Passive Matrix Quantum Dot Display Using Evanescent Field Excitation
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Solution Overview
Problem
Current electronic displays, such as LCDs and electronic ink displays, rely on external illumination and do not emit light, limiting their ability to provide a fully transparent and efficient visual interface.
Innovation Solution
A light emitting device utilizing charged quantum dots suspended in a liquid between an excitation plate and a cover plate, where the quantum dots emit light in response to an evanescent field generated by short-wave excitation light undergoing total internal reflection, with the movement of quantum dots controlled by bias voltages applied to transparent electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If LCDs use liquid crystals with polarizing filters to modulate light, then light modulation capability is improved, but transparency is worsened because the display requires a backlighting device and cannot be fully transparent
Solution Approach 1:
The patent replaces the mechanical/optical system of LCDs (liquid crystals, polarizing filters, backlighting) with an electroluminescent system using quantum dots that generate their own light through electroluminescence when excited by electrical fields, eliminating the need for backlighting and enabling full transparency
Solution Approach 2:
The patent changes the fundamental operating parameter from passive light modulation to active light emission through electroluminescence, allowing the display to be transparent when not emitting light and enabling precise control over light emission at the pixel level
2Adaptability or versatility
If electronic ink displays use microcapsules with charged particles to control color display, then color switching capability is improved, but transparency is worsened because the microcapsules cannot be fully transparent
Solution Approach 1:
The patent replaces the microcapsule-based electrophoretic system with a quantum dot suspension system where charged quantum dots are moved by electrical fields to specific regions, eliminating the need for opaque microcapsules and enabling full transparency
Solution Approach 2:
The patent uses a composite system combining charged quantum dots suspended in a clear or transparent fluid, which maintains transparency while enabling color switching through the movement and positioning of quantum dots with different emission wavelengths
3Measurement precision
If quantum dots are suspended in liquid and moved by bias voltages to control light emission, then light emission control precision is improved, but device complexity is worsened due to the need for transparent electrodes and voltage control mechanisms
Solution Approach 1:
The patent segments the display into a matrix of transparent electrodes (row and column electrodes) that can independently control quantum dots at specific pixel locations, enabling precise light emission control while maintaining overall system simplicity through the passive matrix structure
Solution Approach 2:
The patent uses transparent electrodes as intermediaries between the electrical control system and the quantum dots, allowing voltage to be applied to specific regions to move and position quantum dots without direct mechanical intervention, simplifying the control mechanism
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 light emission without the need for external illumination, allowing for a fully transparent and efficient display with precise control over light emission, enabling denser pixel areas and a high multiplexing ratio, and the use of a passive matrix structure for cost-effectiveness.
Implementation Method 1
Charged quantum dots near the surface of the excitation plate may emit light in response to an evanescent field generated by the short-wave excitation light undergoing total internal reflection within the excitation plate
Implementation Method 2
The movement of charged quantum dots within the liquid may be controlled by applying one or more bias voltages to the one or more transparent electrodes
Data Source
AI summary
A system and method for operating a light emitting device utilizing charged quantum dots is described. In one embodiment, charged quantum dots are suspended in a liquid between an excitation plate and a cover plate. The excitation plate carries short-wave excitation light. Charged quantum dots near the surface of the excitation plate may emit light in response to an evanescent field generated by the short-wave excitation light undergoing total internal reflection within the excitation plate. The excitation plate and the cover plate may be coated with one or more transparent electrodes. The movement of charged quantum dots within the liquid may be controlled by applying one or more bias voltages to the one or more transparent electrodes. Light emission from a particular region near the surface of the excitation plate may be controlled by moving charged quantum dots into or out of the particular region.