Optic Assembly Using Quantum Dots for Warm Light
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Solution Overview
Problem
High power cool white LEDs degrade quantum dots due to heat, limiting their use in producing warm light while maintaining efficiency, as quantum dots are sensitive to high temperatures and are not suitable for high power LED applications.
Innovation Solution
An optic assembly is designed with a housing that positions an LED and a secondary optic remotely, creating a cavity for excitation light to pass through, where quantum dots on the secondary optic convert the light to a warmer wavelength, allowing for warm light production without direct heat exposure, thus maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If quantum dots are used with high power cool white LEDs to produce warm light, then the color temperature can be adjusted to preferred warm levels, but the quantum dots will degrade due to high temperature exposure
Solution Approach 1:
The system separates the LED light source from the quantum dot conversion layer by introducing a reflective cavity structure. The LED is positioned at a distance from the quantum dots, with the cavity reflecting light back through the quantum dot layer. This spatial segmentation allows the quantum dots to be warmed by the reflected light without direct exposure to the high-temperature LED junction, enabling warm light production while maintaining quantum dot stability.
Solution Approach 2:
The reflective cavity acts as an intermediary between the LED and quantum dots. It captures the LED's light output, reflects it back through the quantum dot layer, and enables thermal management by creating a physical barrier that prevents direct heat transfer from the LED to the quantum dots while still allowing optical interaction.
2Productivity
If quantum dots are placed in close proximity to the LED to convert light wavelength, then the light conversion efficiency is maximized, but the quantum dots are exposed to high heat that causes degradation
Solution Approach 1:
The system divides the optical path into separate zones: the LED emission zone, the reflective cavity zone, and the quantum dot conversion zone. By positioning the quantum dots away from the LED and using the cavity to redirect light, the system maintains efficient light conversion while segmenting the heat exposure pathway, allowing quantum dots to convert light without direct thermal contact.
Solution Approach 2:
The system converts the harmful heat radiation from the LED into a beneficial effect by using the reflective cavity to redirect visible light back through the quantum dot layer. The cavity reflects both visible and infrared radiation, allowing the quantum dots to receive sufficient excitation light for efficient conversion while the cavity structure blocks direct thermal contact with the LED heat source.
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
Enables the production of warm white light from high power cool white LEDs while preserving efficiency, allowing quantum dots to be used with high power LEDs without degradation, and providing flexibility in choosing light color temperature at installation.
Implementation Method 1
Quantum dots are semiconductor nanocrystals on the order of 2-10 nanometers in size that alter the wavelength of light as it passes through the quantum dot. When incoming light with sufficient energy strikes a quantum dot, it temporarily displaces an electron from the valence band across a band gap into the higher adjacent conducive band creating a corresponding positively charged hole in the valence band. In this unstable state, the electron drops back to the valence band and in the process emits energy in the form of light.
Data Source
AI summary
An optic assembly is provided. The assembly includes a housing having an upstream end and a downstream end. An LED is positioned in the upstream end of the housing. The LED is configured to generate excitation light therefrom. The excitation light has a first wavelength. An optic is positioned in the downstream end of the housing. The optic is positioned remotely from the LED so that a cavity is formed between the LED and the optic. The excitation light generated from the LED passes downstream through the cavity to the optic. Quantum dots are positioned on the optic. The excitation light excites the quantum dots so that the quantum dots produce emitted light having a second wavelength that is different than the first wavelength of the excitation light.