Dual Alignment Key for LCD Substrate Precision
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Solution Overview
Problem
The existing alignment key forming methods in liquid crystal display (LCD) devices suffer from significant forming errors, particularly during the printing process, leading to misalignment of patterns and increased crosstalk due to parasitic capacitance differences between data lines and pixel electrodes, which complicates the formation of accurate thin film transistor substrates.
Innovation Solution
The use of two alignment keys, where the first alignment key is formed initially and the second alignment key is formed subsequently based on the first, allowing for more precise alignment of patterns, particularly between the data line and pixel electrode, thereby reducing forming errors and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single alignment key is formed through printing process, then the process is simplified, but the forming error increases up to 10 μm
Solution Approach 1:
The patent divides the alignment key into two separate alignment keys (first alignment key and second alignment key) formed at different stages. The first alignment key is formed initially with larger margins, and the second alignment key is formed later with smaller margins based on the first alignment key's position. This segmentation allows each alignment key to serve specific purposes, reducing cumulative forming errors while maintaining process simplicity.
2Ease of manufacture
If alignment key is formed through printing process, then the process is simplified, but the actual forming location shifts from designed location
Solution Approach 1:
The patent uses the first alignment key's actual formed position as feedback to determine the position of the second alignment key. Instead of relying solely on predetermined design locations that may be shifted during printing, the system measures the actual position of the first alignment key and uses this information to correctly position the second alignment key, compensating for printing process variations.
Data Source
AI summary
An alignment key, a method for fabricating the alignment key, and a method for fabricating a thin film transistor substrate using the alignment key are provided. The alignment key includes a base substrate, a first alignment key and a first mark portion of a second alignment key, which are formed on the base substrate using a printing roll, a dielectric that is formed on the base substrate to cover the first alignment key, and a second mark portion of the second alignment key, which is formed on the dielectric and at least partly overlaps the first mark portion of the second alignment key.