Dummy Terminal Mitigates Erosion in LCD Substrate Connections
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Solution Overview
Problem
Conventional liquid crystal display devices experience disconnection issues due to erosion of thin metal terminals when operated in hot and humid environments, particularly those connected to high-potential terminals, as water penetration leads to metal ionization and terminal degradation.
Innovation Solution
Incorporating a dummy terminal with a non-operational potential or wider-sized second terminals to mitigate the electric field effect on first terminals, thereby reducing erosion and preventing disconnection, even in humid conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin first terminals are used to reduce the overall size of the display device, then the device becomes more compact, but the terminals become susceptible to erosion and disconnection in hot and humid environments
Solution Approach 1:
The patent introduces a dummy terminal as an intermediary element between the high-potential terminal and the first terminal. This dummy terminal acts as a potential barrier that prevents water penetration and erosion from reaching the first terminal, thereby maintaining connection reliability without increasing the overall device volume significantly
Solution Approach 2:
The dummy terminal is positioned in advance to cushion or absorb the harmful effect of water penetration before it can reach the first terminal. By placing the dummy terminal beforehand in the potential path of water, it prevents the erosion that would otherwise occur in the thin first terminal during hot and humid operation
2Manufacturing precision
If the thickness of first terminals is reduced to improve manufacturing precision and reduce material usage, then production cost and complexity are reduced, but the terminals are more severely affected by erosion
Solution Approach 1:
The dummy terminal serves as a protective intermediary that shields the thin first terminal from direct exposure to harmful water penetration. This allows the first terminal to remain thin for manufacturing precision while the dummy terminal absorbs the erosion risk
Solution Approach 2:
The dummy terminal can be considered a sacrificial protective element that may degrade or fail before the critical first terminal. By making the dummy terminal replaceable and non-critical, the system allows for easy replacement without affecting the overall device functionality, thus protecting the precision-fabricated first terminal from permanent damage
3Device complexity
If high-potential terminals are positioned adjacent to low-potential terminals to enable compact driver IC design, then the device structure becomes more compact, but the potential difference causes increased erosion of first terminals
Solution Approach 1:
The dummy terminal is positioned between the high-potential terminal and the first terminal, acting as a mediator that reduces the effective potential difference experienced by the first terminal. This allows the compact driver IC structure to be maintained while reducing the erosion-causing potential gradient
Solution Approach 2:
The patent segments the terminal structure by introducing the dummy terminal as a separate element between the high-potential terminal and the first terminal. This segmentation allows the high-potential terminal to remain close to the first terminal for compact design, while the dummy terminal breaks the continuous potential gradient that would cause erosion
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 introduction of a dummy terminal or wider second terminals effectively reduces the electric field strength on first terminals, preventing erosion and ensuring reliable connections in liquid crystal display devices, even under harsh environmental conditions.
Implementation Method 1
The ACF is a connecting material that has conducting, insulating, and adhesion functions, with conductive particles dispersed in an adhesive film
Implementation Method 2
water will penetrate the ACF to cause the following phenomenon in thin first terminals that are connected to high-potential terminals
Implementation Method 3
the constituent metal changes into positive ions and erodes
Implementation Method 4
The introduction of a dummy terminal or wider second terminals effectively reduces the electric field strength on first terminals, preventing erosion
Data Source
AI summary
An object of the present invention is to provide an image display device that is free from disconnection in a connection structure between given substrates even when operated in a hot and humid environment. An image display device according to a preferred embodiment of the invention has a TFT substrate and an FPC. The TFT substrate has a plurality of first terminals capable of application of potential. The FPC has second terminals that are connected respectively with the first terminals through an anisotropic conductive film and that are thicker than the first terminals. The second terminals include a high-potential terminal, a low-potential terminal, and a dummy terminal. The high-potential terminal is supplied with a relatively high potential that contributes to the display operation. The low-potential terminal is supplied with a relatively low potential that contributes to the display operation. The dummy terminal is positioned between the high-potential terminal and the low-potential terminal and is supplied with a potential not contributing to the display operation.