projected image, leading to interference and reduced image quality.
Innovation Solution
A projection screen with a sheet featuring passages or weft structures that have non-zero inclinations relative to the vertical and horizontal edges, along with geometry and orientation variations, to minimize the coincidence with projected pixel structures and reduce Moiré effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If holes are arranged in regular grid pattern for sound permeability, then sound wave transmission is improved, but Moiré effects appear due to alignment with projected pixel structures
Solution Approach 1:
The patent applies asymmetry by rotating the regular grid pattern of holes at a specific angle (e.g., 45 degrees) relative to the projection screen edges. This asymmetric orientation breaks the alignment between the hole grid and the projected pixel matrix, eliminating Moiré effects while preserving sound transmission through the regularly spaced holes.
Solution Approach 2:
The patent changes the angular parameter of the hole arrangement from 0 degrees (aligned with screen edges) to a non-zero angle (e.g., 45 degrees). This parameter change disrupts the periodic coincidence between the hole pattern and pixel structure, preventing Moiré interference while maintaining the acoustic functionality of the regular grid.
2Object-affected harmful factors
If hole size and spacing are reduced to decrease visibility, then aesthetic appearance is improved, but sound permeability may be compromised
Solution Approach 1:
The patent optimizes the parameters of hole diameter and spacing to achieve a balance between visibility and sound permeability. By carefully selecting these parameters and combining them with angular rotation, the holes become less visually prominent while maintaining sufficient acoustic transmission for sound sources placed behind the screen.
3Adaptability or versatility
If screen is made permeable to sound waves by perforation, then sound source placement behind screen is improved, but Moiré effects and optical interference appear
Solution Approach 1:
The patent enables sound source placement behind the screen by providing sound permeability through perforation, while simultaneously applying asymmetric angular rotation to the hole pattern to eliminate optical interference and Moiré effects, thus achieving both audio versatility and visual 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
The solution effectively reduces or eliminates visible optical interference, ensuring compatibility with fixed pixel projectors while maintaining sound wave permeability, even at closer viewing distances and with imperfect screen flatness.
Implementation Method 1
a sheet having a projection face and provided with a plurality of passages adapted to allow sound waves to pass through the sheet
Implementation Method 2
the disposition of the passages of said plurality is such that, if alignments thereof can be detected, at least the main alignments have a non-zero inclination relative to the vertical and horizontal edges of the screen
Data Source
AI summary
A projection screen comprises a film having a projection side and provided with a number of passages adapted for permitting emitted sound waves to pass through said film. The projection screen is characterized in that these passages are arranged in such a manner that, if alignments can be detected, at least the principal ones have an angle that is not zero with regard to the vertical and horizontal edges of the screen.