FFS Common Electrode Slit Design for Liquid Crystal Display
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Solution Overview
Problem
Liquid crystal display devices using the Fringe-Field Switching method suffer from degradation in optical characteristics due to disclination, resulting in reduced transmittance and contrast, particularly in the normally black state, caused by misalignment of liquid crystal molecules at the edges of slits in the common electrode.
Innovation Solution
The design incorporates a common electrode with slits that extend across multiple pixels, reducing the number of edges and optimizing the arrangement to minimize disclination, such as by staggering slits or using vertically oriented slits, to enhance transmittance and contrast while preventing short-circuiting and maintaining aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slits are provided in the common electrode to prevent short-circuiting, then electrical insulation is improved, but the number of edges increases causing disclination and degrading optical characteristics
Solution Approach 1:
The common electrode is divided into multiple segments by providing slits that extend across multiple pixels. This segmentation prevents short-circuiting between the common electrode and pixel electrodes while reducing the total number of edges compared to providing slits only within each pixel. The slits create electrical insulation without excessive edge-induced disclination.
2Object-affected harmful factors
If slits are extended across multiple pixels, then the number of edges is reduced improving optical characteristics, but the electrode structure becomes more complex
Solution Approach 1:
The slits in the common electrode serve multiple functions simultaneously: they provide electrical insulation across pixel boundaries, reduce the total number of edges to minimize disclination, and maintain a relatively simple electrode structure. This multi-functional design optimizes optical characteristics without excessive structural complexity.
3Object-affected harmful factors
If slits are staggered or vertically oriented, then disclination is minimized improving transmittance and contrast, but manufacturing precision requirements increase
Solution Approach 1:
The slits are arranged in an asymmetric staggered pattern or vertical orientation rather than a simple grid pattern. This asymmetric arrangement minimizes disclination by reducing edge effects while the regular staggered or vertical pattern maintains manufacturability. The asymmetric design optimizes optical characteristics without requiring excessive manufacturing precision.
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 reduces the number of edges and disclination-related issues, improving transmittance and contrast while maintaining display quality and preventing crosstalk, thereby enhancing the overall performance of the liquid crystal display device.
Implementation Method 1
a method has been developed to realize a light switching function by rotating the liquid crystal molecules in a plane parallel to the substrate with a lateral electric field generated between the electrodes on the same substrate
Implementation Method 2
rotating the liquid crystal molecules in a plane parallel to the substrate with a lateral electric field
Implementation Method 3
an alignment direction of liquid crystal molecules is controlled by a lateral electric field between electrodes on the same substrate
Data Source
AI summary
Transmittance and contrast of a liquid crystal display device according to FFS method are improved. A plurality of picture elements, each made of an R pixel, a G pixel and a B pixel, is disposed in a matrix form. In each of the pixels, a gate signal line extends in a left to right direction and a display signal line extends in a top to bottom direction so as to cross the gate line. A thin film transistor for pixel selection is disposed around an intersection of the gate line and the display signal line. There is provided a pixel electrode connected with the thin film transistor. A common electrode is provided on the pixel electrode through an insulation film. A plurality of slits having edges at borders between the picture elements is disposed in the common electrode to cross each of the picture elements in the left to right direction.