Translucent Conductive Film Electrostatic Shielding in LCD
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Solution Overview
Problem
Liquid crystal display devices, particularly in FFS mode, face issues with electrostatic discharge resistance, leading to decreased contrast and display non-uniformity due to static electricity from external sources, which existing countermeasures like translucent conductive films cannot adequately address.
Innovation Solution
A liquid crystal display device configuration where a translucent conductive film is positioned on the second substrate, opposed to the pixel and common electrodes, and maintained at a predetermined electric potential, with its outer periphery closer to the center of the substrate than the circuit wiring, and connected through a pull-out portion to an electric potential applying wiring, to effectively shield static electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a translucent conductive film is formed over the entire outer surface of the opposite substrate to release electrostatic charge, then electrostatic discharge resistance is improved, but the outer periphery of the conductive film extends to the edge of the substrate which may cause coupling with external static electricity sources
Solution Approach 1:
The conductive film is extracted from the edge region and repositioned inward, creating a gap between the film periphery and the substrate edge. This extraction removes the harmful coupling path while preserving the electrostatic discharge function through the pull-out portion connection.
Solution Approach 2:
The pull-out portion acts as an intermediary element that connects the conductive film to the FPC terminal. This intermediary structure allows electrostatic charge to be discharged while preventing direct coupling with external static electricity sources at the substrate edge.
2Object-affected harmful factors
If the translucent conductive film is positioned closer to the center of the substrate, then coupling with external static electricity is reduced, but the path for static electricity to reach the FPC terminal may be lengthened
Solution Approach 1:
The conductive film is segmented into two functional regions: a main body portion positioned inward to avoid coupling, and a pull-out portion extending toward the edge to provide a discharge path. This segmentation allows simultaneous optimization of both coupling reduction and discharge efficiency.
Solution Approach 2:
The conductive film is extended in a new spatial dimension by creating a pull-out portion that projects toward the FPC terminal. This dimensional extension provides an optimized discharge path without requiring the main film body to be positioned at the substrate edge.
3Length of moving object
If the outer periphery of the translucent conductive film is located at the edge of the substrate, then electrostatic discharge path is shortened, but coupling with external static electricity sources increases
Solution Approach 1:
The conductive film is extracted from the edge region and repositioned inward, creating a gap between the film periphery and the substrate edge. This extraction removes the harmful coupling path while preserving the electrostatic discharge function through the pull-out portion connection.
4Reliability
If the translucent conductive film covers the entire substrate surface, then electrostatic discharge coverage is maximized, but the complexity of the structure and manufacturing increases
Solution Approach 1:
The conductive film is segmented into a main body portion and a pull-out portion, each serving distinct functions. This segmentation simplifies the overall structure by eliminating the need for edge-to-edge coverage while maintaining effective discharge coverage through the strategically positioned segments.
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 electrostatic discharge resistance by reducing the path for static electricity to reach the circuit wiring, preventing coupling and breakage, and ensuring uniformity in display quality.
Implementation Method 1
a translucent conductive film is positioned on the second substrate, opposed to the pixel and common electrodes, and maintained at a predetermined electric potential
Implementation Method 2
an electric field (horizontal electric field) is generated in a direction perpendicular to the long sides of the slits, and liquid crystal molecules are rotated (horizontally rotated) in a plane parallel to the substrate along the direction of the electric field
Data Source
AI summary
A liquid crystal display device includes a first substrate, a second substrate, and liquid crystal. The first substrate includes pixel electrodes, at least one common electrode, and a circuit wiring. The second substrate is opposed to the first substrate and includes a translucent conductive film. The liquid crystal is held between the first substrate and the second substrate. The circuit wiring is arranged outside a pixel area in which a plurality of pixels, which are formed of the pixel electrodes and the at least one common electrode, are arranged. The translucent conductive film is arranged on an opposite side of the second substrate to a side where the liquid crystal is present, and the translucent conductive film is opposed to the pixel electrodes and the at least one common electrode. The translucent conductive film is maintained at a predetermined electric potential. The translucent conductive film has an outer periphery that is located closer to a center of the second substrate than an outer periphery of the second substrate.