VA-Mode LCD Sub-Pixel TFT Layout for Brightness Uniformity
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Solution Overview
Problem
VA-mode LCD devices exhibit differences in brightness when viewed from the front and side due to deviations in the channel lengths of TFTs, leading to potential smudges and display quality issues.
Innovation Solution
The LCD device incorporates a substrate with first through third TFTs and sub-pixel electrodes, where the second and third TFTs share a single output terminal, minimizing deviations in channel lengths and ensuring consistent voltage application to sub-pixel electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple TFTs are used to supply different voltages to sub-pixel electrodes, then brightness uniformity can be improved, but deviations in channel lengths of TFTs cause smudges and display quality issues
Solution Approach 1:
The patent merges the output terminals of the second and third TFTs into a single shared output terminal. This configuration ensures that both sub-pixel electrodes receive voltages determined by a common channel length, eliminating smudges caused by manufacturing variations in TFT channel lengths while maintaining the ability to achieve uniform brightness display.
2Ease of manufacture
If the exposure apparatus moves in a particular direction, then manufacturing process is simplified, but channel length deviations occur when TFT channel directions do not align with the moving direction
Solution Approach 1:
By combining the output terminals of multiple TFTs, the patent makes the voltage applied to sub-pixel electrodes dependent on a shared channel length. This approach decouples the manufacturing precision requirement from the exposure apparatus moving direction, allowing simplified manufacturing processes without compromising channel length consistency.
Data Source
AI summary
A liquid crystal display device includes a substrate, first through third thin-film transistors (“TFTs”) disposed on the substrate, and first and second sub-pixel electrodes disposed above the first through third TFTs. The second and third TFTs share a single output terminal as their output terminals, the first sub-pixel electrode is electrically connected to an output terminal of the first TFT, and the second sub-pixel electrode is electrically connected to the single output terminal of the second and third TFTs.