Electrophoretic Display Capacitor Configuration for Voltage Stability
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Solution Overview
Problem
Electrophoretic displays face issues with non-uniform image density and image retention due to parasitic capacitance effects, which are exacerbated at higher resolutions where the capacitance of storage capacitors becomes insufficient, leading to variations in effective voltage and gray scale inconsistencies.
Innovation Solution
The design incorporates a configuration where the pixel electrodes are formed with a dot density of at least 200 dpi, and the capacitor electrodes are connected such that the parasitic capacitance is minimized, with one electrode connected to the scanning lines, allowing for increased storage capacitance and reduced parasitic capacitance, thereby stabilizing the effective voltage and reducing image retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel electrode dot density is increased to 200 dpi or higher to achieve high-resolution display, then the display resolution is improved, but the parasitic capacitance effect becomes more significant causing non-uniform image density
Solution Approach 1:
The patent changes the physical parameters of the capacitor by increasing its capacitance value to 1 aF or more, and optimizing the pixel electrode dot density to 200 dpi or higher. These parameter changes allow the system to maintain image density uniformity while achieving high-resolution display, resolving the contradiction between resolution and image quality.
2Reliability
If the capacitance of the storage capacitor is increased to reduce parasitic capacitance effects, then the image density uniformity is improved, but the pixel area required increases
Solution Approach 1:
The patent optimizes the capacitor capacitance to be 1 aF or more, which is sufficient to suppress parasitic capacitance effects without requiring excessive pixel area. This parameter optimization allows the system to achieve image density uniformity while maintaining reasonable pixel dimensions for high-resolution displays.
3Reliability
If the pixel electrode dot density is increased to reduce the ratio of parasitic capacitance to storage capacitance, then the effective voltage variation is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent specifies a pixel electrode dot density of 200 dpi or higher, which optimally balances the reduction of parasitic capacitance effects with manufacturability. This parameter setting reduces effective voltage variation while remaining feasible for conventional manufacturing processes, resolving the contradiction between reliability and ease of manufacture.
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 significantly reduces the variation in effective voltage, enhances image uniformity, and increases response speed, particularly in high-resolution displays by ensuring a low parasitic capacitance ratio and maintaining high storage capacitance, thus improving the overall quality and reliability of the electrophoretic display.
Implementation Method 1
electrophoretic elements having electrophoretic particles dispersed in their respective medium interposed between the base and opposite plates
Data Source
AI summary
An electrophoretic display includes a first substrate, a second substrate, an electrophoretic element interposed therebetween, a plurality of scanning lines on an electrophoretic element side surface of the first substrate, a plurality of data lines extending in the crosswise directions of the plurality of scanning lines on the electrophoretic element side surface of the first substrate, a selection transistor connected to one of the scanning lines and one of the data lines, a pixel electrode connected to the selection transistor, and a capacitor with two electrodes, one of the electrode thereof being connected to the selection transistor and the pixel electrode, and the other electrode thereof being connected to one of the scanning lines, wherein a plurality of pixel electrodes are arranged so that a dot density thereof is more than or equal to 200 dpi.