Liquid Crystal Display Device With Multi-Electrode Field Control
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving excellent viewing angle characteristics and high contrast ratios, particularly when using both vertical and horizontal electric fields, as existing technologies struggle to maintain low transmittance for black images and high transmittance for white images while maintaining horizontal liquid crystal molecule orientation.
Innovation Solution
A liquid crystal display device configuration utilizing three types of electrodes, including a uniformly planar first electrode, a second electrode with teeth and slits, and a third electrode, where specific potential differences between these electrodes control the orientation of liquid crystal molecules to achieve desired viewing angles and contrast ratios, with the potential difference between the second and first electrodes being less than or equal to the potential difference between the first and third electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a vertical electric field is applied to liquid crystal with negative dielectric anisotropy in VA mode, then high contrast ratio is achieved, but viewing angle becomes narrow
Solution Approach 1:
The patent divides the electric field application into two independent components: a vertical electric field (first electric field) applied between the first electrode and third electrode to achieve high contrast ratio, and a horizontal electric field (second electric field) applied between the second electrode and first electrode to expand viewing angle. This segmentation allows each electric field to perform its specific function without interfering with the other, resolving the contradiction between contrast ratio and viewing angle.
Solution Approach 2:
The patent transitions from using only a vertical electric field (one-dimensional control) to using both vertical and horizontal electric fields (two-dimensional control). By adding the horizontal electric field component through the tooth-shaped second electrode, the system gains an additional degree of freedom in controlling liquid crystal orientation, enabling simultaneous achievement of high contrast ratio and wide viewing angle.
2Adaptability or versatility
If a horizontal electric field is applied to liquid crystal layer in IPS mode to improve viewing angle, then contrast ratio becomes insufficient compared to VA mode
Solution Approach 1:
The patent separates the functions of viewing angle control and contrast ratio control into two independent electric field components. The horizontal electric field between the second electrode and first electrode is responsible for viewing angle expansion, while the vertical electric field between the first electrode and third electrode is responsible for maintaining high contrast ratio. This functional segmentation allows the system to achieve both objectives simultaneously.
3Adaptability or versatility
If both vertical and horizontal electric fields are applied to control liquid crystal orientation, then viewing angle and contrast ratio improve, but it becomes difficult to maintain low transmittance for black images and high transmittance for white images
Solution Approach 1:
The patent employs dynamic control of the second electrode potential (V2) relative to the first electrode potential, with the constraint |V2| ≤ |V1|. This dynamic potential control allows the system to adjust liquid crystal orientation continuously while maintaining proper transmittance levels. By dynamically adjusting the horizontal electric field strength based on the vertical electric field strength, the system achieves both wide viewing angle and proper black/white transmittance contrast.
Solution Approach 2:
The patent changes the electrical parameters (potentials) of multiple electrodes to achieve desired liquid crystal orientation states. By independently controlling the potential of the first electrode, second electrode, and third electrode, the system can adjust the strength and direction of both vertical and horizontal electric fields, enabling precise control over liquid crystal orientation and resulting optical properties including viewing angle and transmittance.
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 allows for excellent viewing angle characteristics and high contrast ratios by controlling the azimuth direction of liquid crystal molecules, enabling a wide range of gradations from black to white while maintaining horizontal orientation, thus improving display performance compared to traditional VA and FFS modes.
Implementation Method 1
liquid crystal molecules having negative dielectric anisotropy are oriented vertically with respect to the substrate surface
Implementation Method 2
a horizontal electric field is applied to liquid crystal layer to orient liquid crystal molecules having positive dielectric anisotropy horizontally with respect to the substrate surface
Implementation Method 3
liquid crystal molecules having birefringence
Data Source
AI summary
Provided is a liquid crystal display device having excellent viewing angle characteristics and high contrast in a display mode using both a vertical electric field and a horizontal electric field. This liquid crystal display device is provided with a first substrate and a second substrate disposed facing each other, and a liquid crystal layer held between said first and second substrates. The liquid crystal layer contains liquid crystal molecules having a negative dielectric anisotropy. The first substrate is provided with a flat plate first electrode, a first insulating layer, and a second electrode provided in a layer other than that of the first electrode and provided separated from the first electrode by the first insulating layer. The second electrode has multiple comb-tooth sections and multiple slits, and the second substrate has a flat plate third electrode. Defining V1 as the potential difference between the first electrode and the third electrode, V2 as the potential difference between the first electrode and the second electrode, and V2_B as the potential difference between the first electrode and the second electrode when the lowest gradation is showed, V1, V2 and V2_B satisfy 0<|V2_B|≦|V2|<|V1|.