FFS Liquid Crystal Display Electrode Slit Design
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Solution Overview
Problem
Liquid-crystal display apparatuses operating in the FFS mode of a two-domain type face challenges in achieving a high aperture ratio and uniform display areas due to the orientation of slit openings, leading to increased non-display areas and difficulties in maintaining image quality with changing pixel pitches.
Innovation Solution
The design incorporates a configuration where slits on the upper electrode are oriented in two different inclined directions and joined in a row direction for every pixel, with small protruding portions at the slit edges and between pixels, allowing for continuous slit appearance and reduced disclination areas, thereby enhancing the aperture ratio and uniformity across sub-pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If slit openings are oriented in two directions (two-domain type), then viewing-field angle and image contrast are improved, but aperture ratio decreases due to increased non-display areas
Solution Approach 1:
The upper electrode is divided into multiple independent electrode regions separated by non-conductive portions corresponding to the lower electrode patterns. This segmentation allows each electrode region to function as an independent FFS element, enabling the creation of two-domain configurations while maintaining control over aperture ratio through optimized electrode geometry and spacing.
Solution Approach 2:
The upper and lower electrodes are designed with asymmetric patterns where the upper electrode has slit openings oriented in two different directions while the lower electrode has corresponding non-conductive portions. This asymmetric design creates the two-domain effect for improved viewing angle and contrast while the optimized asymmetry minimizes the impact on aperture ratio.
2Manufacturing precision
If pixel pitch is reduced for high-definition displays, then display resolution is improved, but maintaining uniform display areas and high aperture ratio becomes more difficult
Solution Approach 1:
The electrode pattern design is created as a universal template that can be scaled to different pixel pitches while maintaining the same functional characteristics. The upper electrode with its two-directional slit openings and the lower electrode with corresponding non-conductive portions form a multi-functional unit that simultaneously achieves high resolution, uniform display areas, and high aperture ratio regardless of the specific pixel pitch used.
Solution Approach 2:
The electrode geometry parameters (slit width, electrode spacing, non-conductive portion dimensions) are designed as scalable parameters that can be adjusted proportionally with pixel pitch changes. This allows the same electrode pattern design to be applied across different resolution requirements while maintaining consistent optical performance and aperture ratio through parameter scaling rather than redesign.
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 achieves a high aperture ratio, reduces display unevenness, and maintains excellent image quality by minimizing disclination areas and ripples, while allowing for design flexibility independent of pixel pitch changes.
Implementation Method 1
a pair of electrodes insulated from each other are provided to serve as electrodes for applying an electric field oriented in approximately horizontal direction to liquid-crystal molecules
Implementation Method 2
liquid-crystal molecules are aligned in a direction determined in advance by carrying out a rubbing process for an oriented film. Then, the direction of each liquid-crystal molecule is changed by an electric field
Implementation Method 3
liquid-crystal molecules are aligned in a direction determined in advance by carrying out a rubbing process for an oriented film
Data Source
AI summary
Disclosed herein is a liquid-crystal display apparatus including: a pair of substrates facing each other to sandwich a liquid-crystal layer; signal and scan lines laid out in a matrix form to sandwich a first insulation film on one of the substrates; a lower electrode created in each area enclosed by the signal and scan lines; a second insulation film created on a surface of the lower electrode; an upper electrode on which a plurality of slits are created in parallel all over an entire surface of the second insulation film; and an oriented film created to cover surfaces of the upper electrode and the second insulation film.