Variable Scan Line Width for LCD Brightness Uniformity
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Solution Overview
Problem
Conventional liquid crystal display devices face issues with uneven image quality due to variations in wiring capacitance between the source electrode and scan signal line, leading to differences in brightness across the display area, and this problem is exacerbated when manufacturing multiple substrates from a single mother glass.
Innovation Solution
The solution involves a manufacturing method that adjusts the dimensions and positions of the source and drain electrodes relative to the scan signal lines to maintain consistent wiring capacitance across each pixel, ensuring equal surface areas of overlap and channel lengths, thereby minimizing variations in image quality without widening the scan signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of scan signal lines is widened to enlarge auxiliary capacity, then wiring capacitance between source electrode and scan signal line increases, but the number of aperture decreases
Solution Approach 1:
The patent applies local quality by making the scan signal line width variable rather than uniform. Specifically, the line width is adjusted in different regions (first region vs second region) to control the auxiliary capacity locally, ensuring consistent wiring capacitance between source electrode and scan signal line across different pixels without uniformly widening the lines and reducing aperture count
Solution Approach 2:
The patent changes the geometric parameter (width) of the scan signal line to control its electrical property (auxiliary capacity). By adjusting the line width parameter in different regions, the patent achieves the desired wiring capacitance consistency while maintaining the overall aperture density
2Reliability
If scan signal line width varies across regions, then wiring capacitance can be adjusted, but manufacturing precision of uniform TFT size becomes difficult
Solution Approach 1:
The patent implements local quality by varying the scan signal line width in specific regions (first region with larger width, second region with smaller width) to adjust auxiliary capacity locally. This allows different parts of the substrate to have optimized electrical characteristics while maintaining uniform TFT dimensions through controlled variation in only the signal line geometry
Solution Approach 2:
The patent segments the substrate into different regions (first region and second region) with different scan signal line width characteristics. This segmentation allows independent optimization of wiring capacitance in each region while maintaining overall manufacturing precision through region-specific design parameters
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces uneven image quality by maintaining consistent wiring capacitance, ensuring uniform brightness across the display area and minimizing differences between substrates cut from a single mother glass, without reducing the number of apertures.
Implementation Method 1
a first insulation layer interposed between the scan signal line and the semiconductor layer
Implementation Method 2
there may be a considerable variation in the wiring capacity (parasitic capacity) generated between a source electrode and a scan signal line
Data Source
AI summary
The present invention allows decreasing the uneven image quality in a liquid crystal display device. The display device in accordance with the present invention includes plural scan signal lines, plural video signal lines, plural TFTs placed in a matrix structure, and plural pixel electrodes, when the width of the scan signal line in a region to place one TFT is different from the width of the scan signal line in a region to place another TFT which is different from the one TFT, the channel width and the channel length of the one TFT is almost equal to the channel width and the channel length of the another TFT, and the surface area of the region overlapping the source electrode with the scan signal line of the one TFT when viewing in plan view is almost equal to the surface area of the region overlapping the source electrode with the scan signal line of the another TFT when viewing in plan view.