Anti-glare Filter with Frustum Array for LED Lighting
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Solution Overview
Problem
LED light sources with wide angular distributions cause glare, leading to discomfort and potential safety hazards, and existing solutions often result in high optical losses.
Innovation Solution
An anti-glare filter (AGF) is patterned in a film with an array of frustums on the side facing away from the light source, which narrows the angular distribution of light output through sloped sidewalls, while a light shaping diffuser (LSD) can be added on the light-facing side to improve light homogeneity and transmissivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LED light sources are made brighter to improve illumination intensity, then the illumination intensity is improved, but glare is increased causing discomfort and safety hazards
Solution Approach 1:
The patent segments the light output by using an array of frustums (micro-prisms) that divide and redirect light rays into specific angular ranges. Each frustum acts as an independent light redirecting element, collectively controlling the overall light distribution to reduce glare while maintaining illumination intensity.
Solution Approach 2:
The patent applies local quality by creating regions of different optical properties through the frustum array. The frustums are designed with specific dimensions and orientations to redirect light locally into desired angular ranges, creating zones of controlled light distribution that reduce glare in specific directions while maintaining illumination in others.
2Object-affected harmful factors
If conventional glare reduction methods (e.g., frosted acrylic cover) are used to minimize glare, then glare is reduced, but optical losses increase significantly
Solution Approach 1:
The patent replaces the mechanical scattering approach of frosted surfaces with an optical redirection system using frustums. Instead of randomly scattering light through surface roughness, the frustums use precise geometric optics to redirect light into specific angular ranges, maintaining optical efficiency while reducing glare.
Solution Approach 2:
The patent changes the optical parameters of light distribution by using frustums with specific dimensions, refractive indices, and orientations. By adjusting these parameters, the system controls light redirection angles to minimize glare while maximizing light transmission, avoiding the high optical losses associated with frosted surfaces.
3Object-affected harmful factors
If light is redirected to narrow angular distribution to reduce glare, then glare is reduced, but light homogeneity deteriorates
Solution Approach 1:
The patent applies local quality by varying the frustum dimensions, orientations, and distributions across different regions of the array. This creates localized light redirection patterns that collectively achieve both narrow angular distribution for glare reduction and uniform light homogeneity across the illuminated area.
Solution Approach 2:
The patent uses the third dimension (depth/height of frustums) to control light redirection. By varying frustum heights and orientations in three-dimensional space, the system achieves precise angular control while maintaining light homogeneity, adding a dimensional degree of freedom to resolve the contradiction.
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 AGF effectively reduces glare by narrowing the angular distribution of light, maintaining high transmissivity and achieving efficient illumination without sacrificing optical properties.
Implementation Method 1
The frustums have sloped sidewalls that act, through Snell's law and Fresnel equations, to narrow the angular distribution of light output from the AGF
Implementation Method 2
The frustums have sloped sidewalls that act, through Snell's law and Fresnel equations, to narrow the angular distribution of light output from the AGF
Data Source
AI summary
An anti-glare film for a light source is disclosed. The light source may be a light source with a Lambertian distribution, such as an LED light source. The anti-glare film may include a micro-frustum array to reduce the angular distribution of the light source and thus reduce glare. In some implementations, anti-glare film may further include a light shaping diffuser.