Constant-Potential Wire for Electrostatic Discharge in COG Devices
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Solution Overview
Problem
Electro-optical devices with COG mounting structures, such as liquid crystal display devices, face issues with electrostatic breakage at external connection terminals due to static electricity entering through flexible printed circuits, leading to reliability concerns.
Innovation Solution
Incorporating a constant-potential wire near the connection locations of external connection terminals, which facilitates an electric discharge when static electricity is present, preventing complete wire breakage by allowing charge to escape through intentionally designed protrusions and tapered wire forms, thus enhancing electrostatic resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external connection terminals are provided at the peripheral end of the substrate for connection with FPC, then power supply voltage and image signals can be supplied to the driving IC, but static electricity enters through the FPC causing wire breakage at bent portions of wires connected to external connection terminals
Solution Approach 1:
A constant-potential wire is introduced as an intermediary element between the external connection terminals and the wires connected to the driving IC. This constant-potential wire acts as a mediator that provides a controlled electrical path, allowing static electricity to be discharged safely without causing breakage at the bent portions of the connection wires. The constant-potential wire is connected to a potential source (such as V0 or Vcom) and positioned to facilitate discharge when static electricity enters through the FPC connection.
2Ease of manufacture
If wires are bent to connect external connection terminals to driving IC terminals, then electrical connection is achieved, but bent portions become weak points susceptible to electrostatic breakage
Solution Approach 1:
The constant-potential wire is positioned in advance near the bent portions of the wires connected to external connection terminals. This creates a protective structure before static electricity can cause damage. When static electricity enters through the FPC, the constant-potential wire provides a pre-established discharge path, cushioning the bent portions from the full force of the electrostatic surge and preventing breakage.
3Measurement precision
If electrostatic resistance inspection is performed by applying high voltage to external connection terminals, then electrostatic resistance can be measured, but wire breakage occurs at bent portions closer to the driving IC
Solution Approach 1:
The constant-potential wire serves as a protective intermediary during electrostatic resistance inspection. When high voltage is applied to external connection terminals for measurement, the constant-potential wire provides a controlled discharge path that prevents the full high voltage stress from concentrating at the bent portions of the wires. This allows accurate electrostatic resistance measurement to be performed without causing wire breakage.
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 solution effectively increases the electrostatic resistance at external connection terminals, reducing the risk of wire breakage and improving the reliability of electro-optical devices by stabilizing the electrical potential and promoting efficient discharge of static electricity.
Implementation Method 1
Incorporating a constant-potential wire near the connection locations of external connection terminals, which facilitates an electric discharge when static electricity is present
Data Source
AI summary
An electro-optical device includes a substrate, a plurality of external connection terminals provided on the substrate, an electronic component mounted on the substrate and having a plurality of terminals, and a plurality of wires that electrically connect the plurality of external connection terminals to the plurality of terminals of the electronic component. A constant-potential wire is provided in the vicinity of locations of connections of at least some of the plurality of wires with the respective terminals of the electronic component.