Asymmetric Microprism Light Redistribution
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Solution Overview
Problem
Existing light transmissive structures, such as Direction Turning Film and Image Directing Film II, fail to smoothly and monotonically fade light away from the bend direction, resulting in undesirable light distribution when attempting to redirect Lambertian light sources with wide beam angles like 120 degrees, leading to inefficient illumination patterns.
Innovation Solution
A light transmissive structure comprising a substrate with microprism elements, where the first surface has an inclination angle of approximately 40 degrees and the second surface has an inclination angle of approximately 70 degrees, arranged in a pattern to redirect light with a peak angle of 70 degrees, providing a smooth monotonic decrease in light intensity from 0 to 90 degrees away from the bend direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If existing light transmissive structures (Direction Turning Film, Image Directing Film II) are used to redirect Lambertian light sources, then light can be bent toward a target area, but the light distribution does not smoothly and monotonically fade away from the bend direction, resulting in undesirable secondary light distributions
Solution Approach 1:
The patent applies local quality by varying the inclination angles of different surfaces of the microprism elements. The first surface has an inclination angle of approximately 40 degrees while the second surface has an inclination angle of approximately 70 degrees. This asymmetric local configuration allows different regions of the light transmissive structure to handle different portions of the wide-angle light distribution, achieving smooth monotonic fading without secondary distributions.
Solution Approach 2:
The patent changes the geometric parameters of the microprism elements, specifically the inclination angles of their surfaces. By optimizing these angles (40 degrees for the first surface, 70 degrees for the second surface), the structure effectively redirects light from wide-angle sources while maintaining smooth intensity distribution. This parameter optimization resolves the contradiction between light bending capability and distribution smoothness.
2Ease of operation
If flat diffusers are used to diffuse LEDs and smooth surface appearance, then the LED appearance is hidden and surface is smoothed, but the light distribution impinging upon the diffuser face results in non-monotonic light fading patterns
Solution Approach 1:
The patent replaces the flat diffuser surface with curved microprism elements that have specific inclination angles. The microprism structure introduces controlled curvature and angular variation to the light transmissive surface, which transforms the non-monotonic light fading pattern into a smooth monotonic distribution while preserving the appearance-smoothing function.
3Shape
If internal sidewalls are used to limit beam angle spread, then mid-width source distribution is achieved, but the light distribution still does not provide smooth monotonic fading from 0 to 90 degrees away from the bend direction
Solution Approach 1:
The patent replaces the mechanical beam-limiting approach (using physical sidewalls) with an optical solution based on microprism light redirection. The microprism elements optically transform the light distribution through their specific inclination angles, achieving both beam angle control and smooth angular fading without the need for physical constraints that create discontinuities.
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 microprism structure effectively bends light with a Full Width Half Max distribution between 10 and 120 degrees, achieving a smooth and asymmetric power distribution, enhancing illumination on targeted areas without secondary light distributions, thereby improving lighting efficiency and uniformity.
Implementation Method 1
A light transmissive structure comprising a substrate with microprism elements, where the first surface has an inclination angle of approximately 40 degrees and the second surface has an inclination angle of approximately 70 degrees, arranged in a pattern to redirect light with a peak angle of 70 degrees
Data Source
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AI summary
A light transmissive structure includes a light transmissive substrate having first and second opposing faces, and an array of microprism elements on the first face. Each microprism element includes a first inclined surface disposed at a first inclined angle relative to the second face, and a second inclined surface disposed at a second inclined angle relative to the second face. The first inclined angle is less than the second inclined angle, and a peak angle between the first inclined surface and second inclined surface is in the range of about 70 degrees to about 100 degrees. The second inclined surface has a convex curvature when viewed from angles perpendicular thereto. The light transmissive structure is configured to receive light from a light source facing the first face in a first direction and redistribute light emerging from the second face in a second direction different from the first direction.