Electrophoretic Display Medium With Partially Transmissive Particles
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Solution Overview
Problem
Four particle electrophoretic media are limited to four independent optical states, which is insufficient for displaying black, white, and three primary colors, and increasing the number of particle types complicates charge control and waveform complexity.
Innovation Solution
Incorporating a partially light-transmissive particle into a four particle electrophoretic medium, where one type of particle is white, two are light-reflective, and the remaining two have opposite polarities with varying zeta potentials, allowing for five or six optical states by adjusting electric field polarities and durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If four particle electrophoretic media are used, then the device structure is simple, but only four independent optical states can be displayed which is insufficient for displaying black, white, and three primary colors
Solution Approach 1:
The patent changes the optical parameter of one particle type from fully light-reflective to partially light-transmissive. This parameter change allows the same four particle types to produce additional optical states by controlling the relative positions of the light-transmissive particle and the white particle, enabling display of five or six colors including process black without increasing particle type complexity
Solution Approach 2:
The patent creates a composite electrophoretic medium where a light-transmissive particle is combined with a white particle. When these two particle types are positioned adjacently, they form an optical composite that produces enhanced color saturation and process black, allowing four particle types to achieve functionality equivalent to or exceeding five particle types
2Adaptability or versatility
If the number of particle types is increased to display more colors, then color display capability is improved, but charge control and waveform complexity increase
Solution Approach 1:
By changing one particle's optical parameter to partially light-transmissive, the patent enables enhanced color display capability using the same four particle types, thereby avoiding the increased charge control complexity that would result from adding more particle types
Solution Approach 2:
The light-transmissive particle serves multiple functions: it can be positioned alone to display its intrinsic color, positioned adjacent to white particles to enhance color saturation, and positioned in specific configurations to create process black. This multi-functionality allows four particle types to achieve five or six optical states without requiring additional particle types or more complex charge control
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 enables a four particle electrophoretic medium to display five or six colors, including process black, improving color saturation and reducing complexity in charge control and waveform design.
Implementation Method 1
The electrophoretic medium is disposed between a front electrode and a rear electrode... The first type of particles carry a high positive charge and the second type of particles carry a high negative charge. The third type of particles carry a low positive charge and the fourth type of particles carry a low negative charge.
Implementation Method 2
applying a high electric field of appropriate polarity across the electrophoretic medium... applying a low electric field of opposite polarity
Implementation Method 3
one of the types of particles is white, one of the types of non-white particles is partially light-transmissive, and the remaining two types of non-white particles are light-reflective
Data Source
AI summary
An electrophoretic medium comprises a fluid and first, second, third and fourth types of particles (W, Y, R, B) having four different colors. The first and third particles have charges of one polarity and the second and fourth particles charges of the opposite polarity; the first particles have a greater zeta potential or electrophoretic mobility than the third particles, and the second particles a greater zeta potential or electrophoretic mobility than the fourth particles. One particle is white (W), one non-white particle (R) is partially light-transmissive, and the remaining two non-white particles (B, Y) are light-reflective. A third light-reflective particle (G) may be added to create a five particle medium.