Electro-Optical Device Floating Electrode for Impurity Retention
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Solution Overview
Problem
In electro-optical devices like liquid crystal display devices, impurities such as deteriorated products and ions move from a non-display region back to the display region when the power is disconnected, causing display quality deterioration due to higher luminous flux density and smaller pixel sizes.
Innovation Solution
The device incorporates a first electrode protruding from a base portion in the non-display region, with a surface closer to the second substrate than a second electrode, creating a weak electric field to trap impurities during operation and maintaining them in a floating state when power is off, preventing their return to the display region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If AC signals are applied to electrodes in the non-display region to move impurities away from the display region, then display quality is improved during operation, but impurities return to the display region when power is disconnected
Solution Approach 1:
The patent applies preliminary action by creating a floating electrode structure that pre-establishes a potential well in the non-display region. This potential well is prepared in advance to capture and retain impurities when power is disconnected, preventing their migration back to the display region. The floating electrode is positioned and configured beforehand to ensure impurity retention during power-off periods.
Solution Approach 2:
The floating electrode acts as an intermediary structure between the display region and the sealed non-display region. It mediates the movement and retention of impurities by creating an electric field that attracts and holds charged impurities in the non-display region, serving as a buffer that prevents direct migration of impurities into the display region while maintaining display quality.
2Reliability
If electrodes are provided in the non-display region to move impurities, then impurity distribution is improved, but device complexity increases
Solution Approach 1:
The floating electrode structure serves multiple functions: it acts as an impurity trapping mechanism, creates a potential well for charge retention, and functions as part of the overall electrode system during operation. By making the electrode floating (not connected to a specific potential), it can dynamically adapt to different operational states, reducing the need for separate control circuits and simplifying the overall device architecture while maintaining impurity control capabilities.
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 design effectively suppresses display quality degradation by immobilizing impurities in the non-display region, even when power is off, thereby maintaining image clarity.
Implementation Method 1
creating a weak electric field to trap impurities during operation and maintaining them in a floating state when power is off
Data Source
AI summary
An element substrate of an electro-optical device includes a base portion provided in a non-display region between a display region and a seal material in plan view, a middle portion and an upper portion provided at the base portion, and a shield electrode provided at the element substrate so as to avoid the base portion in plan view, and not in contact with the middle portion and the upper portion. A part of the middle portion and the upper portion has an overhang structure protruding from the base portion in cross-sectional view.