Array Substrate TFT Width-to-Length Ratio for Brightness Uniformity
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Solution Overview
Problem
Liquid crystal display panels suffer from brightness uniformity issues due to RC delay on scan lines, causing reduced charging ratios and voltages at the center compared to the sides, resulting in a 'two sides being whiter' phenomenon.
Innovation Solution
The array substrate is designed with thin film transistors having progressively decreasing width-to-length ratios from the center to the ends of scan lines, ensuring a smaller voltage difference between pixel electrodes, thereby maintaining uniform brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If scan lines are used to input scan signals from both ends, then the scan signals can reach the pixel electrodes, but the RC delay causes voltage distortion and brightness non-uniformity in the middle of the scan line
Solution Approach 1:
The patent applies local quality by setting different width-to-length ratios for thin film transistors at different positions along the scan line. Specifically, TFTs connected to pixel electrodes in the middle of the scan line have a larger width-to-length ratio than those at the ends, compensating for the RC delay effect and achieving uniform brightness across the display panel.
2Area of stationary object
If the scan line length is increased to cover the entire display area, then more pixel electrodes can be controlled, but the RC delay effect becomes more severe causing greater voltage loss
Solution Approach 1:
The patent divides the scan line into different regions (middle and ends) and assigns different width-to-length ratios to TFTs in each region. This localized adjustment compensates for the cumulative RC delay effect in longer scan lines, maintaining voltage stability across the entire display area.
3Ease of manufacture
If all thin film transistors have the same width-to-length ratio, then the manufacturing process is simpler, but the voltage difference between pixel electrodes at different positions increases
Solution Approach 1:
The patent implements local quality by specifying that TFTs at different positions along the scan line should have different width-to-length ratios. TFTs in the middle region have a larger ratio while those at the ends have a smaller ratio, which compensates for RC delay and achieves uniform brightness, albeit with increased manufacturing complexity.
Data Source
AI summary
The present invention provides an array substrate and a liquid crystal display panel. In the array substrate, as to thin film transistors connected with one scan line, a width-to-length ratio of the thin film transistor(s) corresponding to the middle of the scan line is larger than the width-to-length ratio of the thin film transistors corresponding to two ends of the scan line, and thereby when data lines input voltage signals, a voltage difference between a pixel electrode(s) connected with the thin film transistor(s) corresponding to the middle of the scan line and the pixel electrodes connected with the thin film transistors corresponding to the two ends of the scan line is smaller than a threshold value. By the above described manner, the present invention can improve the uniformity of image brightness.