RGBW LCD Viewing Angle Control via White Sub-Pixel Electric Field
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Solution Overview
Problem
Fringe field switching mode LCD devices face challenges in easily converting between narrow and wide viewing angles, leading to reduced aperture ratio and contrast ratio due to the complexity of additional electrode layers and driving methods.
Innovation Solution
Incorporating a white sub-pixel among RGBW-4 sub-pixels, where the RGB sub-pixels operate in the FFS mode for both viewing angles, and the W sub-pixel generates a vertical electric field only for the narrow viewing angle, allowing for controlled viewing angles without additional electrode structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional electrode layers are added to control viewing angle, then viewing angle control is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The white sub-pixel electrode is designed to serve dual purposes: as a common electrode for FFS mode operation in wide viewing angle, and as a view control electrode for narrow viewing angle. This multi-functionality eliminates the need for separate dedicated view control electrode layers, thereby reducing device complexity while maintaining viewing angle control capability
Solution Approach 2:
The pixel electrode is segmented into RGB sub-pixels and a white sub-pixel, with the white sub-pixel electrode specifically configured to provide different electrical functions based on driving mode requirements. This segmentation allows the white sub-pixel to independently control viewing angle without affecting the RGB sub-pixels, achieving precise viewing angle control without requiring additional electrode structures across the entire display
2Adaptability or versatility
If additional electrode layers are added for view control, then viewing angle control is improved, but aperture ratio is reduced
Solution Approach 1:
By making the white sub-pixel electrode multi-functional (serving as both common electrode and view control electrode), the invention eliminates the need for additional dedicated view control electrode layers that would occupy extra aperture space. This maintains the aperture ratio while achieving viewing angle control through the existing electrode structure's dual functionality
3Adaptability or versatility
If additional electrode layers are added for view control, then viewing angle control is improved, but front contrast ratio is reduced
Solution Approach 1:
The view control function is applied locally only to the white sub-pixel electrode, which has different electrical properties and driving characteristics compared to the RGB sub-pixels. This localized approach allows the white sub-pixel to control viewing angle without introducing additional electrode structures that would uniformly degrade the contrast ratio across the entire display. The local configuration enables precise control of light transmission in the white sub-pixel region while preserving the contrast characteristics of the RGB regions
4Adaptability or versatility
If additional electrode layers are added for view control, then viewing angle control is improved, but driving method complexity increases
Solution Approach 1:
The white sub-pixel electrode serves as both a common electrode for FFS mode driving and a view control electrode, eliminating the need for separate driving circuits and control signals for view angle adjustment. This multi-functionality simplifies the driving method by using a single electrode structure for both purposes, reducing the complexity of signal routing and control logic while maintaining the ability to switch between narrow and wide viewing angle modes
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 approach enhances the viewing angle range while maintaining high contrast ratio and simplifying the driving method, reducing manufacturing costs and complexity.
Implementation Method 1
with liquid crystals arranged to have liquid crystal director twisted 90 degrees between two substrates
Implementation Method 2
a fringe field is generated between the counter electrode 24 and the pixel electrode 17
Implementation Method 3
the liquid crystal director is driven via application of a voltage to the electrodes
Data Source
AI summary
A liquid crystal display device employs a white sub-pixel among RGBW-4 sub-pixels as a view control component to realize a narrow viewing angle or a wide viewing angle in a fringe field switching mode. The LCD device comprises gate lines and data lines crossing each other to define RGBW sub-pixels on a first substrate, a thin film transistor formed at each crossing of the gate and data lines; a first common electrode in each region of the RGBW sub-pixels, a pixel electrode connected to the thin film transistor and insulated from the first common electrode, the pixel electrode having at least one slit, a second substrate attached to the first substrate, wherein the first and second substrate face each other with a liquid crystal layer interposed therebetween, and a second common electrode on the second substrate and corresponding to each W sub-pixel.