Liquid Crystal Display Black Matrix ESD Protection
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Solution Overview
Problem
Horizontal electric field type liquid crystal display devices suffer from black uniformity defects due to electrostatic discharge (ESD) causing irregular voltages and bright spots on the display panel, primarily resulting from exposed black matrix edges being shorted by Ag dots during the scribing process.
Innovation Solution
The solution involves forming a black matrix with island-shaped end portions spaced apart from the main black matrix for insulation, and a connection portion that extends over these end portions to connect the transparent conductive film with the ground electrode, preventing ESD from flowing through the black matrix and maintaining insulation during the scribing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the black matrix is formed continuously to the edge of the substrate, then the ESD protection path is complete, but the exposed black matrix edges are shorted by Ag dots during scribing, causing black uniformity defects
Solution Approach 1:
The black matrix is segmented into an island-shaped structure with a gap between the main body and the edge portion. This segmentation prevents the Ag dot from shorting the black matrix while maintaining ESD protection through the transparent conductive film path.
Solution Approach 2:
The transparent conductive film acts as an intermediary between the Ag dot and the black matrix. It provides an alternative ESD protection path that does not require direct contact between the Ag dot and the black matrix, thus preventing shorting while maintaining protection.
2Reliability
If the transparent conductive film is connected directly to the ground electrode, then ESD charges are discharged effectively, but the connection path is exposed and vulnerable to shorting during scribing
Solution Approach 1:
The connection portion is nested within the island-shaped black matrix structure. The transparent conductive film is positioned such that it is covered by the black matrix except for the connection portion, providing protection while maintaining the ESD discharge path.
Solution Approach 2:
The transparent conductive film serves as a protective thin film layer that covers the connection path. This film structure protects the ESD discharge path from external interference while allowing the charges to flow through to the ground electrode.
3Device complexity
If the black matrix extends to the substrate edge, then the structure is simple, but the scribing process removes material exposing the black matrix to shorting
Solution Approach 1:
The black matrix is divided into a main body portion and an island-shaped edge portion separated by a gap. This segmentation maintains structural simplicity while providing insulation during the scribing process, preventing material removal from exposing conductive paths.
Solution Approach 2:
The island-shaped structure is formed in advance during the black matrix fabrication process. This preliminary structuring prevents the need for additional insulation steps during scribing, as the gap is already in place to protect against shorting.
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 reduces black uniformity defects by preventing ESD-induced irregular voltages, ensuring uniform black regions across the liquid crystal display panel and avoiding bright spots.
Implementation Method 1
absorbing charges of electro static discharge (ESD)... preventing ESD from flowing through the black matrix
Implementation Method 2
an alignment state of liquid crystal molecules in the liquid crystal layer is controlled based on whether or not an electric field is applied thereto
Data Source
AI summary
A liquid crystal display device and a method for manufacturing the same are disclosed. The liquid crystal display device comprises first and second substrates facing each other; a transparent conductive film formed on one surface of the first substrate, absorbing charges of electro static discharge (ESD); a black matrix including a first black matrix formed on a corner of the other surface of the first substrate and end portions spaced apart from one end of the first black matrix at a predetermined interval for insulation; a ground electrode formed on one surface of the second substrate; and a connection portion connecting the transparent conductive film with the ground electrode, and extending over the end portions.