Quantum Dot Illuminated Signage for Color Tunability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current illuminated signage technologies lack a system that is inexpensive, easy to manufacture, and offers low operating costs with a wide range of colors spanning the visible spectrum, while also being compact and safe for various applications and environments.
Innovation Solution
The use of a fully soluble quantum dot ink to form a remote phosphor layer, which provides color tuneability across the entire visible spectrum, utilizing heavy metal-free QD phosphorescent materials for signage applications, allowing for the production of signs that are inexpensive to power and safe to maintain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional solid-state lighting is used for illuminated signage, then the signage can be manufactured and operated, but the energy costs are high and the color range is limited
Solution Approach 1:
The patent changes the physical parameter of quantum dot size to tune the emission wavelength across the visible spectrum. By controlling quantum dot dimensions during synthesis, the signage achieves full color range while maintaining energy efficiency, as quantum dots convert LED light with high quantum efficiency regardless of emission wavelength
Solution Approach 2:
The patent uses composite quantum dot materials with heavy metal-free compositions (e.g., Cd-free quantum dots) to achieve both energy efficiency and environmental compliance. The quantum dots are integrated with LED backlights and encapsulation materials to create a composite lighting system that combines the advantages of solid-state lighting with tunable color emission
2Reliability
If incandescent bulbs are used for traffic signs, then the signage can be illuminated, but the failure is instantaneous and energy costs are high
Solution Approach 1:
The patent replaces the mechanical/incandescent lighting system with a solid-state LED and quantum dot system. This substitution eliminates the instantaneous failure mode of incandescent bulbs and provides gradual dimming characteristics, while also dramatically reducing energy consumption through the efficiency of LED excitation of quantum dots
Solution Approach 2:
The patent changes the operational parameter of the lighting system from incandescent thermal radiation to LED photoluminescence excitation of quantum dots. This parameter change enables both improved reliability through gradual failure modes and reduced energy consumption through higher quantum efficiency
3Adaptability or versatility
If quantum dots are used to achieve wide color range, then the color tunability improves, but the use of heavy metals creates environmental safety issues
Solution Approach 1:
The patent changes the compositional parameter of quantum dots from heavy metal-based (CdSe, PbS) to heavy metal-free materials (e.g., InP, AgInS2, CuInSe2). This compositional change maintains the ability to tune emission across the visible spectrum through size control while eliminating environmental and health hazards associated with heavy metals
Solution Approach 2:
The patent applies local quality by using heavy metal-free quantum dot materials specifically in the regions where quantum dot emission is required, while maintaining other components of the signage system. This localized material selection achieves color tunability without the harmful effects of heavy metals
4Ease of manufacture
If traditional phosphors are used for color conversion, then the manufacturing is simpler, but the energy efficiency is lower and color range is limited
Solution Approach 1:
The patent changes the material parameter from traditional bulk phosphors to nanoscale quantum dots. This size parameter change enables quantum confinement effects that provide superior quantum efficiency for light conversion while maintaining ease of manufacture through solution-based processing and spray deposition techniques
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 QD-based signage offers brighter and more efficient lighting with reduced energy losses, enabling the production of strong colors and gradual failure, which is beneficial for safety signage and compliance with regulations on heavy metal usage.
Implementation Method 1
The quantum dot phosphor layer absorbs primary light and emits secondary light
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
An illuminated sign has a primary light source in spaced apart relation to a transparent or translucent substrate having quantum dot phosphors printed or coated thereon. The primary light source may be a blue LED, a white LED or an LED having a significant portion of its emission in the ultraviolet region of the spectrum. The LED may be a backlight for the transparent or translucent substrate and/or an edge light, a down light or an up light.