Electrophoretic Material with Dual-Size Particle System
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Solution Overview
Problem
Existing electrophoretic materials have slow response speed and difficulty in being driven at low voltages due to poor electrophoretic properties, such as low voltage driving and high-speed response.
Innovation Solution
The electrophoretic material is designed with first and second particles of different polarities and sizes, where the second particles have a higher electric charge amount and smaller average radius, allowing them to easily pass through gaps between first particles, enhancing electrophoretic mobility and response speed, and can be driven at low voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional electrophoretic particles (white particles and red particles) are used, then the display can maintain images when power is not supplied, but the response speed with regard to applied voltage is slow and it is difficult to be driven at low voltage
Solution Approach 1:
The patent changes the parameters of the electrophoretic particles by using only black particles with different size distributions (first particles with average radius R1 and second particles with average radius R2 where R1 > R2). This parameter change enables the particles to achieve both fast response speed and low voltage driving capability, resolving the contradiction between response speed and voltage requirement.
Solution Approach 2:
The patent creates a composite electrophoretic material system containing black particles of two different sizes (first particles and second particles) dispersed in a solvent. This composite structure allows the smaller second particles to move faster through gaps between larger first particles, achieving high response speed while maintaining low voltage operation through the synergistic effect of the dual-size particle system.
2Reliability
If the electrophoretic material uses particles with specific size and charge characteristics, then the electrophoretic mobility increases and response speed improves, but the particle distribution and gaps between particles must be precisely controlled
Solution Approach 1:
The patent specifies precise parameter ranges for particle sizes (first particles with average radius R1, second particles with average radius R2 where R1 > R2) and their concentrations in the electrophoretic material. By controlling these parameters within defined ranges, the patent achieves reliable electrophoretic properties while providing manufacturable specifications for particle size control.
Solution Approach 2:
The patent applies different characteristics to different particle populations within the same material system. The first particles and second particles have different sizes, concentrations, and electrophoretic mobilities, creating local quality variations that optimize overall performance. The smaller second particles provide high mobility in specific regions while the larger first particles provide structural stability.
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
This configuration results in an electrophoretic material with improved electrophoretic properties, enabling fast response speed and excellent image retention characteristics, suitable for high-brightness white displays and low-power consumption applications.
Implementation Method 1
an image is formed on a display area by applying a voltage between a pixel electrode and a common electrode which are opposite to each other while interposing an electrophoretic material, and causing charged electrophoretic particles, such as white particles and black particles, to spatially migrate
Data Source
AI summary
In an electrophoretic material, first particles which are charged with a first polarity and second particles which are charged with a second polarity are dispersed in a solvent. A volume, which is obtained by dividing a volume of the solvent by a total number of particles, is called free volume, and a radius of a spherical space, which is occupied by sum of an average volume of the particles and the free volume, is called a free volume radius. A first particle average radius is greater than a second particle average radius. A difference between the free volume radius and the first particle average radius is greater than the second particle average radius.