Shield Common Electrode Cutouts for LCD Transmittance
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Solution Overview
Problem
Liquid crystal display devices of the 4D-RTN, 4D-ECB modes, and those using PSA technology do not achieve sufficient transmittance when a pixel electrode with slits and a shield common electrode are used in combination, due to the shield common electrode potentially preventing alignment of liquid crystal molecules.
Innovation Solution
A liquid crystal display device design featuring a pixel electrode with slits and a shield common electrode that includes cutout portions overlapping the slits, allowing for improved alignment and transmittance, with specific configurations of slits and cutout portions to optimize transmittance and reduce parasitic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a shield common electrode is added to reduce parasitic capacitance, then the numerical aperture is improved, but the transmittance decreases due to prevention of liquid crystal molecule alignment
Solution Approach 1:
The shield common electrode is segmented into multiple regions: a first region that overlaps the pixel electrode and a second region that does not overlap the pixel electrode. This segmentation allows the electrode to maintain its capacitance reduction function while removing the harmful alignment-preventing portion, thereby resolving the contradiction between parasitic capacitance reduction and transmittance improvement
Solution Approach 2:
Different regions of the shield common electrode are designed with different functions: the first region (overlapping the pixel electrode) is optimized for capacitance reduction, while the second region (non-overlapping) is optimized for maintaining transmittance and alignment. This local differentiation resolves the contradiction by assigning appropriate qualities to different spatial locations
2Stability of the object's composition
If slits are formed in the pixel electrode to improve alignment, then the alignment stability is improved, but the transmittance decreases due to the additional structure
Solution Approach 1:
The shield common electrode acts as an intermediary element that mediates between the slit structure and the liquid crystal molecules. By positioning the shield electrode to overlap the slits, it provides additional alignment guidance to the liquid crystal molecules in the slit regions, compensating for the light-blocking effect of the slits and thereby resolving the contradiction between alignment stability 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
The design significantly enhances transmittance while maintaining reduced parasitic capacitance, improving the viewing angle characteristics and display performance of liquid crystal display devices.
Implementation Method 1
a voltage is applied between the pixel electrode and the common electrode
Implementation Method 2
a vertical alignment-type liquid crystal layer provided between the first substrate and the second substrate
Implementation Method 3
A photopolymerizable monomer is incorporated into in a liquid crystal material in advance. After a liquid crystal cell is produced, the photopolymerizable monomer is polymerized in a state where a voltage is applied to a liquid crystal layer
Data Source
AI summary
A liquid crystal display device includes a first substrate, a second substrate, and a vertical alignment-type liquid crystal layer. The first substrate includes source lines and pixel electrodes. A pixel includes first, second, third and fourth liquid crystal domains. The pixel electrode has slits formed therein. The first substrate further includes a shield common electrode. The shield common electrode is located between the source lines and the pixel electrodes. The shield common electrode includes a solid portion overlapping the source lines and one end portion and the other end portion, in a row direction, of the pixel electrode, and also includes a first cutout portion formed across regions corresponding to the first, second, third and fourth liquid crystal domains in each pixel, the first cutout portion including portions overlapping the slits.