Multi-Level Transparent Electrodes for Uniform FFS Electric Fields
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Solution Overview
Problem
In liquid crystal displays, particularly Fringe Field Switching (FFS) displays, non-uniform electric fields due to differences in alignment layer resistance cause afterimage and flicker defects, as residual DC components dissipate at different rates across the screen, leading to uneven image transitions and momentary screen shaking.
Innovation Solution
A thin film transistor substrate design with a pixel electrode and common electrode configuration, including a floating conductive layer and strategically placed slits, ensures uniform electric field distribution by maintaining similar surface areas and resistances across inner and edge areas, thereby reducing residual DC components and their dissipation times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the distance between pixel electrodes is reduced to create a fringe field, then aperture ratio and transmittance are improved, but non-uniform electric fields occur due to different alignment layer resistance in inner and edge areas
Solution Approach 1:
The patent applies local quality by introducing a floating conductive layer specifically in the edge area between the pixel electrode and data line. This localized structural modification compensates for the longer alignment layer resistance path in edge areas, balancing the electric field distribution across different regions without affecting the overall fringe field structure that provides high transmittance.
2Area of stationary object
If the alignment layer length is longer in edge areas, then electrode coverage is maintained, but residual DC components dissipate slower causing afterimage defects
Solution Approach 1:
The floating conductive layer acts as an intermediary element in the edge area, providing an additional charge dissipation path. It mediates between the pixel electrode and data line, accelerating the dissipation of residual DC components in regions with longer alignment layer resistance, thereby preventing afterimage defects while preserving electrode coverage.
3Ease of operation
If pixel electrodes are spaced apart with slits, then liquid crystal molecule control is improved, but resistance difference between inner and edge areas causes non-uniform electric fields
Solution Approach 1:
The patent applies local quality by introducing a floating conductive layer specifically in the edge area between the pixel electrode and data line. This localized structural modification compensates for the longer alignment layer resistance path in edge areas, balancing the electric field distribution across different regions without affecting the overall fringe field structure that provides high transmittance.
4Stability of the object's composition
If floating conductive layer is added to compensate for edge area resistance, then electric field uniformity is improved, but device complexity increases
Solution Approach 1:
The floating conductive layer is merged with the existing electrode structure and formed in the same pixel electrode formation process. This integration approach minimizes additional manufacturing steps and structural complexity while effectively compensating for the resistance difference between inner and edge areas, achieving electric field uniformity without significantly increasing device complexity.
Data Source
AI summary
Disclosed is a display device having a thin film transistor substrate, which may prevent afterimage and flicker defects by reducing the non-uniformity of an electric field. In the thin film transistor substrate, a pixel electrode includes a transparent edge electrode and a transparent inner electrode, which are spaced apart from each other with a first slit having a first width interposed therebetween, and a common electrode is exposed from the other-side end of the transparent edge electrode by a second width, which is smaller than the first width, in the width direction of a data line. As such, an inner area and an edge area in each sub pixel have uniform electric field distribution.