Asymmetric Storage Capacitor Electrode Alignment Tolerance
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Solution Overview
Problem
In liquid crystal display panels, alignment accuracy differences among regions lead to inconsistent storage capacitors, causing watermark defects and affecting display quality, especially in small-sized pixel units where deviations in electrode alignment significantly alter the overlapping area and storage capacitor values.
Innovation Solution
The pixel unit design includes a storage capacitor structure with a first electrode and a second electrode, where the second electrode has additional regions that offset changes in the overlapping area when alignment accuracy varies, maintaining a consistent overlapping region area and thus storage capacitor value across different pixel units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the storage capacitor is designed with a conventional electrode arrangement where the second electrode is smaller than the first electrode, then the manufacturing process can accommodate alignment deviations, but the storage capacitor value changes when alignment accuracy varies across different regions, causing watermark defects
Solution Approach 1:
The patent applies asymmetry by extending the third region of the second electrode beyond the boundary of the first electrode, creating an asymmetric overlapping structure. This asymmetric design ensures that when alignment deviations occur, the overlapping area remains constant because the extended third region compensates for the misalignment, thereby maintaining consistent storage capacitor values across different regions of the panel.
Solution Approach 2:
The patent changes the geometric parameters of the second electrode by adding the third region that extends beyond the first electrode's boundary. This parameter modification (extending the electrode area) ensures that the overlapping area between the first and second electrodes remains constant even when alignment accuracy varies, thus maintaining stable storage capacitor characteristics.
2Area of moving object
If the pixel unit size is reduced to increase pixel density, then the display resolution improves, but the alignment accuracy difference among regions has a greater influence on the storage capacitor value, worsening watermark defects
Solution Approach 1:
In small-sized pixel units, the patent uses the asymmetric third region extension to compensate for alignment deviations more effectively. The extended third region ensures that even with reduced pixel dimensions, the overlapping area remains constant despite the greater relative impact of alignment errors, thereby maintaining storage capacitor uniformity in high-resolution displays.
Solution Approach 2:
The patent addresses the two-dimensional alignment problem by introducing a dimensional extension in the form of the third region that protrudes beyond the first electrode's boundary. This dimensional change creates a buffer zone that absorbs alignment variations, ensuring consistent overlapping area and storage capacitor values even in miniaturized pixel units.
3Reliability
If the overlapping area between electrodes is increased to enlarge the storage capacitor, then the voltage holding capability improves, but the alignment accuracy requirement becomes more stringent, making manufacturing more difficult
Solution Approach 1:
The patent achieves large overlapping area with relaxed alignment requirements by using the asymmetric third region that extends beyond the first electrode. This extension creates a tolerance buffer that allows larger overlapping areas without increasing alignment stringency, as the constant overlapping area is maintained through the geometric compensation provided by the third region.
Solution Approach 2:
The second electrode serves multiple functions: it provides the necessary overlapping area for sufficient storage capacitor value while the extended third region simultaneously provides alignment tolerance. This multi-functionality allows the structure to achieve both large voltage holding capability and ease of manufacture with relaxed alignment requirements.
Data Source
AI summary
The technical field of liquid crystal display is related to. A pixel unit is provided. The pixel unit includes a storage capacitor that is arranged on an array substrate. The storage capacitor includes a first electrode arranged on a first metal layer and a second electrode arranged on a second metal layer. An insulation layer is arranged between the first electrode and the second electrode. The second electrode and the first electrode overlap with each other to form a first overlapping region, an area of which does not change if a deviation of the second electrode relative to the first electrode is within a preset distance. Storage capacitor difference among different pixel units generated by alignment accuracy difference thereof can be eliminated, and watermark which would be generated otherwise can be eliminated as well. An array substrate is further provided, which includes the storage capacitor of the aforesaid pixel unit. A quality of a product can be improved.