ZnO Nanorod Filter Retro-Reflects Blue-Violet Light for LED Efficiency
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Solution Overview
Problem
Fluorescent lamps and white light LEDs inefficiently convert high-energy light into visible light due to phosphors that emit a large portion of light in the blue-violet range, where the human eye has low relative luminous efficiency, resulting in poor light use and energy consumption.
Innovation Solution
An optical device comprising a metal reflector with high reflectance and a nanostructured Zinc Oxide filter that retro-reflects high-energy visible light towards the luminescent layer for conversion into longer wavelengths, increasing total light emission by at least 20% without altering the Chromatic Reproduction Index (CRI).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphors are used to convert high-energy light into visible light, then light emission is produced, but a large portion of light is emitted in the blue-violet range where human eye has low relative luminous efficiency
Solution Approach 1:
The patent introduces an optical device with a dichroic beam splitter and ZnO nanorod filter as an intermediary between the light source and the environment. The beam splitter separates blue-violet light from other wavelengths, and the ZnO nanorod filter converts this separated blue-violet light into longer wavelengths with higher luminous efficiency, thereby mediating the energy conversion process to improve perceived light output.
Solution Approach 2:
The patent changes the wavelength parameter of the emitted light by using the ZnO nanorod filter to convert blue-violet light (400-470 nm) into longer wavelengths. This parameter change transforms light that has low luminous efficiency for the human eye into light with higher luminous efficiency, thereby improving the overall energy utilization without changing the phosphor materials themselves.
2Object-affected harmful factors
If conventional blocking materials are used to block UV radiation, then UV damage is prevented, but the blocked radiation is not exploited and luminous emission is not increased
Solution Approach 1:
The patent converts the previously blocked blue-violet radiation (which was considered harmful or wasted energy) into a beneficial resource. By using the dichroic beam splitter to separate and the ZnO nanorod filter to convert this radiation, the system transforms what was previously wasted energy into useful visible light with higher luminous efficiency, thereby improving productivity while maintaining protection functions.
Solution Approach 2:
Instead of simply discarding or blocking the blue-violet radiation, the patent recovers this energy by capturing it with the dichroic beam splitter and converting it through the ZnO nanorod filter. This recovery process transforms the discarded energy into useful light output, increasing the overall luminous emission without compromising UV protection capabilities.
3Object-affected harmful factors
If ZnO and TiO2 mixture is used as selective wavelength blocking material, then UV emission is blocked and insect attraction is reduced, but total luminous emission is not significantly increased
Solution Approach 1:
The patent replaces the conventional ZnO-TiO2 mixture blocking mechanism with an optical system consisting of a dichroic beam splitter and ZnO nanorod filter. This substitution allows for selective manipulation of different wavelength components, enabling the system to block UV while converting blue-violet light into useful visible light, thereby reducing energy loss and increasing overall luminous emission.
Solution Approach 2:
The patent uses a composite optical system combining the dichroic beam splitter material and the ZnO nanorod filter material. This composite approach allows each material to perform its specialized function - the beam splitter for wavelength separation and the ZnO nanorods for wavelength conversion - achieving both UV blocking and luminous emission enhancement simultaneously.
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 optical device enhances light emission efficiency by converting high-energy blue-violet light into longer wavelengths with higher human eye relative luminous efficiency, thereby increasing lumens per watt without affecting the CRI, leading to improved light output and energy utilization.
Implementation Method 1
The optical filter is capable of retro-reflecting most of the light in the wavelength range from 380 nm to 530 nm towards the luminescent layer
Implementation Method 2
where it becomes into light of shorter wavelength and less energy
Implementation Method 3
an optical reflector and a filter, that operate in combination. The reflector is a metal surface, diffuse or specular, with a reflectance of not less than 98%
Implementation Method 4
enhances light emission efficiency by converting high-energy blue-violet light into longer wavelengths with higher human eye relative luminous efficiency
Data Source
AI summary
This Optical Device is conformed by an optical reflector and a filter, the reflector is a diffuse or specular metallic surface with a reflectance of not less than 98%, of shape and dimensions according to the lamp to be affected. The optical filter is a rigid structure and transparent to visible light, with geometric shape and dimensions also according to the lamp to be affected, it is made of organic or inorganic material, and serves as a substrate on which a layer of zinc oxide is applied, specifically a nano structure of zinc oxide nano wires, to form a partially reflective and anti-reflective layer simultaneously as a function of the wavelength of the light that passes through it. Properly placed on the luminescent layer of a fluorescent lamp or White Light LED, this Optical Device retro reflects to said luminescent layer, most of the light of short wavelength and high enemy to be converted into longer wavelength light and lower energy by the same source luminescent layer, which results in an increase of the total light emission of at least 20%, without modifying the Chromatic Reproduction Index (CRI) of the source.