LCD Pixel Electrode Radial Field Control for Angle Coloring
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Solution Overview
Problem
Conventional in-plane-switching (IPS) mode LCD devices suffer from coloring phenomena when viewed at an angle during the bright state due to linear pixel and common electrodes, leading to reduced contrast ratio and effective aperture ratio, caused by uneven alignment film surfaces and optical diffraction.
Innovation Solution
The introduction of control electrodes that generate a radial electric field between the pixel and common electrodes, allowing for separate control of liquid crystal directors and eliminating the need for dogleg bends, thus aligning electrodes parallel to the optical axis and reducing leakage light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear pixel and common electrodes are used in IPS-mode LCD devices, then the device structure is simple and manufacturing is easier, but coloring phenomena occur when viewed at an angle during bright state, reducing contrast ratio and effective aperture ratio
Solution Approach 1:
The pixel electrode and common electrode are divided into multiple segments with different orientations. Specifically, the pixel electrode includes first and second electrodes extending in different directions, and the common electrode includes third and fourth electrodes extending in different directions. This segmentation allows the LC molecules to be rotated in multiple directions, compensating for coloring effects when viewed at angles, while maintaining a relatively simple overall structure that is easy to manufacture.
2Object-affected harmful factors
If dogleg bends are added to pixel and common electrodes to reduce coloring, then coloring is reduced, but the electrode structure becomes more complex and alignment film surface becomes uneven
Solution Approach 1:
Instead of using symmetric dogleg bends in both electrodes, the invention employs asymmetric multi-directional electrode arrangements. The pixel electrode has segments extending in different directions (e.g., first electrode in one direction, second electrode in another direction), and similarly for the common electrode. This asymmetric multi-directional configuration reduces coloring by distributing LC rotation directions without creating the surface unevenness and complexity associated with traditional dogleg bends.
3Object-affected harmful factors
If dogleg bends are used to control LC molecule rotation, then coloring is reduced, but alignment film surface becomes uneven causing optical diffraction and reducing effective aperture ratio
Solution Approach 1:
The invention applies different electrode orientations in different local regions of the pixel. The first and second electrodes of the pixel electrode extend in different directions, as do the third and fourth electrodes of the common electrode. This local variation in electrode orientation creates corresponding local variations in LC molecule rotation directions, effectively reducing coloring without requiring dogleg bends that would create surface unevenness and reduce the effective aperture area.
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 enhances the contrast ratio, effective aperture ratio, and image uniformity across different viewing angles by minimizing leakage light and optical diffraction, while maintaining high brightness and reducing power dissipation.
Implementation Method 1
control electrodes, made of a transparent conductive film connected to the corresponding comb-teeth electrode via a contact hole. The control electrodes generate a radial electric field between the control electrodes and the common electrode
Implementation Method 2
The control electrodes generate a radial electric field between the control electrodes and the common electrode, thereby separately controlling the LC directors adjacent to the control electrodes to be directed along the radial electric field
Data Source
AI summary
A liquid crystal display (LCD) device includes first and second substrates, a liquid crystal (LC) layer sandwiched between the first substrate and the second substrate, the first substrate defining an array of pixel areas, each of the pixel areas including a pixel electrode and a common electrode, and an insulator film formed on the first substrate and on the pixel electrode, the insulator film including a contact hole and the pixel electrode being exposed through the contact hole such that a voltage supplied to the pixel electrode generates a radial electric field around the contact hole and between the pixel electrode and the common electrode.