LED Illumination Cover with Scattering Particles
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Solution Overview
Problem
Conventional illuminated signs using LEDs face challenges in achieving high visibility both day and night due to directional illumination and differing emission spectra compared to traditional light sources, requiring an adapted plastic cover with specific scattering particle content and properties to ensure consistent luminosity and color rendition.
Innovation Solution
A luminous device featuring a white LED with a luminous flux greater than 3 Lm and a transparent plastic cover containing 0.3 to 5% scattering particles, which maintains a luminosity of less than 40 when unlit and greater than 55 when lit, with a* and b* values within specific ranges to ensure consistent color appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional light sources (incandescent lamps, neon tubes) are used, then 360° omnidirectional illumination is achieved, but energy consumption is high and lifetime is short
Solution Approach 1:
The patent applies local quality by creating non-uniform scattering particle distribution within the cover. The scattering particles are concentrated in specific zones (e.g., closer to the LED or in specific angular regions) rather than uniformly distributed. This allows the cover to redirect the inherently directional LED light into a broader distribution pattern, effectively achieving omnidirectional illumination characteristics while maintaining the energy efficiency of LED sources.
2Illumination intensity
If scattering particles are added to the plastic cover, then light scattering and softening is improved, but luminosity when unlit increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the concentration, size distribution, and optical properties of scattering particles. By adjusting these parameters, the cover achieves optimal light scattering performance when the LED is illuminated while maintaining sufficiently low scattering when unlit. This preserves the contrast needed for daytime visibility without compromising nighttime illumination quality.
3Loss of energy
If high luminous flux LEDs (>3 Lm) are used, then energy efficiency and lifetime are improved, but directional illumination causes uneven light distribution
Solution Approach 1:
The patent uses the plastic cover with scattering particles as an intermediary element between the directional LED light source and the final illumination field. This intermediary component transforms the highly directional light from high-luminous-flux LEDs into a more uniform distribution pattern, preserving the energy efficiency and long lifetime benefits of LEDs while eliminating the uneven light distribution problem.
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 provides enhanced visibility and uniform illumination, reducing dazzling effects and maintaining color consistency, making the sign more effective in capturing attention both during the day and at night.
Implementation Method 1
particles that scatter the light emitted by the light-emitting diode are dispersed in the plastic
Data Source
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Figure 6a~6b
AI summary
The invention relates to a luminous device, in particular an illuminated sign, comprising at least one white LED having a luminous flux of greater than 3 Lm, advantageously greater than 5 Lm, preferably greater than 10 Lm and even more preferably greater than 50 Lm, and to a cover made of a transparent plastic in which scattering particles with a content of 0.3 to 5%, preferably 0.3 to 4%, are dispersed, and having, when the LED is off, a luminosity L of less than 40, preferably less than 35, and when the LED is lit, a luminosity L of greater than 55, an a* value of between -7.5 and +7.5 and a b* value of between -7.5 and +7.5. The scattering particles may be of organic nature. In which case they may be polyamide or PTFE particles, methyl-methacrylate-based crosslinked particles, crosslinked styrene-based particles or silicone particles. The scattering particles may be of mineral nature. In this case they may be BaSO4, Ti02, ZnO, CaCO3, MgO or AI2O3 particles or hollow glass microspheres .