Array Substrate Common Electrode Line Positioning for Aperture Ratio
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Solution Overview
Problem
The aperture ratio of IPS liquid crystal display devices is low due to the occupation of pixel regions by common electrode lines and thin film transistors, leading to reduced light transmittance and display brightness.
Innovation Solution
A common electrode line with the same extending direction as the gate line is positioned near the thin film transistor, forming a storage capacitor with the drain electrode, and a wire connects the common electrode line to the common electrodes, allowing for a more compact design that reduces the occupied area and enhances signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the common electrode line and thin film transistor are disposed in the same layer as pixel electrodes, then the voltage on pixel electrode can be maintained constant, but the aperture ratio is decreased and light transmittance is reduced
Solution Approach 1:
The patent transitions from a planar arrangement where common electrode lines and transistors occupy pixel regions to a three-dimensional stacked architecture. The common electrode line is positioned in a lower layer (first substrate) while pixel electrodes are in an upper layer (second substrate), separated by spacing structures. This vertical separation allows the common electrode line to extend across the pixel region without occupying horizontal space, thereby maintaining voltage stability while increasing aperture ratio.
Solution Approach 2:
The patent divides the display structure into multiple layers: a first substrate containing common electrode lines, a second substrate containing pixel electrodes, and spacing structures separating them. This segmentation allows independent optimization of each layer's function - the common electrode line layer maintains electrical connectivity while the pixel electrode layer maximizes light transmittance area.
2Reliability
If the common electrode line extends across the pixel region, then voltage distribution is improved, but the area occupied by the common electrode line increases, reducing the aperture ratio
Solution Approach 1:
The common electrode line is relocated from the horizontal plane of pixel electrodes to a vertical dimension below, in a separate layer on the first substrate. This allows the common electrode line to maintain its voltage-distributing function across the entire pixel region while its projection area no longer competes with the pixel electrode area, effectively resolving the area conflict.
Solution Approach 2:
The patent creates a spatial copy of the electrode arrangement where common electrodes are positioned directly below their corresponding pixel electrodes in different layers. This vertical stacking allows both electrode types to occupy the same horizontal footprint without interference, maximizing aperture ratio while maintaining voltage distribution.
3Reliability
If a separate storage capacitor zone is provided, then the storage capacitor can be formed, but the pixel region is occupied too much, decreasing aperture ratio
Solution Approach 1:
The patent merges the storage capacitor structure with the common electrode line and pixel electrode arrangement. The storage capacitor is formed by the capacitive coupling between the common electrode line in the first substrate and the pixel electrode in the second substrate, separated by spacing structures that serve as dielectric. This integration eliminates the need for separate storage capacitor zones, freeing up pixel region area.
Solution Approach 2:
The common electrode line serves multiple functions: it distributes voltage across the pixel region, forms storage capacitors with pixel electrodes through capacitive coupling, and provides structural support. This multi-functionality eliminates the need for dedicated storage capacitor regions, maximizing aperture ratio while maintaining all necessary electrical functions.
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 increases the aperture ratio and improves display brightness by minimizing the area occupied by the common electrode line and thin film transistor, while ensuring constant voltage on the pixel electrode during a frame period, thus enhancing picture quality.
Implementation Method 1
the common electrode line... forms a storage capacitor with a drain electrode of the thin film transistor
Data Source
AI summary
An array substrate and a display device are provided. A common electrode line with the same extending direction as a gate line is disposed at one end near a thin film transistor, and forms a storage capacitor with a drain electrode of the thin film transistor. As compared with the case in the prior art that a common electrode line and a thin film transistor in an array substrate are disposed at both ends of a pixel, respectively, and it is necessary to separately provide a storage capacitance electrode useful for forming a storage capacitor with the common electrode line, the pixel region occupied by the thin film transistor and the common electrode line can be effectively decreased. Thus, the aperture ratio is increased, and the display brightness of an IPS liquid crystal display device is enhanced.