Active Matrix Substrate Light Leakage Reduction
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Solution Overview
Problem
Conventional active matrix LCD devices face issues with light leakage and display unevenness due to misalignment and insufficient light-shielding between pixel electrodes, particularly in black display states, which affect the contrast ratio and overall display quality.
Innovation Solution
The active matrix substrate design includes a source line with bend points that overlap with adjacent pixel electrodes and a storage capacitor line or gate line extending to overlap with spaces between pixel electrodes, minimizing parasitic capacitance and light leakage by using these lines as light-shielding members, while maintaining signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a source line is configured to overlap with pixel electrodes to minimize parasitic capacitance, then signal integrity is improved, but light leakage between pixel electrodes increases
Solution Approach 1:
The source line is divided into multiple segments with bend points positioned at specific locations. These segmented sections allow the line to overlap with pixel electrodes for electrical connection while avoiding direct overlap with spaces between pixels, thus reducing light leakage. The segmentation enables independent optimization of electrical and optical properties in different sections of the same conductor.
Solution Approach 2:
Different sections of the source line have different spatial relationships with pixel electrodes and inter-pixel spaces. The bend points create local variations in the line's position, allowing it to be close to pixel electrodes (for low parasitic capacitance) in some areas while being distant from inter-pixel spaces (for light shielding) in other areas. This local quality variation resolves the contradiction between electrical and optical requirements.
2Object-affected harmful factors
If storage capacitor lines or gate lines are extended to overlap with spaces between pixel electrodes for light shielding, then contrast ratio is improved, but parasitic capacitance between lines increases
Solution Approach 1:
An insulating film is introduced as an intermediary between the storage capacitor line/gate line and the source line. This intermediate layer allows the lines to overlap spatially for light shielding purposes while preventing direct electrical contact, thus minimizing parasitic capacitance. The insulating film acts as a mediator that enables both optical and electrical requirements to be satisfied simultaneously.
Solution Approach 2:
The solution moves the problem from a two-dimensional plane to three-dimensional space by stacking conductors in different layers separated by insulating films. This vertical dimensionality allows lines to overlap in the planar view (providing light shielding) while being electrically isolated through the insulating film, thus resolving the contradiction between optical and electrical performance.
3Area of stationary object
If pixel electrodes are arranged in a dense matrix pattern to increase aperture ratio, then display resolution is improved, but light leakage between adjacent pixels increases
Solution Approach 1:
The source line and storage capacitor line/gate line serve multiple functions: electrical connection (low parasitic capacitance) and optical shielding (light blocking). By designing these conductors to extend into inter-pixel spaces, they simultaneously perform their electrical function and provide additional light shielding, thus addressing both aperture ratio and light leakage requirements with multi-functional elements.
Data Source
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AI summary
The present invention provides a liquid crystal display device including an active matrix substrate with improved characteristics and providing high-contrast between black and white displays. The active matrix substrate of the present invention is an active matrix substrate, including: pixel electrodes arranged in a matrix pattern; a source line extending in a column direction and overlapping with any adjacent two of the pixel electrodes in a row direction; and a storage capacitor line extending in the row direction and intersecting with the source line, wherein the pixel electrodes, the source line, and the storage capacitor line are disposed in different layers stacked with an insulating film therebetween, the source line has bend points below both of the adjacent two row pixel electrodes and has a crossing portion passing across a space between the adjacent two row pixel electrodes, the storage capacitor line has a portion extending in the column direction and overlapping with the space between the adjacent two row pixel electrodes, and the source line overlaps with the storage capacitor line substantially only at an intersection thereof.