Projection Screen Grating Absorption Layer for Ambient Light Rejection
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Solution Overview
Problem
Existing projection screens struggle with low contrast due to ambient light interference, leading to poor image quality and increased costs for optical engines as they reflect both projector light and ambient light.
Innovation Solution
A projection screen design featuring a grating absorption layer with ring-shaped light-absorbing units arranged in concentric rings, positioned between an optical collimation layer and a surface diffusion layer, effectively distinguishes between projection light and ambient light, enhancing brightness uniformity and ambient light resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a common projection screen reflects light from both projector and ambient light, then the screen can display images, but the contrast of the reflected image is much lower than the projector due to ambient light interference
Solution Approach 1:
The screen is divided into multiple functional layers: a grating absorption layer with light-absorbing units arranged in concentric rings, an optical collimation layer, and a surface diffusion layer. Each layer performs a specific function in selectively managing light paths to achieve ambient light rejection while maintaining image quality
Solution Approach 2:
The grating absorption layer features light-absorbing units with different properties at different locations - the units are arranged in concentric rings with varying densities and absorption characteristics, creating local variations in light absorption to optimize contrast across different viewing angles and screen regions
2Device complexity
If the grating absorption layer uses uniformly arranged gratings, then the structure is simple, but the brightness uniformity is poor
Solution Approach 1:
The light-absorbing units are arranged asymmetrically in concentric rings rather than in a uniform grid pattern. The radial and tangential spacing between units varies by location, creating an asymmetric distribution that optimizes light absorption from ambient directions while maintaining uniform brightness across the screen surface
Solution Approach 2:
The grating arrangement transitions from a two-dimensional uniform grid to a radially symmetric concentric ring pattern. This dimensional reorganization allows the screen to handle light differently in radial versus tangential directions, improving brightness uniformity through geometric optimization
3Illumination intensity
If the projection screen has high gain to compensate for ambient light, then the image brightness is maintained, but the cost of the optical engine increases
Solution Approach 1:
The screen converts the harmful effect of ambient light into a beneficial selective filtering mechanism. The grating absorption layer is designed to absorb ambient light from specific directions while transmitting projection light, effectively using the ambient light's directional characteristics to improve contrast without requiring higher projector output
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 design achieves high gain and reduced optical engine costs by selectively absorbing ambient light while maintaining high reflectivity for projection light, resulting in improved contrast and brightness uniformity.
Implementation Method 1
The grating absorption layer includes ring-shaped light-absorbing units with different radiuses, the ring-shaped light-absorbing units are arranged in the form of concentric rings, and at least two of gratings are arranged along a circumference of one of the concentric rings
Implementation Method 2
The projection screen includes an optical collimation layer and a surface diffusion layer that are sequentially disposed
Implementation Method 3
The projection screen includes an optical collimation layer and a surface diffusion layer that are sequentially disposed
Data Source
AI summary
A projection screen includes an optical collimating layer and a surface diffusion layer which are arranged in sequence. A grating absorption layer for absorbing ambient light from various directions except a projection light direction is also provided between the optical collimating layer and the surface diffusion layer. The grating absorption layer includes a plurality of light-absorption ring-shaped units with different radii. The plurality of light-absorption ring-shaped units are arranged in a concentric ring. Each of the light-absorption ring-shaped units consists of a plurality of gratings arranged in the circumferential direction of the concentric ring. By taking a vertical symmetrical center line of the projection screen as a center, in a direction extending along the circumferential direction of the concentric ring to the left side and the right side of the projection screen, the distance between two adjacent gratings in the same light-absorption ring-shaped unit gradually increases.