Liquid Crystal Display Common Electrode Resistance Reduction
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Solution Overview
Problem
Large-sized FFS mode liquid crystal display panels experience issues with flickers and crosstalk due to high resistance in the common electrode, which is exacerbated by the high resistivity of the upper electrode when it is formed over all sub-pixels in the display area.
Innovation Solution
The common electrode is electrically connected to the common wiring line at the fringe portion of the display area, with a relay terminal formed between the common line and the common electrode to reduce the resistance and aperture size of the contact hole, and the connection between the relay terminal and the common line is designed to be non-overlapping to prevent concavity and convexity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the upper electrode is formed over all sub-pixels in the display area as the common electrode, then the aperture ratio and contrast are improved, but the resistance of the common electrode increases due to the high resistivity of the transparent conductive material
Solution Approach 1:
The common electrode is divided into multiple segments: the upper electrode formed over all sub-pixels, the common line extending along the peripheral edge, and the contact hole connecting them. This segmentation allows the transparent conductive upper electrode to maintain high aperture ratio while the opaque common line provides low-resistance electrical connection to the common wiring line.
Solution Approach 2:
The contact hole acts as an intermediary connector between the upper electrode and the common line, which in turn connects to the common wiring line. This intermediary structure provides a low-resistance path for electrical connection while maintaining the structural integrity and optical properties of the display area.
2Device complexity
If the common electrode is connected to the common wiring line only in the non-display area, then the wiring is simplified, but the resistance becomes too high for large-sized panels causing flickers and crosstalk
Solution Approach 1:
The connection path is extended from the non-display area into the display area by forming the common line along the peripheral edge within the display area. This dimensional extension provides an additional electrical connection path that reduces resistance without significantly increasing wiring complexity.
3Area of stationary object
If the contact hole size is reduced to maintain high aperture ratio, then the aperture ratio is improved, but the electrical connection between the common electrode and common line becomes weaker
Solution Approach 1:
The common line is merged with the common wiring line at the peripheral edge of the display area, creating a continuous low-resistance electrical path. This merging compensates for the reduced contact hole size by providing an additional parallel conduction path, maintaining both high aperture ratio and reliable electrical connection.
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 the resistance of the common electrode, minimizing flickers and crosstalk, and maintains a high aperture ratio by reducing the size of the contact hole and preventing alignment failures, resulting in improved display quality.
Implementation Method 1
The liquid crystal display panel displays images by changing the alignment of liquid crystal molecules aligned in a given orientation and changing the transmittance of light in a liquid crystal layer
Implementation Method 2
In the horizontal-electric field liquid crystal display panel, a pair of electrodes is provided at one of a pair of substrates arranged sandwiching the liquid crystal layer on the liquid crystal layer side so as to be insulated from each other, in which an approximately horizontal electric field is applied to liquid crystal molecules
Data Source
AI summary
A liquid crystal display panel includes: substrates arranged opposite to each other with a liquid crystal layer therebetween. One of the substrates includes scanning and signal lines arranged in a matrix in a display area, a common wiring line along a peripheral edge portion of the display area, an interlayer resin film at least over the whole display area, and lower and upper electrodes arranged opposite to each other with an inter-electrode insulating film therebetween. The upper electrode includes slits in each pixel area sectioned by the scanning and signal lines. One of the upper and lower electrodes is formed over the whole display area and connected to the common wiring line and operates as a common electrode. In the display area, a common line is formed in parallel to the scanning line, the electrode operating as the common electrode is connected to the common line through a contact hole and the common line is connected to the common wiring line at the peripheral edge portion.