Multilayer Reflective Stack for Electrophoretic Displays
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Solution Overview
Problem
Electrophoretic display devices face manufacturing inefficiencies due to complex processes, low light reflection efficiency, and parasitic capacitors affecting pixel driving, resulting in low luminance, contrast ratio, and color reproduction.
Innovation Solution
A reflector with multiple inorganic reflective layer pairs of varying refractive indices and thicknesses is used to enhance light reflection across different wavelengths, specifically designed for red, green, and blue light, optimizing the structure to increase luminance and color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal reflector is formed on the lower substrate to increase light reflection rate, then light reflection efficiency is improved, but parasitic capacitors are formed between the reflector and pixels, adversely affecting pixel driving
Solution Approach 1:
An organic insulating layer is introduced as an intermediary between the metal reflector and the pixel electrodes. This insulating layer prevents direct electrical contact that would create parasitic capacitors, while still allowing the metal reflector to function as intended for light reflection enhancement.
2Ease of manufacture
If separate manufacturing processes are used for lower substrate, upper substrate, and electrophoretic film, then manufacturing flexibility is maintained, but manufacturing complexity increases and manufacturing time increases
Solution Approach 1:
The metal reflector is formed on the lower substrate before coupling with the upper substrate, merging the reflector formation process into the lower substrate manufacturing sequence. This reduces the total number of separate processes and simplifies the overall manufacturing flow while maintaining the ability to manufacture components separately if needed.
3Ease of manufacture
If separate manufacturing processes are used for lower substrate, upper substrate, and electrophoretic film, then manufacturing flexibility is maintained, but manufacturing time increases
Solution Approach 1:
The metal reflector is formed on the lower substrate in advance, before the upper substrate and electrophoretic film are prepared and coupled. This preliminary formation of the reflector layer eliminates the need for additional post-assembly processes, reducing total manufacturing time while allowing separate component manufacturing.
4Reliability
If microcapsules are used in the electrophoretic film, then electrophoretic display functionality is achieved, but light reflection efficiency remains low
Solution Approach 1:
An organic insulating layer is introduced as an intermediary between the metal reflector and the electrophoretic film containing microcapsules. This insulating layer enables the use of microcapsules for electrophoretic functionality while preventing direct contact that would create parasitic capacitors, thereby maintaining both functionality and improving light reflection efficiency through the metal reflector.
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 significantly enhances luminance, contrast ratio, and color reproduction in electrophoretic display devices, achieving high-quality color images with improved manufacturing efficiency by selectively reflecting incident light.
Implementation Method 1
a first reflective layer pair reflecting red light; a second reflective layer pair reflecting green light; and a third reflective layer pair reflecting blue light
Data Source
AI summary
A reflector is discussed. A reflector can include a first reflective layer pair reflecting red light, a second reflective layer pair reflecting green light and a third reflective layer pair reflecting blue light, wherein the first to third reflective layer pairs are formed as a plurality of inorganic layers, the first, second and third reflective layer pair are sequentially stacked iteratively, the first reflective layer pair includes a stop band corresponds to red color wavelength, the second reflective layer pair includes a stop band corresponds to green color wavelength, and the third reflective layer pair includes a stop band corresponds to blue color wavelength.