Electrophoretic Display Reflectance via Multi-Layer Reflection Part
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Solution Overview
Problem
Conventional electrophoretic display apparatuses face limitations in reflectance, which affects their slimness and weight due to the requirement of a backlight in liquid crystal displays, whereas electrophoretic displays lack a light source but struggle with reflectivity improvements.
Innovation Solution
The electrophoretic display apparatus incorporates a first and second substrate with an electrophoretic material and electrodes, featuring a reflection part with multiple layers of different refractive indices and a barrier wall to enhance reflectance by accommodating electrophoretic particles in a receiving space during white driving mode, improving aperture ratio and reflectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If liquid crystal display uses backlight assembly to provide light, then illumination intensity is improved, but weight and thickness increase
Solution Approach 1:
The patent extracts and removes the backlight assembly from the display device, transitioning from a transmissive liquid crystal display requiring external light to a reflective electrophoretic display that utilizes ambient light. This extraction eliminates the heavy backlight components while maintaining display functionality through the electrophoretic phenomenon and reflective structure.
Solution Approach 2:
The patent replaces the mechanical/optical backlight system with an electrophoretic system that uses electric field control to manipulate pigment particles. This substitution transitions from a complex mechanical lighting system to a simpler electro-optic system that achieves illumination through reflection of ambient light rather than active light generation.
2Illumination intensity
If liquid crystal display uses backlight assembly to provide light, then illumination intensity is improved, but device thickness increases
Solution Approach 1:
The backlight assembly, which is a significant contributor to display thickness, is extracted and removed from the device structure. The electrophoretic display achieves its illumination function without this thick component stack, resulting in a Slimmer overall device profile while maintaining display capabilities through ambient light reflection.
3Device complexity
If reflection part uses single layer structure, then device complexity is reduced, but reflectance is insufficient
Solution Approach 1:
The reflection part employs a composite multi-layer structure with different materials having varying refractive indexes. This composite construction enhances reflectance by creating optical interference effects and improving light reflection efficiency, while the layers are integrated into a unified structure that does not excessively increase device complexity.
Solution Approach 2:
The reflection part is structured with multiple layers stacked in the vertical dimension, creating a multi-dimensional optical path. This vertical stacking of layers with different refractive indexes enhances reflectance by manipulating light propagation in the thickness direction, transforming a simple surface reflection into a multi-layer optical system.
4Area of stationary object
If electrophoretic particles are not accommodated in receiving space, then aperture ratio is reduced, but manufacturing precision requirements are lowered
Solution Approach 1:
The receiving space is pre-formed within the reflection part structure before the electrophoretic particles are introduced or during the device assembly process. This preliminary creation of the accommodation space ensures that particles are properly positioned and contained, improving aperture ratio while the integrated design keeps manufacturing precision requirements manageable through standard fabrication processes.
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 enhances the reflectance of the electrophoretic display apparatus, allowing for improved image display without the need for a backlight, thereby increasing its slimness and weight efficiency.
Implementation Method 1
a reflection part on the first substrate and reflecting a light incident through the second substrate
Implementation Method 2
the reflection part may include at least two layers having different refractive indexes from each other
Implementation Method 3
an electrophoretic phenomenon in which electrified pigment particles move due to an electric field generated between two substrates
Data Source
AI summary
An electrophoretic display apparatus includes a first substrate including a plurality of pixels, a second substrate facing the first substrate, an electrophoretic material between the first and second substrates, and a first electrode on the first substrate or the second substrate. Each pixel includes a reflection part and a second electrode. The reflection part is on the first substrate and reflects light incident through the second substrate. The second electrode is on the first substrate and adjacent to the reflection part. The second electrode forms an electric field with the first electrode such that the electrophoretic material moves to the first electrode or the second electrode. An upper surface of the second electrode is positioned at a first height from the first substrate, and an upper surface of an uppermost layer of the reflection part is positioned at a second height higher than the first height.