LCD Data Link Line Equi-Potential Circuit for Brightness Uniformity
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Solution Overview
Problem
Conventional liquid crystal display (LCD) devices experience threshold voltage differences between thin film transistors (TFTs) connected to odd and even numbered data lines, leading to uneven brightness and deteriorated picture quality, especially when data lines are shared by multiple pixels.
Innovation Solution
The solution involves disconnecting data shorting bars from odd and even numbered data link lines and using equi-potential circuits to maintain equal charging currents, ensuring the length and potential of data link lines are consistent, thereby preventing threshold voltage differences between TFTs connected to odd and even numbered data lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If data lines are shared by multiple pixels to reduce the number of data driving circuits, then device complexity and fabrication cost are reduced, but threshold voltage differences occur between TFTs connected to odd and even numbered data lines, causing uneven brightness
Solution Approach 1:
The patent introduces equi-potential circuits between adjacent data lines (odd and even numbered) to maintain equal potentials across all data lines. This ensures that charging currents flowing through TFTs connected to different data lines are equal, thereby eliminating threshold voltage differences and brightness unevenness while maintaining the data line sharing structure
Solution Approach 2:
The equi-potential circuits act as intermediary elements that couple adjacent data lines together, ensuring they maintain equal potentials. These circuits are positioned between odd and even numbered data lines to mediate the potential differences that would otherwise cause threshold voltage variations in the TFTs
2Device complexity
If one data line is connected to one pixel to simplify the connection structure, then device complexity is reduced, but a large number of expensive data driving circuits are required
Solution Approach 1:
The patent makes each data line serve multiple functions by connecting it to multiple pixels. Specifically, each data line is shared by two adjacent pixels, allowing a single data line to perform the function of serving multiple pixels simultaneously. This reduces the total number of data driving circuits required while maintaining manageable connection complexity through the equi-potential circuit design
3Difficulty of detecting and measuring
If data shorting bars are connected to data link lines to apply test signals, then testing capability is improved, but charging current differences arise between odd and even numbered data lines, causing threshold voltage differences
Solution Approach 1:
The equi-potential circuits compensate for any potential differences that may arise during testing by maintaining equal potentials across all data lines. This ensures that even when data shorting bars are used to apply test signals, the charging currents through different TFTs remain equal, preventing threshold voltage differences
Solution Approach 2:
The equi-potential circuits provide a feedback mechanism that continuously monitors and adjusts potential differences between data lines. By coupling adjacent data lines together, the circuits automatically equalize any potential variations, ensuring uniform charging currents throughout the display panel during both manufacturing and testing phases
Data Source
AI summary
The LCD device of this invention comprises an LC panel having a plurality of pixels defined by a plurality of gate lines and data lines, one or more gate shorting bars disposed outside the LC panel, for applying a test signal to the LC panel through gate lines, first and second data shorting bars disposed outside the LC panel, for applying test signals to odd and even numbered data lines, respectively, an odd numbered data link line connected to the odd numbered data line, and spacing from the first data shorting bar by a predetermined distance, an even numbered data link line connected to the even numbered data line, and spacing from the second data shorting bar by a predetermined distance, and a connection line for electrically connecting the odd numbered data link line and the first data shorting bar with each other, and connecting the even numbered data link line and the second data shorting bar with each other through contact holes, wherein the odd numbered data link line has a length equal to that of the even numbered data link line.