PCB Ground Region ESD Protection for LCD Mobile Terminals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mobile communication terminals with liquid crystal display (LCD) devices are prone to damage from electro-static discharge (ESD), leading to operational failures and 'white screen states', with existing devices failing to maintain functionality under high ESD voltages during manufacturing and usage.
Innovation Solution
The integration of a printed circuit board (PCB) with an extended ground region and a chassis electrically connected to the ground, along with a varistor device and strategically placed via holes, enhances the discharge of ESD currents, protecting internal circuits and improving durability against high ESD voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional PCB and chassis structure is used, then the device complexity is low, but the reliability against ESD damage is poor
Solution Approach 1:
The PCB is divided into distinct functional regions: a driver circuit formation region and an extended outer portion that provides a ground region. This segmentation allows the ground region to be specifically optimized for ESD protection without complicating the overall structure excessively.
Solution Approach 2:
The ground region is extended in the planar dimension of the PCB, creating a larger surface area for ESD discharge. This dimensional extension provides enhanced ESD protection while maintaining a relatively simple two-dimensional layout without adding vertical complexity.
2Reliability
If the ground region is extended to improve ESD protection, then the ESD durability increases, but the area of the PCB increases
Solution Approach 1:
The ground region is merged with the outer portion of the PCB structure, utilizing the existing peripheral area rather than adding a separate component. This combining approach provides extended ground area for ESD protection while minimizing additional PCB area.
Solution Approach 2:
The extended outer portion of the PCB serves dual purposes: it provides structural support and simultaneously functions as the ground region for ESD protection. This self-service approach eliminates the need for additional dedicated ground structures.
3Reliability
If the chassis is electrically connected to the ground region, then the ESD discharge capability improves, but the device complexity increases
Solution Approach 1:
The chassis is merged with the ground region through direct electrical connection, creating a unified ESD discharge path. This integration provides enhanced ESD capability while avoiding the complexity of separate connection mechanisms.
Solution Approach 2:
The extended outer portion of the PCB acts as an intermediary between the chassis and the ground region, facilitating electrical connection and ESD discharge while simplifying the overall connection structure.
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 protects internal circuits against ESD voltages of up to 22 kV in air-type and 15 kV in contact-type discharges, significantly enhancing the durability and stability of LCD devices, preventing 'white screen states and ensuring normal operation.
Implementation Method 1
Electro-static discharge (ESD) is generated while a product mounting an LCD device thereon is in use. When the ESD is generated, internal devices of a mobile communication terminal are damaged
Data Source
AI summary
An LCD device is provided. The LCD device includes a liquid crystal display panel for displaying an image, a PCB (printed circuit board) where a driver circuit driving the liquid crystal display panel is formed and having an outer portion extending a predetermined length and width to provide a ground region, and a chassis where the PCB is located and electrically connected to the ground region.