FFS Array Substrate Contact Hole for Burn-In Prevention
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Solution Overview
Problem
The fringe field switching (FFS) type liquid crystal display devices suffer from screen burn-in due to remnant charges on the lower electrode, which is not covered by an insulating film, leading to afterimages and reduced light transmittance.
Innovation Solution
An array substrate configuration is introduced where a contact hole is provided on a conducting pattern with the same potential as the lower electrode, allowing the insulating film to be removed in areas where the upper electrode is not formed, thereby reducing remnant charges and preventing screen burn-in.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower electrode is covered by an insulating film to prevent charge leakage, then electrical insulation is improved, but remnant charges accumulate leading to screen burn-in
Solution Approach 1:
The patent applies local quality by differentiating the treatment of the lower electrode between display areas and non-display areas. In non-display areas, the insulating film is removed to expose the lower electrode, allowing charges to be discharged without affecting the electrical insulation in display areas where the insulating film remains intact.
Solution Approach 2:
The patent extracts the insulating film from specific regions (non-display areas) of the lower electrode while maintaining it in other regions (display areas). This selective removal allows the lower electrode to discharge remnant charges in non-display areas without compromising the electrical insulation required in display areas.
2Object-generated harmful factors
If the insulating film is removed from the lower electrode to discharge remnant charges, then screen burn-in is prevented, but light transmittance is reduced
Solution Approach 1:
The patent applies local quality by selectively removing the insulating film only in non-display areas where light transmittance is not required. The display areas maintain the insulating film coverage, preserving both light transmittance and electrical insulation functionality.
Solution Approach 2:
The patent segments the lower electrode into display areas and non-display areas, applying different treatments to each segment. The insulating film is removed only from non-display areas, allowing charge discharge without impacting the light transmittance of display areas.
3Ease of manufacture
If an asymmetric electrode configuration is used with the lower electrode covered by insulating film, then manufacturing is simplified, but charge symmetry between electrodes is compromised
Solution Approach 1:
The patent applies local quality by creating regional differences in the electrode structure. The lower electrode has the insulating film removed in non-display areas while maintaining it in display areas, achieving charge symmetry without requiring complete structural symmetry between electrodes.
Solution Approach 2:
The patent uses asymmetry by intentionally creating an asymmetric configuration where the lower electrode has exposed regions in non-display areas while the upper electrode maintains uniform coverage. This controlled asymmetry achieves charge symmetry while preserving manufacturing simplicity.
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 configuration effectively suppresses screen burn-in and maintains light transmittance by ensuring symmetry in the electrical path and reducing charge differences between the lower and upper electrodes, improving the overall performance of FFS liquid crystal display devices.
Implementation Method 1
an upper electrode that is formed on the insulating film to generate a fringe electric field between the lower electrode and the upper electrode
Data Source
AI summary
An array substrate including: a pixel defined by both a scanning line and a signal line intersecting with the scanning line, wherein a display area on a substrate includes a plurality of pixels arranged in a matrix shape, wherein the pixel includes: a switching device; a lower electrode that is connected to the switching device; an insulating film that is formed on the lower electrode; and an upper electrode that is formed on the insulating film to generate a fringe electric field between the lower electrode and the upper electrode, and wherein, in an area where the upper electrode is not formed and light is not transmitted, a contact hole is provided on a conducting pattern having the same potential as the lower electrode, by removing the insulating film.