Hemispherical Lens Array for LED Sparkle Effect
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Solution Overview
Problem
Conventional LED lamps do not produce a sparkling effect due to their non-coherent light emission, which lacks the aesthetic appeal of coherent light sources like lasers, as they do not create the desired speckle effect observed in human eyes.
Innovation Solution
A hemispherical LED lens with an array of small, interconnected lenslets is used to shape the LED light into directional point sources, creating a sparkling effect by producing partially coherent light that changes brightness appearance when the observer or light source moves, achieved through the combination of inner convex lenses and a scattering outer surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED lamps use non-coherent light emission, then the LED structure is simple and manufacturing is easy, but the aesthetic appeal and sparkle effect are lacking
Solution Approach 1:
The lens is divided into an array of small, interconnected lenslets (each approximately 1/100 to 1 mm in diameter) that collectively cover the hemispherical surface. Each lenslet independently shapes light from the LED die into a directional point source, creating multiple sparkle points that combine to produce the overall sparkling effect while maintaining manufacturing simplicity through molding processes.
Solution Approach 2:
Different regions of the lens have different optical functions: the inner surface contains convex lenslets that focus and directionalize light, while the outer surface has a scattering property that diffuses the point sources. This local differentiation of optical properties enables the complex sparkling effect without requiring complex overall lens design.
2Illumination intensity
If a hemispherical lens with array of lenslets is used to create directional point sources, then the sparkling effect is achieved, but the device complexity increases
Solution Approach 1:
Multiple lenslets are interconnected and integrated into a single hemispherical lens structure that can be molded as one piece. This merging of numerous individual optical elements into a unified component achieves the complex sparkling effect while simplifying manufacturing and assembly, as the entire array functions as a single integrated optical element.
Solution Approach 2:
The lens is implemented as a thin hemispherical shell or dome structure that can be easily molded and attached to the LED die. This thin-film approach reduces material usage and structural complexity while maintaining the optical functionality of the lenslet array.
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 generates a sparkling and speckle effect by creating an array of bright point sources that change as the observer moves, enhancing the aesthetic appeal of LED lamps by mimicking the interference patterns of coherent light sources.
Implementation Method 1
Each lenslet shapes the LED light received at its input surface into a substantially point source at its output surface
Implementation Method 2
The observer's rods and cones see a partially coherent light emitted by a single lenslet, assuming the LED emits a narrow range of wavelengths. The point source essentially creates plane waves of light. The different rods and cones detect light that undergoes different degrees of constructive and destructive interference
Implementation Method 3
The outer surface comprises a scattering surface, such as a suitable roughened surface. The roughened surface can be created by molding or by other means. The inner lenses create the point sources at the outer surface, and the scattering by the outer surface causes the point sources to be viewed at random angles relative to the lens.
Data Source
Figure 1~4
Figure 5~6
AI summary
A substantially hemispherical lens surrounding an LED die is described that creates a sparkle as an observer views the lens from different angles. The lens is formed of an interconnected array of 100-10,000 or more lenslets. Each lenslet focuses an image of the LED die at an output of the lenslet such that the LED die image area at the output is less than 1/9 the area of the LED die to create a substantially point source image of the LED die at an outer surface of the lens. When the LED die is energized, the shape of each lenslet causes point source images of the LED die to be perceived by an observer at various viewing angles, such that the emitted LED light appears to sparkle and speckle as the observer moves relative to the lens.